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* Copyright 2013 Google Inc.
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
#ifndef SkGLContext_DEFINED
#define SkGLContext_DEFINED
#include "GrGLInterface.h"
#include "../private/SkGpuFenceSync.h"
* Create an offscreen opengl context with an RGBA8 / 8bit stencil FBO.
* Provides a GrGLInterface struct of function pointers for the context.
* This class is intended for Skia's testing needs and not for general
* use.
class SK_API SkGLContext : public SkNoncopyable {
virtual ~SkGLContext();
bool isValid() const { return NULL != gl(); }
const GrGLInterface* gl() const { return fGL.get(); }
bool fenceSyncSupport() const { return SkToBool(fFenceSync); }
bool getMaxGpuFrameLag(int* maxFrameLag) const {
if (!fFenceSync) {
return false;
*maxFrameLag = kMaxFrameLag;
return true;
void makeCurrent() const;
/** Used for testing EGLImage integration. Take a GL_TEXTURE_2D and wraps it in an EGL Image */
virtual GrEGLImage texture2DToEGLImage(GrGLuint /*texID*/) const { return 0; }
virtual void destroyEGLImage(GrEGLImage) const {}
/** Used for testing GL_TEXTURE_RECTANGLE integration. */
GrGLint createTextureRectangle(int width, int height, GrGLenum internalFormat,
GrGLenum externalFormat, GrGLenum externalType,
GrGLvoid* data);
* Used for testing EGLImage integration. Takes a EGLImage and wraps it in a
virtual GrGLuint eglImageToExternalTexture(GrEGLImage) const { return 0; }
void swapBuffers();
* The only purpose of this function it to provide a means of scheduling
* work on the GPU (since all of the subclasses create primary buffers for
* testing that are small and not meant to be rendered to the screen).
* If the platform supports fence sync (OpenGL 3.2+ or EGL_KHR_fence_sync),
* this will not swap any buffers, but rather emulate triple buffer
* synchronization using fences.
* Otherwise it will call the platform SwapBuffers method. This may or may
* not perform some sort of synchronization, depending on whether the
* drawing surface provided by the platform is double buffered.
void waitOnSyncOrSwap();
* This notifies the context that we are deliberately testing abandoning
* the context. It is useful for debugging contexts that would otherwise
* test that GPU resources are properly deleted. It also allows a debugging
* context to test that further GL calls are not made by Skia GPU code.
void testAbandon();
* Creates a new GL context of the same type and makes the returned context current
* (if not null).
virtual SkGLContext* createNew() const { return nullptr; }
class GLFenceSync; // SkGpuFenceSync implementation that uses the OpenGL functionality.
* returns the fencesync object owned by this SkGLContext
SkGpuFenceSync* fenceSync() { return fFenceSync.get(); }
* Methods that sublcasses must call from their constructors and destructors.
void init(const GrGLInterface*, SkGpuFenceSync* = NULL);
void teardown();
* Operations that have a platform-dependent implementation.
virtual void onPlatformMakeCurrent() const = 0;
virtual void onPlatformSwapBuffers() const = 0;
virtual GrGLFuncPtr onPlatformGetProcAddress(const char*) const = 0;
enum { kMaxFrameLag = 3 };
SkAutoTDelete<SkGpuFenceSync> fFenceSync;
SkPlatformGpuFence fFrameFences[kMaxFrameLag - 1];
int fCurrentFenceIdx;
/** Subclass provides the gl interface object if construction was
* successful. */
SkAutoTUnref<const GrGLInterface> fGL;
friend class GLFenceSync; // For onPlatformGetProcAddress.
/** Creates platform-dependent GL context object. The shareContext parameter is in an optional
* context with which to share display lists. This should be a pointer to an SkGLContext created
* with SkCreatePlatformGLContext. NULL indicates that no sharing is to take place. Returns a valid
* gl context object or NULL if such can not be created.
* Note: If Skia embedder needs a custom GL context that sets up the GL interface, this function
* should be implemented by the embedder. Otherwise, the default implementation for the platform
* should be compiled in the library.
SK_API SkGLContext* SkCreatePlatformGLContext(GrGLStandard forcedGpuAPI,
SkGLContext* shareContext = nullptr);
* Helper macros for using the GL context through the GrGLInterface. Example:
* SK_GL(glCtx, GenTextures(1, &texID));
#define SK_GL(ctx, X) (ctx).gl()->fFunctions.f ## X; \
SkASSERT(0 == (ctx).gl()->fFunctions.fGetError())
#define SK_GL_RET(ctx, RET, X) (RET) = (ctx).gl()->fFunctions.f ## X; \
SkASSERT(0 == (ctx).gl()->fFunctions.fGetError())
#define SK_GL_NOERRCHECK(ctx, X) (ctx).gl()->fFunctions.f ## X
#define SK_GL_RET_NOERRCHECK(ctx, RET, X) (RET) = (ctx).gl()->fFunctions.f ## X