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gtk2/gdk/gdkdnd.c
Carlos Garnacho 2923f69d3c gdkdnd: Add private means to commit the drag status 
The way gdk_drag_status() may be called multiple times during the
processing of drag and drop events throughout the widget hierarchy
brings some superfluous messaging going in, esp. when it's the last
request the one we want to honor, yet we emit messaging requests on
all.

This is barely appreciable in the X11 backend, but due to the design
of the wayland protocol, quick series of changes like this it have
some self-amplificating consequences which may end up flooding the
connection.

We can delegate this to a late "commit" call, performed within GDK
event management. This way gdk_drag_status() calls may be cached
and only result in windowing messaging once per ::drag-motion or
::drag-data-received event. Emitting the final status will also
avoid spurious action changes on the compositor and the other peer.

https://bugzilla.gnome.org/show_bug.cgi?id=763298
2016-03-14 16:50:36 +01:00

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/* 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"
#include "gdkintl.h"
#include "gdkenumtypes.h"
#include "gdkcursor.h"
static struct {
GdkDragAction action;
const gchar *name;
GdkCursor *cursor;
} drag_cursors[] = {
{ GDK_ACTION_DEFAULT, NULL, NULL },
{ GDK_ACTION_ASK, "dnd-ask", NULL },
{ GDK_ACTION_COPY, "dnd-copy", NULL },
{ GDK_ACTION_MOVE, "dnd-move", NULL },
{ GDK_ACTION_LINK, "dnd-link", NULL },
{ 0, "dnd-none", NULL },
};
enum {
CANCEL,
DROP_PERFORMED,
DND_FINISHED,
ACTION_CHANGED,
N_SIGNALS
};
static guint signals[N_SIGNALS] = { 0 };
static GList *contexts = NULL;
/**
* 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)
{
contexts = g_list_prepend (contexts, context);
}
static void
gdk_drag_context_finalize (GObject *object)
{
GdkDragContext *context = GDK_DRAG_CONTEXT (object);
contexts = g_list_remove (contexts, context);
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;
/**
* GdkDragContext::cancel:
* @context: The object on which the signal is emitted
*
* The drag and drop operation was cancelled.
*
* This signal will only be emitted if the #GdkDragContext manages
* the drag and drop operation. See gdk_drag_context_manage_dnd()
* for more information.
*
* Since: 3.20
*/
signals[CANCEL] =
g_signal_new ("cancel",
G_TYPE_FROM_CLASS (object_class),
G_SIGNAL_RUN_LAST,
G_STRUCT_OFFSET (GdkDragContextClass, cancel),
NULL, NULL,
g_cclosure_marshal_VOID__ENUM,
G_TYPE_NONE, 1, GDK_TYPE_DRAG_CANCEL_REASON);
/**
* GdkDragContext::drop-performed:
* @context: The object on which the signal is emitted
* @time: the time at which the drop happened.
*
* The drag and drop operation was performed on an accepting client.
*
* This signal will only be emitted if the #GdkDragContext manages
* the drag and drop operation. See gdk_drag_context_manage_dnd()
* for more information.
*
* Since: 3.20
*/
signals[DROP_PERFORMED] =
g_signal_new ("drop-performed",
G_TYPE_FROM_CLASS (object_class),
G_SIGNAL_RUN_LAST,
G_STRUCT_OFFSET (GdkDragContextClass, drop_performed),
NULL, NULL,
g_cclosure_marshal_VOID__INT,
G_TYPE_NONE, 1, G_TYPE_INT);
/**
* GdkDragContext::dnd-finished:
* @context: The object on which the signal is emitted
*
* The drag and drop operation was finished, the drag destination
* finished reading all data. The drag source can now free all
* miscellaneous data.
*
* This signal will only be emitted if the #GdkDragContext manages
* the drag and drop operation. See gdk_drag_context_manage_dnd()
* for more information.
