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2585 lines
103 KiB
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2585 lines
103 KiB
Plaintext
@c -*-texinfo-*-
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@c This is part of the GNU Emacs Lisp Reference Manual.
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@c Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1998, 1999, 2001,
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@c 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009 Free Software Foundation, Inc.
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@c See the file elisp.texi for copying conditions.
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@setfilename ../../info/windows
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@node Windows, Frames, Buffers, Top
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@chapter Windows
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This chapter describes most of the functions and variables related to
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Emacs windows. @xref{Frames and Windows}, for how windows relate to
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frames. @xref{Display}, for information on how text is displayed in
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windows.
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@menu
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* Basic Windows:: Basic information on using windows.
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* Splitting Windows:: Splitting one window into two windows.
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* Deleting Windows:: Deleting a window gives its space to other windows.
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* Selecting Windows:: The selected window is the one that you edit in.
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* Cyclic Window Ordering:: Moving around the existing windows.
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* Buffers and Windows:: Each window displays the contents of a buffer.
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* Displaying Buffers:: Higher-level functions for displaying a buffer
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and choosing a window for it.
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* Choosing Window:: How to choose a window for displaying a buffer.
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* Dedicated Windows:: How to avoid displaying another buffer in
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a specific window.
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* Window Point:: Each window has its own location of point.
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* Window Start and End:: Buffer positions indicating which text is
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on-screen in a window.
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* Textual Scrolling:: Moving text up and down through the window.
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* Vertical Scrolling:: Moving the contents up and down on the window.
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* Horizontal Scrolling:: Moving the contents sideways on the window.
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* Size of Window:: Accessing the size of a window.
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* Resizing Windows:: Changing the size of a window.
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* Coordinates and Windows:: Converting coordinates to windows.
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* Window Tree:: The layout and sizes of all windows in a frame.
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* Window Configurations:: Saving and restoring the state of the screen.
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* Window Parameters:: Associating additional information with windows.
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* Window Hooks:: Hooks for scrolling, window size changes,
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redisplay going past a certain point,
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or window configuration changes.
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@end menu
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@node Basic Windows
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@section Basic Concepts of Emacs Windows
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@cindex window
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@cindex selected window
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A @dfn{window} in Emacs is the physical area of the screen in which a
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buffer is displayed. The term is also used to refer to a Lisp object that
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represents that screen area in Emacs Lisp. It should be
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clear from the context which is meant.
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Emacs groups windows into frames; see @ref{Frames}. A frame
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represents an area of screen available for Emacs to use. Each frame
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always contains at least one window, but you can subdivide it
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vertically or horizontally into multiple, nonoverlapping Emacs
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windows.
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In each frame, at any time, one and only one window is designated as
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@dfn{selected within the frame}. The frame's cursor appears in that
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window, but the other windows have ``non-selected'' cursors, normally
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less visible. (@xref{Cursor Parameters}, for customizing this.) At
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any time, one frame is the selected frame; and the window selected
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within that frame is @dfn{the selected window}. The selected window's
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buffer is usually the current buffer (except when @code{set-buffer} has
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been used); see @ref{Current Buffer}.
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For practical purposes, a window exists only while it is displayed in
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a frame. Once removed from the frame, the window is effectively deleted
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and should not be used, @emph{even though there may still be references
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to it} from other Lisp objects; see @ref{Deleting Windows}. Restoring a
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saved window configuration is the only way for a window no longer on the
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screen to come back to life; see @ref{Window Configurations}.
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@cindex multiple windows
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Users create multiple windows so they can look at several buffers at
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once. Lisp libraries use multiple windows for a variety of reasons, but
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most often to display related information. In Rmail, for example, you
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can move through a summary buffer in one window while the other window
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shows messages one at a time as they are reached.
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The meaning of ``window'' in Emacs is similar to what it means in the
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context of general-purpose window systems such as X, but not identical.
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The X Window System places X windows on the screen; Emacs uses one or
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more X windows as frames, and subdivides them into
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Emacs windows. When you use Emacs on a character-only terminal, Emacs
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treats the whole terminal screen as one frame.
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@cindex terminal screen
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@cindex screen of terminal
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@cindex tiled windows
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Most window systems support arbitrarily located overlapping windows.
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In contrast, Emacs windows are @dfn{tiled}; they never overlap, and
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together they fill the whole screen or frame. Because of the way in
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which Emacs creates new windows (@pxref{Splitting Windows}) and resizes
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them (@pxref{Resizing Windows}), not all conceivable tilings of windows
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on an Emacs frame are actually possible.
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@defun windowp object
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This function returns @code{t} if @var{object} is a window.
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@end defun
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@node Splitting Windows
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@section Splitting Windows
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@cindex splitting windows
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@cindex window splitting
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The functions described below are the primitives used to split a window
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into two windows. They do not accept a buffer as an argument. Rather,
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the two ``halves'' of the split window initially display the same buffer
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previously visible in the window that was split.
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@deffn Command split-window &optional window size horizontal
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This function splits a new window out of @var{window}'s screen area. It
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returns the new window. The default for @var{window} is the selected
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window. When you split the selected window, it remains selected.
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If @var{horizontal} is non-@code{nil}, then @var{window} splits into two
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side by side windows. The original window keeps the leftmost @var{size}
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columns, and gives the rest of the columns to the new window.
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Otherwise, @var{window} splits into windows one above the other, the
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original window keeps the upper @var{size} lines and gives the rest of
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the lines to the new window. The original window @var{window} is
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therefore the left-hand or upper of the two, and the new window is the
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right-hand or lower.
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If @var{size} is omitted or @code{nil}, then @var{window} is divided
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evenly into two parts. (If there is an odd line, it is allocated to
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the new window.) When @code{split-window} is called interactively,
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all its arguments are @code{nil}.
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If splitting would result in making a window that is smaller than
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@code{window-min-height} or @code{window-min-width} (@pxref{Resizing
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Windows}), @code{split-window} signals an error and does not split the
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window at all.
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The following example starts with one window on a screen that is 50
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lines high by 80 columns wide; then it splits the window.
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@smallexample
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@group
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(setq w (selected-window))
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@result{} #<window 8 on windows.texi>
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(window-edges) ; @r{Edges in order:}
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@result{} (0 0 80 50) ; @r{left--top--right--bottom}
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@end group
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@group
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;; @r{Returns window created}
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(setq w2 (split-window w 15))
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@result{} #<window 28 on windows.texi>
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@end group
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@group
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(window-edges w2)
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@result{} (0 15 80 50) ; @r{Bottom window;}
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; @r{top is line 15}
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@end group
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@group
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(window-edges w)
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@result{} (0 0 80 15) ; @r{Top window}
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@end group
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@end smallexample
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The screen looks like this:
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@smallexample
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@group
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__________
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| | line 0
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| w |
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|__________|
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| | line 15
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| w2 |
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|__________|
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line 50
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column 0 column 80
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@end group
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@end smallexample
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Next, split the top window horizontally:
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@smallexample
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@group
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(setq w3 (split-window w 35 t))
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@result{} #<window 32 on windows.texi>
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@end group
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@group
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(window-edges w3)
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@result{} (35 0 80 15) ; @r{Left edge at column 35}
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@end group
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@group
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(window-edges w)
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@result{} (0 0 35 15) ; @r{Right edge at column 35}
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@end group
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@group
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(window-edges w2)
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@result{} (0 15 80 50) ; @r{Bottom window unchanged}
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@end group
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@end smallexample
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@need 3000
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Now the screen looks like this:
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@smallexample
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@group
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column 35
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__________
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| | | line 0
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| w | w3 |
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|___|______|
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| | line 15
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| w2 |
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|__________|
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line 50
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column 0 column 80
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@end group
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@end smallexample
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Normally, Emacs indicates the border between two side-by-side windows
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with a scroll bar (@pxref{Scroll Bars}), or with @samp{|} characters. The
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display table can specify alternative border characters; see @ref{Display
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Tables}.
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@end deffn
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@deffn Command split-window-vertically &optional size
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This function splits the selected window into two windows, one above the
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other, leaving the upper of the two windows selected, with @var{size}
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lines. (If @var{size} is negative, then the lower of the two windows
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gets @minus{}@var{size} lines and the upper window gets the rest, but
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the upper window is still the one selected.) However, if
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@code{split-window-keep-point} (see below) is @code{nil}, then either
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window can be selected.
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In other respects, this function is similar to @code{split-window}.
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In particular, the upper window is the original one and the return
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value is the new, lower window.
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@end deffn
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@defopt split-window-keep-point
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If this variable is non-@code{nil} (the default), then
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@code{split-window-vertically} behaves as described above.
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If it is @code{nil}, then @code{split-window-vertically} adjusts point
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in each of the two windows to avoid scrolling. (This is useful on
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slow terminals.) It selects whichever window contains the screen line
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that point was previously on.
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This variable affects the behavior of @code{split-window-vertically}
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only. It has no effect on the other functions described here.
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@end defopt
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@deffn Command split-window-horizontally &optional size
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This function splits the selected window into two windows
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side-by-side, leaving the selected window on the left with @var{size}
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columns. If @var{size} is negative, the rightmost window gets
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@minus{}@var{size} columns, but the leftmost window still remains
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selected.
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This function is basically an interface to @code{split-window}.
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You could define a simplified version of the function like this:
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@smallexample
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@group
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(defun split-window-horizontally (&optional arg)
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"Split selected window into two windows, side by side..."
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(interactive "P")
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@end group
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@group
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(let ((size (and arg (prefix-numeric-value arg))))
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(and size (< size 0)
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(setq size (+ (window-width) size)))
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(split-window nil size t)))
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@end group
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@end smallexample
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@end deffn
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@defun one-window-p &optional no-mini all-frames
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This function returns non-@code{nil} if there is only one window. The
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argument @var{no-mini}, if non-@code{nil}, means don't count the
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minibuffer even if it is active; otherwise, the minibuffer window is
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counted when it is active.
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The argument @var{all-frames} specifies which frames to consider. Here
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are the possible values and their meanings:
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@table @asis
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@item @code{nil}
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Count the windows in the selected frame, plus the minibuffer used
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by that frame even if it lies in some other frame.
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@item @code{t}
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Count all windows in all existing frames.
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@item @code{visible}
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Count all windows in all visible frames.
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@item 0
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Count all windows in all visible or iconified frames.
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@item anything else
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Count precisely the windows in the selected frame, and no others.
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@end table
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@end defun
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@node Deleting Windows
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@section Deleting Windows
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@cindex deleting windows
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A window remains visible on its frame unless you @dfn{delete} it by
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calling certain functions that delete windows. A deleted window cannot
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appear on the screen, but continues to exist as a Lisp object until
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there are no references to it. There is no way to cancel the deletion
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of a window aside from restoring a saved window configuration
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(@pxref{Window Configurations}). Restoring a window configuration also
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deletes any windows that aren't part of that configuration.
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When you delete a window, the space it took up is given to one of
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its sibling windows adjacent to it.
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@c Emacs 19 feature
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@defun window-live-p window
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This function returns @code{nil} if @var{window} is deleted, and
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@code{t} otherwise.
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@strong{Warning:} Erroneous information or fatal errors may result from
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using a deleted window as if it were live.
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@end defun
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@deffn Command delete-window &optional window
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This function removes @var{window} from display and returns @code{nil}.
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The default for @var{window} is the selected window. An error is
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signaled if @var{window} is the only window on its frame.
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@end deffn
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@deffn Command delete-other-windows &optional window
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This function makes @var{window} the only window on its frame, by
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deleting the other windows in that frame. The default for @var{window}
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is the selected window. The return value is @code{nil}.
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@end deffn
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@deffn Command delete-windows-on &optional buffer-or-name frame
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This function deletes all windows showing @var{buffer-or-name}. If
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there are no windows showing @var{buffer-or-name}, it does nothing. The
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optional argument @var{buffer-or-name} may be a buffer or the name of an
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existing buffer and defaults to the current buffer.
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@code{delete-windows-on} operates frame by frame. If a frame has
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several windows showing different buffers, then those showing
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@var{buffer-or-name} are removed, and the others expand to fill the
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space. If all windows in some frame are showing @var{buffer-or-name}
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(including the case where there is only one window), then the frame
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winds up with a single window showing another buffer chosen with
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@code{other-buffer} (@pxref{The Buffer List}). If, however, the window
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showing @var{buffer-or-name} is dedicated to its buffer
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(@pxref{Dedicated Windows}), and there are other frames left, that
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window's frame is deleted.
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The optional argument @var{frame} specifies which frames to operate on.
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This function does not use it in quite the same way as the other
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functions which scan all windows; specifically, the values @code{t} and
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@code{nil} have the opposite of their meanings in other functions. Here
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are the full details:
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@itemize @bullet
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@item
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If it is @code{nil}, operate on all frames.
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@item
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If it is @code{t}, operate on the selected frame.
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@item
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If it is @code{visible}, operate on all visible frames.
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@item
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If it is 0, operate on all visible or iconified frames.
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@item
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If it is a frame, operate on that frame.
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@end itemize
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This function always returns @code{nil}.
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@end deffn
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@node Selecting Windows
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@section Selecting Windows
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@cindex selecting a window
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When a window is selected, the buffer in the window becomes the current
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buffer, and the cursor will appear in it.
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@defun selected-window
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This function returns the selected window. This is the window in
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which the cursor appears and to which many commands apply.
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@end defun
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@defun select-window window &optional norecord
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This function makes @var{window} the selected window. The cursor then
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appears in @var{window} (after redisplay). Unless @var{window} was
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already selected, @code{select-window} makes @var{window}'s buffer the
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current buffer. The return value is @var{window}.
