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mutter/cogl/cogl-context.h
Robert Bragg ea3d8eca91 Don't take internal references on the context 
We want applications to fully control the lifetime of a CoglContext
without having to worry that internal resources (such as the default
2d,3d and rectangle textures, or any caches we maintain) could result in
circular references that keep the context alive. We also want to avoid
making CoglContext into a special kind of object that isn't ref-counted
or that can't be used with object apis such as
cogl_object_set_user_data. Being able to reliably destroy the context is
important on platforms such as Android where you may be required
bring-up and tear-down a CoglContext numerous times throughout the
applications lifetime. A dissadvantage of this policy is that it is now
possible to leave other object such as framebuffers in an inconsistent
state if the context is unreferenced and destroyed. The documentation
states that all objects that directly or indirectly depend on a context
that has been destroyed will be left in an inconsistent state and must
not be accessed thereafter. Applications (such as Android applications)
that need to cleanly destroy and re-create Cogl resources should make
sure to manually unref these dependant objects before destroying the
context.

Reviewed-by: Neil Roberts <neil@linux.intel.com>

(cherry picked from commit 23ce51beba1bb739a224e47614a59327dfbb65af)
2012-09-17 23:06:20 +01:00

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/*
* Cogl
*
* An object oriented GL/GLES Abstraction/Utility Layer
*
* Copyright (C) 2010 Intel Corporation.
*
* 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/>.
*
* Authors:
* Robert Bragg <robert@linux.intel.com>
*
*/
#if !defined(__COGL_H_INSIDE__) && !defined(COGL_COMPILATION)
#error "Only <cogl/cogl.h> can be included directly."
#endif
#ifndef __COGL_CONTEXT_H__
#define __COGL_CONTEXT_H__
/* We forward declare the CoglContext type here to avoid some circular
* dependency issues with the following headers.
*/
typedef struct _CoglContext CoglContext;
#include <cogl/cogl-defines.h>
#include <cogl/cogl-display.h>
#include <cogl/cogl-primitive.h>
#ifdef COGL_HAS_EGL_PLATFORM_ANDROID_SUPPORT
#include <android/native_window.h>
#endif
G_BEGIN_DECLS
/**
* SECTION:cogl-context
* @short_description: The top level application context.
*
* A #CoglContext is the top most sandbox of Cogl state for an
* application or toolkit. Its main purpose is to act as a sandbox
* for the memory management of state objects. Normally an application
* will only create a single context since there is no way to share
* resources between contexts.
*
* For those familiar with OpenGL or perhaps Cairo it should be
* understood that unlike these APIs a Cogl context isn't a rendering
* context as such. In other words Cogl doesn't aim to provide a state
* machine style model for configuring rendering parameters. Most
* rendering state in Cogl is directly associated with user managed
* objects called pipelines and geometry is drawn with a specific
* pipeline object to a framebuffer object and those 3 things fully
* define the state for drawing. This is an important part of Cogl's
* design since it helps you write orthogonal rendering components
* that can all access the same GPU without having to worry about
* what state other components have left you with.
*
* <note>Cogl does not maintain internal references to the context for
* resources that depend on the context so applications. This is to
* help applications control the lifetime a context without us needing to
* introduce special api to handle the breakup of internal circular
* references due to internal resources and caches associated with the
* context.
*
* One a context has been destroyed then all directly or indirectly
* dependant resources will be in an inconsistent state and should not
* be manipulated or queried in any way.
*
* For applications that rely on the operating system to clean up
* resources this policy shouldn't affect them, but for applications
* that need to carefully destroy and re-create Cogl contexts multiple
* times throughout their lifetime (such as Android applications) they
* should be careful to destroy all context dependant resources, such as
* framebuffers or textures etc before unrefing and destroying the
* context.<note>
*/
#ifdef COGL_ENABLE_EXPERIMENTAL_API
#define COGL_CONTEXT(OBJECT) ((CoglContext *)OBJECT)
/**
* cogl_context_new:
* @display: A #CoglDisplay pointer
* @error: A GError return location.
*
* Creates a new #CoglContext which acts as an application sandbox
* for any state objects that are allocated.
