[gtk/dnd-gestures-2: 74/175] Simplify some drag dest internals

[Matthias Clasen <matthiasc src gnome org>]

commit 7fdaf1a01cae4bf4030f5ab71b2c06dc31ab7a1c
Author: Matthias Clasen <mclasen redhat com>
Date:   Sun Jan 5 15:54:46 2020 -0500

    Simplify some drag dest internals
    
    Change things around to make the default handler
    of GtkDropTarget::drag-motion implement the default
    handling. Always emit ::drag-motion and ::drag-leave,
    and always arm the drop target.
    
    This makes the GTK_DEST_DEFAULT_MOTION flag and
    the ::track-motion property unnecessary.
    
    Drop targets that are purely after track-motion
    handling for ui switching purposes, such as
    GtkStackSwitcher, will have to undo the automatic
    arming in a notify::armed handler.

 gtk/gtkdnd.c      | 59 ++++-------------------------------------
 gtk/gtkdragdest.c | 78 ++++++++++++++++++++++++++++++++++++++++++++-----------
 2 files changed, 68 insertions(+), 69 deletions(-)
---
diff --git a/gtk/gtkdnd.c b/gtk/gtkdnd.c
index 5e31546b89..d11d94928a 100644
--- a/gtk/gtkdnd.c
+++ b/gtk/gtkdnd.c
@@ -341,26 +341,16 @@ gtk_drag_get_dest_info (GdkDrop  *drop,
  * Default drag handlers
  */
 static void  
-gtk_drag_dest_leave (GtkWidget      *widget,
-                     GdkDrop        *drop,
-                     guint           time)
+gtk_drag_dest_leave (GtkWidget *widget,
+                     GdkDrop   *drop,
+                     guint      time)
 {
   GtkDropTarget *dest;
-  GtkDestDefaults flags;
-  gboolean track_motion;
-  gboolean armed;
 
   dest = gtk_drop_target_get (widget);
   g_return_if_fail (dest != NULL);
 
-  flags = gtk_drop_target_get_defaults (dest);
-  track_motion = gtk_drop_target_get_track_motion (dest);
-  armed = gtk_drop_target_get_armed (dest);
-
-  if (!(flags & GTK_DEST_DEFAULT_MOTION) || armed || track_motion)
-    gtk_drop_target_emit_drag_leave (dest, drop, time);
-  
-  gtk_drop_target_set_armed (dest, FALSE);
+  gtk_drop_target_emit_drag_leave (dest, drop, time);
 }
 
 static gboolean
@@ -371,46 +361,11 @@ gtk_drag_dest_motion (GtkWidget *widget,
                       guint      time)
 {
   GtkDropTarget *dest;
-  GdkDragAction dest_actions;
-  GtkDestDefaults flags;
-  gboolean track_motion;
-  gboolean retval;
 
   dest = gtk_drop_target_get (widget);
   g_return_val_if_fail (dest != NULL, FALSE);
 
-  dest_actions = gtk_drop_target_get_actions (dest);
-  flags = gtk_drop_target_get_defaults (dest);
-  track_motion = gtk_drop_target_get_track_motion (dest);
-
-  if (track_motion || flags & GTK_DEST_DEFAULT_MOTION)
-    {
-      GdkDragAction actions;
-      GdkAtom target;
-      
-      actions = gdk_drop_get_actions (drop);
-
-      if ((dest_actions & actions) == 0)
-        actions = 0;
-
-      target = gtk_drop_target_match (dest, drop);
-
-      if (actions && target)
-        {
-          gtk_drop_target_set_armed (dest, TRUE);
-          gdk_drop_status (drop, dest_actions);
-        }
-      else
-        {
-          gdk_drop_status (drop, 0);
-          if (!track_motion)
-            return TRUE;
-        }
-    }
-
-  retval = gtk_drop_target_emit_drag_motion (dest, drop, x, y);
-
-  return (flags & GTK_DEST_DEFAULT_MOTION) ? TRUE : retval;
+  return gtk_drop_target_emit_drag_motion (dest, drop, x, y);
 }
 
 static gboolean
@@ -421,13 +376,9 @@ gtk_drag_dest_drop (GtkWidget *widget,
                     guint      time)
 {
   GtkDropTarget *dest;
-  GtkDragDestInfo *info;
 
   dest = gtk_drop_target_get (widget);
   g_return_val_if_fail (dest != NULL, FALSE);
 
-  info = gtk_drag_get_dest_info (drop, FALSE);
-  g_return_val_if_fail (info != NULL, FALSE);
-
   return gtk_drop_target_emit_drag_drop (dest, drop, x, y);
 }
diff --git a/gtk/gtkdragdest.c b/gtk/gtkdragdest.c
index 0c1b86c10e..8fcffc52d2 100644
--- a/gtk/gtkdragdest.c
+++ b/gtk/gtkdragdest.c
@@ -56,16 +56,21 @@ struct _GtkDropTarget
   GdkContentFormats *formats;
   GdkDragAction actions;
   GtkDestDefaults defaults;
-  gboolean track_motion;
 
   GtkWidget *widget;
   GdkDrop *drop;
+  gboolean track_motion;
   gboolean armed;
+  gboolean armed_pending;
 };
 
 struct _GtkDropTargetClass
 {
   GObjectClass parent_class;
+
+  gboolean (*drag_motion) (GtkDropTarget *dest,
+                           int            x,
+                           int            y);
 };
 
 enum {
@@ -89,6 +94,10 @@ enum {
 
 static guint signals[NUM_SIGNALS];
 
