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Add GdkDrawingContext

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Instead of giving out Cairo contexts, GdkWindow should provide a
"drawing context", which can then create Cairo contexts on demand; this
allows us to future proof the API for when we're going to use a
different rendering pipeline, like OpenGL.

https://bugzilla.gnome.org/show_bug.cgi?id=766675
This commit is contained in:
Emmanuele Bassi
2016-05-30 09:44:30 +01:00
parent 2c7b21718f
commit a7ef37da2a
10 changed files with 453 additions and 21 deletions
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275
gdk/gdkdrawingcontext.c Normal file
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/* GDK - The GIMP Drawing Kit
* Copyright 2016 Endless
*
* 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/>.
*/
/**
* SECTION:gdkdrawingcontext
* @Title: GdkDrawingContext
* @Short_description: Drawing context for GDK windows
*
* #GdkDrawingContext is an object that represents the current drawing
* state of a #GdkWindow.
*
* It's possible to use a #GdkDrawingContext to draw on a #GdkWindow
* via rendering API like Cairo or OpenGL.
*
* A #GdkDrawingContext can only be created by calling gdk_window_begin_draw_frame()
* and will be valid until a call to gdk_window_end_draw_frame().
*
* #GdkDrawingContext is available since GDK 3.22
*/
#include "config.h"
#include <cairo-gobject.h>
#include "gdkdrawingcontextprivate.h"
#include "gdkrectangle.h"
#include "gdkinternals.h"
#include "gdkintl.h"
#include "gdkframeclockidle.h"
#include "gdkwindowimpl.h"
#include "gdkglcontextprivate.h"
#include "gdk-private.h"
G_DEFINE_TYPE (GdkDrawingContext, gdk_drawing_context, G_TYPE_OBJECT)
enum {
PROP_0,
PROP_WINDOW,
PROP_CLIP,
N_PROPS
};
static GParamSpec *obj_property[N_PROPS];
static void
gdk_drawing_context_dispose (GObject *gobject)
{
GdkDrawingContext *self = GDK_DRAWING_CONTEXT (gobject);
g_clear_object (&self->window);
g_clear_pointer (&self->clip, cairo_region_destroy);
g_clear_pointer (&self->cr, cairo_destroy);
G_OBJECT_CLASS (gdk_drawing_context_parent_class)->dispose (gobject);
}
static void
gdk_drawing_context_set_property (GObject *gobject,
guint prop_id,
const GValue *value,
GParamSpec *pspec)
{
GdkDrawingContext *self = GDK_DRAWING_CONTEXT (gobject);
switch (prop_id)
{
case PROP_WINDOW:
self->window = g_value_dup_object (value);
break;
case PROP_CLIP:
self->clip = g_value_dup_boxed (value);
break;
default:
G_OBJECT_WARN_INVALID_PROPERTY_ID (gobject, prop_id, pspec);
}
}
static void
gdk_drawing_context_get_property (GObject *gobject,
guint prop_id,
GValue *value,
GParamSpec *pspec)
{
GdkDrawingContext *self = GDK_DRAWING_CONTEXT (gobject);
switch (prop_id)
{
case PROP_WINDOW:
g_value_set_object (value, self->window);
break;
case PROP_CLIP:
g_value_set_boxed (value, self->clip);
break;
default:
G_OBJECT_WARN_INVALID_PROPERTY_ID (gobject, prop_id, pspec);
}
}
static void
gdk_drawing_context_constructed (GObject *gobject)
{
GdkDrawingContext *self = GDK_DRAWING_CONTEXT (gobject);
if (self->window == NULL)
{
g_critical ("The drawing context of type %s does not have a window "
"associated to it. Drawing contexts can only be created "
"using gdk_window_begin_draw_frame().",
G_OBJECT_TYPE_NAME (gobject));
}
G_OBJECT_CLASS (gdk_drawing_context_parent_class)->constructed (gobject);
}
static void
gdk_drawing_context_class_init (GdkDrawingContextClass *klass)
{
GObjectClass *gobject_class = G_OBJECT_CLASS (klass);
gobject_class->constructed = gdk_drawing_context_constructed;
gobject_class->set_property = gdk_drawing_context_set_property;
gobject_class->get_property = gdk_drawing_context_get_property;
gobject_class->dispose = gdk_drawing_context_dispose;
/**
* GdkDrawingContext:window:
*
* The #GdkWindow that created the drawing context.
