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(Accessing Events): Clarify posn-col-row and posn-actual-col-row.

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(Accessing Events): New functions posn-at-point and posn-at-x-y.
Add example to posn-x-y.
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Richard M. Stallman 2004-06-24 20:11:31 +00:00
parent eb8f5dabec
commit 6e41ce9c47
1 changed files with 45 additions and 10 deletions
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55
lispref/commands.texi
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@ -1695,7 +1695,7 @@ position such events have.
@end defun
@cindex mouse position list, accessing
These seven functions take a position list as described above, and
These functions take a position list as described above, and
return various parts of it.
@defun posn-window position
@ -1716,23 +1716,37 @@ is undefined.
@end defun
@defun posn-x-y position
Return the pixel-based x and y coordinates in @var{position}, as a cons
cell @code{(@var{x} . @var{y})}.
Return the pixel-based x and y coordinates in @var{position}, as a
cons cell @code{(@var{x} . @var{y})}. These coordinates are relative
to the window given by @code{posn-window}.
This example shows how to convert these window-relative coordinates
into frame-relative coordinates:
@example
(defun frame-relative-coordinates (position)
"Return frame-relative coordinates from POSITION."
(let* ((x-y (posn-x-y position))
(window (posn-window position))
(edges (window-inside-pixel-edges window)))
(cons (+ (car x-y) (car edges))
(+ (cdr x-y) (cadr edges)))))
@end example
@end defun
@defun posn-col-row position
Return the row and column (in units of frame default characters) of
@var{position}, as a cons cell @code{(@var{col} . @var{row})}. These
are computed from the @var{x} and @var{y} values actually found in
@var{position}.
Return the row and column (in units of the frame's default character
height and width) of @var{position}, as a cons cell @code{(@var{col} .
@var{row})}. These are computed from the @var{x} and @var{y} values
actually found in @var{position}.
@end defun
@defun posn-actual-col-row position
Return the actual row and column in @var{position}, as a cons cell
@code{(@var{col} . @var{row})}. The values are the actual row number
in the window, and the actual character number in that row. Return
@code{nil} if @var{position} does not include the actual positions; in that
case, @code{posn-col-row} can be used to get approximate values.
in the window, and the actual character number in that row. It returns
@code{nil} if @var{position} does not include actual positions values.
You can use @code{posn-col-row} to get approximate values.
@end defun
@defun posn-string position
@ -1769,6 +1783,27 @@ is a buffer position, return the size of the character at that position.
@defun posn-timestamp
Return the timestamp in @var{position}. This is the time at which the
event occurred, in milliseconds.
@end defun
These functions compute a position list given particular buffer
position or screen position. You can access the data in this position
list with the functions described above.
@defun posn-at-point &optional pos window
This function returns a position list for position @var{pos} in
@var{window}. @var{pos} defaults to point in @var{window};
@var{window} defaults to the selected window.
@code{posn-at-point} returns @code{nil} if @var{pos} is not visible in
@var{window}.
@end defun
@defun posn-at-x-y x y &optional frame-or-window
This function returns position information corresponding to pixel
coordinates @var{x} and @var{y} in a specified frame or window,
@var{frame-or-window}, which defaults to the selected window.
The coordinates @var{x} and @var{y} are relative to the
frame or window used.
@end defun
These functions are useful for decoding scroll bar events.