*
* Since: 3.20
*/
signals[DND_FINISHED] =
g_signal_new ("dnd-finished",
G_TYPE_FROM_CLASS (object_class),
G_SIGNAL_RUN_LAST,
G_STRUCT_OFFSET (GdkDragContextClass, dnd_finished),
NULL, NULL,
g_cclosure_marshal_VOID__VOID,
G_TYPE_NONE, 0);
/**
* GdkDragContext::action-changed:
* @context: The object on which the signal is emitted
* @action: The action currently chosen
*
* A new action is being chosen for the drag and drop operation.
*
* This signal will only be emitted if the #GdkDragContext manages
* the drag and drop operation. See gdk_drag_context_manage_dnd()
* for more information.
*
* Since: 3.20
*/
signals[ACTION_CHANGED] =
g_signal_new ("action-changed",
G_TYPE_FROM_CLASS (object_class),
G_SIGNAL_RUN_LAST,
G_STRUCT_OFFSET (GdkDragContextClass, action_changed),
NULL, NULL,
g_cclosure_marshal_VOID__FLAGS,
G_TYPE_NONE, 1, GDK_TYPE_DRAG_ACTION);
}
/**
* 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.
*
* This function does not need to be called in managed drag and drop
* operations. See gdk_drag_context_manage_dnd() for more information.
*
* 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.
*
* This function does not need to be called in managed drag and drop
* operations. See gdk_drag_context_manage_dnd() for more information.
*/
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.
*
* This function does not need to be called in managed drag and drop
* operations. See gdk_drag_context_manage_dnd() for more information.
*/
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);
return GDK_DRAG_CONTEXT_GET_CLASS (context)->get_selection (context);
}
/**
* gdk_drag_context_get_drag_window:
* @context: a #GdkDragContext
*
* Returns the window on which the drag icon should be rendered
* during the drag operation. Note that the window may not be
* available until the drag operation has begun. GDK will move
* the window in accordance with the ongoing drag operation.
* The window is owned by @context and will be destroyed when
* the drag operation is over.
*
* Returns: (transfer none): the drag window, or %NULL
*
* Since: 3.20
*/
GdkWindow *
gdk_drag_context_get_drag_window (GdkDragContext *context)
{
g_return_val_if_fail (GDK_IS_DRAG_CONTEXT (context), NULL);
if (GDK_DRAG_CONTEXT_GET_CLASS (context)->get_drag_window)
return GDK_DRAG_CONTEXT_GET_CLASS (context)->get_drag_window (context);
return NULL;
}
/**
* gdk_drag_context_set_hotspot:
* @context: a #GdkDragContext
* @hot_x: x coordinate of the drag window hotspot
* @hot_y: y coordinate of the drag window hotspot
*
* Sets the position of the drag window that will be kept
* under the cursor hotspot. Initially, the hotspot is at the
* top left corner of the drag window.
*
* Since: 3.20
*/
void
gdk_drag_context_set_hotspot (GdkDragContext *context,
gint hot_x,
gint hot_y)
{
g_return_if_fail (GDK_IS_DRAG_CONTEXT (context));
if (GDK_DRAG_CONTEXT_GET_CLASS (context)->set_hotspot)
GDK_DRAG_CONTEXT_GET_CLASS (context)->set_hotspot (context, hot_x, hot_y);
}
/**
* gdk_drag_drop_done:
* @context: a #GdkDragContext
* @success: whether the drag was ultimatively successful
*
* Inform GDK if the drop ended successfully. Passing %FALSE
* for @success may trigger a drag cancellation animation.
*
* This function is called by the drag source, and should
* be the last call before dropping the reference to the
* @context.
*
* The #GdkDragContext will only take the first gdk_drag_drop_done()
* call as effective, if this function is called multiple times,
* all subsequent calls will be ignored.
*
* Since: 3.20
*/
void
gdk_drag_drop_done (GdkDragContext *context,
gboolean success)
{
g_return_if_fail (GDK_IS_DRAG_CONTEXT (context));
if (context->drop_done)
return;
context->drop_done = TRUE;
if (GDK_DRAG_CONTEXT_GET_CLASS (context)->drop_done)
GDK_DRAG_CONTEXT_GET_CLASS (context)->drop_done (context, success);
}
/**
* gdk_drag_context_manage_dnd:
* @context: a #GdkDragContext
* @ipc_window: Window to use for IPC messaging/events
* @actions: the actions supported by the drag source
*
* Requests the drag and drop operation to be managed by @context.
