Run window change functions during redisplay

* doc/lispref/windows.texi (Window Sizes): Move (and rename)
descriptions of 'window-pixel-height-before-size-change' and
'window-pixel-width-before-size-change' to Window Hooks
section.
(Window Configurations): Remove warning against use of
'save-window-excursion' in 'window-size-change-functions'.
(Window Hooks): Rewrite section according to redesign of
window change functions.
* lisp/erc/erc-track.el (erc-window-configuration-change)
(erc-modified-channels-update): Call latter directly from
'window-configuration-change-hook' instead via
'post-command-hook'.
* lisp/frame.el (frame-size-changed-p): Change nomenclature
in let bindings.
* lisp/net/rcirc.el (rcirc-window-configuration-change)
(rcirc-window-configuration-change-1): Call latter directly
from 'window-configuration-change-hook' instead via
'post-command-hook'.
* lisp/window.el (window-pixel-width-before-size-change)
(window-pixel-height-before-size-change): Defalias.
(window--resize-mini-window, window-resize)
(adjust-window-trailing-edge, delete-window)
(delete-other-windows, balance-windows): Don't run
'window-configuration-change-hook' any more from here.
(split-window): Don't run 'window-configuration-change-hook'
from here.  'run-window-scroll-functions' from here.
(window--adjust-process-windows): Run from
'window-configuration-change-hook' only.
* src/frame.c (old_selected_frame): New Lisp variable.
(make_frame): Initialize frame's change_stamp slot.
(Fold_selected_frame): New function.
* src/frame.h (struct frame): New slots old_selected_window,
window_change, change_stamp and number_of_windows.
(fset_old_selected_window): New inlined function.
(FRAME_WINDOW_CHANGE, FRAME_OLD_SELECTED_WINDOW): New macros.
* src/window.c (old_selected_window): New Lisp variable.
(wset_old_buffer): New inlined function.
(Fframe_old_selected_window, Fold_selected_window)
(Fwindow_old_buffer): New functions.
(Fwindow_old_pixel_width, Fwindow_old_pixel_height): Rename
from Fwindow_pixel_width_before_size_change and
Fwindow_pixel_height_before_size_change.  Update doc-strings.
(Fwindow_old_body_pixel_width, Fwindow_old_body_pixel_height):
New functions.
(Fdelete_other_windows_internal): Set frame's window_change
slot instead of running 'window-configuration-change-hook'.
(Frun_window_configuration_change_hook): In doc-string tell
that this function is no more needed.
(Frun_window_scroll_functions): Amend doc-string.  Run with
window's buffer current.
(window_sub_list, window_change_record_windows)
(window_change_record_frame, window_change_record)
(run_window_change_functions_1, run_window_change_functions):
New functions.
(set_window_buffer): Set frame's window_change slot instead of
running 'window-configuration-change-hook'.
(make_window): Don't initialize pixel_width_before_size_change
and pixel_height_before_size_change slots.
(window_resize_apply, Fdelete_window_internal): Set frame's
window_change slot.
(Fsplit_window_internal): Set frame's window_change slot.
Don't run 'window-scroll-functions' from here.
* src/window.h (struct window): New slots old_buffer,
change_stamp, old_pixel_width (renamed from
pixel_width_before_size_change), old_pixel_height (renamed
from pixel_height_before_size_change), old_body_pixel_width
and old_body_pixel_height.
* src/xdisp.c (init_iterator): Set frame's window_change slot
when the body height or width changes.
(prepare_menu_bars): Don't run_window_size_change_functions.
(redisplay_internal): Don't run_window_size_change_functions,
run_window_change_functions instead.

