From 3addec3d592b9fc81e2a1503a37ccb078f03118c Mon Sep 17 00:00:00 2001
From: Ryan Prior <ryanprior@gmail.com>
Date: Fri, 2 Oct 2015 19:22:28 -0500
Subject: [PATCH] Adjust overlay position on hidpi screens

Scale the display positions of tooltips and menus according to the
window scaling factor provided by GTK3, if it is available (Bug#21348).
* src/gtkutil.h (xg_scale_x_y_with_widget):
* src/gtkutil.c (xg_scale_x_y_with_widget):
Fuction finds scaling factor and performs scaling.
(xg_show_tooltip): Divide position of tooltip by scaling factor.
* src/xmenu.c (create_and_show_popup_menu) [HAVE_GTK3]:
Divide position of native GTK3 menus by scaling factor.
---
 src/gtkutil.c | 14 ++++++++++++++
 src/gtkutil.h |  4 ++++
 src/xmenu.c   |  6 ++++++
 3 files changed, 24 insertions(+)

diff --git a/src/gtkutil.c b/src/gtkutil.c
index 34e81b5..db80b2e 100644
--- a/src/gtkutil.c
+++ b/src/gtkutil.c
@@ -748,6 +748,7 @@ xg_show_tooltip (struct frame *f, int root_x, int root_y)
   if (x->ttip_window)
     {
       block_input ();
+      xg_scale_x_y_with_widget(GTK_WIDGET(x->ttip_window), &root_x, &root_y);
       gtk_window_move (x->ttip_window, root_x, root_y);
       gtk_widget_show_all (GTK_WIDGET (x->ttip_window));
       unblock_input ();
@@ -3223,6 +3224,19 @@ xg_update_submenu (GtkWidget *submenu,
   return newsub;
 }
 
+/* Scale X and Y.
+   WIDGET the gtk widget from which to get the scaling factor */
+void
+xg_scale_x_y_with_widget (GtkWidget *widget,
+                          int *x,
+                          int *y)
+{
+  gint scale_factor = gtk_widget_get_scale_factor(widget);
+  if(x) *x /= scale_factor;
+  if(y) *y /= scale_factor;
+}
+
+
 /* Update the MENUBAR.
    F is the frame the menu bar belongs to.
    VAL describes the contents of the menu bar.
diff --git a/src/gtkutil.h b/src/gtkutil.h
index 34338db..8db063a 100644
--- a/src/gtkutil.h
+++ b/src/gtkutil.h
@@ -96,6 +96,10 @@ extern GtkWidget *xg_create_widget (const char *type,
                                     GCallback deactivate_cb,
                                     GCallback highlight_cb);
 
+extern void xg_scale_x_y_with_widget (GtkWidget *widget,
+                                      int *x,
+                                      int *y);
+
 extern void xg_modify_menubar_widgets (GtkWidget *menubar,
                                        struct frame *f,
                                        struct _widget_value *val,
diff --git a/src/xmenu.c b/src/xmenu.c
index 192ed89..1b7bbb5 100644
--- a/src/xmenu.c
+++ b/src/xmenu.c
@@ -1229,6 +1229,12 @@ create_and_show_popup_menu (struct frame *f, widget_value *first_wv,
 
                              /* Child of win.  */
                              &dummy_window);
+#ifdef HAVE_GTK3
+      /* Use window scaling factor to adjust position for hidpi screens. */
+      xg_scale_x_y_with_widget(GTK_WIDGET(f->output_data.x->ttip_window),
+                               &x,
+                               &y);
+#endif
       unblock_input ();
       popup_x_y.x = x;
       popup_x_y.y = y;
-- 
2.6.1