[gtk/dnd-gestures-2: 170/242] Use normal event propagation for DND events

[Matthias Clasen <matthiasc src gnome org>]

commit 35c779ba4cb61f7ea0a891d08133108dedf9e757
Author: Matthias Clasen <mclasen redhat com>
Date:   Sun Jan 5 23:49:22 2020 -0500

    Use normal event propagation for DND events
    
    This works just fine, now that drop targets are
    event controllers. There is only a very vestigial
    gtk_drag_dest_handle_event() left that deals with
    corner cases.

 gtk/gtkdnd.c        | 104 ++++------------------------------------------------
 gtk/gtkdndprivate.h |   4 +-
 gtk/gtkmain.c       |  67 ++++++++++++++++++++++++++++-----
 gtk/gtkmain.h       |   2 +-
 gtk/gtkprivate.h    |   2 +-
 5 files changed, 68 insertions(+), 111 deletions(-)
---
diff --git a/gtk/gtkdnd.c b/gtk/gtkdnd.c
index 1ebbf9666a..5bb5b45190 100644
--- a/gtk/gtkdnd.c
+++ b/gtk/gtkdnd.c
@@ -62,23 +62,19 @@
  * Drop API makes use of signals in the #GtkWidget class.
  */
 
-
-/* Forward declarations */
-static gboolean gtk_drop_find_widget            (GtkWidget        *widget,
-                                                 GdkEvent         *event);
-
-
 /*
- * _gtk_drag_dest_handle_event:
+ * gtk_drag_dest_handle_event:
  * @toplevel: Toplevel widget that received the event
  * @event: the event to handle
  *
  * Called from widget event handling code on Drag events
- * for destinations.
+ * for destinations. For drag-motion and drop-start events,
+ * this function is only called if no event handler has
+ * handled the event.
  */
 void
-_gtk_drag_dest_handle_event (GtkWidget *toplevel,
-                             GdkEvent  *event)
+gtk_drag_dest_handle_event (GtkWidget *toplevel,
+                            GdkEvent  *event)
 {
   GtkDropTarget *dest;
   GdkDrop *drop;
@@ -107,10 +103,7 @@ _gtk_drag_dest_handle_event (GtkWidget *toplevel,
 
     case GDK_DRAG_MOTION:
     case GDK_DROP_START:
-      {
-        if (!gtk_drop_find_widget (toplevel, event))
-          gdk_drop_status (drop, 0);
-      }
+      gdk_drop_status (drop, 0);
       break;
 
     default:
@@ -118,89 +111,6 @@ _gtk_drag_dest_handle_event (GtkWidget *toplevel,
     }
 }
 