+static gboolean gtk_drop_target_drag_motion (GtkDropTarget *dest,
+                                             int            x,
+                                             int            y);
+
 G_DEFINE_TYPE (GtkDropTarget, gtk_drop_target, G_TYPE_OBJECT);
 
 static void
@@ -182,6 +191,8 @@ gtk_drop_target_class_init (GtkDropTargetClass *class)
   object_class->set_property = gtk_drop_target_set_property;
   object_class->get_property = gtk_drop_target_get_property;
 
+  class->drag_motion = gtk_drop_target_drag_motion;
+
   /**
    * GtkDropTarget:formats:
    *
@@ -271,15 +282,15 @@ gtk_drop_target_class_init (GtkDropTargetClass *class)
    * handler is responsible for providing the necessary information for
    * displaying feedback to the user, by calling gdk_drag_status().
    *
+   * The default handler for this signal decides whether to accept the drop
+   * based on the type of the data.
+   *
    * If the decision whether the drop will be accepted or rejected can't be
    * made based solely on the cursor position and the type of the data, the
    * handler may inspect the dragged data by calling one of the #GdkDrop
    * read functions, and defer the gdk_drag_status() call to when it has
    * received the data.
    *
-   * Note that you must pass #GTK_DEST_DEFAULT_MOTION to gtk_drop_target_attach()
-   * when using the ::drag-motion signal that way.
-   *
    * Also note that there is no drag-enter signal. The drag receiver has to
    * keep track of whether he has received any drag-motion signals since the
    * last #GtkWidget::drag-leave and if not, treat the drag-motion signal as
@@ -292,8 +303,8 @@ gtk_drop_target_class_init (GtkDropTargetClass *class)
       g_signal_new (I_("drag-motion"),
                     G_TYPE_FROM_CLASS (class),
                     G_SIGNAL_RUN_LAST,
-                    0,
-                    NULL, NULL,
+                    G_STRUCT_OFFSET (GtkDropTargetClass, drag_motion),
+                    g_signal_accumulator_first_wins, NULL,
                     NULL,
                     G_TYPE_BOOLEAN, 2,
                     G_TYPE_INT, G_TYPE_INT);
@@ -671,6 +682,35 @@ gtk_drop_target_find_mimetype (GtkDropTarget *dest)
   return gtk_drop_target_match (dest, dest->drop);
 }
 
+static gboolean
+gtk_drop_target_drag_motion (GtkDropTarget *dest,
+                             int            x,
+                             int            y)
+{
+  GdkDrop *drop = dest->drop;
+  GdkDragAction dest_actions;
+  GdkDragAction actions;
+  GdkAtom target;
+
+  dest_actions = gtk_drop_target_get_actions (dest);
+
+  actions = dest_actions & gdk_drop_get_actions (drop);
+  target = gtk_drop_target_match (dest, drop);
+
+  if (actions && target)
+    {
+      gdk_drop_status (drop, dest_actions);
+      gtk_drop_target_set_armed (dest, TRUE);
+    }
+  else
+    {
+      gdk_drop_status (drop, 0);
+      gtk_drop_target_set_armed (dest, FALSE);
+    }
+
+  return TRUE;
+}
+
 static void
 set_drop (GtkDropTarget *dest,
           GdkDrop       *drop)
@@ -695,6 +735,7 @@ gtk_drop_target_emit_drag_leave (GtkDropTarget    *dest,
   set_drop (dest, drop);
   g_signal_emit (dest, signals[DRAG_LEAVE], 0, time);
   set_drop (dest, NULL);
+  gtk_drop_target_set_armed (dest, FALSE);
 }
 
 gboolean
@@ -705,9 +746,14 @@ gtk_drop_target_emit_drag_motion (GtkDropTarget    *dest,
 {
   gboolean result = FALSE;
 
+  dest->armed_pending = TRUE;
+
   set_drop (dest, drop);
   g_signal_emit (dest, signals[DRAG_MOTION], 0, x, y, &result);
 
+  if (dest->armed_pending)
+    gtk_drop_target_set_armed (dest, result);
+
   return result;
 }
 
@@ -726,29 +772,31 @@ gtk_drop_target_emit_drag_drop (GtkDropTarget    *dest,
 }
 
 void
-gtk_drop_target_set_armed (GtkDropTarget *target,
+gtk_drop_target_set_armed (GtkDropTarget *dest,
                            gboolean       armed)
 {
-  if (target->armed == armed)
+  dest->armed_pending = FALSE;
+
+  if (dest->armed == armed)
     return;
 
-  target->armed = armed;
+  dest->armed = armed;
 
-  if (target->widget)
+  if (dest->widget)
     {
       if (armed)
-        gtk_drag_highlight (target->widget);
+        gtk_drag_highlight (dest->widget);
       else
-        gtk_drag_unhighlight (target->widget);
+        gtk_drag_unhighlight (dest->widget);
     }
 
-  g_object_notify_by_pspec (G_OBJECT (target), properties[PROP_ARMED]);
+  g_object_notify_by_pspec (G_OBJECT (dest), properties[PROP_ARMED]);
 }
 
 gboolean
-gtk_drop_target_get_armed (GtkDropTarget *target)
+gtk_drop_target_get_armed (GtkDropTarget *dest)
 {
-  return target->armed;
+  return dest->armed;
 }
 
 /**