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264 lines
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264 lines
12 KiB
Plaintext
@c This is part of the Emacs manual.
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@c Copyright (C) 1985, 86, 87, 93, 94, 95, 1997 Free Software Foundation, Inc.
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@c See file emacs.texi for copying conditions.
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@node Picture, Sending Mail, Abbrevs, Top
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@chapter Editing Pictures
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@cindex pictures
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@cindex making pictures out of text characters
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@findex edit-picture
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To edit a picture made out of text characters (for example, a picture
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of the division of a register into fields, as a comment in a program),
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use the command @kbd{M-x edit-picture} to enter Picture mode.
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In Picture mode, editing is based on the @dfn{quarter-plane} model of
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text, according to which the text characters lie studded on an area that
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stretches infinitely far to the right and downward. The concept of the end
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of a line does not exist in this model; the most you can say is where the
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last nonblank character on the line is found.
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Of course, Emacs really always considers text as a sequence of
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characters, and lines really do have ends. But Picture mode replaces
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the most frequently-used commands with variants that simulate the
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quarter-plane model of text. They do this by inserting spaces or by
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converting tabs to spaces.
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Most of the basic editing commands of Emacs are redefined by Picture mode
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to do essentially the same thing but in a quarter-plane way. In addition,
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Picture mode defines various keys starting with the @kbd{C-c} prefix to
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run special picture editing commands.
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One of these keys, @kbd{C-c C-c}, is pretty important. Often a
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picture is part of a larger file that is usually edited in some other
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major mode. @kbd{M-x edit-picture} records the name of the previous
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major mode so you can use the @kbd{C-c C-c} command
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(@code{picture-mode-exit}) later to go back to that mode. @kbd{C-c C-c}
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also deletes spaces from the ends of lines, unless given a numeric
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argument.
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The special commands of Picture mode all work in other modes (provided
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the @file{picture} library is loaded), but are not bound to keys except
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in Picture mode. The descriptions below talk of moving ``one column''
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and so on, but all the picture mode commands handle numeric arguments as
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their normal equivalents do.
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@vindex picture-mode-hook
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Turning on Picture mode runs the hook @code{picture-mode-hook}
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(@pxref{Hooks}).
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@menu
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* Basic Picture:: Basic concepts and simple commands of Picture Mode.
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* Insert in Picture:: Controlling direction of cursor motion
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after "self-inserting" characters.
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* Tabs in Picture:: Various features for tab stops and indentation.
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* Rectangles in Picture:: Clearing and superimposing rectangles.
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@end menu
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@node Basic Picture, Insert in Picture, Picture, Picture
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@section Basic Editing in Picture Mode
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@findex picture-forward-column
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@findex picture-backward-column
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@findex picture-move-down
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@findex picture-move-up
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@cindex editing in Picture mode
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Most keys do the same thing in Picture mode that they usually do, but
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do it in a quarter-plane style. For example, @kbd{C-f} is rebound to
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run @code{picture-forward-column}, a command which moves point one
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column to the right, inserting a space if necessary so that the actual
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end of the line makes no difference. @kbd{C-b} is rebound to run
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@code{picture-backward-column}, which always moves point left one
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column, converting a tab to multiple spaces if necessary. @kbd{C-n} and
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@kbd{C-p} are rebound to run @code{picture-move-down} and
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@code{picture-move-up}, which can either insert spaces or convert tabs
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as necessary to make sure that point stays in exactly the same column.
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@kbd{C-e} runs @code{picture-end-of-line}, which moves to after the last
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nonblank character on the line. There is no need to change @kbd{C-a},
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as the choice of screen model does not affect beginnings of
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lines.
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@findex picture-newline
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Insertion of text is adapted to the quarter-plane screen model through
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the use of Overwrite mode (@pxref{Minor Modes}). Self-inserting characters
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replace existing text, column by column, rather than pushing existing text
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to the right. @key{RET} runs @code{picture-newline}, which just moves to
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the beginning of the following line so that new text will replace that
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line.