*
* Return value: (transfer full): A newly allocated #CoglContext
* Since: 1.8
* Stability: unstable
*/
CoglContext *
cogl_context_new (CoglDisplay *display,
GError **error);
/**
* cogl_context_get_display:
* @context: A #CoglContext pointer
*
* Retrieves the #CoglDisplay that is internally associated with the
* given @context. This will return the same #CoglDisplay that was
* passed to cogl_context_new() or if %NULL was passed to
* cogl_context_new() then this function returns a pointer to the
* display that was automatically setup internally.
*
* Return value: (transfer none): The #CoglDisplay associated with the
* given @context.
* Since: 1.8
* Stability: unstable
*/
CoglDisplay *
cogl_context_get_display (CoglContext *context);
#ifdef COGL_HAS_EGL_PLATFORM_ANDROID_SUPPORT
/**
* cogl_android_set_native_window:
* @window: A native Android window
*
* Allows Android applications to inform Cogl of the native window
* that they have been given which Cogl can render too. On Android
* this API must be used before creating a #CoglRenderer, #CoglDisplay
* and #CoglContext.
*
* Since: 1.8
* Stability: unstable
*/
void
cogl_android_set_native_window (ANativeWindow *window);
#endif
/**
* cogl_is_context:
* @object: An object or %NULL
*
* Gets whether the given object references an existing context object.
*
* Return value: %TRUE if the @object references a #CoglContext,
* %FALSE otherwise
*
* Since: 1.10
* Stability: Unstable
*/
CoglBool
cogl_is_context (void *object);
#endif /* COGL_ENABLE_EXPERIMENTAL_2_0_API */
/* XXX: not guarded by the EXPERIMENTAL_API defines to avoid
* upsetting glib-mkenums, but this can still be considered implicitly
* experimental since it's only useable with experimental API... */
/**
* CoglFeatureID:
* @COGL_FEATURE_ID_TEXTURE_NPOT_BASIC: The hardware supports non power
* of two textures, but you also need to check the
* %COGL_FEATURE_ID_TEXTURE_NPOT_MIPMAP and %COGL_FEATURE_ID_TEXTURE_NPOT_REPEAT
* features to know if the hardware supports npot texture mipmaps
* or repeat modes other than
* %COGL_RENDERER_PIPELINE_WRAP_MODE_CLAMP_TO_EDGE respectively.
* @COGL_FEATURE_ID_TEXTURE_NPOT_MIPMAP: Mipmapping is supported in
* conjuntion with non power of two textures.
* @COGL_FEATURE_ID_TEXTURE_NPOT_REPEAT: Repeat modes other than
* %COGL_RENDERER_PIPELINE_WRAP_MODE_CLAMP_TO_EDGE are supported by the
* hardware.
* @COGL_FEATURE_ID_TEXTURE_NPOT: Non power of two textures are supported
* by the hardware. This is a equivalent to the
* %COGL_FEATURE_ID_TEXTURE_NPOT_BASIC, %COGL_FEATURE_ID_TEXTURE_NPOT_MIPMAP
* and %COGL_FEATURE_ID_TEXTURE_NPOT_REPEAT features combined.
* @COGL_FEATURE_ID_TEXTURE_RECTANGLE: Support for rectangular
* textures with non-normalized texture coordinates.
* @COGL_FEATURE_ID_TEXTURE_3D: 3D texture support
* @COGL_FEATURE_ID_OFFSCREEN: Offscreen rendering support
* @COGL_FEATURE_ID_OFFSCREEN_MULTISAMPLE: Multisample support for
* offscreen framebuffers
* @COGL_FEATURE_ID_ONSCREEN_MULTIPLE: Multiple onscreen framebuffers
* supported.
* @COGL_FEATURE_ID_GLSL: GLSL support
* @COGL_FEATURE_ID_ARBFP: ARBFP support
* @COGL_FEATURE_ID_UNSIGNED_INT_INDICES: Set if
* %COGL_RENDERER_INDICES_TYPE_UNSIGNED_INT is supported in
* cogl_indices_new().
* @COGL_FEATURE_ID_DEPTH_RANGE: cogl_pipeline_set_depth_range() support
* @COGL_FEATURE_ID_POINT_SPRITE: Whether
* cogl_pipeline_set_layer_point_sprite_coords_enabled() is supported.
* @COGL_FEATURE_ID_MAP_BUFFER_FOR_READ: Whether cogl_buffer_map() is
* supported with CoglBufferAccess including read support.
* @COGL_FEATURE_ID_MAP_BUFFER_FOR_WRITE: Whether cogl_buffer_map() is
* supported with CoglBufferAccess including write support.
