Re: emacs-27 c49d379: Fix some problems with moving and resizing child frames

[Dmitry Gutov <dgutov@yandex.ru>]

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Hi Martin,

On 06.04.2020 10:24, Martin Rudalics wrote:
> +
> +      if (totalwidth != gwidth || totalheight != gheight)
> +	{

Speaking of this optimization, can we make it apply to 'resize-mode' 
child frames too?

I've been doing some testing, and in certain situations, the value 
'hide' actually seems more performant when the size doesn't need to be 
changed. This largely makes a difference when, at random times, the 
child frame takes ~100ms to resize (which corresponds to the value of 
x-wait-for-event-timeout).

The attached patch seems to help.

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diff --git a/src/gtkutil.c b/src/gtkutil.c
index e374bdbe03..9fcaeed097 100644
--- a/src/gtkutil.c
+++ b/src/gtkutil.c
@@ -954,6 +954,7 @@ xg_frame_set_char_size (struct frame *f, int width, int height)
     = pixelheight + FRAME_TOOLBAR_HEIGHT (f) + FRAME_MENUBAR_HEIGHT (f);
   int totalwidth = pixelwidth + FRAME_TOOLBAR_WIDTH (f);
   bool was_visible = false;
+  bool hide_child_frame = false;
 
   if (FRAME_PIXEL_HEIGHT (f) == 0)
     return;
@@ -996,26 +997,33 @@ xg_frame_set_char_size (struct frame *f, int width, int height)
       gtk_window_resize (GTK_WINDOW (FRAME_GTK_OUTER_WIDGET (f)),
 			 totalwidth, gheight);
     }
-  else if (FRAME_PARENT_FRAME (f) && FRAME_VISIBLE_P (f)
-	   && EQ (x_gtk_resize_child_frames, Qhide))
+  else if (FRAME_PARENT_FRAME (f) && FRAME_VISIBLE_P (f))
     {
       was_visible = true;
+      hide_child_frame = EQ (x_gtk_resize_child_frames, Qhide);
 
       if (totalwidth != gwidth || totalheight != gheight)
 	{
 	  frame_size_history_add
 	    (f, Qxg_frame_set_char_size_4, width, height,
 	     list2i (totalwidth, totalheight));
-	  block_input ();
-	  gtk_widget_hide (FRAME_GTK_OUTER_WIDGET (f));
-	  unblock_input ();
+
+          if (hide_child_frame)
+            {
+              block_input ();
+              gtk_widget_hide (FRAME_GTK_OUTER_WIDGET (f));
+              unblock_input ();
+            }
 
 	  gtk_window_resize (GTK_WINDOW (FRAME_GTK_OUTER_WIDGET (f)),
 			     totalwidth, totalheight);
 
-	  block_input ();
-	  gtk_widget_show_all (FRAME_GTK_OUTER_WIDGET (f));
-	  unblock_input ();
+          if (hide_child_frame)
+            {
+              block_input ();
+              gtk_widget_show_all (FRAME_GTK_OUTER_WIDGET (f));
+              unblock_input ();
+            }
 
 	  fullscreen = Qnil;
 	}