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@findex picture-backward-clear-column
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@findex picture-clear-column
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@findex picture-clear-line
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Picture mode provides erasure instead of deletion and killing of
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text. @key{DEL} (@code{picture-backward-clear-column}) replaces the
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preceding character with a space rather than removing it; this moves
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point backwards. @kbd{C-d} (@code{picture-clear-column}) replaces the
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next character or characters with spaces, but does not move point. (If
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you want to clear characters to spaces and move forward over them, use
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@key{SPC}.) @kbd{C-k} (@code{picture-clear-line}) really kills the
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contents of lines, but does not delete the newlines from the
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buffer.
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@findex picture-open-line
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To do actual insertion, you must use special commands. @kbd{C-o}
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(@code{picture-open-line}) creates a blank line after the current line;
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it never splits a line. @kbd{C-M-o} (@code{split-line}) makes sense in
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Picture mode, so it is not changed. @kbd{C-j}
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(@code{picture-duplicate-line}) inserts below the current line another
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line with the same contents.@refill
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@kindex C-c C-d @r{(Picture mode)}
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To do actual deletion in Picture mode, use @kbd{C-w}, @kbd{C-c C-d}
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(which is defined as @code{delete-char}, as @kbd{C-d} is in other
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modes), or one of the picture rectangle commands (@pxref{Rectangles in
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Picture}).
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@node Insert in Picture, Tabs in Picture, Basic Picture, Picture
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@section Controlling Motion after Insert
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@findex picture-movement-up
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@findex picture-movement-down
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@findex picture-movement-left
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@findex picture-movement-right
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@findex picture-movement-nw
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@findex picture-movement-ne
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@findex picture-movement-sw
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@findex picture-movement-se
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@kindex C-c < @r{(Picture mode)}
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@kindex C-c > @r{(Picture mode)}
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@kindex C-c ^ @r{(Picture mode)}
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@kindex C-c . @r{(Picture mode)}
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@kindex C-c ` @r{(Picture mode)}
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@kindex C-c ' @r{(Picture mode)}
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@kindex C-c / @r{(Picture mode)}
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@kindex C-c \ @r{(Picture mode)}
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Since ``self-inserting'' characters in Picture mode overwrite and move
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point, there is no essential restriction on how point should be moved.
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Normally point moves right, but you can specify any of the eight
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orthogonal or diagonal directions for motion after a ``self-inserting''
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character. This is useful for drawing lines in the buffer.
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@table @kbd
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@item C-c <
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Move left after insertion (@code{picture-movement-left}).
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@item C-c >
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Move right after insertion (@code{picture-movement-right}).
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@item C-c ^
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Move up after insertion (@code{picture-movement-up}).
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@item C-c .
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Move down after insertion (@code{picture-movement-down}).
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@item C-c `
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Move up and left (``northwest'') after insertion (@code{picture-movement-nw}).
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@item C-c '
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Move up and right (``northeast'') after insertion
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(@code{picture-movement-ne}).
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@item C-c /
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Move down and left (``southwest'') after insertion
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@*(@code{picture-movement-sw}).
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@item C-c \
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Move down and right (``southeast'') after insertion
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@*(@code{picture-movement-se}).
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@end table
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@kindex C-c C-f @r{(Picture mode)}
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@kindex C-c C-b @r{(Picture mode)}
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@findex picture-motion
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@findex picture-motion-reverse
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Two motion commands move based on the current Picture insertion
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direction. The command @kbd{C-c C-f} (@code{picture-motion}) moves in the
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same direction as motion after ``insertion'' currently does, while @kbd{C-c
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C-b} (@code{picture-motion-reverse}) moves in the opposite direction.
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@node Tabs in Picture, Rectangles in Picture, Insert in Picture, Picture
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@section Picture Mode Tabs
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@kindex M-TAB @r{(Picture mode)}
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@findex picture-tab-search
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@vindex picture-tab-chars
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Two kinds of tab-like action are provided in Picture mode. Use
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@kbd{M-@key{TAB}} (@code{picture-tab-search}) for context-based tabbing.
