dragsource: Reshuffle api a bit

Remove arguments from the constructor.

For actions, we now default to COPY, which is the most common one
that we should enable by default (MOVE requires handling deletion
on the the source side, and ASK only makes sense if we have
multiple actions).

For the content provider, we add a new ::prepare signal where
it should be provided just-in-time.

1 files changed, 30 insertions, 17 deletions

diff --git a/gtk/gtkdragsource.c b/gtk/gtkdragsource.c
index 6fa40897f4..68a0a344df 100644
--- a/gtk/gtkdragsource.c
+++ b/gtk/gtkdragsource.c
@@ -107,6 +107,7 @@ enum {
 static GParamSpec *properties[NUM_PROPERTIES];
 
 enum {
+  PREPARE,
   DRAG_BEGIN,
   DRAG_END,
   DRAG_FAILED,
@@ -115,11 +116,21 @@ enum {
 
 static guint signals[NUM_SIGNALS];
 
+static void gtk_drag_source_dnd_finished_cb   (GdkDrag             *drag,
+                                               GtkDragSource       *source);
+static void gtk_drag_source_drop_performed_cb (GdkDrag             *drag,
+                                               GtkDragSource       *source);
+static void gtk_drag_source_cancel_cb         (GdkDrag             *drag,
+                                               GdkDragCancelReason  reason,
+                                               GtkDragSource       *source);
+
+
 G_DEFINE_TYPE (GtkDragSource, gtk_drag_source, G_TYPE_OBJECT);
 
 static void
 gtk_drag_source_init (GtkDragSource *source)
 {
+  source->actions = GDK_ACTION_COPY;
 }
 
 static void
@@ -216,11 +227,21 @@ gtk_drag_source_class_init (GtkDragSourceClass *class)
        g_param_spec_flags ("actions",
                            P_("Actions"),
                            P_("Supported actions"),
-                           GDK_TYPE_DRAG_ACTION, 0,
+                           GDK_TYPE_DRAG_ACTION, GDK_ACTION_COPY,
                            G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS | G_PARAM_EXPLICIT_NOTIFY);
 
   g_object_class_install_properties (object_class, NUM_PROPERTIES, properties);
 
+  signals[PREPARE] =
+      g_signal_new (I_("prepare"),
+                    G_TYPE_FROM_CLASS (class),
+                    G_SIGNAL_RUN_LAST,
+                    0,
+                    NULL, NULL,
+                    NULL,
+                    G_TYPE_NONE, 2,
+                    G_TYPE_DOUBLE, G_TYPE_DOUBLE);
+
   /**
    * GtkDragSource::drag-begin:
    * @source: the #GtkDragSource
@@ -287,14 +308,6 @@ gtk_drag_source_class_init (GtkDragSourceClass *class)
                     GDK_TYPE_DRAG_CANCEL_REASON);
 }
 
-static void gtk_drag_source_dnd_finished_cb   (GdkDrag             *drag,
-                                               GtkDragSource       *source);
-static void gtk_drag_source_drop_performed_cb (GdkDrag             *drag,
-                                               GtkDragSource       *source);
-static void gtk_drag_source_cancel_cb         (GdkDrag             *drag,
-                                               GdkDragCancelReason  reason,
-                                               GtkDragSource       *source);
-
 static void
 drag_end (GtkDragSource *source,
           gboolean       success)
@@ -390,7 +403,13 @@ gtk_drag_source_drag_begin (GtkDragSource *source,
   dx = round (px) - x;
   dy = round (py) - y;
 
+  g_signal_emit (source, signals[PREPARE], 0, x, y);
+
+  if (source->content == NULL || source->actions == 0)
+    return;
+
   source->drag = gdk_drag_begin (surface, device, source->content, source->actions, dx, dy);
+
   if (source->drag == NULL)
     {
       g_print ("no drag :(\n");
@@ -439,21 +458,15 @@ gtk_drag_source_drag_begin (GtkDragSource *source,
 
 /**
  * gtk_drag_source_new:
- * @content: (nullable): the #GdkContentProvider to use, or %NULL
- * @actions: the actions to offer
  *
  * Creates a new #GtkDragSource object.
  *
  * Returns: the new #GtkDragSource
  */
 GtkDragSource *
-gtk_drag_source_new (GdkContentProvider *content,
-                     GdkDragAction       actions)
+gtk_drag_source_new (void)
 {
-  return g_object_new (GTK_TYPE_DRAG_SOURCE,
-                       "content", content,
-                       "actions", actions,
-                       NULL);
+  return g_object_new (GTK_TYPE_DRAG_SOURCE, NULL);
 }
 
 /**