gtk/gesturestylus: Convert motion history from surface coordinates

Motion history coordinates are based on GdkSurface coordinates. Transform
the coordinates from the GtkNative they are received on, accounting for the
possible transforms (e.g. due to window borders and shadows).

Fixes: https://gitlab.gnome.org/GNOME/gtk/-/issues/3491

diff --git a/gtk/gtkgesturestylus.c b/gtk/gtkgesturestylus.c
index bd6238f3a8e1ecbd03619f0b19e215f15efe56f6..2d49783baf399e821c9e3fee1025af052b9e4ecb 100644 (file)
--- a/gtk/gtkgesturestylus.c
+++ b/gtk/gtkgesturestylus.c
@@ -35,6 +35,7 @@
 #include "gtkintl.h"
 #include "gtkmarshalers.h"
 #include "gtkmain.h"
+#include "gtknative.h"
 
 G_DEFINE_TYPE (GtkGestureStylus, gtk_gesture_stylus, GTK_TYPE_GESTURE_SINGLE)
 
@@ -319,6 +320,8 @@ gtk_gesture_stylus_get_backlog (GtkGestureStylus  *gesture,
   GArray *backlog_array;
   GdkTimeCoord *history = NULL;
   guint n_coords = 0, i;
+  double surf_x, surf_y;
+  GtkNative *native;
 
   g_return_val_if_fail (GTK_IS_GESTURE_STYLUS (gesture), FALSE);
   g_return_val_if_fail (backlog != NULL && n_elems != NULL, FALSE);
@@ -331,6 +334,9 @@ gtk_gesture_stylus_get_backlog (GtkGestureStylus  *gesture,
   if (!history)
     return FALSE;
 
+  native = gtk_widget_get_native (gtk_get_event_widget (event));
+  gtk_native_get_surface_transform (native, &surf_x, &surf_y);
+
   backlog_array = g_array_new (FALSE, FALSE, sizeof (GdkTimeCoord));
   for (i = 0; i < n_coords; i++)
     {
@@ -339,10 +345,11 @@ gtk_gesture_stylus_get_backlog (GtkGestureStylus  *gesture,
 
       g_array_append_val (backlog_array, *time_coord);
       time_coord = &g_array_index (backlog_array, GdkTimeCoord, backlog_array->len - 1);
-      if (gtk_widget_compute_point (gtk_get_event_widget (event),
+
+      if (gtk_widget_compute_point (GTK_WIDGET (native),
                                     gtk_event_controller_get_widget (GTK_EVENT_CONTROLLER (gesture)),
-                                    &GRAPHENE_POINT_INIT (time_coord->axes[GDK_AXIS_X],
-                                                          time_coord->axes[GDK_AXIS_Y]),
+                                    &GRAPHENE_POINT_INIT (time_coord->axes[GDK_AXIS_X] - surf_x,
+                                                          time_coord->axes[GDK_AXIS_Y] - surf_y),
                                     &p))
         {
           time_coord->axes[GDK_AXIS_X] = p.x;