*
* Since: 3.22
*/
obj_property[PROP_WINDOW] =
g_param_spec_object ("window", "Window", "The window that created the context",
GDK_TYPE_WINDOW,
G_PARAM_CONSTRUCT_ONLY |
G_PARAM_READWRITE |
G_PARAM_STATIC_STRINGS);
/**
* GdkDrawingContext:clip:
*
* The clip region applied to the drawing context.
*
* Since: 3.22
*/
obj_property[PROP_CLIP] =
g_param_spec_boxed ("clip", "Clip", "The clip region of the context",
CAIRO_GOBJECT_TYPE_REGION,
G_PARAM_CONSTRUCT_ONLY |
G_PARAM_READWRITE |
G_PARAM_STATIC_STRINGS);
g_object_class_install_properties (gobject_class, N_PROPS, obj_property);
}
static void
gdk_drawing_context_init (GdkDrawingContext *self)
{
}
/**
* gdk_drawing_context_get_cairo_context:
* @context:
*
* Retrieves a Cairo context to be used to draw on the #GdkWindow
* that created the #GdkDrawingContext.
*
* The returned context is guaranteed to be valid as long as the
* #GdkDrawingContext is valid, that is between a call to
* gdk_window_begin_draw_frame() and gdk_window_end_draw_frame().
*
* Returns: (transfer none): a Cairo context to be used to draw
* the contents of the #GdkWindow. The context is owned by the
* #GdkDrawingContext and should not be destroyed
*
* Since: 3.22
*/
cairo_t *
gdk_drawing_context_get_cairo_context (GdkDrawingContext *context)
{
g_return_val_if_fail (GDK_IS_DRAWING_CONTEXT (context), NULL);
g_return_val_if_fail (GDK_IS_WINDOW (context->window), NULL);
if (context->cr == NULL)
{
context->cr = gdk_cairo_create (context->window);
gdk_cairo_region (context->cr, context->clip);
cairo_clip (context->cr);
}
return context->cr;
}
/**
* gdk_drawing_context_get_window:
* @context: a #GdkDrawingContext
*
* Retrieves the window that created the drawing @context.
*
* Returns: (transfer none): a #GdkWindow
*
* Since: 3.22
*/
GdkWindow *
gdk_drawing_context_get_window (GdkDrawingContext *context)
{
g_return_val_if_fail (GDK_IS_DRAWING_CONTEXT (context), NULL);
return context->window;
}
/**
* gdk_drawing_context_get_clip:
* @context: a #GdkDrawingContext
*
* Retrieves a copy of the clip region used when creating the @context.
*
* Returns: (transfer full) (nullable): a Cairo region
*
* Since: 3.22
*/
cairo_region_t *
gdk_drawing_context_get_clip (GdkDrawingContext *context)
{
g_return_val_if_fail (GDK_IS_DRAWING_CONTEXT (context), NULL);
if (context->clip == NULL)
return NULL;
return cairo_region_copy (context->clip);
}
/**
* gdk_drawing_context_is_valid:
* @context: a #GdkDrawingContext
*
* Checks whether the given #GdkDrawingContext is valid.
*
* Returns: %TRUE if the context is valid
*
* Since: 3.22
*/
gboolean
gdk_drawing_context_is_valid (GdkDrawingContext *context)
{
g_return_val_if_fail (GDK_IS_DRAWING_CONTEXT (context), FALSE);
if (context->window == NULL)
return FALSE;
if (gdk_window_get_drawing_context (context->window) != context)
return FALSE;
return TRUE;
}