wayland: scale down reported monitor geometry

According to the documentation, gdk_monitor_get_geometry() reports the
monitor geometry in ”application pixels”, not in ”device pixels”,
meaning that the actual device resolution needs to be scaled down by the
scale factor of the output.

x11 backend does that downscaling, whereas Wayland backend did not,
causing a discrepancy depending on the backend used.

https://bugzilla.gnome.org/show_bug.cgi?id=783995

diff --git a/gdk/wayland/gdkscreen-wayland.c b/gdk/wayland/gdkscreen-wayland.c
index af2e2e28ab3214fe6d0d1e091ca3b1e39c0649cb..b939fef1a054652e99abc588f4b2871ad64d3b01 100644 (file)
--- a/gdk/wayland/gdkscreen-wayland.c
+++ b/gdk/wayland/gdkscreen-wayland.c
@@ -754,11 +754,22 @@ output_handle_scale (void             *data,
                      int32_t           scale)
 {
   GdkWaylandMonitor *monitor = (GdkWaylandMonitor *)data;
+  GdkRectangle previous_geometry;
+  int previous_scale;
+  int width;
+  int height;
 
   GDK_NOTE (MISC,
             g_message ("handle scale output %d, scale %d", monitor->id, scale));
 
+  gdk_monitor_get_geometry (GDK_MONITOR (monitor), &previous_geometry);
+  previous_scale = gdk_monitor_get_scale_factor (GDK_MONITOR (monitor));
+
+  width = previous_geometry.width * previous_scale;
+  height = previous_geometry.height * previous_scale;
+
   gdk_monitor_set_scale_factor (GDK_MONITOR (monitor), scale);
+  gdk_monitor_set_size (GDK_MONITOR (monitor), width / scale, height / scale);
 
   if (GDK_MONITOR (monitor)->geometry.width != 0 && monitor->version < OUTPUT_VERSION_WITH_DONE)
     {
@@ -776,6 +787,7 @@ output_handle_mode (void             *data,
                     int               refresh)
 {
   GdkWaylandMonitor *monitor = (GdkWaylandMonitor *)data;
+  int scale;
 
   GDK_NOTE (MISC,
             g_message ("handle mode output %d, size %d %d, rate %d",
@@ -784,7 +796,8 @@ output_handle_mode (void             *data,
   if ((flags & WL_OUTPUT_MODE_CURRENT) == 0)
     return;
 
-  gdk_monitor_set_size (GDK_MONITOR (monitor), width, height);
+  scale = gdk_monitor_get_scale_factor (GDK_MONITOR (monitor));
+  gdk_monitor_set_size (GDK_MONITOR (monitor), width / scale, height / scale);
   gdk_monitor_set_refresh_rate (GDK_MONITOR (monitor), refresh);
 
   if (width != 0 && monitor->version < OUTPUT_VERSION_WITH_DONE)