[gtk/dnd-gestures-2: 9/14] dragdest: Steps towards allowing nested drop sites

[Matthias Clasen <matthiasc src gnome org>]

commit 449b0258ab48d89fe107f02f4ac14497537f60f0
Author: Matthias Clasen <mclasen redhat com>
Date:   Wed Jan 8 00:25:51 2020 -0500

    dragdest: Steps towards allowing nested drop sites

 gtk/gtkdragdest.c | 99 ++++++++++++++++++++++++-------------------------------
 1 file changed, 43 insertions(+), 56 deletions(-)
---
diff --git a/gtk/gtkdragdest.c b/gtk/gtkdragdest.c
index 7af2f36914..26ffa3e8e2 100644
--- a/gtk/gtkdragdest.c
+++ b/gtk/gtkdragdest.c
@@ -514,15 +514,9 @@ gtk_drop_target_drag_motion (GtkDropTarget *dest,
   target = gtk_drop_target_match (dest, drop);
 
   if (actions && target)
-    {
-      gdk_drop_status (drop, dest_actions);
-      gtk_drop_target_set_contains (dest, TRUE);
-    }
+    gdk_drop_status (drop, dest_actions);
   else
-    {
-      gdk_drop_status (drop, 0);
-      gtk_drop_target_set_contains (dest, FALSE);
-    }
+    gdk_drop_status (drop, 0);
 
   return TRUE;
 }
@@ -550,7 +544,6 @@ gtk_drop_target_emit_drag_leave (GtkDropTarget    *dest,
   set_drop (dest, drop);
   g_signal_emit (dest, signals[DRAG_LEAVE], 0, drop, time);
   set_drop (dest, NULL);
-  gtk_drop_target_set_contains (dest, FALSE);
 }
 
 static gboolean
@@ -561,14 +554,9 @@ gtk_drop_target_emit_drag_motion (GtkDropTarget    *dest,
 {
   gboolean result = FALSE;
 
-  dest->contains_pending = TRUE;
-
   set_drop (dest, drop);
   g_signal_emit (dest, signals[DRAG_MOTION], 0, drop, x, y, &result);
 
-  if (dest->contains_pending)
-    gtk_drop_target_set_contains (dest, result);
-
   return result;
 }
 
@@ -590,22 +578,11 @@ static void
 gtk_drop_target_set_contains (GtkDropTarget *dest,
                               gboolean       contains)
 {
-  GtkWidget *widget;
-
-  widget = gtk_event_controller_get_widget (GTK_EVENT_CONTROLLER (dest));
-
-  dest->contains_pending = FALSE;
-
   if (dest->contains == contains)
     return;
 
   dest->contains = contains;
 
-  if (contains)
-    gtk_widget_set_state_flags (widget, GTK_STATE_FLAG_DROP_ACTIVE, FALSE);
-  else
-    gtk_widget_unset_state_flags (widget, GTK_STATE_FLAG_DROP_ACTIVE);
-
   g_object_notify_by_pspec (G_OBJECT (dest), properties[PROP_CONTAINS]);
 }
 
@@ -639,27 +616,55 @@ clear_current_dest (gpointer data, GObject *former_object)
   g_object_set_data (G_OBJECT (data), "current-dest", NULL);
 }
 
+static void
+unset_current_dest (gpointer data)
+{
+  GtkDropTarget *dest = data;
+  GtkWidget *widget = gtk_event_controller_get_widget (GTK_EVENT_CONTROLLER (dest));
+
+  gtk_drop_target_set_contains (dest, FALSE);
+  if (widget)
+    gtk_widget_unset_state_flags (widget, GTK_STATE_FLAG_DROP_ACTIVE);
+}
+
 static void
 gtk_drop_set_current_dest (GdkDrop       *drop,
                            GtkDropTarget *dest)
 {
   GtkDropTarget *old_dest;
+  GtkWidget *widget;
 
   old_dest = g_object_get_data (G_OBJECT (drop), "current-dest");
 
