master beaddd8: Allow 'display-buffer' to set up body size of chosen window (Bug#17065)

[Martin Rudalics]

branch: master
commit beaddd87f79b69fe2723206c9cbb2efacf34620d
Author: Martin Rudalics <rudalics@gmx.at>
Commit: Martin Rudalics <rudalics@gmx.at>

    Allow 'display-buffer' to set up body size of chosen window (Bug#17065)
    
    * doc/lispref/windows.texi (Buffer Display Action Alists):
    Describe new possible values for 'window-height', 'window-width'
    and 'window-size' action alist entries.
    * lisp/window.el (window--display-buffer): Handle new values for
    'window-height', 'window-width' and 'window-size' ALIST entries.
    (display-buffer): Update doc-string for new values of some
    action alist entries.
    * etc/NEWS: Mention new values of some action alist entries.
---
 doc/lispref/windows.texi |  20 ++++++-
 etc/NEWS                 |   6 +++
 lisp/window.el           | 132 ++++++++++++++++++++++++++++-------------------
 3 files changed, 104 insertions(+), 54 deletions(-)

diff --git a/doc/lispref/windows.texi b/doc/lispref/windows.texi
index 2625160..9ce185a 100644
--- a/doc/lispref/windows.texi
+++ b/doc/lispref/windows.texi
@@ -3036,6 +3036,11 @@ desired total height with respect to the total height of 
its frame's
 root window.
 
 @item
+A cons cell whose @sc{car} is @code{body-lines} and whose @sc{cdr} is an
+integer that specifies the height of the chosen window's body in frame
+lines.
+
+@item
 If the value specifies a function, that function is called with one
 argument---the chosen window.  The function is supposed to adjust the
 height of the window; its return value is ignored.  Suitable functions
@@ -3069,6 +3074,11 @@ desired total width with respect to the total width of 
the frame's
 root window.
 
 @item
+A cons cell whose @sc{car} is @code{body-columns} and whose @sc{cdr} is
+an integer that specifies the width of the chosen window's body in frame
+columns.
+
+@item
 If the value specifies a function, that function is called with one
 argument---the chosen window.  The function is supposed to adjust the
 width of the window; its return value is ignored.
@@ -3077,8 +3087,8 @@ width of the window; its return value is ignored.
 @vindex window-size@r{, a buffer display action alist entry}
 @item window-size
 This entry is a combination of the two preceding ones and can be used to
-adjust the chosen window's height and width.  Since windows can be
-resized in one direction only without affecting other windows,
+adjust the chosen window's height @emph{and} width.  Since windows can
+be resized in one direction only without affecting other windows,
 @code{window-size} is effective only to set up the size of a window
 appearing alone on a frame.  The value can be one of the following:
 
@@ -3092,6 +3102,12 @@ of the chosen window in lines and columns.  It's effect 
is to adjust the
 size of the frame accordingly.
 
 @item
+A cons cell whose @sc{car} equals @code{body-chars} and whose @sc{cdr}
+is a cons cell of two integers---the desired body width and height of
+the chosen window in frame columns and lines.  It's effect is to adjust
+the size of the frame accordingly.
+
+@item
 If the value specifies a function, that function is called with one
 argument---the chosen window.  The function is supposed to adjust the
 size of the window's frame; its return value is ignored.
diff --git a/etc/NEWS b/etc/NEWS
index f6d36f1..90ad8d3 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -67,6 +67,12 @@ This support is built by default when the libwebp library is
 available.  To disable it, use the '--without-webp' configure flag.
 Image specifiers can now use ':type webp'.
 
+** Windows
+
++++
+*** 'display-buffer' now can set up the body size of the chosen window.
+For example, an alist entry as '(window-width . (body-columns . 40))'
+will make the body of the chosen window 40 columns wide.
 
