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 "SkShaderBase.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 SkEmptyShader : public SkShaderBase {
20 public:
SkEmptyShader()21     SkEmptyShader() {}
22 
23     SK_TO_STRING_OVERRIDE()
SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkEmptyShader)24     SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkEmptyShader)
25 
26 protected:
27     Context* onMakeContext(const ContextRec&, SkArenaAlloc*) const override {
28         return nullptr;
29     }
30 
flatten(SkWriteBuffer & buffer)31     void flatten(SkWriteBuffer& buffer) const override {
32         // Do nothing.
33         // We just don't want to fall through to SkShader::flatten(),
34         // which will write data we don't care to serialize or decode.
35     }
36 
onAppendStages(const StageRec &)37     bool onAppendStages(const StageRec&) const override {
38         return false;
39     }
40 
41 private:
42     typedef SkShaderBase INHERITED;
43 };
44 
45 #endif
46