dnd: Add GdkDrop base class for GdkDragContext

The ultimate goal of this patch series is to split GdkDragContext into
GdkDrop + GdkDrag classes for the destination and source side of a dnd
operation.

The refactoring is meant to work something like this:
1. Introduce GdkDrop as a base class
2. Make all drop related code (like GdkEvent) use GdkDrop instead of
   GdkDragContext. Move/duplicate APIs to allow that.
3. Port all drop contexts in the backends from GdkDragContext to GdkDrop
4. Delete all APIs in GdkDragContext that aren't needed anymore.
5. Make GdkDragContext no longer a GdkDrop subclass
6. Rename GdkDragContext to GdkDrag

gdk/gdk.h

@@ -46,6 +46,7 @@
 #include <gdk/gdkdisplaymanager.h>
 #include <gdk/gdkdnd.h>
 #include <gdk/gdkdrawcontext.h>
+#include <gdk/gdkdrop.h>
 #include <gdk/gdkenumtypes.h>
 #include <gdk/gdkevents.h>
 #include <gdk/gdkframeclock.h>

gdk/gdkdnd.c

@@ -35,12 +35,16 @@
 #include "gdkenumtypes.h"
 #include "gdkeventsprivate.h"
 
+#define DROP_SUBCLASS 1
+
 typedef struct _GdkDragContextPrivate GdkDragContextPrivate;
 
 struct _GdkDragContextPrivate 
 {
+#ifndef DROP_SUBCLASS
   GdkDisplay *display;
   GdkDevice *device;
+#endif
   GdkContentFormats *formats;
 };
 
@@ -60,9 +64,11 @@ static struct {
 enum {
   PROP_0,
   PROP_CONTENT,
+#ifndef DROP_SUBCLASS
   PROP_DEVICE,
   PROP_DISPLAY,
   PROP_FORMATS,
+#endif
   N_PROPERTIES
 };
 
@@ -78,7 +84,7 @@ static GParamSpec *properties[N_PROPERTIES] = { NULL, };
 static guint signals[N_SIGNALS] = { 0 };
 static GList *contexts = NULL;
 
-G_DEFINE_TYPE_WITH_PRIVATE (GdkDragContext, gdk_drag_context, G_TYPE_OBJECT)
+G_DEFINE_TYPE_WITH_PRIVATE (GdkDragContext, gdk_drag_context, GDK_TYPE_DROP)
 
 /**
  * SECTION:dnd
@@ -114,11 +120,15 @@ G_DEFINE_TYPE_WITH_PRIVATE (GdkDragContext, gdk_drag_context, G_TYPE_OBJECT)
 GdkDisplay *
 gdk_drag_context_get_display (GdkDragContext *context)
 {
+#ifdef DROP_SUBCLASS
+  return gdk_drop_get_display (GDK_DROP (context));
+#else
   GdkDragContextPrivate *priv = gdk_drag_context_get_instance_private (context);
 
   g_return_val_if_fail (GDK_IS_DRAG_CONTEXT (context), NULL);
 
   return priv->display;
+#endif
 }
 
 /**
@@ -136,6 +146,12 @@ gdk_drag_context_get_formats (GdkDragContext *context)
 
   g_return_val_if_fail (GDK_IS_DRAG_CONTEXT (context), NULL);
 
+#ifdef DROP_SUBCLASS
+  GdkContentFormats *formats = gdk_drop_get_formats (GDK_DROP (context));
+
+  if (formats)
+    return formats;
+#endif
   return priv->formats;
 }
 
@@ -231,11 +247,15 @@ gdk_drag_context_get_dest_surface (GdkDragContext *context)
 GdkDevice *
 gdk_drag_context_get_device (GdkDragContext *context)
 {
+#ifdef DROP_SUBCLASS
+  return gdk_drop_get_device (GDK_DROP (context));
+#else
   GdkDragContextPrivate *priv = gdk_drag_context_get_instance_private (context);
 
   g_return_val_if_fail (GDK_IS_DRAG_CONTEXT (context), NULL);
 
   return priv->device;
+#endif
 }
 
 static void
@@ -264,6 +284,7 @@ gdk_drag_context_set_property (GObject      *gobject,
         }
       break;
 
+#ifndef DROP_SUBCLASS
     case PROP_DEVICE:
       priv->device = g_value_dup_object (value);
       g_assert (priv->device != NULL);
@@ -286,6 +307,7 @@ gdk_drag_context_set_property (GObject      *gobject,
           g_assert (priv->formats != NULL);
         }
       break;
+#endif
 