 * Editing Changes in Emacs 29.1
 
diff --git a/lisp/window.el b/lisp/window.el
index 132f093..848e618 100644
--- a/lisp/window.el
+++ b/lisp/window.el
@@ -7234,7 +7234,8 @@ Return WINDOW if BUFFER and WINDOW are live."
             (inhibit-modification-hooks t))
         (funcall (cdr (assq 'body-function alist)) window)))
 
-    (let* ((quit-restore (window-parameter window 'quit-restore))
+    (let* ((frame (window-frame window))
+           (quit-restore (window-parameter window 'quit-restore))
           (window-height (assq 'window-height alist))
            (height (cdr window-height))
           (window-width (assq 'window-width alist))
@@ -7256,29 +7257,35 @@ Return WINDOW if BUFFER and WINDOW are live."
           (when window-size
             (setq resize-temp-buffer-window-inhibit t)))
         ((consp size)
-         (let ((width (car size))
-               (height (cdr size))
-               (frame (window-frame window)))
-           (when (and (numberp width) (numberp height))
-              ;; Modifying the parameters of a newly created frame might
-              ;; not work everywhere, but then `temp-buffer-resize-mode'
-              ;; will certainly fail in a similar fashion.
+          ;; Modifying the parameters of a newly created frame might
+          ;; not work everywhere, but then `temp-buffer-resize-mode'
+          ;; will certainly fail in a similar fashion.
+          (if (eq (car size) 'body-chars)
+             (let ((width (+ (frame-text-width frame)
+                              (* (frame-char-width frame) (cadr size))
+                              (- (window-body-width window t))))
+                    (height (+ (frame-text-height frame)
+                               (* (frame-char-height frame) (cddr size))
+                               (- (window-body-height window t)))))
+               (modify-frame-parameters
+                frame `((height . (text-pixels . ,height))
+                         (width . (text-pixels . ,width)))))
+           (let ((width (- (+ (frame-width frame) (car size))
+                            (window-total-width window)))
+                  (height (- (+ (frame-height frame) (cdr size))
+                             (window-total-height window))))
              (modify-frame-parameters
-              frame `((height . ,(+ (frame-height frame)
-                                    (- height (window-total-height window))))
-                       (width . ,(+ (frame-width frame)
-                                   (- width (window-total-width window))))))))
+              frame `((height . ,height) (width . ,width)))))
           (setq resize-temp-buffer-window-inhibit t))
-        ((functionp size)
+         ((functionp size)
          (ignore-errors (funcall size window))
           (setq resize-temp-buffer-window-inhibit t))))
        ((or (eq type 'window)
            (and (eq (car quit-restore) 'same)
                 (eq (nth 1 quit-restore) 'window)))
        ;; A window that never showed another buffer but BUFFER ever
-        ;; since it was created on an existing frame.
-        ;;
-        ;; Adjust width and/or height of window if asked for.
+        ;; since it was created on an existing frame.  Adjust its width
+        ;; and/or height if asked for.
        (cond
          ((not height)
          (when window-height
@@ -7295,7 +7302,14 @@ Return WINDOW if BUFFER and WINDOW are live."
                       (window-combined-p window))
              (window-resize window delta nil 'safe)))
           (setq resize-temp-buffer-window-inhibit 'vertical))
-        ((functionp height)
+         ((and (consp height) (eq (car height) 'body-lines))
+         (let* ((delta (- (* (frame-char-height frame) (cdr height))
+                           (window-body-height window t))))
+           (and (window--resizable-p window delta nil 'safe nil nil nil t)
+                (window-combined-p window)
+                (window-resize window delta nil 'safe t)))
+          (setq resize-temp-buffer-window-inhibit 'vertical))
+         ((functionp height)
          (ignore-errors (funcall height window))
           (setq resize-temp-buffer-window-inhibit 'vertical)))
        ;; Adjust width of window if asked for.
@@ -7315,6 +7329,13 @@ Return WINDOW if BUFFER and WINDOW are live."
                       (window-combined-p window t))
              (window-resize window delta t 'safe)))
           (setq resize-temp-buffer-window-inhibit 'horizontal))
+         ((and (consp width) (eq (car width) 'body-columns))
+         (let* ((delta (- (* (frame-char-width frame) (cdr width))
+                           (window-body-width window t))))
+           (and (window--resizable-p window delta t 'safe nil nil nil t)
+                (window-combined-p window t)
+                (window-resize window delta t 'safe t)))
+          (setq resize-temp-buffer-window-inhibit 'horizontal))
         ((functionp width)
          (ignore-errors (funcall width window))
           (setq resize-temp-buffer-window-inhibit 'horizontal)))
@@ -7564,11 +7585,12 @@ perform.
 Action alist entries are:
  `inhibit-same-window' -- A non-nil value prevents the same
     window from being used for display.
-`inhibit-switch-frame' -- A non-nil value prevents any frame used
-    for showing the buffer from being raised or selected.  Note
-    that a window manager may still raise a new frame and give it
