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 NULL.
18 */
19class SK_API SkEmptyShader : public SkShader {
20public:
21    SkEmptyShader() {}
22
23    virtual size_t contextSize() const SK_OVERRIDE {
24        // Even though createContext returns NULL 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
32protected:
33#ifdef SK_SUPPORT_LEGACY_DEEPFLATTENING
34    SkEmptyShader(SkReadBuffer& buffer) : INHERITED(buffer) {}
35#endif
36
37    virtual SkShader::Context* onCreateContext(const ContextRec&, void*) const SK_OVERRIDE {
38        return NULL;
39    }
40
41private:
42    typedef SkShader INHERITED;
43};
44
45#endif
46