gtk/gdk/gdkdnd.c

/* GDK - The GIMP Drawing Kit
 * Copyright (C) 1995-1999 Peter Mattis, Spencer Kimball and Josh MacDonald
 *
 * 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 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/>.
 */

/*
 * Modified by the GTK+ Team and others 1997-2000.  See the AUTHORS
 * file for a list of people on the GTK+ Team.  See the ChangeLog
 * files for a list of changes.  These files are distributed with
 * GTK+ at ftp://ftp.gtk.org/pub/gtk/. 
 */

#include "config.h"

#include "gdkdndprivate.h"
#include "gdkdisplay.h"
#include "gdkwindow.h"


/**
 * SECTION:dnd
 * @title: Drag And Drop
 * @short_description: Functions for controlling drag and drop handling
 *
 * These functions provide a low level interface for drag and drop.
 * The X backend of GDK supports both the Xdnd and Motif drag and drop
 * protocols transparently, the Win32 backend supports the WM_DROPFILES
 * protocol.
 *
 * GTK+ provides a higher level abstraction based on top of these functions,
 * and so they are not normally needed in GTK+ applications.
 * See the [Drag and Drop][gtk3-Drag-and-Drop] section of
 * the GTK+ documentation for more information.
 */

/**
 * gdk_drag_context_list_targets:
 * @context: a #GdkDragContext
 *
 * Retrieves the list of targets of the context.
 *
 * Returns: (transfer none) (element-type GdkAtom): a #GList of targets
 *
 * Since: 2.22
 **/
GList *
gdk_drag_context_list_targets (GdkDragContext *context)
{
  g_return_val_if_fail (GDK_IS_DRAG_CONTEXT (context), NULL);

  return context->targets;
}

/**
 * gdk_drag_context_get_actions:
 * @context: a #GdkDragContext
 *
 * Determines the bitmask of actions proposed by the source if
 * gdk_drag_context_get_suggested_action() returns GDK_ACTION_ASK.
 *
 * Returns: the #GdkDragAction flags
 *
 * Since: 2.22
 **/
GdkDragAction
gdk_drag_context_get_actions (GdkDragContext *context)
{
  g_return_val_if_fail (GDK_IS_DRAG_CONTEXT (context), GDK_ACTION_DEFAULT);

  return context->actions;
}

/**
 * gdk_drag_context_get_suggested_action:
 * @context: a #GdkDragContext
 *
 * Determines the suggested drag action of the context.
 *
 * Returns: a #GdkDragAction value
 *
 * Since: 2.22
 **/
GdkDragAction
gdk_drag_context_get_suggested_action (GdkDragContext *context)
{
  g_return_val_if_fail (GDK_IS_DRAG_CONTEXT (context), 0);

  return context->suggested_action;
}

/**
 * gdk_drag_context_get_selected_action:
 * @context: a #GdkDragContext
 *
 * Determines the action chosen by the drag destination.
 *
 * Returns: a #GdkDragAction value
 *
 * Since: 2.22
 **/
GdkDragAction
gdk_drag_context_get_selected_action (GdkDragContext *context)
{
  g_return_val_if_fail (GDK_IS_DRAG_CONTEXT (context), 0);

  return context->action;
}

/**
 * gdk_drag_context_get_source_window:
 * @context: a #GdkDragContext
 *
 * Returns the #GdkWindow where the DND operation started.
 *
 * Returns: (transfer none): a #GdkWindow
 *
 * Since: 2.22
 **/
GdkWindow *
gdk_drag_context_get_source_window (GdkDragContext *context)
{
  g_return_val_if_fail (GDK_IS_DRAG_CONTEXT (context), NULL);

  return context->source_window;
}

/**
 * gdk_drag_context_get_dest_window:
 * @context: a #GdkDragContext
 *
 * Returns the destination windw for the DND operation.
 *
 * Returns: (transfer none): a #GdkWindow
 *
 * Since: 3.0
 **/
GdkWindow *
gdk_drag_context_get_dest_window (GdkDragContext *context)
{
  g_return_val_if_fail (GDK_IS_DRAG_CONTEXT (context), NULL);

  return context->dest_window;
}

/**
 * gdk_drag_context_get_protocol:
 * @context: a #GdkDragContext
 *
 * Returns the drag protocol thats used by this context.
 *
 * Returns: the drag protocol
 *
 * Since: 3.0
 */
GdkDragProtocol
gdk_drag_context_get_protocol (GdkDragContext *context)
{
  g_return_val_if_fail (GDK_IS_DRAG_CONTEXT (context), GDK_DRAG_PROTO_NONE);