+  if (old_dest == dest)
+    return;
+
+g_print ("set current dest %p\n", dest);
   if (old_dest)
-    g_object_weak_unref (G_OBJECT (old_dest), clear_current_dest, drop);
+    {
+      gtk_drop_target_set_contains (old_dest, FALSE);
+
+      widget = gtk_event_controller_get_widget (GTK_EVENT_CONTROLLER (old_dest));
+      if (widget)
+        gtk_widget_unset_state_flags (widget, GTK_STATE_FLAG_DROP_ACTIVE);
+
+      gtk_drop_target_emit_drag_leave (old_dest, drop);
+
+      g_object_weak_unref (G_OBJECT (old_dest), clear_current_dest, drop);
+    }
 
-  g_object_set_data (G_OBJECT (drop), "current-dest", dest);
+  g_object_set_data_full (G_OBJECT (drop), "current-dest", dest, unset_current_dest);
 
   if (dest)
-    g_object_weak_ref (G_OBJECT (dest), clear_current_dest, drop);
-}
+    {
+      g_object_weak_ref (G_OBJECT (dest), clear_current_dest, drop);
 
-static GtkDropTarget *
-gtk_drop_get_current_dest (GdkDrop *drop)
-{
-  return g_object_get_data (G_OBJECT (drop), "current-dest");
+      widget = gtk_event_controller_get_widget (GTK_EVENT_CONTROLLER (dest));
+      if (widget)
+        gtk_widget_set_state_flags (widget, GTK_STATE_FLAG_DROP_ACTIVE, FALSE);
+
+      gtk_drop_target_set_contains (dest, TRUE);
+    }
 }
 
 static gboolean
@@ -668,14 +673,12 @@ gtk_drop_target_handle_event (GtkEventController *controller,
 {
   GtkDropTarget *dest = GTK_DROP_TARGET (controller);
   GdkDrop *drop;
-  GtkDropTarget *old_dest;
   double x, y;
   gboolean found = FALSE;
 
   gdk_event_get_coords (event, &x, &y);
 
   drop = gdk_event_get_drop (event);
-  old_dest = gtk_drop_get_current_dest (drop);
 
   switch ((int)gdk_event_get_event_type (event))
     {
@@ -684,14 +687,6 @@ gtk_drop_target_handle_event (GtkEventController *controller,
       break;
 
     case GDK_DROP_START:
-      /* We send a leave before the drop so that the widget unhighlights properly.
-       */
-      if (old_dest)
-        {
-          gtk_drop_target_emit_drag_leave (old_dest, drop);
-          gtk_drop_set_current_dest (drop, NULL);
-        }
-
       found = gtk_drop_target_emit_drag_drop (dest, drop, x, y);
       break;
 
@@ -701,12 +696,7 @@ gtk_drop_target_handle_event (GtkEventController *controller,
 
   if (found)
     {
-      if (old_dest && old_dest != dest)
-        {
-          gtk_drop_target_emit_drag_leave (old_dest, drop);
-          gtk_drop_set_current_dest (drop, NULL);
-        }
-
+      g_print ("setting dest from event controller handle_event\n");
       gtk_drop_set_current_dest (drop, dest);
     }
 
@@ -721,7 +711,6 @@ void
 gtk_drag_dest_handle_event (GtkWidget *toplevel,
                             GdkEvent  *event)
 {
-  GtkDropTarget *dest;
   GdkDrop *drop;
   GdkEventType event_type;
 
@@ -737,16 +726,14 @@ gtk_drag_dest_handle_event (GtkWidget *toplevel,
       break;
 
     case GDK_DRAG_LEAVE:
-      dest = gtk_drop_get_current_dest (drop);
-      if (dest)
-        {
-          gtk_drop_target_emit_drag_leave (dest, drop);
-          gtk_drop_set_current_dest (drop, NULL);
-        }
+      g_print ("setting dest from fallback handle_event for LEAVE\n");
+      gtk_drop_set_current_dest (drop, NULL);
       break;
 
     case GDK_DRAG_MOTION:
     case GDK_DROP_START:
+      g_print ("setting dest from fallback handle_event for MOTION or START\n");
+      gtk_drop_set_current_dest (drop, NULL);
       gdk_drop_status (drop, 0);
       break;