df21e20f65
Although we use GLib internally in Cogl we would rather not leak GLib api through Cogl's own api, except through explicitly namespaced cogl_glib_ / cogl_gtype_ feature apis. One of the benefits we see to not leaking GLib through Cogl's public API is that documentation for Cogl won't need to first introduce the Glib API to newcomers, thus hopefully lowering the barrier to learning Cogl. This patch provides a Cogl specific typedef for reporting runtime errors which by no coincidence matches the typedef for GError exactly. If Cogl is built with --enable-glib (default) then developers can even safely assume that a CoglError is a GError under the hood. This patch also enforces a consistent policy for when NULL is passed as an error argument and an error is thrown. In this case we log the error and abort the application, instead of silently ignoring it. In common cases where nothing has been implemented to handle a particular error and/or where applications are just printing the error and aborting themselves then this saves some typing. This also seems more consistent with language based exceptions which usually cause a program to abort if they are not explicitly caught (which passing a non-NULL error signifies in this case) Since this policy for NULL error pointers is stricter than the standard GError convention, there is a clear note in the documentation to warn developers that are used to using the GError api. Reviewed-by: Neil Roberts <neil@linux.intel.com> (cherry picked from commit b068d5ea09ab32c37e8c965fc8582c85d1b2db46) Note: Since we can't change the Cogl 1.x api the patch was changed to not rename _error_quark() functions to be _error_domain() functions and although it's a bit ugly, instead of providing our own CoglError type that's compatible with GError we simply #define CoglError to GError unless Cogl is built with glib disabled. Note: this patch does technically introduce an API break since it drops the cogl_error_get_type() symbol generated by glib-mkenum (Since the CoglError enum was replaced by a CoglSystemError enum) but for now we are assuming that this will not affect anyone currently using the Cogl API. If this does turn out to be a problem in practice then we would be able to fix this my manually copying an implementation of cogl_error_get_type() generated by glib-mkenum into a compatibility source file and we could also define the original COGL_ERROR_ enums for compatibility too. Note: another minor concern with cherry-picking this patch to the 1.14 branch is that an api scanner would be lead to believe that some APIs have changed, and for example the gobject-introspection parser which understands the semantics of GError will not understand the semantics of CoglError. We expect most people that have tried to use gobject-introspection with Cogl already understand though that it is not well suited to generating bindings of the Cogl api anyway and we aren't aware or anyone depending on such bindings for apis involving GErrors. (GnomeShell only makes very-very minimal use of Cogl via the gjs bindings for the cogl_rectangle and cogl_color apis.) The main reason we have cherry-picked this patch to the 1.14 branch even given the above concerns is that without it it would become very awkward for us to cherry-pick other beneficial patches from master.
191 lines
6.2 KiB
C
191 lines
6.2 KiB
C
/*
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* Cogl
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*
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* An object oriented GL/GLES Abstraction/Utility Layer
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*
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* Copyright (C) 2010 Intel Corporation.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library. If not, see
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* <http://www.gnu.org/licenses/>.
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*
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* Authors:
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* Robert Bragg <robert@linux.intel.com>
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*
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*/
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#if !defined(__COGL_H_INSIDE__) && !defined(COGL_COMPILATION)
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#error "Only <cogl/cogl.h> can be included directly."
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#endif
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#ifndef __COGL_DISPLAY_H__
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#define __COGL_DISPLAY_H__
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#include <cogl/cogl-renderer.h>
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#include <cogl/cogl-onscreen-template.h>
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G_BEGIN_DECLS
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#ifdef COGL_HAS_EGL_PLATFORM_GDL_SUPPORT
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#include <libgdl.h>
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#endif
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/**
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* SECTION:cogl-display
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* @short_description: Common aspects of a display pipeline
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*
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* The basic intention for this object is to let the application
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* configure common display preferences before creating a context, and
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* there are a few different aspects to this...
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*
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* Firstly there are options directly relating to the physical display
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* pipeline that is currently being used including the digital to
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* analogue conversion hardware and the screens the user sees.
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*
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* Another aspect is that display options may constrain or affect how
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* onscreen framebuffers should later be configured. The original
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* rationale for the display object in fact was to let us handle GLX
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* and EGLs requirements that framebuffers must be "compatible" with
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* the config associated with the current context meaning we have to
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* force the user to describe how they would like to create their
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* onscreen windows before we can choose a suitable fbconfig and
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* create a GLContext.
