Expand spectrum of window change functions

* src/window.c (run_window_change_functions): Run window
change functions for Qwindow_state_change_functions.
(resize_frame_windows): Set frame's window_change slot when
single-window frames change size.
(Qwindow_state_change_functions): New symbol.
(Vwindow_state_change_functions): New Lisp variable.
* doc/lispref/windows.texi (Selecting Windows): Mention
'window-selection/state-change-functions' and add reference to
Window Hooks.
(Window Hooks): Document 'window-state-change-functions'.
* etc/NEWS: Mention new hook 'window-state-change-functions'.

1 files changed, 52 insertions, 1 deletions

diff --git a/src/window.c b/src/window.c
index 7eb532f78cf..c0d745995a8 100644
--- a/src/window.c
+++ b/src/window.c
@@ -3799,7 +3799,7 @@ run_window_change_functions (void)
             run_window_change_functions_1
               (Qwindow_size_change_functions, buffer, window);
 
-          /* This window's selection has changed when it it was
+          /* This window's selection has changed when it was
              (de-)selected as its frame's or the globally selected
              window.  */
           if (((frame_selected_change
@@ -3811,6 +3811,21 @@ run_window_change_functions (void)
               && WINDOW_LIVE_P (window))
             run_window_change_functions_1
               (Qwindow_selection_change_functions, buffer, window);
+
+          /* This window's state has changed when its buffer or size
+             changed or it was (de-)selected as its frame's or the
+             globally selected window.  */
+          if ((window_buffer_change
+               || window_size_change
+               || ((frame_selected_change
+                    && (EQ (window, old_selected_window)
+                        || EQ (window, selected_window)))
+                   || (frame_selected_window_change
+                       && (EQ (window, FRAME_OLD_SELECTED_WINDOW (f))
+                           || EQ (window, FRAME_SELECTED_WINDOW (f))))))
+              && WINDOW_LIVE_P (window))
+            run_window_change_functions_1
+              (Qwindow_state_change_functions, buffer, window);
         }
 
       /* When the number of windows on a frame has decreased, at least
@@ -3840,6 +3855,15 @@ run_window_change_functions (void)
         run_window_change_functions_1
           (Qwindow_selection_change_functions, Qnil, frame);
 
+      /* A frame has changed state when a size or buffer change
+         occurrd or its selected window has changed or when it was
+         (de-)selected.  */
+      if ((frame_selected_change || frame_selected_window_change
+           || frame_buffer_change || window_deleted || frame_size_change)
+          && FRAME_LIVE_P (f))
+        run_window_change_functions_1
+          (Qwindow_state_change_functions, Qnil, frame);
+
       /* A frame's configuration changed when one of its windows has
          changed buffer or size or at least one window was deleted.  */
       if ((frame_size_change || window_deleted) && FRAME_LIVE_P (f))
@@ -4650,16 +4674,26 @@ resize_frame_windows (struct frame *f, int size, bool horflag, bool pixelwise)
     /* For a leaf root window just set the size.  */
     if (horflag)
       {
+        bool changed = r->pixel_width != new_pixel_size;
+
         r->total_cols = new_size;
         r->pixel_width = new_pixel_size;
+
+        if (changed && !WINDOW_PSEUDO_P (r))
+          FRAME_WINDOW_CHANGE (f) = true;
       }
     else
       {
+        bool changed = r->pixel_height != new_pixel_size;
+
         r->top_line = FRAME_TOP_MARGIN (f);
         r->pixel_top = FRAME_TOP_MARGIN_HEIGHT (f);
 
         r->total_lines = new_size;
         r->pixel_height = new_pixel_size;
+
+        if (changed && !WINDOW_PSEUDO_P (r))
+          FRAME_WINDOW_CHANGE (f) = true;
       }
   else
     {
@@ -7953,6 +7987,7 @@ syms_of_window (void)
   Fput (Qscroll_down, Qscroll_command, Qt);
 
   DEFSYM (Qwindow_configuration_change_hook, "window-configuration-change-hook");
+  DEFSYM (Qwindow_state_change_functions, "window-state-change-functions");
   DEFSYM (Qwindow_size_change_functions, "window-size-change-functions");
   DEFSYM (Qwindow_buffer_change_functions, "window-buffer-change-functions");
   DEFSYM (Qwindow_selection_change_functions, "window-selection-change-functions");
@@ -8074,6 +8109,22 @@ the frame's selected window has changed since the last redisplay.  In
 this case the frame is passed as argument.  */);
   Vwindow_selection_change_functions = Qnil;
 
+  DEFVAR_LISP ("window-state-change-functions", Vwindow_state_change_functions,
+               doc: /* Functions called during redisplay when the window state changed.
+The value should be a list of functions that take one argument.
+
+Functions specified buffer-locally are called for each window showing
+the corresponding buffer if and only if that window has been added,
+resized, changed its buffer or has been (de-)selected since the last
+redisplay.  In this case the window is passed as argument.
+
+Functions specified by the default value are called for each frame if
+at least one window on that frame has been added, deleted, changed its
+buffer or its total or body size or the frame has been (de-)selected
+or its selected window has changed since the last redisplay.  In this
+case the frame is passed as argument.  */);
+  Vwindow_selection_change_functions = Qnil;
+
   DEFVAR_LISP ("window-configuration-change-hook", Vwindow_configuration_change_hook,
                doc: /* Functions called during redisplay when window configuration has changed.
 The value should be a list of functions that take no argument.