-static gboolean
-gtk_drop_find_widget (GtkWidget *event_widget,
-                      GdkEvent  *event)
-{
-  GtkWidget *widget;
-  double x, y;
-  int wx, wy;
-
-  if (!gtk_widget_get_mapped (event_widget) ||
-      !gtk_widget_get_sensitive (event_widget))
-    return FALSE;
-
-  gdk_event_get_coords (event, &x, &y);
-
-  widget = gtk_widget_pick (event_widget, x, y, GTK_PICK_DEFAULT);
-
-  if (!widget)
-    return FALSE;
-
-  gtk_widget_translate_coordinates (event_widget, widget, x, y, &wx, &wy);
-
-  while (widget)
-    {
-      GtkWidget *parent;
-      GList *hierarchy = NULL;
-      gboolean found = FALSE;
-
-      if (!gtk_widget_get_mapped (widget))
-        return FALSE;
-
-      if (gtk_widget_get_state_flags (widget) & GTK_STATE_FLAG_INSENSITIVE)
-        {
-          widget = gtk_widget_get_parent (widget);
-          continue;
-        }
-
-      /* need to reference the entire hierarchy temporarily in case the
-       * ::drag-motion/::drag-drop callbacks change the widget hierarchy.
-       */
-      for (parent = widget;
-           parent;
-           parent = gtk_widget_get_parent (parent))
-        {
-          hierarchy = g_list_prepend (hierarchy, g_object_ref (parent));
-        }
-
-      gdk_event_set_coords (event, wx, wy);
-      found = gtk_widget_run_controllers (widget, event, GTK_PHASE_BUBBLE);
-      gdk_event_set_coords (event, x, y);
-
-      if (!found)
-        {
-          /* Get the parent before unreffing the hierarchy because
-           * invoking the callback might have destroyed the widget
-           */
-          parent = gtk_widget_get_parent (widget);
-
-          /* The parent might be going away when unreffing the
-           * hierarchy, so also protect againt that
-           */
-          if (parent)
-            g_object_add_weak_pointer (G_OBJECT (parent), (gpointer *) &parent);
-        }
-
-      g_list_free_full (hierarchy, g_object_unref);
-
-      if (found)
-        return TRUE;
-
-      if (parent)
-        g_object_remove_weak_pointer (G_OBJECT (parent), (gpointer *) &parent);
-      else
-        return FALSE;
-
-      if (!gtk_widget_translate_coordinates (widget, parent, wx, wy, &wx, &wy))
-        return FALSE;
-
-      widget = parent;
-    }
-
-  return FALSE;
-}
-
 static void
 clear_current_dest (gpointer data, GObject *former_object)
 {
diff --git a/gtk/gtkdndprivate.h b/gtk/gtkdndprivate.h
index a520b1cf08..4de9a173d5 100644
--- a/gtk/gtkdndprivate.h
+++ b/gtk/gtkdndprivate.h
@@ -25,8 +25,8 @@
 
 G_BEGIN_DECLS
 
-void           _gtk_drag_dest_handle_event (GtkWidget     *toplevel,
-                                           GdkEvent      *event);
+void           gtk_drag_dest_handle_event (GtkWidget     *toplevel,
+                                           GdkEvent      *event);
 
 void           gtk_drop_set_current_dest (GdkDrop       *drop,
                                           GtkDropTarget *dest);
diff --git a/gtk/gtkmain.c b/gtk/gtkmain.c
index fe5868a95d..504fe53382 100644
--- a/gtk/gtkmain.c
+++ b/gtk/gtkmain.c
@@ -1676,6 +1676,20 @@ is_focus_event (GdkEvent *event)
     }
 }
 
+static gboolean
+is_dnd_event (GdkEvent *event)
+{
+  switch ((guint) event->any.type)
+    {
+    case GDK_DRAG_ENTER:
+    case GDK_DRAG_LEAVE:
+    case GDK_DRAG_MOTION:
+    case GDK_DROP_START:
+      return TRUE;
+    default:
+      return FALSE;
+    }
+}
 
 static inline void
 set_widget_active_state (GtkWidget       *target,
@@ -1818,6 +1832,25 @@ handle_key_event (GdkEvent *event)
   return focus_widget ? focus_widget : event_widget;
 }
 
+static GtkWidget *
+handle_dnd_event (GdkEvent *event)
+{
+  GtkWidget *event_widget;
+  GtkWidget *target;
+  gdouble x, y;
+  GtkWidget *native;
+
+  event_widget = gtk_get_event_widget (event);
+
+  if (!gdk_event_get_coords (event, &x, &y))
+    return event_widget;
+
+  native = GTK_WIDGET (gtk_widget_get_native (event_widget));
+  target = gtk_widget_pick (native, x, y, GTK_PICK_DEFAULT);
+
+  return target;
+}
+
 /**
  * gtk_main_do_event:
  * @event: An event to process (normally passed by GDK)
@@ -1914,6 +1947,8 @@ gtk_main_do_event (GdkEvent *event)
           goto cleanup;
         }
     }
+  else if (is_dnd_event (event))
+    target_widget = handle_dnd_event (event);
 
   if (!target_widget)
     goto cleanup;
@@ -2028,12 +2063,17 @@ gtk_main_do_event (GdkEvent *event)
       /* Crossing event propagation happens during picking */
       break;
 