1 files changed, 38 insertions, 8 deletions

diff --git a/src/frame.h b/src/frame.h
index b7059027fbe..ab3efdfa926 100644
--- a/src/frame.h
+++ b/src/frame.h
@@ -125,6 +125,10 @@ struct frame
      The selected window of the selected frame is Emacs's selected window.  */
   Lisp_Object selected_window;
 
+  /* This frame's selected window when run_window_change_functions was
+     called the last time on this frame.  */
+  Lisp_Object old_selected_window;
+
   /* This frame's minibuffer window.
      Most frames have their own minibuffer windows,
      but only the selected frame's minibuffer window
@@ -321,9 +325,14 @@ struct frame
      cleared.  */
   bool_bf explicit_name : 1;
 
-  /* True if configuration of windows on this frame has changed since
-     last call of run_window_size_change_functions.  */
-  bool_bf window_configuration_changed : 1;
+  /* True if at least one window on this frame changed since the last
+     call of run_window_change_functions.  Changes are either "state
+     changes" (a window has been created, deleted or got assigned
+     another buffer) or "size changes" (the total or body size of a
+     window changed).  run_window_change_functions exits early unless
+     either this flag is true or a window selection happened on this
+     frame.  */
+  bool_bf window_change : 1;
 
   /* True if the mouse has moved on this display device
      since the last time we checked.  */
@@ -406,6 +415,20 @@ struct frame
 
   /* Bitfield area ends here.  */
 
+  /* This frame's change stamp, set the last time window change
+     functions were run for this frame.  Should never be 0 because
+     that's the change stamp of a new window.  A window was not on a
+     frame the last run_window_change_functions was called on it if
+     it's change stamp differs from that of its frame.  */
+  int change_stamp;
+
+  /* This frame's number of windows, set the last time window change
+     functions were run for this frame.  Should never be 0 even for
+     minibuffer-only frames.  If no window has been added, this allows
+     to detect whether a window was deleted on this frame since the
+     last time run_window_change_functions was called on it.  */
+  ptrdiff_t number_of_windows;
+
   /* Number of lines (rounded up) of tool bar.  REMOVE THIS  */
   int tool_bar_lines;
 
@@ -662,6 +685,11 @@ fset_selected_window (struct frame *f, Lisp_Object val)
   f->selected_window = val;
 }
 INLINE void
+fset_old_selected_window (struct frame *f, Lisp_Object val)
+{
+  f->old_selected_window = val;
+}
+INLINE void
 fset_title (struct frame *f, Lisp_Object val)
 {
   f->title = val;
@@ -908,10 +936,9 @@ default_pixels_per_inch_y (void)
    are frozen on frame F.  */
 #define FRAME_WINDOWS_FROZEN(f) (f)->frozen_window_starts
 
-/* True if the frame's window configuration has changed since last call
-   of run_window_size_change_functions.  */
-#define FRAME_WINDOW_CONFIGURATION_CHANGED(f)	\
-  (f)->window_configuration_changed
+/* True if at least one window changed on frame F since the last time
+   window change functions were run on F.  */
+#define FRAME_WINDOW_CHANGE(f) (f)->window_change
 
 /* The minibuffer window of frame F, if it has one; otherwise nil.  */
 #define FRAME_MINIBUF_WINDOW(f) f->minibuffer_window
@@ -919,8 +946,10 @@ default_pixels_per_inch_y (void)
 /* The root window of the window tree of frame F.  */
 #define FRAME_ROOT_WINDOW(f) f->root_window
 
-/* The currently selected window of the window tree of frame F.  */
+/* The currently selected window of frame F.  */
 #define FRAME_SELECTED_WINDOW(f) f->selected_window
+/* The old selected window of frame F.  */
+#define FRAME_OLD_SELECTED_WINDOW(f) f->old_selected_window
 
 #define FRAME_INSERT_COST(f) (f)->insert_line_cost
 #define FRAME_DELETE_COST(f) (f)->delete_line_cost
@@ -1215,6 +1244,7 @@ SET_FRAME_VISIBLE (struct frame *f, int v)
   (f)->iconified = (eassert (0 <= (i) && (i) <= 1), (i))
 
 extern Lisp_Object selected_frame;
+extern Lisp_Object old_selected_frame;
 
 #if ! (defined USE_GTK || defined HAVE_NS)
 extern int frame_default_tool_bar_height;