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 "GrGLExtensions.h" 12 #include "GrGLInterface.h" 13 14 /** 15 * Create an offscreen opengl context with an RGBA8 / 8bit stencil FBO. 16 * Provides a GrGLInterface struct of function pointers for the context. 17 */ 18 19 class SkGLContextHelper : public SkRefCnt { 20 public: 21 SK_DECLARE_INST_COUNT(SkGLContextHelper) 22 23 SkGLContextHelper(); 24 virtual ~SkGLContextHelper(); 25 26 /** 27 * Initializes the context and makes it current. 28 */ 29 bool init(const int width, const int height); 30 getFBOID()31 int getFBOID() const { return fFBO; } 32 gl()33 const GrGLInterface* gl() const { return fGL; } 34 35 virtual void makeCurrent() const = 0; 36 37 /** 38 * The primary purpose of this function it to provide a means of scheduling 39 * work on the GPU (since all of the subclasses create primary buffers for 40 * testing that are small and not meant to be rendered to the screen). 41 * 42 * If the drawing surface provided by the platform is double buffered this 43 * call will cause the platform to swap which buffer is currently being 44 * targeted. If the current surface does not include a back buffer, this 45 * call has no effect. 46 */ 47 virtual void swapBuffers() const = 0; 48 hasExtension(const char * extensionName)49 bool hasExtension(const char* extensionName) const { 50 SkASSERT(NULL != fGL); 51 return fExtensions.has(extensionName); 52 } 53 54 protected: 55 /** 56 * Subclass implements this to make a GL context. The returned GrGLInterface 57 * should be populated with functions compatible with the context. The 58 * format and size of backbuffers does not matter since an FBO will be 59 * created. 60 */ 61 virtual const GrGLInterface* createGLContext() = 0; 62 63 /** 64 * Subclass should destroy the underlying GL context. 65 */ 66 virtual void destroyGLContext() = 0; 67 68 private: 69 GrGLExtensions fExtensions; 70 GrGLuint fFBO; 71 GrGLuint fColorBufferID; 72 GrGLuint fDepthStencilBufferID; 73 const GrGLInterface* fGL; 74 75 typedef SkRefCnt INHERITED; 76 }; 77 78 /** 79 * Helper macros for using the GL context through the GrGLInterface. Example: 80 * SK_GL(glCtx, GenTextures(1, &texID)); 81 */ 82 #define SK_GL(ctx, X) (ctx).gl()->f ## X; \ 83 SkASSERT(GR_GL_NO_ERROR == (ctx).gl()->fGetError()) 84 #define SK_GL_RET(ctx, RET, X) (RET) = (ctx).gl()->f ## X; \ 85 SkASSERT(GR_GL_NO_ERROR == (ctx).gl()->fGetError()) 86 #define SK_GL_NOERRCHECK(ctx, X) (ctx).gl()->f ## X 87 #define SK_GL_RET_NOERRCHECK(ctx, RET, X) (RET) = (ctx).gl()->f ## X 88 89 #endif 90