1 2 /* 3 * Copyright 2013 Google Inc. 4 * 5 * Use of this source code is governed by a BSD-style license that can be 6 * found in the LICENSE file. 7 */ 8 #ifndef SkGLContextHelper_DEFINED 9 #define SkGLContextHelper_DEFINED 10 11 #include "GrGLInterface.h" 12 13 /** 14 * Create an offscreen opengl context with an RGBA8 / 8bit stencil FBO. 15 * Provides a GrGLInterface struct of function pointers for the context. 16 */ 17 18 class SK_API SkGLContextHelper : public SkRefCnt { 19 public: 20 SK_DECLARE_INST_COUNT(SkGLContextHelper) 21 22 SkGLContextHelper(); 23 virtual ~SkGLContextHelper(); 24 25 /** 26 * Initializes the context and makes it current. 27 */ 28 bool init(const int width, const int height); 29 getFBOID()30 int getFBOID() const { return fFBO; } 31 gl()32 const GrGLInterface* gl() const { return fGL; } 33 34 virtual void makeCurrent() const = 0; 35 36 /** 37 * The primary purpose of this function it to provide a means of scheduling 38 * work on the GPU (since all of the subclasses create primary buffers for 39 * testing that are small and not meant to be rendered to the screen). 40 * 41 * If the drawing surface provided by the platform is double buffered this 42 * call will cause the platform to swap which buffer is currently being 43 * targeted. If the current surface does not include a back buffer, this 44 * call has no effect. 45 */ 46 virtual void swapBuffers() const = 0; 47 hasExtension(const char * extensionName)48 bool hasExtension(const char* extensionName) const { 49 SkASSERT(NULL != fGL); 50 return fGL->hasExtension(extensionName); 51 } 52 53 protected: 54 /** 55 * Subclass implements this to make a GL context. The returned GrGLInterface 56 * should be populated with functions compatible with the context. The 57 * format and size of backbuffers does not matter since an FBO will be 58 * created. 59 */ 60 virtual const GrGLInterface* createGLContext() = 0; 61 62 /** 63 * Subclass should destroy the underlying GL context. 64 */ 65 virtual void destroyGLContext() = 0; 66 67 private: 68 GrGLuint fFBO; 69 GrGLuint fColorBufferID; 70 GrGLuint fDepthStencilBufferID; 71 const GrGLInterface* fGL; 72 73 typedef SkRefCnt INHERITED; 74 }; 75 76 /** 77 * Helper macros for using the GL context through the GrGLInterface. Example: 78 * SK_GL(glCtx, GenTextures(1, &texID)); 79 */ 80 #define SK_GL(ctx, X) (ctx).gl()->fFunctions.f ## X; \ 81 SkASSERT(GR_GL_NO_ERROR == (ctx).gl()->fFunctions.fGetError()) 82 #define SK_GL_RET(ctx, RET, X) (RET) = (ctx).gl()->fFunctions.f ## X; \ 83 SkASSERT(GR_GL_NO_ERROR == (ctx).gl()->fFunctions.fGetError()) 84 #define SK_GL_NOERRCHECK(ctx, X) (ctx).gl()->fFunctions.f ## X 85 #define SK_GL_RET_NOERRCHECK(ctx, RET, X) (RET) = (ctx).gl()->fFunctions.f ## X 86 87 #endif 88