1 /* 2 * Copyright 2011 Google Inc. 3 * 4 * Use of this source code is governed by a BSD-style license that can be 5 * found in the LICENSE file. 6 */ 7 8 #ifndef SkEmptyShader_DEFINED 9 #define SkEmptyShader_DEFINED 10 11 #include "SkShader.h" 12 13 // TODO: move this to private, as there is a public factory on SkShader 14 15 /** 16 * \class SkEmptyShader 17 * A Shader that always draws nothing. Its createContext always returns nullptr. 18 */ 19 class SK_API SkEmptyShader : public SkShader { 20 public: 21 SkEmptyShader() {} 22 23 size_t contextSize(const ContextRec&) const override { 24 // Even though createContext returns nullptr we have to return a value of at least 25 // sizeof(SkShader::Context) to satisfy SkSmallAllocator. 26 return sizeof(SkShader::Context); 27 } 28 29 SK_TO_STRING_OVERRIDE() 30 SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkEmptyShader) 31 32 protected: 33 SkShader::Context* onCreateContext(const ContextRec&, void*) const override { 34 return nullptr; 35 } 36 37 void flatten(SkWriteBuffer& buffer) const override { 38 // Do nothing. 39 // We just don't want to fall through to SkShader::flatten(), 40 // which will write data we don't care to serialize or decode. 41 } 42 43 private: 44 typedef SkShader INHERITED; 45 }; 46 47 #endif 48