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*/
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typedef struct _CoglDisplay CoglDisplay;
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#define COGL_DISPLAY(OBJECT) ((CoglDisplay *)OBJECT)
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/**
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* cogl_display_new:
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* @renderer: A #CoglRenderer
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* @onscreen_template: A #CoglOnscreenTemplate
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*
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* Explicitly allocates a new #CoglDisplay object to encapsulate the
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* common state of the display pipeline that applies to the whole
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* application.
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*
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* <note>Many applications don't need to explicitly use
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* cogl_display_new() and can just jump straight to cogl_context_new()
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* and pass a %NULL display argument so Cogl will automatically
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* connect and setup a renderer and display.</note>
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*
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* A @display can only be made for a specific choice of renderer which
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* is why this takes the @renderer argument.
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*
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* A common use for explicitly allocating a display object is to
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* define a template for allocating onscreen framebuffers which is
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* what the @onscreen_template argument is for.
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*
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* When a display is first allocated via cogl_display_new() it is in a
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* mutable configuration mode. It's designed this way so we can
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* extend the apis available for configuring a display without
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* requiring huge numbers of constructor arguements.
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*
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* When you have finished configuring a display object you can
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* optionally call cogl_display_setup() to explicitly apply the
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* configuration and check for errors. Alternaitvely you can pass the
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* display to cogl_context_new() and Cogl will implicitly apply your
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* configuration but if there are errors then the application will
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* abort with a message. For simple applications with no fallback
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* options then relying on the implicit setup can be fine.
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*
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* Return value: A newly allocated #CoglDisplay object in a mutable
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* configuration mode.
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* Since: 1.10
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* Stability: unstable
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*/
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CoglDisplay *
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cogl_display_new (CoglRenderer *renderer,
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CoglOnscreenTemplate *onscreen_template);
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/**
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* cogl_display_get_renderer:
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* @display: a #CoglDisplay
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*
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* Queries the #CoglRenderer associated with the given @display.
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*
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* Since: 1.10
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* Stability: unstable
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*/
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CoglRenderer *
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cogl_display_get_renderer (CoglDisplay *display);
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/**
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* cogl_display_setup:
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* @display: a #CoglDisplay
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* @error: return location for a #CoglError
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*
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* Explicitly sets up the given @display object. Use of this api is
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* optional since Cogl will internally setup the display if not done
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* explicitly.
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*
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* When a display is first allocated via cogl_display_new() it is in a
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* mutable configuration mode. This allows us to extend the apis
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* available for configuring a display without requiring huge numbers
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* of constructor arguements.
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*
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* Its possible to request a configuration that might not be
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* supportable on the current system and so this api provides a means
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* to apply the configuration explicitly but if it fails then an
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* exception will be returned so you can handle the error gracefully
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* and perhaps fall back to an alternative configuration.
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*
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* If you instead rely on Cogl implicitly calling cogl_display_setup()
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* for you then if there is an error with the configuration you won't
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* get an opportunity to handle that and the application may abort
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* with a message. For simple applications that don't have any
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* fallback options this behaviour may be fine.
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*
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* Return value: Returns %TRUE if there was no error, else it returns
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* %FALSE and returns an exception via @error.
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* Since: 1.10
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* Stability: unstable
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*/
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CoglBool
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cogl_display_setup (CoglDisplay *display,
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CoglError **error);
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#ifdef COGL_HAS_EGL_PLATFORM_GDL_SUPPORT
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/**
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* cogl_gdl_display_set_plane:
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* @display: a #CoglDisplay
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*
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* Request that Cogl output to a specific GDL overlay @plane.
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*
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* Since: 1.10
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* Stability: unstable
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*/
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void
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cogl_gdl_display_set_plane (CoglDisplay *display,
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gdl_plane_id_t plane);
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#endif
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/**
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* cogl_is_display:
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* @object: A #CoglObject pointer
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*
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* Gets whether the given object references a #CoglDisplay.
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*
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* Return value: %TRUE if the object references a #CoglDisplay
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* and %FALSE otherwise.
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* Since: 1.10
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* Stability: unstable
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*/
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CoglBool
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cogl_is_display (void *object);
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G_END_DECLS
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#endif /* __COGL_DISPLAY_H__ */
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