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID (gobject, prop_id, pspec);
@@ -300,7 +322,9 @@ gdk_drag_context_get_property (GObject    *gobject,
                                GParamSpec *pspec)
 {
   GdkDragContext *context = GDK_DRAG_CONTEXT (gobject);
+#ifndef DROP_SUBCLASS
   GdkDragContextPrivate *priv = gdk_drag_context_get_instance_private (context);
+#endif
 
   switch (prop_id)
     {
@@ -308,6 +332,7 @@ gdk_drag_context_get_property (GObject    *gobject,
       g_value_set_object (value, context->content);
       break;
 
+#ifndef DROP_SUBCLASS
     case PROP_DEVICE:
       g_value_set_object (value, priv->device);
       break;
@@ -319,6 +344,7 @@ gdk_drag_context_get_property (GObject    *gobject,
     case PROP_FORMATS:
       g_value_set_boxed (value, priv->formats);
       break;
+#endif
 
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID (gobject, prop_id, pspec);
@@ -405,6 +431,7 @@ gdk_drag_context_class_init (GdkDragContextClass *klass)
                          G_PARAM_STATIC_STRINGS |
                          G_PARAM_EXPLICIT_NOTIFY);
 
+#ifndef DROP_SUBCLASS
   /**
    * GdkDragContext:device:
    *
@@ -448,6 +475,7 @@ gdk_drag_context_class_init (GdkDragContextClass *klass)
                         G_PARAM_CONSTRUCT_ONLY |
                         G_PARAM_STATIC_STRINGS |
                         G_PARAM_EXPLICIT_NOTIFY);
+#endif
 
   /**
    * GdkDragContext::cancel:

gdk/gdkdndprivate.h

@@ -20,6 +20,8 @@
 
 #include "gdkdnd.h"
 
+#include "gdkdropprivate.h"
+
 G_BEGIN_DECLS
 
 
@@ -31,7 +33,7 @@ typedef struct _GdkDragContextClass GdkDragContextClass;
 
 
 struct _GdkDragContextClass {
-  GObjectClass parent_class;
+  GdkDropClass parent_class;
 
   void        (*drag_status)   (GdkDragContext  *context,
                                 GdkDragAction    action,
@@ -77,7 +79,7 @@ struct _GdkDragContextClass {
 };
 
 struct _GdkDragContext {
-  GObject parent_instance;
+  GdkDrop parent_instance;
 
   /*< private >*/
   gboolean is_source;

