[gtk/wip/baedert/for-master: 4/4] gesturestylus: Only add histroy element if translation succeeded

[Timm Bäder <baedert src gnome org>]

commit cad18166b90c0a63d2032625eafe04f6dde17383
Author: Timm Bäder <mail baedert org>
Date:   Fri Dec 25 10:07:43 2020 +0100

    gesturestylus: Only add histroy element if translation succeeded
    
    Instead of always doing it and then undoing it if the translation does
    not succeed.

 gtk/gtkgesturestylus.c | 18 ++++++++----------
 1 file changed, 8 insertions(+), 10 deletions(-)
---
diff --git a/gtk/gtkgesturestylus.c b/gtk/gtkgesturestylus.c
index 14f5635590..bd90390233 100644
--- a/gtk/gtkgesturestylus.c
+++ b/gtk/gtkgesturestylus.c
@@ -338,24 +338,22 @@ gtk_gesture_stylus_get_backlog (GtkGestureStylus  *gesture,
   controller_widget = gtk_event_controller_get_widget (GTK_EVENT_CONTROLLER (gesture));
   for (i = 0; i < n_coords; i++)
     {
-      GdkTimeCoord *time_coord = &history[i];
+      const GdkTimeCoord *time_coord = &history[i];
       graphene_point_t p;
 
-      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 (event_widget, controller_widget,
                                     &GRAPHENE_POINT_INIT (time_coord->axes[GDK_AXIS_X],
                                                           time_coord->axes[GDK_AXIS_Y]),
                                     &p))
         {
-          time_coord->axes[GDK_AXIS_X] = p.x;
-          time_coord->axes[GDK_AXIS_Y] = p.y;
-        }
-      else
-        {
-          g_array_set_size (backlog_array, backlog_array->len - 1);
+          GdkTimeCoord translated_coord = *time_coord;
+
+          translated_coord.axes[GDK_AXIS_X] = p.x;
+          translated_coord.axes[GDK_AXIS_Y] = p.y;
+
+          g_array_append_val (backlog_array, translated_coord);
         }
-    }
+      }
 
   *n_elems = backlog_array->len;
   *backlog = (GdkTimeCoord *) g_array_free (backlog_array, FALSE);