1
2/*
3 * Copyright 2011 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
9
10
11#ifndef SkEmptyShader_DEFINED
12#define SkEmptyShader_DEFINED
13
14#include "SkShader.h"
15
16/**
17 *  \class SkEmptyShader
18 *  A Shader that always draws nothing. Its setContext always returns false,
19 *  so it never expects that its shadeSpan() methods will get called.
20 */
21class SK_API SkEmptyShader : public SkShader {
22public:
23    SkEmptyShader() {}
24
25    virtual uint32_t getFlags() SK_OVERRIDE;
26    virtual uint8_t getSpan16Alpha() const SK_OVERRIDE;
27    virtual bool setContext(const SkBitmap&, const SkPaint&,
28                            const SkMatrix&) SK_OVERRIDE;
29    virtual void shadeSpan(int x, int y, SkPMColor span[], int count) SK_OVERRIDE;
30    virtual void shadeSpan16(int x, int y, uint16_t span[], int count) SK_OVERRIDE;
31    virtual void shadeSpanAlpha(int x, int y, uint8_t alpha[], int count) SK_OVERRIDE;
32
33protected:
34    SkEmptyShader(SkFlattenableReadBuffer&);
35
36    virtual Factory getFactory() SK_OVERRIDE;
37    virtual void flatten(SkFlattenableWriteBuffer&) SK_OVERRIDE;
38
39private:
40    typedef SkShader INHERITED;
41};
42
43#endif
44