gdk/gdkdrop.c

@@ -0,0 +1,242 @@
+/*
+ * Copyright © 2018 Benjamin Otte
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Authors: Benjamin Otte <otte@gnome.org>
+ */
+
+#include "config.h"
+
+#include "gdkdndprivate.h"
+#include "gdkdisplay.h"
+#include "gdksurface.h"
+#include "gdkintl.h"
+#include "gdkcontentformats.h"
+#include "gdkcontentprovider.h"
+#include "gdkcontentserializer.h"
+#include "gdkcursor.h"
+#include "gdkenumtypes.h"
+#include "gdkeventsprivate.h"
+
+typedef struct _GdkDropPrivate GdkDropPrivate;
+
+struct _GdkDropPrivate {
+  GdkDevice *device;
+  GdkContentFormats *formats;
+};
+
+enum {
+  PROP_0,
+  PROP_DEVICE,
+  PROP_DISPLAY,
+  PROP_FORMATS,
+  N_PROPERTIES
+};
+
+static GParamSpec *properties[N_PROPERTIES] = { NULL, };
+
+G_DEFINE_TYPE_WITH_PRIVATE (GdkDrop, gdk_drop, G_TYPE_OBJECT)
+
+/**
+ * GdkDrop:
+ *
+ * The GdkDrop struct contains only private fields and
+ * should not be accessed directly.
+ */
+
+static void
+gdk_drop_init (GdkDrop *self)
+{
+}
+
+static void
+gdk_drop_set_property (GObject      *gobject,
+                       guint         prop_id,
+                       const GValue *value,
+                       GParamSpec   *pspec)
+{
+  GdkDrop *self = GDK_DROP (gobject);
+  GdkDropPrivate *priv = gdk_drop_get_instance_private (self);
+
+  switch (prop_id)
+    {
+    case PROP_DEVICE:
+      priv->device = g_value_dup_object (value);
+      g_assert (priv->device != NULL);
+      break;
+
+    case PROP_FORMATS:
+      priv->formats = g_value_dup_boxed (value);
+#ifdef DROP_SUBCLASS
+      g_assert (priv->formats != NULL);
+#endif
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (gobject, prop_id, pspec);
+      break;
+    }
+}
+
+static void
+gdk_drop_get_property (GObject    *gobject,
+                       guint       prop_id,
+                       GValue     *value,
+                       GParamSpec *pspec)
+{
+  GdkDrop *self = GDK_DROP (gobject);
+  GdkDropPrivate *priv = gdk_drop_get_instance_private (self);
+
+  switch (prop_id)
+    {
+    case PROP_DEVICE:
+      g_value_set_object (value, priv->device);
+      break;
+
+    case PROP_DISPLAY:
+      g_value_set_object (value, gdk_device_get_display (priv->device));
+      break;
+
+    case PROP_FORMATS:
+      g_value_set_boxed (value, priv->formats);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (gobject, prop_id, pspec);
+      break;
+    }
+}
+
+static void
+gdk_drop_finalize (GObject *object)
+{
+  GdkDrop *self = GDK_DROP (object);
+  GdkDropPrivate *priv = gdk_drop_get_instance_private (self);
+
+  g_clear_object (&priv->device);
+
+  G_OBJECT_CLASS (gdk_drop_parent_class)->finalize (object);
+}
+
+static void
+gdk_drop_class_init (GdkDropClass *klass)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
+
+  object_class->get_property = gdk_drop_get_property;
+  object_class->set_property = gdk_drop_set_property;
+  object_class->finalize = gdk_drop_finalize;
+
+  /**
+   * GdkDrop:device:
+   *
+   * The #GdkDevice performing the drop
+   */
+  properties[PROP_DEVICE] =
+    g_param_spec_object ("device",
+                         "Device",
+                         "The device performing the drop",
+                         GDK_TYPE_DEVICE,
+                         G_PARAM_READWRITE |
+                         G_PARAM_CONSTRUCT_ONLY |
+                         G_PARAM_STATIC_STRINGS |
+                         G_PARAM_EXPLICIT_NOTIFY);
+
+  /**
+   * GdkDrop:display:
+   *
+   * The #GdkDisplay that the drop belongs to.
+   */
+  properties[PROP_DISPLAY] =
+    g_param_spec_object ("display",
+                         "Display",
+                         "Display this drag belongs to",
+                         GDK_TYPE_DISPLAY,
+                         G_PARAM_READABLE |
+                         G_PARAM_STATIC_STRINGS |
+                         G_PARAM_EXPLICIT_NOTIFY);
+
+  /**
+   * GdkDrop:formats:
+   *
+   * The possible formats that the drop can provide its data in.
+   */
+  properties[PROP_FORMATS] =
+    g_param_spec_boxed ("formats",
+                        "Formats",
+                        "The possible formats for data",
+                        GDK_TYPE_CONTENT_FORMATS,
+                        G_PARAM_READWRITE |
+                        G_PARAM_CONSTRUCT_ONLY |
+                        G_PARAM_STATIC_STRINGS |
+                        G_PARAM_EXPLICIT_NOTIFY);
+  g_object_class_install_properties (object_class, N_PROPERTIES, properties);
+}
+
+/**
+ * gdk_drop_get_display:
+ * @self: a #GdkDrop
+ *
+ * Gets the #GdkDisplay that @self was created for.
+ *
+ * Returns: (transfer none): a #GdkDisplay
+ **/
+GdkDisplay *
+gdk_drop_get_display (GdkDrop *self)
+{
+  GdkDropPrivate *priv = gdk_drop_get_instance_private (self);
+
+  g_return_val_if_fail (GDK_IS_DROP (self), NULL);
+
+  return gdk_device_get_display (priv->device);
+}
+
+/**
+ * gdk_drop_get_device:
+ * @self: a #GdkDrop
+ *
+ * Returns the #GdkDevice performing the drop.
+ *
+ * Returns: (transfer none): The #GdkDevice performing the drop.
+ **/
+GdkDevice *
+gdk_drop_get_device (GdkDrop *self)
+{
+  GdkDropPrivate *priv = gdk_drop_get_instance_private (self);
+
+  g_return_val_if_fail (GDK_IS_DROP (self), NULL);
+
+  return priv->device;
+}
+
+/**
+ * gdk_drop_get_formats:
+ * @self: a #GdkDrop
+ *
+ * Returns the #GdkContentFormats that the drop offers the data
+ * to be read in.
+ *
+ * Returns: (transfer none): The possible #GdkContentFormats
+ **/
+GdkContentFormats *
+gdk_drop_get_formats (GdkDrop *self)
+{
+  GdkDropPrivate *priv = gdk_drop_get_instance_private (self);
+
+  g_return_val_if_fail (GDK_IS_DROP (self), NULL);
+
+  return priv->formats;
+}
+