* When a drag and drop operation becomes managed, the #GdkDragContext
* will internally handle all input and source-side #GdkEventDND events
* as required by the windowing system.
*
* Once the drag and drop operation is managed, the drag context will
* emit the following signals:
* - The #GdkDragContext::action-changed signal whenever the final action
* to be performed by the drag and drop operation changes.
* - The #GdkDragContext::drop-performed signal after the user performs
* the drag and drop gesture (typically by releasing the mouse button).
* - The #GdkDragContext::dnd-finished signal after the drag and drop
* operation concludes (after all #GdkSelection transfers happen).
* - The #GdkDragContext::cancel signal if the drag and drop operation is
* finished but doesn't happen over an accepting destination, or is
* cancelled through other means.
*
* Returns: #TRUE if the drag and drop operation is managed.
**/
gboolean
gdk_drag_context_manage_dnd (GdkDragContext *context,
GdkWindow *ipc_window,
GdkDragAction actions)
{
g_return_val_if_fail (GDK_IS_DRAG_CONTEXT (context), FALSE);
g_return_val_if_fail (GDK_IS_WINDOW (ipc_window), FALSE);
if (GDK_DRAG_CONTEXT_GET_CLASS (context)->manage_dnd)
return GDK_DRAG_CONTEXT_GET_CLASS (context)->manage_dnd (context, ipc_window,
actions);
return FALSE;
}
void
gdk_drag_context_set_cursor (GdkDragContext *context,
GdkCursor *cursor)
{
g_return_if_fail (GDK_IS_DRAG_CONTEXT (context));
if (GDK_DRAG_CONTEXT_GET_CLASS (context)->set_cursor)
GDK_DRAG_CONTEXT_GET_CLASS (context)->set_cursor (context, cursor);
}
void
gdk_drag_context_cancel (GdkDragContext *context,
GdkDragCancelReason reason)
{
g_return_if_fail (GDK_IS_DRAG_CONTEXT (context));
g_signal_emit (context, signals[CANCEL], 0, reason);
}
GList *
gdk_drag_context_list (void)
{
return contexts;
}
gboolean
gdk_drag_context_handle_source_event (GdkEvent *event)
{
GdkDragContext *context;
GList *l;
for (l = contexts; l; l = l->next)
{
context = l->data;
if (!context->is_source)
continue;
if (!GDK_DRAG_CONTEXT_GET_CLASS (context)->handle_event)
continue;
if (GDK_DRAG_CONTEXT_GET_CLASS (context)->handle_event (context, event))
return TRUE;
}
return FALSE;
}
GdkCursor *
gdk_drag_get_cursor (GdkDragAction action)
{
gint i;
for (i = 0 ; i < G_N_ELEMENTS (drag_cursors) - 1; i++)
if (drag_cursors[i].action == action)
break;
if (drag_cursors[i].cursor == NULL)
drag_cursors[i].cursor = gdk_cursor_new_from_name (gdk_display_get_default (),
drag_cursors[i].name);
return drag_cursors[i].cursor;
}
static void
gdk_drag_context_commit_drag_status (GdkDragContext *context)
{
GdkDragContextClass *context_class;
g_return_if_fail (GDK_IS_DRAG_CONTEXT (context));
g_return_if_fail (!context->is_source);
context_class = GDK_DRAG_CONTEXT_GET_CLASS (context);
if (context_class->commit_drag_status)
context_class->commit_drag_status (context);
}
gboolean
gdk_drag_context_handle_dest_event (GdkEvent *event)
{
GdkDragContext *context = NULL;
GList *l;
switch (event->type)
{
case GDK_DRAG_MOTION:
case GDK_DROP_START:
context = event->dnd.context;
break;
case GDK_SELECTION_NOTIFY:
for (l = contexts; l; l = l->next)
{
GdkDragContext *c = l->data;
if (!c->is_source &&
event->selection.selection == gdk_drag_get_selection (c))
{
context = c;
break;
}
}
break;
default:
return FALSE;
}
if (!context)
return FALSE;
gdk_drag_context_commit_drag_status (context);
return TRUE;;
}
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