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Normally, @var{window}'s selected buffer is moved to the front of the
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buffer list (@pxref{The Buffer List}) and @var{window} becomes the most
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recently selected window. But if @var{norecord} is non-@code{nil}, the
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buffer list remains unchanged and @var{window} does not become the most
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recently selected one.
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@example
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@group
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(setq w (next-window))
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(select-window w)
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@result{} #<window 65 on windows.texi>
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@end group
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@end example
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@end defun
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@defmac save-selected-window forms@dots{}
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This macro records the selected frame, as well as the selected window
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of each frame, executes @var{forms} in sequence, then restores the
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earlier selected frame and windows. It also saves and restores the
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current buffer. It returns the value of the last form in @var{forms}.
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This macro does not save or restore anything about the sizes,
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arrangement or contents of windows; therefore, if @var{forms} change
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them, the change persists. If the previously selected window of some
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frame is no longer live at the time of exit from @var{forms}, that
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frame's selected window is left alone. If the previously selected
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window is no longer live, then whatever window is selected at the end of
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@var{forms} remains selected. The current buffer is restored if and
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only if it is still live when exiting @var{forms}.
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This macro changes neither the ordering of recently selected windows nor
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the buffer list.
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@end defmac
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@defmac with-selected-window window forms@dots{}
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This macro selects @var{window}, executes @var{forms} in sequence, then
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restores the previously selected window and current buffer. The ordering
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of recently selected windows and the buffer list remain unchanged unless
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you deliberately change them within @var{forms}, for example, by calling
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@code{select-window} with argument @var{norecord} @code{nil} or omitted
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there.
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@end defmac
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@cindex finding windows
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The following functions choose one of the windows on the screen,
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offering various criteria for the choice.
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@defun get-lru-window &optional frame dedicated
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This function returns the window least recently ``used'' (that is,
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selected). If any full-width windows are present, it only considers
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these.
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The selected window can be the least recently used window if it is the
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only window. A newly created window becomes the least recently used
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window until it is selected. A minibuffer window is never a candidate.
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A dedicated window (@pxref{Dedicated Windows}) is never a candidate
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unless the optional argument @var{dedicated} is non-@code{nil}.
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The optional argument @var{frame} specifies which windows are
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considered.
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@itemize @bullet
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@item
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If it is @code{nil}, consider windows on the selected frame.
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@item
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If it is @code{t}, consider windows on all frames.
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@item
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If it is @code{visible}, consider windows on all visible frames.
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@item
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If it is 0, consider windows on all visible or iconified frames.
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@item
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If it is a frame, consider windows on that frame.
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@end itemize
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@end defun
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@defun get-largest-window &optional frame dedicated
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This function returns the window with the largest area (height times
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width). If there are no side-by-side windows, then this is the window
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with the most lines. A minibuffer window is never a candidate. A
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dedicated window (@pxref{Dedicated Windows}) is never a candidate unless
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the optional argument @var{dedicated} is non-@code{nil}.
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If there are two candidate windows of the same size, this function
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|
prefers the one that comes first in the cyclic ordering of windows,
|
|
starting from the selected window (@pxref{Cyclic Window Ordering}).
|
|
|
|
The optional argument @var{frame} specifies which set of windows to
|
|
consider, see @code{get-lru-window} above.
|
|
@end defun
|
|
|
|
@cindex window that satisfies a predicate
|
|
@cindex conditional selection of windows
|
|
@defun get-window-with-predicate predicate &optional minibuf all-frames default
|
|
This function returns a window satisfying @var{predicate}. It cycles
|
|
through all visible windows using @code{walk-windows} (@pxref{Cyclic
|
|
Window Ordering}), calling @var{predicate} on each one of them with that
|
|
window as its argument. The function returns the first window for which
|
|
@var{predicate} returns a non-@code{nil} value; if that never happens,
|
|
it returns @var{default} (which defaults to @code{nil}).
|
|
|
|
The optional arguments @var{minibuf} and @var{all-frames} specify the
|
|
set of windows to include in the scan. See the description of
|
|
@code{next-window} in @ref{Cyclic Window Ordering}, for details.
|
|
@end defun
|
|
|
|
@node Cyclic Window Ordering
|
|
@comment node-name, next, previous, up
|
|
@section Cyclic Ordering of Windows
|
|
@cindex cyclic ordering of windows
|
|
@cindex ordering of windows, cyclic
|
|
@cindex window ordering, cyclic
|
|
|
|
When you use the command @kbd{C-x o} (@code{other-window}) to select
|
|
some other window, it moves through the windows on the screen in a
|
|
specific order. For any given configuration of windows, this order
|
|
never varies. It is called the @dfn{cyclic ordering of windows}.
|
|
|
|
This ordering generally goes from top to bottom, and from left to
|
|
right. But it may go down first or go right first, depending on the
|
|
order in which windows were split.
|
|
|
|
If the first split was vertical (into windows one above each other),
|
|
and then the subwindows were split horizontally, then the ordering is
|
|
left to right in the top of the frame, and then left to right in the
|
|
next lower part of the frame, and so on. If the first split was
|
|
horizontal, the ordering is top to bottom in the left part, and so on.
|
|
In general, within each set of siblings at any level in the window tree
|
|
(@pxref{Window Tree}), the order is left to right, or top to bottom.
|
|
|
|
@deffn Command next-window &optional window minibuf all-frames
|
|
@cindex minibuffer window, and @code{next-window}
|
|
This function returns the window following @var{window} in the cyclic
|
|
ordering of windows. This is the window @kbd{C-x o} selects if typed
|
|
when @var{window} is selected. The default for @var{window} is the
|
|
selected window.
|
|
|
|
The value of the optional argument @var{minibuf} specifies whether the
|
|
minibuffer is included in the window order. Normally, when
|
|
@var{minibuf} is @code{nil}, the minibuffer is included only if it is
|
|
currently ``active''; this matches the behavior of @kbd{C-x o}. (The
|
|
minibuffer window is active while the minibuffer is in use; see
|
|
@ref{Minibuffers}.)
|
|
|
|
If @var{minibuf} is @code{t}, the cyclic ordering includes the
|
|
minibuffer window even if it is not active. If @var{minibuf} is neither
|
|
@code{t} nor @code{nil}, the minibuffer window is not included even if
|
|
it is active.
|
|
|
|
The optional argument @var{all-frames} specifies which frames to
|
|
consider. Here are the possible values and their meanings:
|
|
|
|
@table @asis
|
|
@item @code{nil}
|
|
Consider all the windows in @var{window}'s frame, plus the minibuffer
|
|
used by that frame even if it lies in some other frame. If the
|
|
minibuffer counts (as determined by @var{minibuf}), then all windows on
|
|
all frames that share that minibuffer count too.
|
|
|
|
@item @code{t}
|
|
Consider all windows in all existing frames.
|
|
|
|
@item @code{visible}
|
|
Consider all windows in all visible frames. (To get useful results, you
|
|
must ensure @var{window} is in a visible frame.)
|
|
|
|
@item 0
|
|
Consider all windows in all visible or iconified frames.
|
|
|
|
@item a frame
|
|
Consider all windows on that frame.
|
|
|
|
@item anything else
|
|
Consider precisely the windows in @var{window}'s frame, and no others.
|
|
@end table
|
|
|
|
This example assumes there are two windows, both displaying the
|
|
buffer @samp{windows.texi}:
|
|
|
|
@example
|
|
@group
|
|
(selected-window)
|
|
@result{} #<window 56 on windows.texi>
|
|
@end group
|
|
@group
|
|
(next-window (selected-window))
|
|
@result{} #<window 52 on windows.texi>
|
|
@end group
|
|
@group
|
|
(next-window (next-window (selected-window)))
|
|
@result{} #<window 56 on windows.texi>
|
|
@end group
|
|
@end example
|
|
@end deffn
|
|
|
|
@deffn Command previous-window &optional window minibuf all-frames
|
|
This function returns the window preceding @var{window} in the cyclic
|
|
ordering of windows. The other arguments specify which windows to
|
|
include in the cycle, as in @code{next-window}.
|
|
@end deffn
|
|
|
|
@deffn Command other-window count &optional all-frames
|
|
This function selects another window in the cyclic ordering of windows.
|
|
@var{count} specifies the number of windows to skip in the ordering,
|
|
starting with the selected window, before making the selection. If
|
|
@var{count} is a positive number, it skips @var{count} windows forwards.
|
|
@var{count} negative means skip @minus{}@var{count} windows backwards.
|
|
If @var{count} is zero, it does not skip any window, thus re-selecting
|
|
the selected window. In an interactive call, @var{count} is the numeric
|
|
prefix argument.
|
|
|
|
The optional argument @var{all-frames} has the same meaning as in
|
|
@code{next-window}, but the @var{minibuf} argument of @code{next-window}
|
|
is always effectively @code{nil}. This function returns @code{nil}.
|
|
@end deffn
|
|
|
|
@c Emacs 19 feature
|
|
@defun walk-windows proc &optional minibuf all-frames
|
|
This function cycles through all windows. It calls the function
|
|
@code{proc} once for each window, with the window as its sole
|
|
argument.
|
|
|
|
The optional arguments @var{minibuf} and @var{all-frames} specify the
|
|
set of windows to include in the walk. See @code{next-window}, above,
|
|
for details.
|
|
@end defun
|
|
|
|
@defun window-list &optional frame minibuf window
|
|
This function returns a list of all windows on @var{frame}, starting
|
|
with @var{window}. The default for @var{frame} is the selected frame;
|
|
the default for @var{window} is the selected window.
|
|
|
|
The value of @var{minibuf} specifies if the minibuffer window shall be
|
|
included in the result list. If @var{minibuf} is @code{t}, the result
|
|
always includes the minibuffer window. If @var{minibuf} is @code{nil}
|
|
or omitted, that includes the minibuffer window if it is active. If
|
|
@var{minibuf} is neither @code{nil} nor @code{t}, the result never
|
|
includes the minibuffer window.
|
|
@end defun
|
|
|
|
@node Buffers and Windows
|
|
@section Buffers and Windows
|
|
@cindex examining windows
|
|
@cindex windows, controlling precisely
|
|
@cindex buffers, controlled in windows
|
|
|
|
This section describes low-level functions to examine windows or to
|
|
display buffers in windows in a precisely controlled fashion.
|
|
@iftex
|
|
See the following section for
|
|
@end iftex
|
|
@ifnottex
|
|
@xref{Displaying Buffers}, for
|
|
@end ifnottex
|
|
related functions that find a window to use and specify a buffer for it.
|
|
The functions described there are easier to use, but they employ
|
|
heuristics in choosing or creating a window; use the functions described
|
|
here when you need complete control.
|
|
|
|
@defun set-window-buffer window buffer-or-name &optional keep-margins
|
|
This function makes @var{window} display @var{buffer-or-name} as its
|
|
contents. It returns @code{nil}. The default for @var{window} is the
|
|
selected window. The argument @var{buffer-or-name} must specify a
|
|
buffer or the name of an existing buffer.
|
|
|
|
@code{set-window-buffer} is the fundamental primitive for changing which
|
|
buffer is displayed in a window, and all ways of doing that call this
|
|
function.
|
|
|
|
@example
|
|
@group
|
|
(set-window-buffer (selected-window) "foo")
|
|
@result{} nil
|
|
@end group
|
|
@end example
|
|
|
|
Normally, displaying @var{buffer-or-name} in @var{window} resets the
|
|
window's position, display margins, fringe widths, and scroll bar
|
|
settings based on the local variables of that buffer.
|
|
However, if @var{keep-margins} is non-@code{nil}, display margins and
|
|
fringe widths of @var{window} remain unchanged. @xref{Fringes}.
|
|
|
|
@code{set-window-buffer} signals an error when @var{window} is
|
|
@dfn{strongly} dedicated to its buffer (@pxref{Dedicated Windows}) and
|
|
does not already display @var{buffer-or-name}.
|
|
|
|
Note that this function runs @code{window-scroll-functions} before
|
|
running @code{window-configuration-change-hook}.
|
|
@end defun
|
|
|
|
@defvar buffer-display-count
|
|
This buffer-local variable records the number of times a buffer has been
|
|
displayed in a window. It is incremented each time
|
|
@code{set-window-buffer} is called for the buffer.
|
|
@end defvar
|
|
|
|
@defun window-buffer &optional window
|
|
This function returns the buffer that @var{window} is displaying. The
|
|
default for @var{window} is the selected window.
|
|
|
|
@example
|
|
@group
|
|
(window-buffer)
|
|
@result{} #<buffer windows.texi>
|
|
@end group
|
|
@end example
|
|
@end defun
|
|
|
|
@defun get-buffer-window &optional buffer-or-name all-frames
|
|
This function returns a window currently displaying
|
|
@var{buffer-or-name}, or @code{nil} if there is none. If there are
|
|
several such windows, then the function returns the first one in the
|
|
cyclic ordering of windows, starting from the selected window.
|
|
@xref{Cyclic Window Ordering}.
|
|
|
|
The argument @var{BUFFER-OR-NAME} may be a buffer or a buffer name and
|
|
defaults to the current buffer. The optional argument @var{all-frames}
|
|
specifies which windows to consider:
|
|
|
|
@itemize @bullet
|
|
@item
|
|
@code{nil} means consider windows on the selected frame.
|
|
@item
|
|
@code{t} means consider windows on all existing frames.
|
|
@item
|
|
@code{visible} means consider windows on all visible frames.
|
|
@item
|
|
0 means consider windows on all visible or iconified frames.
|
|
@item
|
|
A frame means consider windows on that frame only.