gdk/gdkdrop.h

@@ -0,0 +1,51 @@
+/*
+ * Copyright © 2018 Benjamin Otte
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Authors: Benjamin Otte <otte@gnome.org>
+ */
+
+
+#ifndef __GDK_DROP_H__
+#define __GDK_DROP_H__
+
+#if !defined (__GDK_H_INSIDE__) && !defined (GDK_COMPILATION)
+#error "Only <gdk/gdk.h> can be included directly."
+#endif
+
+#include <gdk/gdktypes.h>
+#include <gdk/gdkversionmacros.h>
+
+G_BEGIN_DECLS
+
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GdkDrop, g_object_unref)
+
+#define GDK_TYPE_DROP              (gdk_drop_get_type ())
+#define GDK_DROP(object)           (G_TYPE_CHECK_INSTANCE_CAST ((object), GDK_TYPE_DROP, GdkDrop))
+#define GDK_IS_DROP(object)        (G_TYPE_CHECK_INSTANCE_TYPE ((object), GDK_TYPE_DROP))
+
+GDK_AVAILABLE_IN_ALL
+GType                   gdk_drop_get_type               (void) G_GNUC_CONST;
+
+GDK_AVAILABLE_IN_ALL
+GdkDisplay *            gdk_drop_get_display            (GdkDrop                *self);
+GDK_AVAILABLE_IN_ALL
+GdkDevice *             gdk_drop_get_device             (GdkDrop                *self);
+GDK_AVAILABLE_IN_ALL
+GdkContentFormats *     gdk_drop_get_formats            (GdkDrop                *self);
+
+G_END_DECLS
+
+#endif /* __GDK_DROP_H__ */

gdk/gdkdropprivate.h

@@ -0,0 +1,46 @@
+/*
+ * Copyright © 2018 Benjamin Otte
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Authors: Benjamin Otte <otte@gnome.org>
+ */
+
+#ifndef __GDK_DROP_PRIVATE_H__
+#define __GDK_DROP_PRIVATE_H__
+
+#include "gdkdrop.h"
+
+G_BEGIN_DECLS
+
+
+#define GDK_DROP_CLASS(klass)      (G_TYPE_CHECK_CLASS_CAST ((klass), GDK_TYPE_DROP, GdkDropClass))
+#define GDK_IS_DROP_CLASS(klass)   (G_TYPE_CHECK_CLASS_TYPE ((klass), GDK_TYPE_DROP))
+#define GDK_DROP_GET_CLASS(obj)    (G_TYPE_INSTANCE_GET_CLASS ((obj), GDK_TYPE_DROP, GdkDropClass))
+
+typedef struct _GdkDropClass GdkDropClass;
+
+
+struct _GdkDrop {
+  GObject parent_instance;
+};
+
+struct _GdkDropClass {
+  GObjectClass parent_class;
+};
+
+
+G_END_DECLS
+
+#endif

gdk/gdktypes.h

@@ -124,6 +124,7 @@ typedef struct _GdkCursor             GdkCursor;
 typedef struct _GdkTexture            GdkTexture;
 typedef struct _GdkDevice             GdkDevice;
 typedef struct _GdkDragContext        GdkDragContext;
+typedef struct _GdkDrop               GdkDrop;
 
 typedef struct _GdkClipboard          GdkClipboard;
 typedef struct _GdkDisplayManager     GdkDisplayManager;

gdk/meson.build

@@ -17,6 +17,7 @@ gdk_public_sources = files([
   'gdkdisplaymanager.c',
   'gdkdnd.c',
   'gdkdrawcontext.c',
+  'gdkdrop.c',
   'gdkevents.c',
   'gdkframeclock.c',
   'gdkframeclockidle.c',
@@ -66,6 +67,7 @@ gdk_public_headers = files([
   'gdkdisplaymanager.h',
   'gdkdnd.h',
   'gdkdrawcontext.h',
+  'gdkdrop.h',
   'gdkevents.h',
   'gdkframeclock.h',
   'gdkframetimings.h',

testsuite/gtk/notify.c

@@ -419,6 +419,15 @@ test_type (gconstpointer data)
                                NULL);
       gdk_content_formats_unref (formats);
     }
+  else if (g_str_equal (g_type_name (type), "GdkDrop"))
+    {
+      GdkContentFormats *formats = gdk_content_formats_new_for_gtype (G_TYPE_STRING);
+      instance = g_object_new (type,
+                               "device", gdk_seat_get_pointer (gdk_display_get_default_seat (gdk_display_get_default ())),
+                               "formats", formats,
+                               NULL);
+      gdk_content_formats_unref (formats);
+    }
   else
     instance = g_object_new (type, NULL);
 

testsuite/gtk/objects-finalize.c

@@ -54,7 +54,8 @@ test_finalize_object (gconstpointer data)
 
   if (g_str_equal (g_type_name (test_type), "GdkClipboard"))
     object = g_object_new (test_type, "display", gdk_display_get_default (), NULL);
-  else if (g_str_equal (g_type_name (test_type), "GdkDragContext"))
+  else if (g_str_equal (g_type_name (test_type), "GdkDragContext") ||
+           g_str_equal (g_type_name (test_type), "GdkDrop"))
     {
       GdkContentFormats *formats = gdk_content_formats_new_for_gtype (G_TYPE_STRING);
       object = g_object_new (test_type,