  return context->protocol;
}

/**
 * gdk_drag_context_set_device:
 * @context: a #GdkDragContext
 * @device: a #GdkDevice
 *
 * Associates a #GdkDevice to @context, so all Drag and Drop events
 * for @context are emitted as if they came from this device.
 */
void
gdk_drag_context_set_device (GdkDragContext *context,
                             GdkDevice      *device)
{
  g_return_if_fail (GDK_IS_DRAG_CONTEXT (context));
  g_return_if_fail (GDK_IS_DEVICE (device));

  if (context->device)
    g_object_unref (context->device);

  context->device = device;

  if (context->device)
    g_object_ref (context->device);
}

/**
 * gdk_drag_context_get_device:
 * @context: a #GdkDragContext
 *
 * Returns the #GdkDevice associated to the drag context.
 *
 * Returns: (transfer none): The #GdkDevice associated to @context.
 **/
GdkDevice *
gdk_drag_context_get_device (GdkDragContext *context)
{
  g_return_val_if_fail (GDK_IS_DRAG_CONTEXT (context), NULL);

  return context->device;
}

G_DEFINE_TYPE (GdkDragContext, gdk_drag_context, G_TYPE_OBJECT)

static void
gdk_drag_context_init (GdkDragContext *context)
{
}

static void
gdk_drag_context_finalize (GObject *object)
{
  GdkDragContext *context = GDK_DRAG_CONTEXT (object);

  g_list_free (context->targets);

  if (context->source_window)
    g_object_unref (context->source_window);

  if (context->dest_window)
    g_object_unref (context->dest_window);

  G_OBJECT_CLASS (gdk_drag_context_parent_class)->finalize (object);
}

static void
gdk_drag_context_class_init (GdkDragContextClass *klass)
{
  GObjectClass *object_class = G_OBJECT_CLASS (klass);

  object_class->finalize = gdk_drag_context_finalize;
}

/**
 * gdk_drag_find_window_for_screen:
 * @context: a #GdkDragContext
 * @drag_window: a window which may be at the pointer position, but
 *     should be ignored, since it is put up by the drag source as an icon
 * @screen: the screen where the destination window is sought
 * @x_root: the x position of the pointer in root coordinates
 * @y_root: the y position of the pointer in root coordinates
 * @dest_window: (out): location to store the destination window in
 * @protocol: (out): location to store the DND protocol in
 *
 * Finds the destination window and DND protocol to use at the
 * given pointer position.
 *
 * This function is called by the drag source to obtain the
 * @dest_window and @protocol parameters for gdk_drag_motion().
 *
 * Since: 2.2
 */
void
gdk_drag_find_window_for_screen (GdkDragContext  *context,
                                 GdkWindow       *drag_window,
                                 GdkScreen       *screen,
                                 gint             x_root,
                                 gint             y_root,
                                 GdkWindow      **dest_window,
                                 GdkDragProtocol *protocol)
{
  g_return_if_fail (GDK_IS_DRAG_CONTEXT (context));

  *dest_window = GDK_DRAG_CONTEXT_GET_CLASS (context)
      ->find_window (context, drag_window, screen, x_root, y_root, protocol);
}

/**
 * gdk_drag_status:
 * @context: a #GdkDragContext
 * @action: the selected action which will be taken when a drop happens,
 *    or 0 to indicate that a drop will not be accepted
 * @time_: the timestamp for this operation
 *
 * Selects one of the actions offered by the drag source.
 *
 * This function is called by the drag destination in response to
 * gdk_drag_motion() called by the drag source.
 */
void
gdk_drag_status (GdkDragContext *context,
                 GdkDragAction   action,
                 guint32         time_)
{
  g_return_if_fail (GDK_IS_DRAG_CONTEXT (context));