|
|
@end itemize
|
|
|
|
Observe that the behavior of @code{get-buffer-window} may differ from
|
|
that of @code{next-window} (@pxref{Cyclic Window Ordering}) when
|
|
@var{all-frames} equals @code{nil} or any value not listed here.
|
|
Perhaps we will change @code{get-buffer-window} in the future to make it
|
|
compatible with the other functions.
|
|
@end defun
|
|
|
|
@defun get-buffer-window-list &optional buffer-or-name minibuf all-frames
|
|
This function returns a list of all windows currently displaying
|
|
@var{buffer-or-name}. The argument @var{buffer-or-name} may be a buffer
|
|
or the name of an existing buffer and defaults to the current buffer.
|
|
|
|
The two remaining arguments work like the same-named arguments of
|
|
@code{next-window}; they are @emph{not} like the optional arguments of
|
|
@code{get-buffer-window}.
|
|
@end defun
|
|
|
|
@defvar buffer-display-time
|
|
This variable records the time at which a buffer was last made visible
|
|
in a window. It is always local in each buffer; each time
|
|
@code{set-window-buffer} is called, it sets this variable to
|
|
@code{(current-time)} in the specified buffer (@pxref{Time of Day}).
|
|
When a buffer is first created, @code{buffer-display-time} starts out
|
|
with the value @code{nil}.
|
|
@end defvar
|
|
|
|
@node Displaying Buffers
|
|
@section Displaying Buffers in Windows
|
|
@cindex switching to a buffer
|
|
@cindex displaying a buffer
|
|
|
|
In this section we describe convenient functions that choose a window
|
|
automatically and use it to display a specified buffer. These functions
|
|
can also split an existing window in certain circumstances. We also
|
|
describe variables that parameterize the heuristics used for choosing a
|
|
window.
|
|
@iftex
|
|
See the preceding section for
|
|
@end iftex
|
|
@ifnottex
|
|
@xref{Buffers and Windows}, for
|
|
@end ifnottex
|
|
low-level primitives that give you more precise control. All of these
|
|
functions work by calling @code{set-window-buffer}.
|
|
|
|
Do not use the functions in this section in order to make a buffer
|
|
current so that a Lisp program can access or modify it; they are too
|
|
drastic for that purpose, since they change the display of buffers in
|
|
windows, which would be gratuitous and surprise the user. Instead, use
|
|
@code{set-buffer} and @code{save-current-buffer} (@pxref{Current
|
|
Buffer}), which designate buffers as current for programmed access
|
|
without affecting the display of buffers in windows.
|
|
|
|
@deffn Command switch-to-buffer buffer-or-name &optional norecord
|
|
This function makes @var{buffer-or-name} the current buffer, and also
|
|
displays the buffer in the selected window. This means that a human can
|
|
see the buffer and subsequent keyboard commands will apply to it.
|
|
Contrast this with @code{set-buffer}, which makes @var{buffer-or-name}
|
|
the current buffer but does not display it in the selected window;
|
|
see @ref{Current Buffer}.
|
|
|
|
If @var{buffer-or-name} is @code{nil}, @code{switch-to-buffer} chooses a
|
|
buffer using @code{other-buffer}. If @var{buffer-or-name} is a string
|
|
that does not identify an existing buffer, then a new buffer by that
|
|
name is created. The major mode for the new buffer is set according to
|
|
the variable @code{default-major-mode}; see @ref{Auto Major Mode}.
|
|
|
|
When @code{enable-recursive-minibuffers} is non-@code{nil} and the
|
|
selected window is either the minibuffer window or is dedicated to its
|
|
buffer (@pxref{Dedicated Windows}), @code{switch-to-buffer} calls
|
|
@code{pop-to-buffer} (see below) to display the buffer in some other
|
|
window.
|
|
|
|
Normally the specified buffer is put at the front of the buffer list
|
|
(both the selected frame's buffer list and the frame-independent buffer
|
|
list). This affects the operation of @code{other-buffer}. However, if
|
|
@var{norecord} is non-@code{nil}, this is not done. @xref{The Buffer
|
|
List}.
|
|
|
|
The @code{switch-to-buffer} function is often used interactively, as
|
|
the binding of @kbd{C-x b}. It is also used frequently in programs. It
|
|
returns the buffer that it switched to.
|
|
@end deffn
|
|
|
|
The next two functions are similar to @code{switch-to-buffer}, except
|
|
for the described features.
|
|
|
|
@deffn Command switch-to-buffer-other-window buffer-or-name &optional norecord
|
|
This function makes the buffer specified by @var{buffer-or-name} current
|
|
and displays it in a window not currently selected. It then selects
|
|
that window. The handling of the buffer is the same as in
|
|
@code{switch-to-buffer}.
|
|
|
|
The currently selected window is absolutely never used to do the job.
|
|
If it is the only window, then it is split to make a distinct window for
|
|
this purpose. If the selected window is already displaying the buffer,
|
|
then it continues to do so, but another window is nonetheless found to
|
|
display it in as well.
|
|
|
|
This function updates the buffer list just like @code{switch-to-buffer}
|
|
unless @var{norecord} is non-@code{nil}.
|
|
@end deffn
|
|
|
|
@deffn Command pop-to-buffer buffer-or-name &optional other-window norecord
|
|
This command makes @var{buffer-or-name} the current buffer and switches
|
|
to it in some window, preferably not the window previously selected.
|
|
The ``popped-to'' window becomes the selected window. Its frame is
|
|
given the X server's focus, if possible; see @ref{Input Focus}. The return
|
|
value is the buffer that was switched to.
|
|
|
|
If @var{buffer-or-name} is @code{nil}, that means to choose some other
|
|
buffer, but you don't specify which. If @var{buffer-or-name} is a
|
|
string that does not name an existing buffer, a buffer by that name is
|
|
created. The major mode for the new buffer is set according to the
|
|
variable @code{default-major-mode}. @xref{Auto Major Mode}.
|
|
|
|
If the variable @code{pop-up-frames} is non-@code{nil},
|
|
@code{pop-to-buffer} looks for a window in any visible frame already
|
|
displaying the buffer; if there is one, it selects and returns that
|
|
window. If no such window exists, it creates a new frame and displays
|
|
the buffer in it.
|
|
|
|
If @code{pop-up-frames} is @code{nil}, then @code{pop-to-buffer}
|
|
operates entirely within the selected frame. (If the selected frame has
|
|
just a minibuffer, @code{pop-to-buffer} operates within the most
|
|
recently selected frame that was not just a minibuffer.)
|
|
|
|
If the variable @code{pop-up-windows} is non-@code{nil}, windows may be
|
|
split to create a new window that is different from the original window.
|
|
For details, see @ref{Choosing Window}.
|
|
|
|
If @var{other-window} is non-@code{nil}, @code{pop-to-buffer} finds or
|
|
creates another window even if @var{buffer-or-name} is already visible
|
|
in the selected window. Thus @var{buffer-or-name} could end up
|
|
displayed in two windows. On the other hand, if @var{buffer-or-name} is
|
|
already displayed in the selected window and @var{other-window} is
|
|
@code{nil}, then the selected window is considered sufficient for
|
|
displaying @var{buffer-or-name}, so that nothing needs to be done.
|
|
|
|
All the variables that affect @code{display-buffer} affect
|
|
@code{pop-to-buffer} as well. @xref{Choosing Window}.
|
|
|
|
This function updates the buffer list just like @code{switch-to-buffer}
|
|
unless @var{norecord} is non-@code{nil}.
|
|
@end deffn
|
|
|
|
@deffn Command replace-buffer-in-windows &optional buffer-or-name
|
|
This function replaces @var{buffer-or-name} in all windows displaying
|
|
it with some other buffer. It uses @code{other-buffer} to choose the
|
|
other buffer. In the usual applications of this function, you
|
|
don't care which other buffer is used; you just want to make sure that
|
|
@var{buffer-or-name} is no longer displayed.
|
|
|
|
The argument @var{buffer-or-name} may be a buffer or the name of an
|
|
existing buffer and defaults to the current buffer.
|
|
|
|
If a window displaying @var{buffer-or-name} is dedicated
|
|
(@pxref{Dedicated Windows}), and is not the only window on its frame,
|
|
that window is deleted. If that window is the only window on its frame
|
|
and there are other frames left, the window's frame is deleted too. If
|
|
there are no other frames left, some other buffer is displayed in that
|
|
window.
|
|
|
|
This function returns @code{nil}.
|
|
@end deffn
|
|
|
|
@node Choosing Window
|
|
@section Choosing a Window for Display
|
|
|
|
This section describes the basic facility that chooses a window to
|
|
display a buffer in---@code{display-buffer}. Higher-level functions and
|
|
commands, like @code{switch-to-buffer} and @code{pop-to-buffer}, use this
|
|
subroutine. Here we describe how to use @code{display-buffer} and how
|
|
to customize it.
|
|
|
|
@deffn Command display-buffer buffer-or-name &optional not-this-window frame
|
|
This command makes @var{buffer-or-name} appear in some window, but it
|
|
does not select that window and does not make the buffer specified by
|
|
@var{buffer-or-name} current. The identity of the selected window is
|
|
unaltered by this function. The argument @var{buffer-or-name} must be a
|
|
buffer or the name of an existing buffer.
|
|
|
|
@var{not-this-window} non-@code{nil} means to display the specified
|
|
buffer in a window other than the selected one, even if it is already
|
|
displayed in the selected window. This can cause the buffer to appear
|
|
in two windows at once. Otherwise, if @var{buffer-or-name} is already
|
|
being displayed in any window, that is good enough, so this function
|
|
does nothing.
|
|
|
|
@code{display-buffer} returns the window chosen to display
|
|
@var{buffer-or-name}.
|
|
|
|
If the optional argument @var{frame} is non-@code{nil}, it specifies
|
|
which frames to check when deciding whether the buffer is already
|
|
displayed. If the buffer is already displayed in some window on one of
|
|
these frames, @code{display-buffer} simply returns that window. Here
|
|
are the possible values of @var{frame}:
|
|
|
|
@itemize @bullet
|
|
@item
|
|
@code{nil} means consider windows on the selected frame.
|
|
(Actually, the last non-minibuffer frame.)
|
|
@item
|
|
@code{t} means consider windows on all frames.
|
|
@item
|
|
@code{visible} means consider windows on all visible frames.
|
|
@item
|
|
0 means consider windows on all visible or iconified frames.
|
|
@item
|
|
A frame means consider windows on that frame only.
|
|
@end itemize
|
|
|
|
Precisely how @code{display-buffer} finds or creates a window depends on
|
|
the variables described below.
|
|
@end deffn
|
|
|
|
@defopt display-buffer-reuse-frames
|
|
If this variable is non-@code{nil}, @code{display-buffer} searches
|
|
existing frames for a window displaying @var{buffer-or-name}. If the
|
|
buffer is already displayed in a window in some frame,
|
|
@code{display-buffer} makes the frame visible and raises it, to use that
|
|
window. If the buffer is not already displayed, or
|
|
@code{display-buffer-reuse-frames} is @code{nil}, the behavior of
|
|
@code{display-buffer} is determined by the variables described next.
|
|
@end defopt
|
|
|
|
@defopt pop-up-windows
|
|
This variable specifies whether @code{display-buffer} is allowed to
|
|
split (@pxref{Splitting Windows}) an existing window . If it is
|
|
non-@code{nil}, @code{display-buffer} tries to the split the largest
|
|
or least recently used window on the selected frame. (If the selected
|
|
frame is a minibuffer-only frame, it tries to split a window on
|
|
another frame instead.) If @code{pop-up-windows} is @code{nil} or the
|
|
variable @code{pop-up-frames} (see below) is non-@code{nil},
|
|
@code{display-buffer} does not split any window.
|
|
@end defopt
|
|
|
|
@defvar split-window-preferred-function
|
|
This variable specifies how to split a window. Its value, if
|
|
non-@code{nil}, should be a function of one argument, which is a
|
|
window. If this variable specifies a function, @code{display-buffer}
|
|
will call it with one or more candidate windows when it looks for a
|
|
window to split. If the argument window fits, the function is
|
|
expected to split it and return a new window. If the function returns
|
|
@code{nil}, the argument window will not be split.
|
|
|
|
If the value of this variable is @code{nil}, @code{display-buffer}
|
|
uses the two variables described next to decide whether and which
|
|
window to split.
|
|
@end defvar
|
|
|
|
@defopt split-height-threshold
|
|
This variable specifies whether @code{display-buffer} may split a window
|
|
vertically, provided there are multiple windows. If the value is a
|
|
number, @code{display-buffer} splits a window only if it has at least
|
|
this many lines. If no window is tall enough, or if the value of this
|
|
variable is @code{nil}, @code{display-buffer} tries to split some window
|
|
horizontally, subject to restrictions of @code{split-width-threshold}
|
|
(see below). If splitting horizontally is impossible too,
|
|
@code{display-buffer} splits a window vertically only if it's the only
|
|
window on its frame and not the minibuffer window, and only if
|
|
@code{pop-up-windows} is non-@code{nil}.
|
|
|
|
A window whose height is fixed (@pxref{Resizing Windows}) cannot be
|
|
split vertically by @code{display-buffer}. Also, @code{display-buffer}
|
|
splits a window vertically only if it can accommodate two windows that
|
|
are both at least `window-min-height' lines tall. Moreover, if the
|
|
window that shall be split has a mode line, the window must be at least
|
|
four lines tall in order to make sure that the new window can have a
|
|
mode line as well. If the original window doesn't have a mode line, a
|
|
height of two lines suffices.
