Learning_GTK4_tree/gdk/gdkdragsurface.c

122 lines
3.5 KiB
C

/*
* Copyright © 2020 Red Hat, Inc.
*
* 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: Matthias Clasen <mclasen@redhat.com>
*/
#include "config.h"
#include "gdkprivate.h"
#include "gdkdragsurfaceprivate.h"
#include <glib/gi18n-lib.h>
/**
* GdkDragSurface:
*
* A `GdkDragSurface` is an interface for surfaces used during DND.
*/
/**
* GdkDragSurfaceInterface:
*
* The `GdkDragSurfaceInterface` implementation is private to GDK.
*/
G_DEFINE_INTERFACE (GdkDragSurface, gdk_drag_surface, GDK_TYPE_SURFACE)
enum
{
COMPUTE_SIZE,
N_SIGNALS
};
static guint signals[N_SIGNALS] = { 0 };
void
gdk_drag_surface_notify_compute_size (GdkDragSurface *surface,
GdkDragSurfaceSize *size)
{
g_signal_emit (surface, signals[COMPUTE_SIZE], 0, size);
}
static gboolean
gdk_drag_surface_default_present (GdkDragSurface *drag_surface,
int width,
int height)
{
return FALSE;
}
static void
gdk_drag_surface_default_init (GdkDragSurfaceInterface *iface)
{
iface->present = gdk_drag_surface_default_present;
/**
* GdkDragSurface::compute-size:
* @surface: a `GdkDragSurface`
* @size: (type Gdk.DragSurfaceSize): the size of the drag surface
*
* Emitted when the size for the surface needs to be computed, when it is
* present.
*
* This signal will normally be emitted during the native surface layout
* cycle when the surface size needs to be recomputed.
*
* It is the responsibility of the drag surface user to handle this signal
* and compute the desired size of the surface, storing the computed size
* in the [struct@Gdk.DragSurfaceSize] object that is passed to the signal
* handler, using [method@Gdk.DragSurfaceSize.set_size].
*
* Failing to set a size so will result in an arbitrary size being used as
* a result.
*
* Since: 4.12
*/
signals[COMPUTE_SIZE] =
g_signal_new (I_("compute-size"),
GDK_TYPE_DRAG_SURFACE,
G_SIGNAL_RUN_LAST,
0,
NULL, NULL,
NULL,
G_TYPE_NONE, 1,
GDK_TYPE_DRAG_SURFACE_SIZE);
}
/**
* gdk_drag_surface_present:
* @drag_surface: the `GdkDragSurface` to show
* @width: the unconstrained drag_surface width to layout
* @height: the unconstrained drag_surface height to layout
*
* Present @drag_surface.
*
* Returns: %FALSE if it failed to be presented, otherwise %TRUE.
*/
gboolean
gdk_drag_surface_present (GdkDragSurface *drag_surface,
int width,
int height)
{
g_return_val_if_fail (GDK_IS_DRAG_SURFACE (drag_surface), FALSE);
g_return_val_if_fail (width > 0, FALSE);
g_return_val_if_fail (height > 0, FALSE);
return GDK_DRAG_SURFACE_GET_IFACE (drag_surface)->present (drag_surface, width, height);
}