-    focus, effectively overriding the value specified here.
-`reusable-frames' -- The value specifies the set of frames to
+ `inhibit-switch-frame' -- A non-nil value prevents any frame
+    used for showing the buffer from being raised or selected.
+    Note that a window manager may still raise a new frame and
+    give it focus, effectively overriding the value specified
+    here.
+ `reusable-frames' -- The value specifies the set of frames to
     search for a window that already displays the buffer.
     Possible values are nil (the selected frame), t (any live
     frame), visible (any visible frame), 0 (any visible or
@@ -7577,45 +7599,51 @@ Action alist entries are:
     frame parameters to give a new frame, if one is created.
  `window-height' -- The value specifies the desired height of the
     window chosen and is either an integer (the total height of
-    the window), a floating point number (the fraction of its
-    total height with respect to the total height of the frame's
-    root window) or a function to be called with one argument -
-    the chosen window.  The function is supposed to adjust the
-    height of the window; its return value is ignored.  Suitable
-    functions are `shrink-window-if-larger-than-buffer' and
-    `fit-window-to-buffer'.
+    the window specified in frame lines), a floating point
+    number (the fraction of its total height with respect to the
+    total height of the frame's root window), a cons cell whose
+    car is 'body-lines' and whose cdr is an integer that
+    specifies the height of the window's body in frame lines, or
+    a function to be called with one argument - the chosen
+    window.  That function is supposed to adjust the height of
+    the window.  Suitable functions are `fit-window-to-buffer'
+    and `shrink-window-if-larger-than-buffer'.
  `window-width' -- The value specifies the desired width of the
     window chosen and is either an integer (the total width of
-    the window), a floating point number (the fraction of its
-    total width with respect to the width of the frame's root
-    window) or a function to be called with one argument - the
-    chosen window.  The function is supposed to adjust the width
-    of the window; its return value is ignored.
+    the window specified in frame lines), a floating point
+    number (the fraction of its total width with respect to the
+    width of the frame's root window), a cons cell whose car is
+    'body-columns' and whose cdr is an integer that specifies the
+    width of the window's body in frame columns, or a function to
+    be called with one argument - the chosen window.  That
+    function is supposed to adjust the width of the window.
  `window-size' -- This entry is only useful for windows appearing
     alone on their frame and specifies the desired size of that
     window either as a cons of integers (the total width and
-    height of the window on that frame), or a function to be
-    called with one argument - the chosen window.  The function
-    is supposed to adjust the size of the frame; its return value
-    is ignored.
-`preserve-size' -- The value should be either (t . nil) to
+    height of the window on that frame), a cons cell whose car is
+    'body-chars' and whose cdr is a cons of integers (the desired
+    width and height of the window's body in columns and lines of
+    its frame), or a function to be called with one argument -
+    the chosen window.  That function is supposed to adjust the
+    size of the frame.
+ `preserve-size' -- The value should be either (t . nil) to
     preserve the width of the chosen window, (nil . t) to
     preserve its height or (t . t) to preserve its height and
     width in future changes of the window configuration.
  `window-parameters' -- The value specifies an alist of window
-    parameters to give the chosen window.
- `allow-no-window' -- A non-nil value means that `display-buffer'
-    may not display the buffer and return nil immediately.
- `body-function' -- A function called with one argument - the
-    displayed window.  It is called after the buffer is
-    displayed, and before `window-height', `window-width'
-    and `preserve-size' are applied.  The function is supposed
-    to fill the window body with some contents that might depend
-    on dimensions of the displayed window.
-
-The entries `window-height', `window-width' and `preserve-size'
-are applied only when the window used for displaying the buffer
-never showed another buffer before.
+    parameters to give the chosen window.  `allow-no-window' -- A
+    non-nil value means that `display-buffer' may not display the
+    buffer and return nil immediately.  `body-function' -- A
+    function called with one argument - the displayed window.  It
+    is called after the buffer is displayed, and before
+    `window-height', `window-width' and `preserve-size' are
+    applied.  The function is supposed to fill the window body
+    with some contents that might depend on dimensions of the
+    displayed window.
+
+The entries `window-height', `window-width', `window-size' and
+`preserve-size' are applied only when the window used for
+displaying the buffer never showed another buffer before.
 
 The ACTION argument can also have a non-nil and non-list value.
 This means to display the buffer in a window other than the