|
|
@end defopt
|
|
|
|
@defopt split-width-threshold
|
|
This variable specifies whether @code{display-buffer} may split a window
|
|
horizontally. If the value is a number, @code{display-buffer} may split
|
|
a window if it has at least this many columns. If the value of this
|
|
variable is @code{nil}, @code{display-buffer} will not split any windows
|
|
horizontally. (It still might split some window vertically, though, see
|
|
above.)
|
|
|
|
A window whose width is fixed (@pxref{Resizing Windows}) cannot be split
|
|
horizontally by @code{display-buffer}. Also, @code{display-buffer}
|
|
splits a window horizontally only if it can accommodate two windows that
|
|
are both at least `window-min-width' columns wide.
|
|
@end defopt
|
|
|
|
@defopt even-window-heights
|
|
This variable specifies whether @code{display-buffer} should even out
|
|
window heights if the buffer gets displayed in an existing window, above
|
|
or beneath another window. If @code{even-window-heights} is
|
|
non-@code{nil}, the default, window heights will be evened out. If
|
|
either of the involved window has fixed height (@pxref{Resizing
|
|
Windows}) or @code{even-window-heights} is @code{nil}, the original
|
|
window heights will be left alone.
|
|
@end defopt
|
|
|
|
@c Emacs 19 feature
|
|
@defopt pop-up-frames
|
|
This variable specifies whether @code{display-buffer} makes new frames.
|
|
If it is non-@code{nil}, @code{display-buffer} looks for an existing
|
|
window already displaying the desired buffer, on any visible frame. If
|
|
it finds one, it returns that window. Otherwise it makes a new frame,
|
|
unless the variable's value is @code{graphic-only} and the selected
|
|
frame is not on a graphic display. @xref{Frames}, for more information.
|
|
|
|
Note that the value of @code{pop-up-windows} does not matter if
|
|
@code{pop-up-frames} is non-@code{nil}. If @code{pop-up-frames} is
|
|
@code{nil}, then @code{display-buffer} either splits a window or reuses
|
|
one.
|
|
@end defopt
|
|
|
|
@c Emacs 19 feature
|
|
@defopt pop-up-frame-function
|
|
This variable specifies how to make a new frame if @code{pop-up-frames}
|
|
is non-@code{nil}.
|
|
|
|
Its value should be a function of no arguments. When
|
|
@code{display-buffer} makes a new frame, it does so by calling that
|
|
function, which should return a frame. The default value of the
|
|
variable is a function that creates a frame using parameters from
|
|
@code{pop-up-frame-alist}.
|
|
@end defopt
|
|
|
|
@defopt pop-up-frame-alist
|
|
This variable holds an alist specifying frame parameters used by the
|
|
default value of @code{pop-up-frame-function} for making new frames.
|
|
@xref{Frame Parameters}, for more information about frame parameters.
|
|
@end defopt
|
|
|
|
@defopt special-display-buffer-names
|
|
A list of buffer names identifying buffers that should be displayed
|
|
specially. If the name of @var{buffer-or-name} is in this list,
|
|
@code{display-buffer} handles the buffer specially. By default, special
|
|
display means to give the buffer a dedicated frame.
|
|
|
|
If an element is a list, instead of a string, then the @sc{car} of that
|
|
list is the buffer name, and the rest of that list says how to create
|
|
the frame. There are two possibilities for the rest of that list (its
|
|
@sc{cdr}): It can be an alist, specifying frame parameters, or it can
|
|
contain a function and arguments to give to it. (The function's first
|
|
argument is always the buffer to be displayed; the arguments from the
|
|
list come after that.)
|
|
|
|
For example:
|
|
|
|
@example
|
|
(("myfile" (minibuffer) (menu-bar-lines . 0)))
|
|
@end example
|
|
|
|
@noindent
|
|
specifies to display a buffer named @samp{myfile} in a dedicated frame
|
|
with specified @code{minibuffer} and @code{menu-bar-lines} parameters.
|
|
|
|
The list of frame parameters can also use the phony frame parameters
|
|
@code{same-frame} and @code{same-window}. If the specified frame
|
|
parameters include @code{(same-window . @var{value})} and @var{value}
|
|
is non-@code{nil}, that means to display the buffer in the current
|
|
selected window. Otherwise, if they include @code{(same-frame .
|
|
@var{value})} and @var{value} is non-@code{nil}, that means to display
|
|
the buffer in a new window in the currently selected frame.
|
|
@end defopt
|
|
|
|
@defopt special-display-regexps
|
|
A list of regular expressions specifying buffers that should be
|
|
displayed specially. If the buffer's name matches any of the regular
|
|
expressions in this list, @code{display-buffer} handles the buffer
|
|
specially. By default, special display means to give the buffer a
|
|
dedicated frame.
|
|
|
|
If an element is a list, instead of a string, then the @sc{car} of the
|
|
list is the regular expression, and the rest of the list says how to
|
|
create the frame. See @code{special-display-buffer-names} above.
|
|
@end defopt
|
|
|
|
@defun special-display-p buffer-name
|
|
This function returns non-@code{nil} if displaying a buffer
|
|
named @var{buffer-name} with @code{display-buffer} would
|
|
create a special frame. The value is @code{t} if it would
|
|
use the default frame parameters, or else the specified list
|
|
of frame parameters.
|
|
@end defun
|
|
|
|
@defvar special-display-function
|
|
This variable holds the function to call to display a buffer specially.
|
|
It receives the buffer as an argument, and should return the window in
|
|
which it is displayed. The default value of this variable is
|
|
@code{special-display-popup-frame}, see below.
|
|
@end defvar
|
|
|
|
@defun special-display-popup-frame buffer &optional args
|
|
This function tries to make @var{buffer} visible in a frame of its own.
|
|
If @var{buffer} is already displayed in some window, it makes that
|
|
window's frame visible and raises it. Otherwise, it creates a frame
|
|
that is dedicated to @var{buffer}. The return value is the window used
|
|
to display @var{buffer}.
|
|
|
|
If @var{args} is an alist, it specifies frame parameters for the new
|
|
frame. If @var{args} is a list whose @sc{car} is a symbol, then
|
|
@code{(car @var{args})} is called as a function to actually create and
|
|
set up the frame; it is called with @var{buffer} as first argument, and
|
|
@code{(cdr @var{args})} as additional arguments.
|
|
|
|
This function always uses an existing window displaying @var{buffer},
|
|
whether or not it is in a frame of its own; but if you set up the above
|
|
variables in your init file, before @var{buffer} was created, then
|
|
presumably the window was previously made by this function.
|
|
@end defun
|
|
|
|
@defopt special-display-frame-alist
|
|
@anchor{Definition of special-display-frame-alist}
|
|
This variable holds frame parameters for
|
|
@code{special-display-popup-frame} to use when it creates a frame.
|
|
@end defopt
|
|
|
|
@defopt same-window-buffer-names
|
|
A list of buffer names for buffers that should be displayed in the
|
|
selected window. If the buffer's name is in this list,
|
|
@code{display-buffer} handles the buffer by switching to it in the
|
|
selected window.
|
|
@end defopt
|
|
|
|
@defopt same-window-regexps
|
|
A list of regular expressions that specify buffers that should be
|
|
displayed in the selected window. If the buffer's name matches any of
|
|
the regular expressions in this list, @code{display-buffer} handles the
|
|
buffer by switching to it in the selected window.
|
|
@end defopt
|
|
|
|
@defun same-window-p buffer-name
|
|
This function returns @code{t} if displaying a buffer
|
|
named @var{buffer-name} with @code{display-buffer} would
|
|
put it in the selected window.
|
|
@end defun
|
|
|
|
@c Emacs 19 feature
|
|
@defvar display-buffer-function
|
|
This variable is the most flexible way to customize the behavior of
|
|
@code{display-buffer}. If it is non-@code{nil}, it should be a function
|
|
that @code{display-buffer} calls to do the work. The function should
|
|
accept two arguments, the first two arguments that @code{display-buffer}
|
|
received. It should choose or create a window, display the specified
|
|
buffer in it, and then return the window.
|
|
|
|
This variable takes precedence over all the other options described
|
|
above.
|
|
@end defvar
|
|
|
|
If all options described above fail to produce a suitable window,
|
|
@code{display-buffer} tries to reuse an existing window. As a last
|
|
resort, it will try to display @var{buffer-or-name} on a separate frame.
|
|
In that case, the value of @code{pop-up-frames} is disregarded.
|
|
|
|
@node Dedicated Windows
|
|
@section Dedicated Windows
|
|
@cindex dedicated window
|
|
|
|
Functions for displaying a buffer can be told to not use specific
|
|
windows by marking these window as @dfn{dedicated} to their buffers.
|
|
@code{display-buffer} (@pxref{Choosing Window}) never uses a dedicated
|
|
window for displaying another buffer in it. @code{get-lru-window} and
|
|
@code{get-largest-window} (@pxref{Selecting Windows}) do not consider
|
|
dedicated windows as candidates when their @var{dedicated} argument is
|
|
non-@code{nil}. The behavior of @code{set-window-buffer}
|
|
(@pxref{Buffers and Windows}) with respect to dedicated windows is
|
|
slightly different, see below.
|
|
|
|
When @code{delete-windows-on} (@pxref{Deleting Windows}) wants to delete
|
|
a dedicated window and that window is the only window on its frame, it
|
|
deletes the window's frame too, provided there are other frames left.
|
|
@code{replace-buffer-in-windows} (@pxref{Displaying Buffers}) tries to
|
|
delete all dedicated windows showing its buffer argument. When such a
|
|
window is the only window on its frame, that frame is deleted, provided
|
|
there are other frames left. If there are no more frames left, some
|
|
other buffer is displayed in the window, and the window is marked as
|
|
non-dedicated.
|
|
|
|
When you kill a buffer (@pxref{Killing Buffers}) displayed in a
|
|
dedicated window, any such window usually gets deleted too, since
|
|
@code{kill-buffer} calls @code{replace-buffer-in-windows} for cleaning
|
|
up windows. Burying a buffer (@pxref{The Buffer List}) deletes the
|
|
selected window if it is dedicated and shows that buffer. However, if
|
|
that window is the only window on its frame, another buffer is displayed
|
|
in it and the frame is iconified.
|
|
|
|
@defun window-dedicated-p &optional window
|
|
This function returns non-@code{nil} if @var{window} is dedicated to its
|
|
buffer and @code{nil} otherwise. More precisely, the return value is
|
|
the value assigned by the last call of @code{set-window-dedicated-p} for
|
|
@var{window} or @code{nil} if that function was never called with
|
|
@var{window} as its argument. The default for @var{window} is the
|
|
selected window.
|
|
@end defun
|
|
|
|
@defun set-window-dedicated-p window flag
|
|
This function marks @var{window} as dedicated to its buffer if
|
|
@var{flag} is non-@code{nil}, and non-dedicated otherwise.
|
|
|
|
As a special case, if @var{flag} is @code{t}, @var{window} becomes
|
|
@dfn{strongly} dedicated to its buffer. @code{set-window-buffer}
|
|
signals an error when the window it acts upon is strongly dedicated to
|
|
its buffer and does not already display the buffer it is asked to
|
|
display. In any other case, @code{set-window-buffer} will display
|
|
another buffer in that window. Other functions do not treat @code{t}
|
|
differently from any non-@code{nil} value.
|
|
@end defun
|
|
|
|
@node Window Point
|
|
@section Windows and Point
|
|
@cindex window position
|
|
@cindex window point
|
|
@cindex position in window
|
|
@cindex point in window
|
|
|
|
Each window has its own value of point (@pxref{Point}), independent of
|
|
the value of point in other windows displaying the same buffer. This
|
|
makes it useful to have multiple windows showing one buffer.
|
|
|
|
@itemize @bullet
|
|
@item
|
|
The window point is established when a window is first created; it is
|
|
initialized from the buffer's point, or from the window point of another
|
|
window opened on the buffer if such a window exists.
|
|
|
|
@item
|
|
Selecting a window sets the value of point in its buffer from the
|
|
window's value of point. Conversely, deselecting a window sets the
|
|
window's value of point from that of the buffer. Thus, when you switch
|
|
between windows that display a given buffer, the point value for the
|
|
selected window is in effect in the buffer, while the point values for
|
|
the other windows are stored in those windows.
|
|
|
|
@item
|
|
As long as the selected window displays the current buffer, the window's
|
|
point and the buffer's point always move together; they remain equal.
|
|
@end itemize
|
|
|
|
@cindex cursor
|
|
As far as the user is concerned, point is where the cursor is, and
|
|
when the user switches to another buffer, the cursor jumps to the
|
|
position of point in that buffer.
|
|
|
|
@defun window-point &optional window
|
|
This function returns the current position of point in @var{window}.
|
|
For a nonselected window, this is the value point would have (in that
|
|
window's buffer) if that window were selected. The default for
|
|
@var{window} is the selected window.
|
|
|
|
When @var{window} is the selected window and its buffer is also the
|
|
current buffer, the value returned is the same as point in that buffer.
|
|
Strictly speaking, it would be more correct to return the ``top-level''
|
|
value of point, outside of any @code{save-excursion} forms. But that
|
|
value is hard to find.
|
|
@end defun
|
|
|
|
@defun set-window-point window position
|
|
This function positions point in @var{window} at position
|
|
@var{position} in @var{window}'s buffer. It returns @var{position}.
|
|
|
|
If @var{window} is selected, and its buffer is current,
|
|
this simply does @code{goto-char}.
|
|
@end defun
|
|
|
|
@defvar window-point-insertion-type
|
|
This variable specifies the marker insertion type (@pxref{Marker
|
|
Insertion Types}) of @code{window-point}. The default is @code{nil},
|
|
so @code{window-point} will stay behind text inserted there.
