Use scaled coordinates when calling into GTK

This is part two of a two part fix for the GTK scaling
problems.  See the thread starting at
http://lists.gnu.org/archive/html/emacs-devel/2018-01/msg00372.html
for an explanation of why it has been added to Emacs 26.

* src/gtkutil.c (xg_set_geometry): Scale down the coordinates that we
pass to gtk_window_move and to gtk_window_parse_geometry.
* src/xterm.c (x_set_offset): Likewise.

1 files changed, 6 insertions, 3 deletions

diff --git a/src/gtkutil.c b/src/gtkutil.c
index 123236f5f08..83b306a730a 100644
--- a/src/gtkutil.c
+++ b/src/gtkutil.c
@@ -823,6 +823,7 @@ xg_set_geometry (struct frame *f)
 {
   if (f->size_hint_flags & (USPosition | PPosition))
     {
+      int scale = xg_get_scale (f);
 #if ! GTK_CHECK_VERSION (3, 22, 0)
       if (x_gtk_use_window_move)
         {
@@ -838,8 +839,9 @@ xg_set_geometry (struct frame *f)
             f->top_pos = (x_display_pixel_height (FRAME_DISPLAY_INFO (f))
                           - FRAME_PIXEL_HEIGHT (f) + f->top_pos);
 
+          /* GTK works in scaled pixels, so convert from X pixels.  */
           gtk_window_move (GTK_WINDOW (FRAME_GTK_OUTER_WIDGET (f)),
-                           f->left_pos, f->top_pos);
+                           f->left_pos / scale, f->top_pos / scale);
 
           /* Reset size hint flags.  */
           f->size_hint_flags &= ~ (XNegative | YNegative);
@@ -847,9 +849,10 @@ xg_set_geometry (struct frame *f)
         }
       else
         {
-          int left = f->left_pos;
+          /* GTK works in scaled pixels, so convert from X pixels.  */
+          int left = f->left_pos / scale;
           int xneg = f->size_hint_flags & XNegative;
-          int top = f->top_pos;
+          int top = f->top_pos / scale;
           int yneg = f->size_hint_flags & YNegative;
           char geom_str[sizeof "=x--" + 4 * INT_STRLEN_BOUND (int)];
           guint id;