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With no argument, it moves to a point underneath the next
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``interesting'' character that follows whitespace in the previous
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nonblank line. ``Next'' here means ``appearing at a horizontal position
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greater than the one point starts out at.'' With an argument, as in
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@kbd{C-u M-@key{TAB}}, this command moves to the next such interesting
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character in the current line. @kbd{M-@key{TAB}} does not change the
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text; it only moves point. ``Interesting'' characters are defined by
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the variable @code{picture-tab-chars}, which should define a set of
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characters. The syntax for this variable is like the syntax used inside
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of @samp{[@dots{}]} in a regular expression---but without the @samp{[}
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and the @samp{]}. Its default value is @code{"!-~"}.
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@findex picture-tab
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@key{TAB} itself runs @code{picture-tab}, which operates based on the
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current tab stop settings; it is the Picture mode equivalent of
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@code{tab-to-tab-stop}. Normally it just moves point, but with a numeric
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argument it clears the text that it moves over.
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@kindex C-c TAB @r{(Picture mode)}
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@findex picture-set-tab-stops
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The context-based and tab-stop-based forms of tabbing are brought
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together by the command @kbd{C-c @key{TAB}} (@code{picture-set-tab-stops}).
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This command sets the tab stops to the positions which @kbd{M-@key{TAB}}
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would consider significant in the current line. The use of this command,
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together with @key{TAB}, can get the effect of context-based tabbing. But
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@kbd{M-@key{TAB}} is more convenient in the cases where it is sufficient.
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It may be convenient to prevent use of actual tab characters in
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pictures. For example, this prevents @kbd{C-x @key{TAB}} from messing
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up the picture. You can do this by setting the variable
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@code{indent-tabs-mode} to @code{nil}. @xref{Just Spaces}.
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@node Rectangles in Picture,, Tabs in Picture, Picture
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@section Picture Mode Rectangle Commands
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@cindex rectangles and Picture mode
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@cindex Picture mode and rectangles
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Picture mode defines commands for working on rectangular pieces of the
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text in ways that fit with the quarter-plane model. The standard rectangle
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commands may also be useful (@pxref{Rectangles}).
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@table @kbd
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@item C-c C-k
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Clear out the region-rectangle with spaces
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(@code{picture-clear-rectangle}). With argument, delete the text.
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@item C-c C-w @var{r}
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Similar, but save rectangle contents in register @var{r} first
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(@code{picture-clear-rectangle-to-register}).
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@item C-c C-y
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Copy last killed rectangle into the buffer by overwriting, with upper
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left corner at point (@code{picture-yank-rectangle}). With argument,
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insert instead.
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@item C-c C-x @var{r}
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Similar, but use the rectangle in register @var{r}
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(@code{picture-yank-rectangle-from-register}).
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@end table
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@kindex C-c C-k @r{(Picture mode)}
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@kindex C-c C-w @r{(Picture mode)}
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@findex picture-clear-rectangle
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@findex picture-clear-rectangle-to-register
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The picture rectangle commands @kbd{C-c C-k}
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(@code{picture-clear-rectangle}) and @kbd{C-c C-w}
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(@code{picture-clear-rectangle-to-register}) differ from the standard
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rectangle commands in that they normally clear the rectangle instead of
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deleting it; this is analogous with the way @kbd{C-d} is changed in Picture
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mode.
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However, deletion of rectangles can be useful in Picture mode, so
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these commands delete the rectangle if given a numeric argument.
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@kbd{C-c C-k} either with or without a numeric argument saves the
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rectangle for @kbd{C-c C-y}.
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@kindex C-c C-y @r{(Picture mode)}
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@kindex C-c C-x @r{(Picture mode)}
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@findex picture-yank-rectangle
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@findex picture-yank-rectangle-from-register
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The Picture mode commands for yanking rectangles differ from the
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standard ones in that they overwrite instead of inserting. This is
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the same way that Picture mode insertion of other text differs from
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other modes. @kbd{C-c C-y} (@code{picture-yank-rectangle}) inserts
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(by overwriting) the rectangle that was most recently killed, while
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@kbd{C-c C-x} (@code{picture-yank-rectangle-from-register}) does
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likewise for the rectangle found in a specified register.
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