|
|
@end defvar
|
|
|
|
@node Window Start and End
|
|
@section The Window Start and End Positions
|
|
@cindex window start position
|
|
|
|
Each window maintains a marker used to keep track of a buffer position
|
|
that specifies where in the buffer display should start. This position
|
|
is called the @dfn{display-start} position of the window (or just the
|
|
@dfn{start}). The character after this position is the one that appears
|
|
at the upper left corner of the window. It is usually, but not
|
|
inevitably, at the beginning of a text line.
|
|
|
|
After switching windows or buffers, and in some other cases, if the
|
|
window start is in the middle of a line, Emacs adjusts the window
|
|
start to the start of a line. This prevents certain operations from
|
|
leaving the window start at a meaningless point within a line. This
|
|
feature may interfere with testing some Lisp code by executing it
|
|
using the commands of Lisp mode, because they trigger this
|
|
readjustment. To test such code, put it into a command and bind the
|
|
command to a key.
|
|
|
|
@defun window-start &optional window
|
|
@cindex window top line
|
|
This function returns the display-start position of window
|
|
@var{window}. If @var{window} is @code{nil}, the selected window is
|
|
used. For example,
|
|
|
|
@example
|
|
@group
|
|
(window-start)
|
|
@result{} 7058
|
|
@end group
|
|
@end example
|
|
|
|
When you create a window, or display a different buffer in it, the
|
|
display-start position is set to a display-start position recently used
|
|
for the same buffer, or to @code{point-min} if the buffer doesn't have
|
|
any.
|
|
|
|
Redisplay updates the window-start position (if you have not specified
|
|
it explicitly since the previous redisplay)---to make sure point appears
|
|
on the screen. Nothing except redisplay automatically changes the
|
|
window-start position; if you move point, do not expect the window-start
|
|
position to change in response until after the next redisplay.
|
|
|
|
For a realistic example of using @code{window-start}, see the
|
|
description of @code{count-lines}. @xref{Definition of count-lines}.
|
|
@end defun
|
|
|
|
@cindex window end position
|
|
@defun window-end &optional window update
|
|
This function returns the position where display of its buffer ends in
|
|
@var{window}. The default for @var{window} is the selected window.
|
|
|
|
Simply changing the buffer text or moving point does not update the
|
|
value that @code{window-end} returns. The value is updated only when
|
|
Emacs redisplays and redisplay completes without being preempted.
|
|
|
|
If the last redisplay of @var{window} was preempted, and did not finish,
|
|
Emacs does not know the position of the end of display in that window.
|
|
In that case, this function returns @code{nil}.
|
|
|
|
If @var{update} is non-@code{nil}, @code{window-end} always returns an
|
|
up-to-date value for where display ends, based on the current
|
|
@code{window-start} value. If a previously saved value of that position
|
|
is still valid, @code{window-end} returns that value; otherwise it
|
|
computes the correct value by scanning the buffer text.
|
|
|
|
Even if @var{update} is non-@code{nil}, @code{window-end} does not
|
|
attempt to scroll the display if point has moved off the screen, the
|
|
way real redisplay would do. It does not alter the
|
|
@code{window-start} value. In effect, it reports where the displayed
|
|
text will end if scrolling is not required.
|
|
@end defun
|
|
|
|
@defun set-window-start window position &optional noforce
|
|
This function sets the display-start position of @var{window} to
|
|
@var{position} in @var{window}'s buffer. It returns @var{position}.
|
|
|
|
The display routines insist that the position of point be visible when a
|
|
buffer is displayed. Normally, they change the display-start position
|
|
(that is, scroll the window) whenever necessary to make point visible.
|
|
However, if you specify the start position with this function using
|
|
@code{nil} for @var{noforce}, it means you want display to start at
|
|
@var{position} even if that would put the location of point off the
|
|
screen. If this does place point off screen, the display routines move
|
|
point to the left margin on the middle line in the window.
|
|
|
|
For example, if point @w{is 1} and you set the start of the window
|
|
@w{to 37}, the start of the next line, point will be ``above'' the top
|
|
of the window. The display routines will automatically move point if
|
|
it is still 1 when redisplay occurs. Here is an example:
|
|
|
|
@example
|
|
@group
|
|
;; @r{Here is what @samp{foo} looks like before executing}
|
|
;; @r{the @code{set-window-start} expression.}
|
|
@end group
|
|
|
|
@group
|
|
---------- Buffer: foo ----------
|
|
@point{}This is the contents of buffer foo.
|
|
2
|
|
3
|
|
4
|
|
5
|
|
6
|
|
---------- Buffer: foo ----------
|
|
@end group
|
|
|
|
@group
|
|
(set-window-start
|
|
(selected-window)
|
|
(save-excursion
|
|
(goto-char 1)
|
|
(forward-line 1)
|
|
(point)))
|
|
@result{} 37
|
|
@end group
|
|
|
|
@group
|
|
;; @r{Here is what @samp{foo} looks like after executing}
|
|
;; @r{the @code{set-window-start} expression.}
|
|
---------- Buffer: foo ----------
|
|
2
|
|
3
|
|
@point{}4
|
|
5
|
|
6
|
|
---------- Buffer: foo ----------
|
|
@end group
|
|
@end example
|
|
|
|
If @var{noforce} is non-@code{nil}, and @var{position} would place point
|
|
off screen at the next redisplay, then redisplay computes a new window-start
|
|
position that works well with point, and thus @var{position} is not used.
|
|
@end defun
|
|
|
|
@defun pos-visible-in-window-p &optional position window partially
|
|
This function returns non-@code{nil} if @var{position} is within the
|
|
range of text currently visible on the screen in @var{window}. It
|
|
returns @code{nil} if @var{position} is scrolled vertically out of view.
|
|
Locations that are partially obscured are not considered visible unless
|
|
@var{partially} is non-@code{nil}. The argument @var{position} defaults
|
|
to the current position of point in @var{window}; @var{window}, to the
|
|
selected window. If @var{position} is @code{t}, that means to check the
|
|
last visible position in @var{window}.
|
|
|
|
The @code{pos-visible-in-window-p} function considers only vertical
|
|
scrolling. If @var{position} is out of view only because @var{window}
|
|
has been scrolled horizontally, @code{pos-visible-in-window-p} returns
|
|
non-@code{nil} anyway. @xref{Horizontal Scrolling}.
|
|
|
|
If @var{position} is visible, @code{pos-visible-in-window-p} returns
|
|
@code{t} if @var{partially} is @code{nil}; if @var{partially} is
|
|
non-@code{nil}, and the character following @var{position} is fully
|
|
visible, it returns a list of the form @code{(@var{x} @var{y})}, where
|
|
@var{x} and @var{y} are the pixel coordinates relative to the top left
|
|
corner of the window; otherwise it returns an extended list of the form
|
|
@code{(@var{x} @var{y} @var{rtop} @var{rbot} @var{rowh} @var{vpos})},
|
|
where @var{rtop} and @var{rbot} specify the number of off-window pixels
|
|
at the top and bottom of the row at @var{position}, @var{rowh} specifies
|
|
the visible height of that row, and @var{vpos} specifies the vertical
|
|
position (zero-based row number) of that row.
|
|
|
|
Here is an example:
|
|
|
|
@example
|
|
@group
|
|
;; @r{If point is off the screen now, recenter it now.}
|
|
(or (pos-visible-in-window-p
|
|
(point) (selected-window))
|
|
(recenter 0))
|
|
@end group
|
|
@end example
|
|
@end defun
|
|
|
|
@defun window-line-height &optional line window
|
|
This function returns the height of text line @var{line} in
|
|
@var{window}. If @var{line} is one of @code{header-line} or
|
|
@code{mode-line}, @code{window-line-height} returns information about
|
|
the corresponding line of the window. Otherwise, @var{line} is a text
|
|
line number starting from 0. A negative number counts from the end of
|
|
the window. The default for @var{line} is the current line in
|
|
@var{window}; the default for @var{window} is the selected window.
|
|
|
|
If the display is not up to date, @code{window-line-height} returns
|
|
@code{nil}. In that case, @code{pos-visible-in-window-p} may be used
|
|
to obtain related information.
|
|
|
|
If there is no line corresponding to the specified @var{line},
|
|
@code{window-line-height} returns @code{nil}. Otherwise, it returns
|
|
a list @code{(@var{height} @var{vpos} @var{ypos} @var{offbot})},
|
|
where @var{height} is the height in pixels of the visible part of the
|
|
line, @var{vpos} and @var{ypos} are the vertical position in lines and
|
|
pixels of the line relative to the top of the first text line, and
|
|
@var{offbot} is the number of off-window pixels at the bottom of the
|
|
text line. If there are off-window pixels at the top of the (first)
|
|
text line, @var{ypos} is negative.
|
|
@end defun
|
|
|
|
@node Textual Scrolling
|
|
@section Textual Scrolling
|
|
@cindex textual scrolling
|
|
@cindex scrolling textually
|
|
|
|
@dfn{Textual scrolling} means moving the text up or down through a
|
|
window. It works by changing the value of the window's display-start
|
|
location. It may also change the value of @code{window-point} to keep
|
|
point on the screen.
|
|
|
|
Textual scrolling was formerly called ``vertical scrolling,'' but we
|
|
changed its name to distinguish it from the new vertical fractional
|
|
scrolling feature (@pxref{Vertical Scrolling}).
|
|
|
|
In the commands @code{scroll-up} and @code{scroll-down}, the directions
|
|
``up'' and ``down'' refer to the motion of the text in the buffer at which
|
|
you are looking through the window. Imagine that the text is
|
|
written on a long roll of paper and that the scrolling commands move the
|
|
paper up and down. Thus, if you are looking at text in the middle of a
|
|
buffer and repeatedly call @code{scroll-down}, you will eventually see
|
|
the beginning of the buffer.
|
|
|
|
Some people have urged that the opposite convention be used: they
|
|
imagine that the window moves over text that remains in place. Then
|
|
``down'' commands would take you to the end of the buffer. This view is
|
|
more consistent with the actual relationship between windows and the
|
|
text in the buffer, but it is less like what the user sees. The
|
|
position of a window on the terminal does not move, and short scrolling
|
|
commands clearly move the text up or down on the screen. We have chosen
|
|
names that fit the user's point of view.
|
|
|
|
The textual scrolling functions (aside from
|
|
@code{scroll-other-window}) have unpredictable results if the current
|
|
buffer is different from the buffer that is displayed in the selected
|
|
window. @xref{Current Buffer}.
|
|
|
|
If the window contains a row which is taller than the height of the
|
|
window (for example in the presence of a large image), the scroll
|
|
functions will adjust the window vscroll to scroll the partially
|
|
visible row. To disable this feature, Lisp code may bind the variable
|
|
`auto-window-vscroll' to @code{nil} (@pxref{Vertical Scrolling}).
|
|
|
|
@deffn Command scroll-up &optional count
|
|
This function scrolls the text in the selected window upward
|
|
@var{count} lines. If @var{count} is negative, scrolling is actually
|
|
downward.
|
|
|
|
If @var{count} is @code{nil} (or omitted), then the length of scroll
|
|
is @code{next-screen-context-lines} lines less than the usable height of
|
|
the window (not counting its mode line).
|
|
|
|
@code{scroll-up} returns @code{nil}, unless it gets an error
|
|
because it can't scroll any further.
|
|
@end deffn
|
|
|
|
@deffn Command scroll-down &optional count
|
|
This function scrolls the text in the selected window downward
|
|
@var{count} lines. If @var{count} is negative, scrolling is actually
|
|
upward.
|
|
|
|
If @var{count} is omitted or @code{nil}, then the length of the scroll
|
|
is @code{next-screen-context-lines} lines less than the usable height of
|
|
the window (not counting its mode line).
|
|
|
|
@code{scroll-down} returns @code{nil}, unless it gets an error because
|
|
it can't scroll any further.
|
|
@end deffn
|
|
|
|
@deffn Command scroll-other-window &optional count
|
|
This function scrolls the text in another window upward @var{count}
|
|
lines. Negative values of @var{count}, or @code{nil}, are handled
|
|
as in @code{scroll-up}.
|
|
|
|
You can specify which buffer to scroll by setting the variable
|
|
@code{other-window-scroll-buffer} to a buffer. If that buffer isn't
|
|
already displayed, @code{scroll-other-window} displays it in some
|
|
window.
|
|
|
|
When the selected window is the minibuffer, the next window is normally
|
|
the one at the top left corner. You can specify a different window to
|
|
scroll, when the minibuffer is selected, by setting the variable
|
|
@code{minibuffer-scroll-window}. This variable has no effect when any
|
|
other window is selected. When it is non-@code{nil} and the
|
|
minibuffer is selected, it takes precedence over
|
|
@code{other-window-scroll-buffer}. @xref{Definition of
|
|
minibuffer-scroll-window}.
|
|
|
|
When the minibuffer is active, it is the next window if the selected
|
|
window is the one at the bottom right corner. In this case,
|
|
@code{scroll-other-window} attempts to scroll the minibuffer. If the
|
|
minibuffer contains just one line, it has nowhere to scroll to, so the
|
|
line reappears after the echo area momentarily displays the message
|
|
@samp{Beginning of buffer}.
|
|
@end deffn
|
|
|
|
@c Emacs 19 feature
|
|
@defvar other-window-scroll-buffer
|
|
If this variable is non-@code{nil}, it tells @code{scroll-other-window}
|
|
which buffer's window to scroll.
