skia2/include/gpu/gl/SkGLContextHelper.h
2014-01-21 16:09:18 +00:00

88 lines
2.6 KiB
C++

/*
* 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 SkGLContextHelper_DEFINED
#define SkGLContextHelper_DEFINED
#include "GrGLInterface.h"
/**
* Create an offscreen opengl context with an RGBA8 / 8bit stencil FBO.
* Provides a GrGLInterface struct of function pointers for the context.
*/
class SK_API SkGLContextHelper : public SkRefCnt {
public:
SK_DECLARE_INST_COUNT(SkGLContextHelper)
SkGLContextHelper();
virtual ~SkGLContextHelper();
/**
* Initializes the context and makes it current.
*/
bool init(const int width, const int height);
int getFBOID() const { return fFBO; }
const GrGLInterface* gl() const { return fGL; }
virtual void makeCurrent() const = 0;
/**
* The primary 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 drawing surface provided by the platform is double buffered this
* call will cause the platform to swap which buffer is currently being
* targeted. If the current surface does not include a back buffer, this
* call has no effect.
*/
virtual void swapBuffers() const = 0;
bool hasExtension(const char* extensionName) const {
SkASSERT(NULL != fGL);
return fGL->hasExtension(extensionName);
}
protected:
/**
* Subclass implements this to make a GL context. The returned GrGLInterface
* should be populated with functions compatible with the context. The
* format and size of backbuffers does not matter since an FBO will be
* created.
*/
virtual const GrGLInterface* createGLContext() = 0;
/**
* Subclass should destroy the underlying GL context.
*/
virtual void destroyGLContext() = 0;
private:
GrGLuint fFBO;
GrGLuint fColorBufferID;
GrGLuint fDepthStencilBufferID;
const GrGLInterface* fGL;
typedef SkRefCnt INHERITED;
};
/**
* 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(GR_GL_NO_ERROR == (ctx).gl()->fFunctions.fGetError())
#define SK_GL_RET(ctx, RET, X) (RET) = (ctx).gl()->fFunctions.f ## X; \
SkASSERT(GR_GL_NO_ERROR == (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
#endif