  GDK_DRAG_CONTEXT_GET_CLASS (context)->drag_status (context, action, time_);
}

/**
 * gdk_drag_motion:
 * @context: a #GdkDragContext
 * @dest_window: the new destination window, obtained by
 *     gdk_drag_find_window()
 * @protocol: the DND protocol in use, obtained by gdk_drag_find_window()
 * @x_root: the x position of the pointer in root coordinates
 * @y_root: the y position of the pointer in root coordinates
 * @suggested_action: the suggested action
 * @possible_actions: the possible actions
 * @time_: the timestamp for this operation
 *
 * Updates the drag context when the pointer moves or the
 * set of actions changes.
 *
 * This function is called by the drag source.
 *
 * Returns:
 */
gboolean
gdk_drag_motion (GdkDragContext *context,
                 GdkWindow      *dest_window,
                 GdkDragProtocol protocol,
                 gint            x_root,
                 gint            y_root,
                 GdkDragAction   suggested_action,
                 GdkDragAction   possible_actions,
                 guint32         time_)
{
  g_return_val_if_fail (GDK_IS_DRAG_CONTEXT (context), FALSE);

  return GDK_DRAG_CONTEXT_GET_CLASS (context)
       ->drag_motion (context,
                      dest_window,
                      protocol,
                      x_root,
                      y_root,
                      suggested_action,
                      possible_actions,
                      time_);
}

/**
 * gdk_drag_abort:
 * @context: a #GdkDragContext
 * @time_: the timestamp for this operation
 *
 * Aborts a drag without dropping.
 *
 * This function is called by the drag source.
 */
void
gdk_drag_abort (GdkDragContext *context,
                guint32         time_)
{
  g_return_if_fail (GDK_IS_DRAG_CONTEXT (context));

  GDK_DRAG_CONTEXT_GET_CLASS (context)->drag_abort (context, time_);
}

/**
 * gdk_drag_drop:
 * @context: a #GdkDragContext
 * @time_: the timestamp for this operation
 *
 * Drops on the current destination.
 *
 * This function is called by the drag source.
 */
void
gdk_drag_drop (GdkDragContext *context,
               guint32         time_)
{
  g_return_if_fail (GDK_IS_DRAG_CONTEXT (context));

  GDK_DRAG_CONTEXT_GET_CLASS (context)->drag_drop (context, time_);
}

/**
 * gdk_drop_reply:
 * @context: a #GdkDragContext
 * @accepted: %TRUE if the drop is accepted
 * @time_: the timestamp for this operation
 *
 * Accepts or rejects a drop.
 *
 * This function is called by the drag destination in response
 * to a drop initiated by the drag source.
 */
void
gdk_drop_reply (GdkDragContext *context,
                gboolean        accepted,
                guint32         time_)
{
  g_return_if_fail (GDK_IS_DRAG_CONTEXT (context));

  GDK_DRAG_CONTEXT_GET_CLASS (context)->drop_reply (context, accepted, time_);
}

/**
 * gdk_drop_finish:
 * @context: a #GdkDragContext
 * @success: %TRUE if the data was successfully received
 * @time_: the timestamp for this operation
 *
 * Ends the drag operation after a drop.
 *
 * This function is called by the drag destination.
 */
void
gdk_drop_finish (GdkDragContext *context,
                 gboolean        success,
                 guint32         time_)
{
  g_return_if_fail (GDK_IS_DRAG_CONTEXT (context));

  GDK_DRAG_CONTEXT_GET_CLASS (context)->drop_finish (context, success, time_);
}

/**
 * gdk_drag_drop_succeeded:
 * @context: a #GdkDragContext
 *
 * Returns whether the dropped data has been successfully
 * transferred. This function is intended to be used while
 * handling a %GDK_DROP_FINISHED event, its return value is
 * meaningless at other times.
 *
 * Returns: %TRUE if the drop was successful.
 *
 * Since: 2.6
 **/
gboolean
gdk_drag_drop_succeeded (GdkDragContext *context)
{
  g_return_val_if_fail (GDK_IS_DRAG_CONTEXT (context), FALSE);

  return GDK_DRAG_CONTEXT_GET_CLASS (context)->drop_status (context);
}

/**
 * gdk_drag_get_selection:
 * @context: a #GdkDragContext.
 *
 * Returns the selection atom for the current source window.
 *
 * Returns: (transfer none): the selection atom, or %GDK_NONE
 */
GdkAtom
gdk_drag_get_selection (GdkDragContext *context)
{
  g_return_val_if_fail (GDK_IS_DRAG_CONTEXT (context), GDK_NONE);
  g_return_val_if_fail (context->source_window != NULL, GDK_NONE);

  return GDK_DRAG_CONTEXT_GET_CLASS (context)->get_selection (context);
}