|
|
@end defvar
|
|
|
|
@defopt scroll-margin
|
|
This option specifies the size of the scroll margin---a minimum number
|
|
of lines between point and the top or bottom of a window. Whenever
|
|
point gets within this many lines of the top or bottom of the window,
|
|
redisplay scrolls the text automatically (if possible) to move point
|
|
out of the margin, closer to the center of the window.
|
|
@end defopt
|
|
|
|
@defopt scroll-conservatively
|
|
This variable controls how scrolling is done automatically when point
|
|
moves off the screen (or into the scroll margin). If the value is a
|
|
positive integer @var{n}, then redisplay scrolls the text up to
|
|
@var{n} lines in either direction, if that will bring point back into
|
|
proper view. This behavior is called @dfn{conservative scrolling}.
|
|
Otherwise, scrolling happens in the usual way, under the control of
|
|
other variables such as @code{scroll-up-aggressively} and
|
|
@code{scroll-down-aggressively}.
|
|
|
|
The default value is zero, which means that conservative scrolling
|
|
never happens.
|
|
@end defopt
|
|
|
|
@defopt scroll-down-aggressively
|
|
The value of this variable should be either @code{nil} or a fraction
|
|
@var{f} between 0 and 1. If it is a fraction, that specifies where on
|
|
the screen to put point when scrolling down. More precisely, when a
|
|
window scrolls down because point is above the window start, the new
|
|
start position is chosen to put point @var{f} part of the window
|
|
height from the top. The larger @var{f}, the more aggressive the
|
|
scrolling.
|
|
|
|
A value of @code{nil} is equivalent to .5, since its effect is to center
|
|
point. This variable automatically becomes buffer-local when set in any
|
|
fashion.
|
|
@end defopt
|
|
|
|
@defopt scroll-up-aggressively
|
|
Likewise, for scrolling up. The value, @var{f}, specifies how far
|
|
point should be placed from the bottom of the window; thus, as with
|
|
@code{scroll-up-aggressively}, a larger value scrolls more aggressively.
|
|
@end defopt
|
|
|
|
@defopt scroll-step
|
|
This variable is an older variant of @code{scroll-conservatively}. The
|
|
difference is that it if its value is @var{n}, that permits scrolling
|
|
only by precisely @var{n} lines, not a smaller number. This feature
|
|
does not work with @code{scroll-margin}. The default value is zero.
|
|
@end defopt
|
|
|
|
@defopt scroll-preserve-screen-position
|
|
If this option is @code{t}, scrolling which would move the current
|
|
point position out of the window chooses the new position of point
|
|
so that the vertical position of the cursor is unchanged, if possible.
|
|
|
|
If it is non-@code{nil} and not @code{t}, then the scrolling functions
|
|
always preserve the vertical position of point, if possible.
|
|
@end defopt
|
|
|
|
@defopt next-screen-context-lines
|
|
The value of this variable is the number of lines of continuity to
|
|
retain when scrolling by full screens. For example, @code{scroll-up}
|
|
with an argument of @code{nil} scrolls so that this many lines at the
|
|
bottom of the window appear instead at the top. The default value is
|
|
@code{2}.
|
|
@end defopt
|
|
|
|
@deffn Command recenter &optional count
|
|
@cindex centering point
|
|
This function scrolls the text in the selected window so that point is
|
|
displayed at a specified vertical position within the window. It does
|
|
not ``move point'' with respect to the text.
|
|
|
|
If @var{count} is a nonnegative number, that puts the line containing
|
|
point @var{count} lines down from the top of the window. If
|
|
@var{count} is a negative number, then it counts upward from the
|
|
bottom of the window, so that @minus{}1 stands for the last usable
|
|
line in the window. If @var{count} is a non-@code{nil} list, then it
|
|
stands for the line in the middle of the window.
|
|
|
|
If @var{count} is @code{nil}, @code{recenter} puts the line containing
|
|
point in the middle of the window, then clears and redisplays the entire
|
|
selected frame.
|
|
|
|
When @code{recenter} is called interactively, @var{count} is the raw
|
|
prefix argument. Thus, typing @kbd{C-u} as the prefix sets the
|
|
@var{count} to a non-@code{nil} list, while typing @kbd{C-u 4} sets
|
|
@var{count} to 4, which positions the current line four lines from the
|
|
top.
|
|
|
|
With an argument of zero, @code{recenter} positions the current line at
|
|
the top of the window. This action is so handy that some people make a
|
|
separate key binding to do this. For example,
|
|
|
|
@example
|
|
@group
|
|
(defun line-to-top-of-window ()
|
|
"Scroll current line to top of window.
|
|
Replaces three keystroke sequence C-u 0 C-l."
|
|
(interactive)
|
|
(recenter 0))
|
|
|
|
(global-set-key [kp-multiply] 'line-to-top-of-window)
|
|
@end group
|
|
@end example
|
|
@end deffn
|
|
|
|
@node Vertical Scrolling
|
|
@section Vertical Fractional Scrolling
|
|
@cindex vertical fractional scrolling
|
|
@cindex vertical scroll position
|
|
|
|
@dfn{Vertical fractional scrolling} means shifting text in a window
|
|
up or down by a specified multiple or fraction of a line. Each window
|
|
has a @dfn{vertical scroll position}, which is a number, never less than
|
|
zero. It specifies how far to raise the contents of the window.
|
|
Raising the window contents generally makes all or part of some lines
|
|
disappear off the top, and all or part of some other lines appear at the
|
|
bottom. The usual value is zero.
|
|
|
|
The vertical scroll position is measured in units of the normal line
|
|
height, which is the height of the default font. Thus, if the value is
|
|
.5, that means the window contents are scrolled up half the normal line
|
|
height. If it is 3.3, that means the window contents are scrolled up
|
|
somewhat over three times the normal line height.
|
|
|
|
What fraction of a line the vertical scrolling covers, or how many
|
|
lines, depends on what the lines contain. A value of .5 could scroll a
|
|
line whose height is very short off the screen, while a value of 3.3
|
|
could scroll just part of the way through a tall line or an image.
|
|
|
|
@defun window-vscroll &optional window pixels-p
|
|
This function returns the current vertical scroll position of
|
|
@var{window}. The default for @var{window} is the selected window.
|
|
If @var{pixels-p} is non-@code{nil}, the return value is measured in
|
|
pixels, rather than in units of the normal line height.
|
|
|
|
@example
|
|
@group
|
|
(window-vscroll)
|
|
@result{} 0
|
|
@end group
|
|
@end example
|
|
@end defun
|
|
|
|
@defun set-window-vscroll window lines &optional pixels-p
|
|
This function sets @var{window}'s vertical scroll position to
|
|
@var{lines}. If @var{window} is @code{nil}, the selected window is
|
|
used. The argument @var{lines} should be zero or positive; if not, it
|
|
is taken as zero.
|
|
|
|
|
|
The actual vertical scroll position must always correspond
|
|
to an integral number of pixels, so the value you specify
|
|
is rounded accordingly.
|
|
|
|
The return value is the result of this rounding.
|
|
|
|
@example
|
|
@group
|
|
(set-window-vscroll (selected-window) 1.2)
|
|
@result{} 1.13
|
|
@end group
|
|
@end example
|
|
|
|
If @var{pixels-p} is non-@code{nil}, @var{lines} specifies a number of
|
|
pixels. In this case, the return value is @var{lines}.
|
|
@end defun
|
|
|
|
@defvar auto-window-vscroll
|
|
If this variable is non-@code{nil}, the line-move, scroll-up, and
|
|
scroll-down functions will automatically modify the vertical scroll
|
|
position to scroll through display rows that are taller that the height
|
|
of the window, for example in the presence of large images.
|
|
@end defvar
|
|
|
|
@node Horizontal Scrolling
|
|
@section Horizontal Scrolling
|
|
@cindex horizontal scrolling
|
|
|
|
@dfn{Horizontal scrolling} means shifting the image in the window left
|
|
or right by a specified multiple of the normal character width. Each
|
|
window has a @dfn{horizontal scroll position}, which is a number, never
|
|
less than zero. It specifies how far to shift the contents left.
|
|
Shifting the window contents left generally makes all or part of some
|
|
characters disappear off the left, and all or part of some other
|
|
characters appear at the right. The usual value is zero.
|
|
|
|
The horizontal scroll position is measured in units of the normal
|
|
character width, which is the width of space in the default font. Thus,
|
|
if the value is 5, that means the window contents are scrolled left by 5
|
|
times the normal character width. How many characters actually
|
|
disappear off to the left depends on their width, and could vary from
|
|
line to line.
|
|
|
|
Because we read from side to side in the ``inner loop,'' and from top
|
|
to bottom in the ``outer loop,'' the effect of horizontal scrolling is
|
|
not like that of textual or vertical scrolling. Textual scrolling
|
|
involves selection of a portion of text to display, and vertical
|
|
scrolling moves the window contents contiguously; but horizontal
|
|
scrolling causes part of @emph{each line} to go off screen.
|
|
|
|
Usually, no horizontal scrolling is in effect; then the leftmost
|
|
column is at the left edge of the window. In this state, scrolling to
|
|
the right is meaningless, since there is no data to the left of the edge
|
|
to be revealed by it; so this is not allowed. Scrolling to the left is
|
|
allowed; it scrolls the first columns of text off the edge of the window
|
|
and can reveal additional columns on the right that were truncated
|
|
before. Once a window has a nonzero amount of leftward horizontal
|
|
scrolling, you can scroll it back to the right, but only so far as to
|
|
reduce the net horizontal scroll to zero. There is no limit to how far
|
|
left you can scroll, but eventually all the text will disappear off the
|
|
left edge.
|
|
|
|
@vindex auto-hscroll-mode
|
|
If @code{auto-hscroll-mode} is set, redisplay automatically alters
|
|
the horizontal scrolling of a window as necessary to ensure that point
|
|
is always visible. However, you can still set the horizontal
|
|
scrolling value explicitly. The value you specify serves as a lower
|
|
bound for automatic scrolling, i.e. automatic scrolling will not
|
|
scroll a window to a column less than the specified one.
|
|
|
|
@deffn Command scroll-left &optional count set-minimum
|
|
This function scrolls the selected window @var{count} columns to the
|
|
left (or to the right if @var{count} is negative). The default
|
|
for @var{count} is the window width, minus 2.
|
|
|
|
The return value is the total amount of leftward horizontal scrolling in
|
|
effect after the change---just like the value returned by
|
|
@code{window-hscroll} (below).
|
|
|
|
Once you scroll a window as far right as it can go, back to its normal
|
|
position where the total leftward scrolling is zero, attempts to scroll
|
|
any farther right have no effect.
|
|
|
|
If @var{set-minimum} is non-@code{nil}, the new scroll amount becomes
|
|
the lower bound for automatic scrolling; that is, automatic scrolling
|
|
will not scroll a window to a column less than the value returned by
|
|
this function. Interactive calls pass non-@code{nil} for
|
|
@var{set-minimum}.
|
|
@end deffn
|
|
|
|
@deffn Command scroll-right &optional count set-minimum
|
|
This function scrolls the selected window @var{count} columns to the
|
|
right (or to the left if @var{count} is negative). The default
|
|
for @var{count} is the window width, minus 2. Aside from the direction
|
|
of scrolling, this works just like @code{scroll-left}.
|
|
@end deffn
|
|
|
|
@defun window-hscroll &optional window
|
|
This function returns the total leftward horizontal scrolling of
|
|
@var{window}---the number of columns by which the text in @var{window}
|
|
is scrolled left past the left margin. The default for
|
|
@var{window} is the selected window.
|
|
|
|
The return value is never negative. It is zero when no horizontal
|
|
scrolling has been done in @var{window} (which is usually the case).
|
|
|
|
|
|
@example
|
|
@group
|
|
(window-hscroll)
|
|
@result{} 0
|
|
@end group
|
|
@group
|
|
(scroll-left 5)
|
|
@result{} 5
|
|
@end group
|
|
@group
|
|
(window-hscroll)
|
|
@result{} 5
|
|
@end group
|
|
@end example
|
|
@end defun
|
|
|
|
@defun set-window-hscroll window columns
|
|
This function sets horizontal scrolling of @var{window}. The value of
|
|
@var{columns} specifies the amount of scrolling, in terms of columns
|
|
from the left margin. The argument @var{columns} should be zero or
|
|
positive; if not, it is taken as zero. Fractional values of
|
|
@var{columns} are not supported at present.
|
|
|
|
Note that @code{set-window-hscroll} may appear not to work if you test
|
|
it by evaluating a call with @kbd{M-:} in a simple way. What happens
|
|
is that the function sets the horizontal scroll value and returns, but
|
|
then redisplay adjusts the horizontal scrolling to make point visible,
|
|
and this overrides what the function did. You can observe the
|
|
function's effect if you call it while point is sufficiently far from
|
|
the left margin that it will remain visible.
|
|
|
|
The value returned is @var{columns}.
|
|
|
|
@example
|
|
@group
|
|
(set-window-hscroll (selected-window) 10)
|
|
@result{} 10
|
|
@end group
|
|
@end example
|
|
@end defun
|
|
|
|
Here is how you can determine whether a given position @var{position}
|
|
is off the screen due to horizontal scrolling:
|
|
|
|
@example
|
|
@group
|
|
(defun hscroll-on-screen (window position)
|
|
(save-excursion
|
|
(goto-char position)
|
|
(and
|
|
(>= (- (current-column) (window-hscroll window)) 0)
|
|
(< (- (current-column) (window-hscroll window))
|
|
(window-width window)))))
|
|
@end group
|
|
@end example
|
|
|
|
@node Size of Window
|
|
@section The Size of a Window
|
|
@cindex window size
|
|
@cindex size of window
|
|
|
|
An Emacs window is rectangular, and its size information consists of
|
|
the height (the number of lines) and the width (the number of character
|
|
positions in each line). The mode line is included in the height. But
|
|
the width does not count the scroll bar or the column of @samp{|}
|
|
characters that separates side-by-side windows.