-    case GDK_DRAG_ENTER:
-    case GDK_DRAG_LEAVE:
     case GDK_DRAG_MOTION:
     case GDK_DROP_START:
-      _gtk_drag_dest_handle_event (target_widget, event);
+      if (gtk_propagate_event (target_widget, event))
+        break;
+      G_GNUC_FALLTHROUGH;
+
+    case GDK_DRAG_ENTER:
+    case GDK_DRAG_LEAVE:
+      gtk_drag_dest_handle_event (target_widget, event);
       break;
+
     case GDK_EVENT_LAST:
     default:
       g_assert_not_reached ();
@@ -2623,14 +2663,19 @@ propagate_event_down (GtkWidget *widget,
   return handled_event;
 }
 
-void
+gboolean
 gtk_propagate_event_internal (GtkWidget *widget,
                               GdkEvent  *event,
                               GtkWidget *topmost)
 {
   /* Propagate the event down and up */
-  if (!propagate_event_down (widget, event, topmost))
-    propagate_event_up (widget, event, topmost);
+  if (propagate_event_down (widget, event, topmost))
+    return TRUE;
+
+  if (propagate_event_up (widget, event, topmost))
+    return TRUE;
+
+  return FALSE;
 }
 
 /**
@@ -2657,8 +2702,10 @@ gtk_propagate_event_internal (GtkWidget *widget,
  * certainly better ways to achieve your goals. For example, use
  * gtk_widget_queue_draw() instead
  * of making up expose events.
+ *
+ * Returns: %TRUE if the event was handled
  */
-void
+gboolean
 gtk_propagate_event (GtkWidget *widget,
                      GdkEvent  *event)
 {
@@ -2666,8 +2713,8 @@ gtk_propagate_event (GtkWidget *widget,
   GtkWidget *event_widget, *topmost = NULL;
   GdkDevice *device;
 
-  g_return_if_fail (GTK_IS_WIDGET (widget));
-  g_return_if_fail (event != NULL);
+  g_return_val_if_fail (GTK_IS_WIDGET (widget), FALSE);
+  g_return_val_if_fail (event != NULL, FALSE);
 
   event_widget = gtk_get_event_widget (event);
   window_group = gtk_main_get_window_group (event_widget);
@@ -2679,5 +2726,5 @@ gtk_propagate_event (GtkWidget *widget,
   if (!topmost)
     topmost = gtk_window_group_get_current_grab (window_group);
 
-  gtk_propagate_event_internal (widget, event, topmost);
+  return gtk_propagate_event_internal (widget, event, topmost);
 }
diff --git a/gtk/gtkmain.h b/gtk/gtkmain.h
index 81c1e574ad..0009c4d90e 100644
--- a/gtk/gtkmain.h
+++ b/gtk/gtkmain.h
@@ -160,7 +160,7 @@ GtkWidget *gtk_get_event_target_with_type (GdkEvent *event,
                                            GType     type);
 
 GDK_AVAILABLE_IN_ALL
-void       gtk_propagate_event          (GtkWidget       *widget,
+gboolean   gtk_propagate_event          (GtkWidget       *widget,
                                          GdkEvent        *event);
 
 
diff --git a/gtk/gtkprivate.h b/gtk/gtkprivate.h
index 2732f064c8..38dfe92a31 100644
--- a/gtk/gtkprivate.h
+++ b/gtk/gtkprivate.h
@@ -90,7 +90,7 @@ gboolean _gtk_translate_keyboard_accel_state   (GdkKeymap       *keymap,
                                                 gint            *level,
                                                 GdkModifierType *consumed_modifiers);
 
-void             gtk_propagate_event_internal  (GtkWidget       *widget,
+gboolean         gtk_propagate_event_internal  (GtkWidget       *widget,
                                                 GdkEvent        *event,
                                                 GtkWidget       *topmost);