michael@0: 
michael@0: /*
michael@0:  * Copyright 2013 Google Inc.
michael@0:  *
michael@0:  * Use of this source code is governed by a BSD-style license that can be
michael@0:  * found in the LICENSE file.
michael@0:  */
michael@0: #ifndef SkGLContextHelper_DEFINED
michael@0: #define SkGLContextHelper_DEFINED
michael@0: 
michael@0: #include "GrGLInterface.h"
michael@0: 
michael@0: /**
michael@0:  * Create an offscreen opengl context with an RGBA8 / 8bit stencil FBO.
michael@0:  * Provides a GrGLInterface struct of function pointers for the context.
michael@0:  */
michael@0: 
michael@0: class SK_API SkGLContextHelper : public SkRefCnt {
michael@0: public:
michael@0:     SK_DECLARE_INST_COUNT(SkGLContextHelper)
michael@0: 
michael@0:     SkGLContextHelper();
michael@0:     virtual ~SkGLContextHelper();
michael@0: 
michael@0:     /**
michael@0:      * Initializes the context and makes it current.
michael@0:      */
michael@0:     bool init(const int width, const int height);
michael@0: 
michael@0:     int getFBOID() const { return fFBO; }
michael@0: 
michael@0:     const GrGLInterface* gl() const { return fGL; }
michael@0: 
michael@0:     virtual void makeCurrent() const = 0;
michael@0: 
michael@0:     /**
michael@0:      * The primary purpose of this function it to provide a means of scheduling
michael@0:      * work on the GPU (since all of the subclasses create primary buffers for
michael@0:      * testing that are small and not meant to be rendered to the screen).
michael@0:      *
michael@0:      * If the drawing surface provided by the platform is double buffered this
michael@0:      * call will cause the platform to swap which buffer is currently being
michael@0:      * targeted.  If the current surface does not include a back buffer, this
michael@0:      * call has no effect.
michael@0:      */
michael@0:     virtual void swapBuffers() const = 0;
michael@0: 
michael@0:     bool hasExtension(const char* extensionName) const {
michael@0:         SkASSERT(NULL != fGL);
michael@0:         return fGL->hasExtension(extensionName);
michael@0:     }
michael@0: 
michael@0: protected:
michael@0:     /**
michael@0:      * Subclass implements this to make a GL context. The returned GrGLInterface
michael@0:      * should be populated with functions compatible with the context. The
michael@0:      * format and size of backbuffers does not matter since an FBO will be
michael@0:      * created.
michael@0:      */
michael@0:     virtual const GrGLInterface* createGLContext() = 0;
michael@0: 
michael@0:     /**
michael@0:      * Subclass should destroy the underlying GL context.
michael@0:      */
michael@0:     virtual void destroyGLContext() = 0;
michael@0: 
michael@0: private:
michael@0:     GrGLuint fFBO;
michael@0:     GrGLuint fColorBufferID;
michael@0:     GrGLuint fDepthStencilBufferID;
michael@0:     const GrGLInterface* fGL;
michael@0: 
michael@0:     typedef SkRefCnt INHERITED;
michael@0: };
michael@0: 
michael@0: /**
michael@0:  * Helper macros for using the GL context through the GrGLInterface. Example:
michael@0:  * SK_GL(glCtx, GenTextures(1, &texID));
michael@0:  */
michael@0: #define SK_GL(ctx, X) (ctx).gl()->fFunctions.f ## X;    \
michael@0:                       SkASSERT(GR_GL_NO_ERROR == (ctx).gl()->fFunctions.fGetError())
michael@0: #define SK_GL_RET(ctx, RET, X) (RET) = (ctx).gl()->fFunctions.f ## X;    \
michael@0:                   SkASSERT(GR_GL_NO_ERROR == (ctx).gl()->fFunctions.fGetError())
michael@0: #define SK_GL_NOERRCHECK(ctx, X) (ctx).gl()->fFunctions.f ## X
michael@0: #define SK_GL_RET_NOERRCHECK(ctx, RET, X) (RET) = (ctx).gl()->fFunctions.f ## X
michael@0: 
michael@0: #endif