|
|
|
|
The following three functions return size information about a window:
|
|
|
|
@defun window-height &optional window
|
|
This function returns the number of lines in @var{window}, including its
|
|
mode line and header line, if any. If @var{window} fills its entire
|
|
frame except for the echo area, this is typically one less than the
|
|
value of @code{frame-height} on that frame. The default for
|
|
@var{window} is the selected window.
|
|
|
|
@example
|
|
@group
|
|
(window-height)
|
|
@result{} 23
|
|
@end group
|
|
@group
|
|
(split-window-vertically)
|
|
@result{} #<window 4 on windows.texi>
|
|
@end group
|
|
@group
|
|
(window-height)
|
|
@result{} 11
|
|
@end group
|
|
@end example
|
|
@end defun
|
|
|
|
@defun window-body-height &optional window
|
|
Like @code{window-height} but the value does not include the
|
|
mode line (if any) or the header line (if any).
|
|
@end defun
|
|
|
|
@defun window-width &optional window
|
|
This function returns the number of columns in @var{window}. The
|
|
default for @var{window} is the selected window.
|
|
|
|
The return value does not include the window's scroll bar or the column
|
|
of @samp{|} characters that separates side-by-side windows. Moreover,
|
|
the return value does not include the space used for displaying fringes
|
|
and margins. Hence you cannot, in general, compare the return values of
|
|
@code{window-width} and @code{frame-width} for equality to determine
|
|
whether a window is a wide as the containing frame. Use the function
|
|
@code{window-full-width-p}, see below, instead.
|
|
|
|
@example
|
|
@group
|
|
(window-width)
|
|
@result{} 80
|
|
@end group
|
|
@end example
|
|
@end defun
|
|
|
|
@defun window-full-width-p &optional window
|
|
This function returns non-@code{nil} if @var{window} is as wide as the
|
|
frame that contains it; otherwise @code{nil}. The default for
|
|
@var{window} is the selected window.
|
|
@end defun
|
|
|
|
@defun window-edges &optional window
|
|
This function returns a list of the edge coordinates of @var{window}.
|
|
The default for @var{window} is the selected window.
|
|
|
|
The order of the list is @code{(@var{left} @var{top} @var{right}
|
|
@var{bottom})}, all elements relative to 0, 0 at the top left corner of
|
|
the frame. The element @var{right} of the value is one more than the
|
|
rightmost column used by @var{window}, and @var{bottom} is one more than
|
|
the bottommost row used by @var{window} and its mode-line.
|
|
|
|
The edges include the space used by the window's scroll bar, display
|
|
margins, fringes, header line, and mode line, if it has them. Also,
|
|
if the window has a neighbor on the right, its right edge value
|
|
includes the width of the separator line between the window and that
|
|
neighbor. Since the width of the window does not include this
|
|
separator, the width does not usually equal the difference between the
|
|
right and left edges.
|
|
@end defun
|
|
|
|
@defun window-inside-edges &optional window
|
|
This is similar to @code{window-edges}, but the edge values
|
|
it returns include only the text area of the window. They
|
|
do not include the header line, mode line, scroll bar or
|
|
vertical separator, fringes, or display margins.
|
|
@end defun
|
|
|
|
Here are the results obtained on a typical 24-line terminal with just
|
|
one window, with menu bar enabled:
|
|
|
|
@example
|
|
@group
|
|
(window-edges (selected-window))
|
|
@result{} (0 1 80 23)
|
|
@end group
|
|
@group
|
|
(window-inside-edges (selected-window))
|
|
@result{} (0 1 80 22)
|
|
@end group
|
|
@end example
|
|
|
|
@noindent
|
|
The bottom edge is at line 23 because the last line is the echo area.
|
|
The bottom inside edge is at line 22, which is the window's mode line.
|
|
|
|
If @var{window} is at the upper left corner of its frame, and there is
|
|
no menu bar, then @var{bottom} returned by @code{window-edges} is the
|
|
same as the value of @code{(window-height)}, @var{right} is almost the
|
|
same as the value of @code{(window-width)}, and @var{top} and
|
|
@var{left} are zero. For example, the edges of the following window
|
|
are @w{@samp{0 0 8 5}}. Assuming that the frame has more than 8
|
|
columns, the last column of the window (column 7) holds a border
|
|
rather than text. The last row (row 4) holds the mode line, shown
|
|
here with @samp{xxxxxxxxx}.
|
|
|
|
@example
|
|
@group
|
|
0
|
|
_______
|
|
0 | |
|
|
| |
|
|
| |
|
|
| |
|
|
xxxxxxxxx 4
|
|
|
|
7
|
|
@end group
|
|
@end example
|
|
|
|
In the following example, let's suppose that the frame is 7
|
|
columns wide. Then the edges of the left window are @w{@samp{0 0 4 3}}
|
|
and the edges of the right window are @w{@samp{4 0 7 3}}.
|
|
The inside edges of the left window are @w{@samp{0 0 3 2}},
|
|
and the inside edges of the right window are @w{@samp{4 0 7 2}},
|
|
|
|
@example
|
|
@group
|
|
___ ___
|
|
| | |
|
|
| | |
|
|
xxxxxxxxx
|
|
|
|
0 34 7
|
|
@end group
|
|
@end example
|
|
|
|
@defun window-pixel-edges &optional window
|
|
This function is like @code{window-edges} except that, on a graphical
|
|
display, the edge values are measured in pixels instead of in
|
|
character lines and columns.
|
|
@end defun
|
|
|
|
@defun window-inside-pixel-edges &optional window
|
|
This function is like @code{window-inside-edges} except that, on a
|
|
graphical display, the edge values are measured in pixels instead of
|
|
in character lines and columns.
|
|
@end defun
|
|
|
|
@node Resizing Windows
|
|
@section Changing the Size of a Window
|
|
@cindex window resizing
|
|
@cindex resize window
|
|
@cindex changing window size
|
|
@cindex window size, changing
|
|
|
|
The window size functions fall into two classes: high-level commands
|
|
that change the size of windows and low-level functions that access
|
|
window size. Emacs does not permit overlapping windows or gaps between
|
|
windows, so resizing a window always affects at least one other window.
|
|
|
|
@deffn Command enlarge-window size &optional horizontal
|
|
This function makes the selected window @var{size} lines taller by
|
|
stealing lines from windows above or below. In a first round, it takes
|
|
lines from one window at a time until that window is
|
|
@code{window-min-height} lines tall, then takes from another. If, at
|
|
the end of the first round, the selected window is still not tall
|
|
enough, @code{enlarge-window} starts a second round, where it deletes
|
|
windows above or below the selected one.
|
|
|
|
If @var{horizontal} is non-@code{nil}, this function makes the window
|
|
@var{size} columns wider, stealing columns instead of lines. If a
|
|
window from which columns are stolen shrinks below
|
|
@code{window-min-width} columns, that window disappears.
|
|
|
|
If the requested size would exceed that of the window's frame, then the
|
|
function makes the window occupy the entire height (or width) of the
|
|
frame.
|
|
|
|
If there are various other windows from which lines or columns can be
|
|
stolen, and some of them specify fixed size (using
|
|
@code{window-size-fixed}, see below), they are left untouched while
|
|
other windows are ``robbed.'' If it would be necessary to alter the
|
|
size of a fixed-size window, @code{enlarge-window} gets an error
|
|
instead.
|
|
|
|
If @var{size} is negative, this function shrinks the selected window by
|
|
@minus{}@var{size} lines or columns. If that makes the window smaller
|
|
than the minimum size (@code{window-min-height} and
|
|
@code{window-min-width}), then @code{enlarge-window} deletes the window.
|
|
|
|
@code{enlarge-window} returns @code{nil}.
|
|
@end deffn
|
|
|
|
@deffn Command enlarge-window-horizontally columns
|
|
This function makes the selected window @var{columns} wider.
|
|
It could be defined as follows:
|
|
|
|
@example
|
|
@group
|
|
(defun enlarge-window-horizontally (columns)
|
|
(interactive "p")
|
|
(enlarge-window columns t))
|
|
@end group
|
|
@end example
|
|
@end deffn
|
|
|
|
@deffn Command shrink-window size &optional horizontal
|
|
This function is like @code{enlarge-window} but negates the argument
|
|
@var{size}, making the selected window smaller by giving lines (or
|
|
columns) to the other windows. If the window shrinks below
|
|
@code{window-min-height} or @code{window-min-width}, then it disappears.
|
|
|
|
If @var{size} is negative, the window is enlarged by @minus{}@var{size}
|
|
lines or columns.
|
|
@end deffn
|
|
|
|
@deffn Command shrink-window-horizontally columns
|
|
This function makes the selected window @var{columns} narrower.
|
|
It could be defined as follows:
|
|
|
|
@example
|
|
@group
|
|
(defun shrink-window-horizontally (columns)
|
|
(interactive "p")
|
|
(shrink-window columns t))
|
|
@end group
|
|
@end example
|
|
@end deffn
|
|
|
|
@defun adjust-window-trailing-edge window delta horizontal
|
|
This function makes the selected window @var{delta} lines taller or
|
|
@var{delta} columns wider, by moving the bottom or right edge. This
|
|
function does not delete other windows; if it cannot make the
|
|
requested size adjustment, it signals an error. On success, this
|
|
function returns @code{nil}.
|
|
@end defun
|
|
|
|
@defun fit-window-to-buffer &optional window max-height min-height
|
|
This function makes @var{window} the right height to display its
|
|
contents exactly. The default for @var{window} is the selected window.
|
|
|
|
The optional argument @var{max-height} specifies the maximum height the
|
|
window is allowed to be; @code{nil} means use the maximum permissible
|
|
height of a window on @var{window}'s frame. The optional argument
|
|
@var{min-height} specifies the minimum height for the window; @code{nil}
|
|
means use @code{window-min-height}. All these height values include the
|
|
mode line and/or header line.
|
|
|
|
This function can delete windows when their height shrinks below
|
|
@var{min-height}. It returns non-@code{nil} if it orderly resized
|
|
@var{window}, and @code{nil} otherwise.
|
|
@end defun
|
|
|
|
@deffn Command shrink-window-if-larger-than-buffer &optional window
|
|
This command shrinks @var{window} vertically to be as small as possible
|
|
while still showing the full contents of its buffer---but not less than
|
|
@code{window-min-height} lines. The default for @var{window} is
|
|
the selected window.
|
|
|
|
However, this command does nothing if the window is already too small to
|
|
display the whole text of the buffer, or if part of the contents are
|
|
currently scrolled off screen, or if the window is not the full width of
|
|
its frame, or if the window is the only window in its frame.
|
|
|
|
This command returns non-@code{nil} if it actually shrank the window
|
|
and @code{nil} otherwise.
|
|
@end deffn
|
|
|
|
@cindex fixed-size window
|
|
@defvar window-size-fixed
|
|
If this variable is non-@code{nil}, in a given buffer, then the size of
|
|
any window displaying that buffer remains fixed unless you either
|
|
explicitly change it or Emacs has no other choice.
|
|
|
|
If the value is @code{height}, then only the window's height is fixed;
|
|
if the value is @code{width}, then only the window's width is fixed.
|
|
Any other non-@code{nil} value fixes both the width and the height.
|
|
|
|
This variable automatically becomes buffer-local when set.
|
|
|
|
Explicit size-change functions such as @code{enlarge-window}
|
|
get an error if they would have to change a window size which is fixed.
|
|
Therefore, when you want to change the size of such a window,
|
|
you should bind @code{window-size-fixed} to @code{nil}, like this:
|
|
|
|
@example
|
|
(let ((window-size-fixed nil))
|
|
(enlarge-window 10))
|
|
@end example
|
|
|
|
Deleting an adjacent window or changing the frame size may change the
|
|
size of a fixed-size window, if there is no other alternative.
|
|
@end defvar
|
|
|
|
@cindex minimum window size
|
|
The following two variables constrain the window-structure-changing
|
|
functions to a minimum height and width.
|
|
|
|
@defopt window-min-height
|
|
The value of this variable specifies how short a window may become
|
|
before it is automatically deleted. Making a window smaller than
|
|
@code{window-min-height} automatically deletes it, and no window may be
|
|
created shorter than this. The value is measured in line units. When
|
|
the window wants a mode line and/or a header line, they are counted as
|
|
one line each. The default value is @code{4}. A value less than
|
|
@code{1} is ignored.
|
|
@end defopt
|
|
|
|
@defopt window-min-width
|
|
The value of this variable specifies how narrow a window may become
|
|
before it is automatically deleted. Making a window smaller than
|
|
@code{window-min-width} automatically deletes it, and no window may be
|
|
created narrower than this. The value is measured in characters and
|
|
includes any fringes or the scroll bar. The default value is @code{10}.
|
|
A value less than @code{2} is ignored.
|
|
@end defopt
|
|
|
|
@cindex balancing window sizes
|
|
Emacs provides two functions to balance windows, that is, to even out
|
|
the sizes of windows on the same frame. The minibuffer window and
|
|
fixed-size windows are not resized by these functions.