* @COGL_FEATURE_ID_MIRRORED_REPEAT: Whether
* %COGL_PIPELINE_WRAP_MODE_MIRRORED_REPEAT is supported.
* @COGL_FEATURE_ID_SWAP_BUFFERS_EVENT:
* Available if the window system supports reporting an event
* for swap buffer completions.
* @COGL_FEATURE_ID_GLES2_CONTEXT: Whether creating new GLES2 contexts is
* suported.
*
*
* All the capabilities that can vary between different GPUs supported
* by Cogl. Applications that depend on any of these features should explicitly
* check for them using cogl_has_feature() or cogl_has_features().
*
* Since: 1.10
*/
typedef enum _CoglFeatureID
{
COGL_FEATURE_ID_TEXTURE_NPOT_BASIC = 1,
COGL_FEATURE_ID_TEXTURE_NPOT_MIPMAP,
COGL_FEATURE_ID_TEXTURE_NPOT_REPEAT,
COGL_FEATURE_ID_TEXTURE_NPOT,
COGL_FEATURE_ID_TEXTURE_RECTANGLE,
COGL_FEATURE_ID_TEXTURE_3D,
COGL_FEATURE_ID_GLSL,
COGL_FEATURE_ID_ARBFP,
COGL_FEATURE_ID_OFFSCREEN,
COGL_FEATURE_ID_OFFSCREEN_MULTISAMPLE,
COGL_FEATURE_ID_ONSCREEN_MULTIPLE,
COGL_FEATURE_ID_UNSIGNED_INT_INDICES,
COGL_FEATURE_ID_DEPTH_RANGE,
COGL_FEATURE_ID_POINT_SPRITE,
COGL_FEATURE_ID_MAP_BUFFER_FOR_READ,
COGL_FEATURE_ID_MAP_BUFFER_FOR_WRITE,
COGL_FEATURE_ID_MIRRORED_REPEAT,
COGL_FEATURE_ID_SWAP_BUFFERS_EVENT,
COGL_FEATURE_ID_GLES2_CONTEXT,
/*< private > */
_COGL_N_FEATURE_IDS
} CoglFeatureID;
#ifdef COGL_ENABLE_EXPERIMENTAL_API
/**
* cogl_has_feature:
* @context: A #CoglContext pointer
* @feature: A #CoglFeatureID
*
* Checks if a given @feature is currently available
*
* Cogl does not aim to be a lowest common denominator API, it aims to
* expose all the interesting features of GPUs to application which
* means applications have some responsibility to explicitly check
* that certain features are available before depending on them.
*
* Returns: %TRUE if the @feature is currently supported or %FALSE if
* not.
*
* Since: 1.10
* Stability: unstable
*/
CoglBool
cogl_has_feature (CoglContext *context, CoglFeatureID feature);
/**
* cogl_has_features:
* @context: A #CoglContext pointer
* @...: A 0 terminated list of CoglFeatureID<!-- -->s
*
* Checks if a list of features are all currently available.
*
* This checks all of the listed features using cogl_has_feature() and
* returns %TRUE if all the features are available or %FALSE
* otherwise.
*
* Return value: %TRUE if all the features are available, %FALSE
* otherwise.
*
* Since: 1.10
* Stability: unstable
*/
CoglBool
cogl_has_features (CoglContext *context, ...);
/**
* CoglFeatureCallback:
* @feature: A single feature currently supported by Cogl
* @user_data: A private pointer passed to cogl_foreach_feature().
*
* A callback used with cogl_foreach_feature() for enumerating all
* context level features supported by Cogl.
*
* Since: 0.10
* Stability: unstable
*/
typedef void (*CoglFeatureCallback) (CoglFeatureID feature, void *user_data);
/**
* cogl_foreach_feature:
* @context: A #CoglContext pointer
* @callback: A #CoglFeatureCallback called for each supported feature
* @user_data: Private data to pass to the callback
*
* Iterates through all the context level features currently supported
* for a given @context and for each feature @callback is called.
*
* Since: 1.10
* Stability: unstable
*/
void
cogl_foreach_feature (CoglContext *context,
CoglFeatureCallback callback,
void *user_data);
#endif /* COGL_ENABLE_EXPERIMENTAL_API */
G_END_DECLS
#endif /* __COGL_CONTEXT_H__ */
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