bug#38402: [PATCH] Fix empty/incorrect GTK menus on HiDPI monitors with window scaling factor > 1

[Tobias Bading <tbading@web.de>]

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This should fix Bug#31223, Bug#28106, Bug#23672 as well as Ubuntu bug
https://bugs.launchpad.net/ubuntu/+source/emacs25/+bug/1695228

Also fixes the formerly unscaled Y value returned by
frame-monitor-workarea (and display-monitor-attributes-list).

For details on why some GTK menus were empty please see thread
https://lists.gnu.org/archive/html/emacs-devel/2019-11/msg01061.html

* src/gtkutil.c
   (menubar_map_cb): properly scale req.height so that the menu bar's
   height is in device pixels as expected
   (xg_update_frame_menubar): dito
   (xg_event_is_for_menubar): properly scale rec.x and rec.y so that
   gtk_widget_intersect() works as intended
* src/xfns.c
   (Fx_display_monitor_attributes_list): properly scale work.x and work.y


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From ee5855067f50f6e208a960994eec7184d44d324e Mon Sep 17 00:00:00 2001
From: Tobias Bading <tbading@web.de>
Date: Wed, 27 Nov 2019 16:51:26 +0100
Subject: [PATCH] Fix empty/incorrect GTK menus on HiDPI monitors with window
 scaling factor > 1

This should fix Bug#31223, Bug#28106, Bug#23672 as well as Ubuntu bug
https://bugs.launchpad.net/ubuntu/+source/emacs25/+bug/1695228

Also fixes the formerly unscaled Y value returned by
frame-monitor-workarea (and display-monitor-attributes-list).

For details on why some GTK menus were empty please see thread
https://lists.gnu.org/archive/html/emacs-devel/2019-11/msg01061.html

* src/gtkutil.c
  (menubar_map_cb): properly scale req.height so that the menu bar's
  height is in device pixels as expected
  (xg_update_frame_menubar): dito
  (xg_event_is_for_menubar): properly scale rec.x and rec.y so that
  gtk_widget_intersect() works as intended
* src/xfns.c
  (Fx_display_monitor_attributes_list): properly scale work.x and work.y
---
 src/gtkutil.c | 8 +++++---
 src/xfns.c    | 2 ++
 2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/src/gtkutil.c b/src/gtkutil.c
index cf5c31aa20..7e6db57c9d 100644
--- a/src/gtkutil.c
+++ b/src/gtkutil.c
@@ -3471,6 +3471,7 @@ menubar_map_cb (GtkWidget *w, gpointer user_data)
   GtkRequisition req;
   struct frame *f = user_data;
   gtk_widget_get_preferred_size (w, NULL, &req);
+  req.height *= xg_get_scale (f);
   if (FRAME_MENUBAR_HEIGHT (f) != req.height)
     {
       FRAME_MENUBAR_HEIGHT (f) = req.height;
@@ -3502,7 +3503,7 @@ xg_update_frame_menubar (struct frame *f)
   g_signal_connect (x->menubar_widget, "map", G_CALLBACK (menubar_map_cb), f);
   gtk_widget_show_all (x->menubar_widget);
   gtk_widget_get_preferred_size (x->menubar_widget, NULL, &req);
-
+  req.height *= xg_get_scale (f);
   if (FRAME_MENUBAR_HEIGHT (f) != req.height)
     {
       FRAME_MENUBAR_HEIGHT (f) = req.height;
@@ -3568,8 +3569,9 @@ xg_event_is_for_menubar (struct frame *f, const XEvent *event)

   list = gtk_container_get_children (GTK_CONTAINER (x->menubar_widget));
   if (! list) return 0;
-  rec.x = event->xbutton.x;
-  rec.y = event->xbutton.y;
+  int scale = xg_get_scale (f);
+  rec.x = event->xbutton.x / scale;
+  rec.y = event->xbutton.y / scale;
   rec.width = 1;
   rec.height = 1;

diff --git a/src/xfns.c b/src/xfns.c
index b1b40702c2..47aa19607f 100644
--- a/src/xfns.c
+++ b/src/xfns.c
@@ -5093,6 +5093,8 @@ DEFUN ("x-display-monitor-attributes-list", Fx_display_monitor_attributes_list,
 #endif
       rec.width *= scale;
       rec.height *= scale;
+      work.x *= scale;
+      work.y *= scale;
       work.width *= scale;
       work.height *= scale;

--
2.20.1