|
|
|
|
@deffn Command balance-windows &optional window-or-frame
|
|
This function balances windows in a way that gives more space to
|
|
full-width and/or full-height windows. If @var{window-or-frame}
|
|
specifies a frame, it balances all windows on that frame. If
|
|
@var{window-or-frame} specifies a window, it balances this window and
|
|
its ``siblings'' only. Think of a sibling as the other (original or
|
|
new) window with respect to the present one, involved in the process of
|
|
splitting; see @ref{Splitting Windows}. Since a sibling may have been
|
|
split again, a window can have more than one sibling.
|
|
@end deffn
|
|
|
|
@deffn Command balance-windows-area
|
|
This function attempts to give all windows on the selected frame
|
|
approximately the same share of the screen area. This means that
|
|
full-width or full-height windows are not given more space than other
|
|
windows.
|
|
@end deffn
|
|
|
|
@node Coordinates and Windows
|
|
@section Coordinates and Windows
|
|
|
|
This section describes how to relate screen coordinates to windows.
|
|
|
|
@defun window-at x y &optional frame
|
|
This function returns the window containing the specified cursor
|
|
position in the frame @var{frame}. The coordinates @var{x} and @var{y}
|
|
are measured in characters and count from the top left corner of the
|
|
frame. If they are out of range, @code{window-at} returns @code{nil}.
|
|
|
|
If you omit @var{frame}, the selected frame is used.
|
|
@end defun
|
|
|
|
@defun coordinates-in-window-p coordinates window
|
|
This function checks whether a particular frame position falls within
|
|
the window @var{window}.
|
|
|
|
The argument @var{coordinates} is a cons cell of the form @code{(@var{x}
|
|
. @var{y})}. The coordinates @var{x} and @var{y} are measured in
|
|
characters, and count from the top left corner of the screen or frame.
|
|
|
|
The value returned by @code{coordinates-in-window-p} is non-@code{nil}
|
|
if the coordinates are inside @var{window}. The value also indicates
|
|
what part of the window the position is in, as follows:
|
|
|
|
@table @code
|
|
@item (@var{relx} . @var{rely})
|
|
The coordinates are inside @var{window}. The numbers @var{relx} and
|
|
@var{rely} are the equivalent window-relative coordinates for the
|
|
specified position, counting from 0 at the top left corner of the
|
|
window.
|
|
|
|
@item mode-line
|
|
The coordinates are in the mode line of @var{window}.
|
|
|
|
@item header-line
|
|
The coordinates are in the header line of @var{window}.
|
|
|
|
@item vertical-line
|
|
The coordinates are in the vertical line between @var{window} and its
|
|
neighbor to the right. This value occurs only if the window doesn't
|
|
have a scroll bar; positions in a scroll bar are considered outside the
|
|
window for these purposes.
|
|
|
|
@item left-fringe
|
|
@itemx right-fringe
|
|
The coordinates are in the left or right fringe of the window.
|
|
|
|
@item left-margin
|
|
@itemx right-margin
|
|
The coordinates are in the left or right margin of the window.
|
|
|
|
@item nil
|
|
The coordinates are not in any part of @var{window}.
|
|
@end table
|
|
|
|
The function @code{coordinates-in-window-p} does not require a frame as
|
|
argument because it always uses the frame that @var{window} is on.
|
|
@end defun
|
|
|
|
@node Window Tree
|
|
@section The Window Tree
|
|
@cindex window tree
|
|
|
|
A @dfn{window tree} specifies the layout, size, and relationship
|
|
between all windows in one frame.
|
|
|
|
@defun window-tree &optional frame
|
|
This function returns the window tree for frame @var{frame}.
|
|
If @var{frame} is omitted, the selected frame is used.
|
|
|
|
The return value is a list of the form @code{(@var{root} @var{mini})},
|
|
where @var{root} represents the window tree of the frame's
|
|
root window, and @var{mini} is the frame's minibuffer window.
|
|
|
|
If the root window is not split, @var{root} is the root window itself.
|
|
Otherwise, @var{root} is a list @code{(@var{dir} @var{edges} @var{w1}
|
|
@var{w2} ...)} where @var{dir} is @code{nil} for a horizontal split,
|
|
and @code{t} for a vertical split, @var{edges} gives the combined size and
|
|
position of the subwindows in the split, and the rest of the elements
|
|
are the subwindows in the split. Each of the subwindows may again be
|
|
a window or a list representing a window split, and so on. The
|
|
@var{edges} element is a list @code{(@var{left}@var{ top}@var{ right}@var{ bottom})}
|
|
similar to the value returned by @code{window-edges}.
|
|
@end defun
|
|
|
|
@node Window Configurations
|
|
@section Window Configurations
|
|
@cindex window configurations
|
|
@cindex saving window information
|
|
|
|
A @dfn{window configuration} records the entire layout of one
|
|
frame---all windows, their sizes, which buffers they contain, how those
|
|
buffers are scrolled, and their values of point and the mark; also their
|
|
fringes, margins, and scroll bar settings. It also includes the value
|
|
of @code{minibuffer-scroll-window}. As a special exception, the window
|
|
configuration does not record the value of point in the selected window
|
|
for the current buffer. Also, the window configuration does not record
|
|
the values of window parameters; see @ref{Window Parameters}.
|
|
|
|
You can bring back an entire frame layout by restoring a previously
|
|
saved window configuration. If you want to record the layout of all
|
|
frames instead of just one, use a frame configuration instead of a
|
|
window configuration; see @ref{Frame Configurations}.
|
|
|
|
@defun current-window-configuration &optional frame
|
|
This function returns a new object representing @var{frame}'s current
|
|
window configuration. The default for @var{frame} is the selected
|
|
frame.
|
|
@end defun
|
|
|
|
@defun set-window-configuration configuration
|
|
This function restores the configuration of windows and buffers as
|
|
specified by @var{configuration}, for the frame that @var{configuration}
|
|
was created for.
|
|
|
|
The argument @var{configuration} must be a value that was previously
|
|
returned by @code{current-window-configuration}. The configuration is
|
|
restored in the frame from which @var{configuration} was made, whether
|
|
that frame is selected or not. This always counts as a window size
|
|
change and triggers execution of the @code{window-size-change-functions}
|
|
(@pxref{Window Hooks}), because @code{set-window-configuration} doesn't
|
|
know how to tell whether the new configuration actually differs from the
|
|
old one.
|
|
|
|
If the frame which @var{configuration} was saved from is dead, all this
|
|
function does is restore the three variables @code{window-min-height},
|
|
@code{window-min-width} and @code{minibuffer-scroll-window}. In this
|
|
case, the function returns @code{nil}. Otherwise, it returns @code{t}.
|
|
|
|
Here is a way of using this function to get the same effect
|
|
as @code{save-window-excursion}:
|
|
|
|
@example
|
|
@group
|
|
(let ((config (current-window-configuration)))
|
|
(unwind-protect
|
|
(progn (split-window-vertically nil)
|
|
@dots{})
|
|
(set-window-configuration config)))
|
|
@end group
|
|
@end example
|
|
@end defun
|
|
|
|
@defspec save-window-excursion forms@dots{}
|
|
This special form records the window configuration, executes @var{forms}
|
|
in sequence, then restores the earlier window configuration. The window
|
|
configuration includes, for each window, the value of point and the
|
|
portion of the buffer that is visible. It also includes the choice of
|
|
selected window. However, it does not include the value of point in
|
|
the current buffer; use @code{save-excursion} also, if you wish to
|
|
preserve that.
|
|
|
|
Don't use this construct when @code{save-selected-window} is sufficient.
|
|
|
|
Exit from @code{save-window-excursion} always triggers execution of
|
|
@code{window-size-change-functions}. (It doesn't know how to tell
|
|
whether the restored configuration actually differs from the one in
|
|
effect at the end of the @var{forms}.)
|
|
|
|
The return value is the value of the final form in @var{forms}.
|
|
For example:
|
|
|
|
@example
|
|
@group
|
|
(split-window)
|
|
@result{} #<window 25 on control.texi>
|
|
@end group
|
|
@group
|
|
(setq w (selected-window))
|
|
@result{} #<window 19 on control.texi>
|
|
@end group
|
|
@group
|
|
(save-window-excursion
|
|
(delete-other-windows w)
|
|
(switch-to-buffer "foo")
|
|
'do-something)
|
|
@result{} do-something
|
|
;; @r{The screen is now split again.}
|
|
@end group
|
|
@end example
|
|
@end defspec
|
|
|
|
@defun window-configuration-p object
|
|
This function returns @code{t} if @var{object} is a window configuration.
|
|
@end defun
|
|
|
|
@defun compare-window-configurations config1 config2
|
|
This function compares two window configurations as regards the
|
|
structure of windows, but ignores the values of point and mark and the
|
|
saved scrolling positions---it can return @code{t} even if those
|
|
aspects differ.
|
|
|
|
The function @code{equal} can also compare two window configurations; it
|
|
regards configurations as unequal if they differ in any respect, even a
|
|
saved point or mark.
|
|
@end defun
|
|
|
|
@defun window-configuration-frame config
|
|
This function returns the frame for which the window configuration
|
|
@var{config} was made.
|
|
@end defun
|
|
|
|
Other primitives to look inside of window configurations would make
|
|
sense, but are not implemented because we did not need them. See the
|
|
file @file{winner.el} for some more operations on windows
|
|
configurations.
|
|
|
|
@node Window Parameters
|
|
@section Window Parameters
|
|
@cindex window parameters
|
|
|
|
This sections describes how window parameters can be used to associate
|
|
additional information with windows.
|
|
|
|
@defun window-parameter window parameter
|
|
This function returns @var{window}'s value for @var{parameter}. The
|
|
default for @var{window} is the selected window. If @var{window}
|
|
has no setting for @var{parameter}, this function returns @code{nil}.
|
|
@end defun
|
|
|
|
@defun window-parameters &optional window
|
|
This function returns all parameters of @var{window} and their values.
|
|
The default for @var{window} is the selected window. The return value
|
|
is an association list of elements of the form @code{(@var{parameter}
|
|
. @var{value})}.
|
|
@end defun
|
|
|
|
@defun set-window-parameter window parameter value
|
|
This function sets @var{window}'s value of @var{parameter} to
|
|
@var{value} and returns @var{value}. The default for @var{window}
|
|
is the selected window.
|
|
@end defun
|
|
|
|
Currently, window parameters are not saved in window configurations and
|
|
consequently not restored by @code{set-window-configuration}. Hence,
|
|
any change of a parameter introduced via @code{set-window-parameter} can
|
|
be undone only by invoking @code{set-window-parameter} for the same
|
|
parameter again. Since @code{save-window-excursion} relies on window
|
|
configurations (@pxref{Window Configurations}), window parameters are
|
|
not saved and restored by that special form, either.
|
|
|
|
@node Window Hooks
|
|
@section Hooks for Window Scrolling and Changes
|
|
@cindex hooks for window operations
|
|
|
|
This section describes how a Lisp program can take action whenever a
|
|
window displays a different part of its buffer or a different buffer.
|
|
There are three actions that can change this: scrolling the window,
|
|
switching buffers in the window, and changing the size of the window.
|
|
The first two actions run @code{window-scroll-functions}; the last runs
|
|
@code{window-size-change-functions}.
|
|
|
|
@defvar window-scroll-functions
|
|
This variable holds a list of functions that Emacs should call before
|
|
redisplaying a window with scrolling. Displaying a different buffer in
|
|
the window also runs these functions.
|
|
|
|
This variable is not a normal hook, because each function is called with
|
|
two arguments: the window, and its new display-start position.
|
|
|
|
These functions must be careful in using @code{window-end}
|
|
(@pxref{Window Start and End}); if you need an up-to-date value, you
|
|
must use the @var{update} argument to ensure you get it.
|
|
|
|
@strong{Warning:} don't use this feature to alter the way the window
|
|
is scrolled. It's not designed for that, and such use probably won't
|
|
work.
|
|
@end defvar
|
|
|
|
@defvar window-size-change-functions
|
|
This variable holds a list of functions to be called if the size of any
|
|
window changes for any reason. The functions are called just once per
|
|
redisplay, and just once for each frame on which size changes have
|
|
occurred.
|
|
|
|
Each function receives the frame as its sole argument. There is no
|
|
direct way to find out which windows on that frame have changed size, or
|
|
precisely how. However, if a size-change function records, at each
|
|
call, the existing windows and their sizes, it can also compare the
|
|
present sizes and the previous sizes.
|
|
|
|
Creating or deleting windows counts as a size change, and therefore
|
|
causes these functions to be called. Changing the frame size also
|
|
counts, because it changes the sizes of the existing windows.
|
|
|
|
It is not a good idea to use @code{save-window-excursion} (@pxref{Window
|
|
Configurations}) in these functions, because that always counts as a
|
|
size change, and it would cause these functions to be called over and
|
|
over. In most cases, @code{save-selected-window} (@pxref{Selecting
|
|
Windows}) is what you need here.
|
|
@end defvar
|
|
|
|
@defvar window-configuration-change-hook
|
|
A normal hook that is run every time you change the window configuration
|
|
of an existing frame. This includes splitting or deleting windows,
|
|
changing the sizes of windows, or displaying a different buffer in a
|
|
window.
|
|
|
|
The buffer-local part of this hook is run once per each window on the
|
|
affected frame, with the relevant window selected and its buffer
|
|
current. The global part is run once for the modified frame, with that
|
|
frame selected.
|
|
@end defvar
|
|
|
|
In addition, you can use @code{jit-lock-register} to register a Font
|
|
Lock fontification function, which will be called whenever part of the
|
|
buffer needs to be refontified (usually because it has been changed).
|
|
@xref{Other Font Lock Variables}.
|
|
|
|
@ignore
|
|
arch-tag: 3f6c36e8-df49-4986-b757-417feed88be3
|
|
@end ignore
|