SkBlurDrawLooper.h revision 3f3b3d003527861dc0bd89733857576408906431 
1/*
2 * Copyright 2008 The Android Open Source Project
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
9#ifndef SkBlurDrawLooper_DEFINED
10#define SkBlurDrawLooper_DEFINED
11
12#include "SkDrawLooper.h"
13#include "SkColor.h"
14
15class SkMaskFilter;
16class SkColorFilter;
17
18/** \class SkBlurDrawLooper
19    This class draws a shadow of the object (possibly offset), and then draws
20    the original object in its original position.
21    should there be an option to just draw the shadow/blur layer? webkit?
22*/
23class SK_API SkBlurDrawLooper : public SkDrawLooper {
24public:
25    enum BlurFlags {
26        kNone_BlurFlag = 0x00,
27        /**
28            The blur layer's dx/dy/radius aren't affected by the canvas
29            transform.
30        */
31        kIgnoreTransform_BlurFlag   = 0x01,
32        kOverrideColor_BlurFlag     = 0x02,
33        kHighQuality_BlurFlag       = 0x04,
34        /** mask for all blur flags */
35        kAll_BlurFlag               = 0x07
36    };
37
38    static SkBlurDrawLooper* Create(SkColor color, SkScalar sigma, SkScalar dx, SkScalar dy,
39                                    uint32_t flags = kNone_BlurFlag) {
40        return SkNEW_ARGS(SkBlurDrawLooper, (color, sigma, dx, dy, flags));
41    }
42
43    virtual ~SkBlurDrawLooper();
44
45    virtual SkDrawLooper::Context* createContext(SkCanvas*, void* storage) const SK_OVERRIDE;
46
47    virtual size_t contextSize() const SK_OVERRIDE { return sizeof(BlurDrawLooperContext); }
48
49    SK_TO_STRING_OVERRIDE()
50    SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkBlurDrawLooper)
51
52protected:
53    SkBlurDrawLooper(SkColor color, SkScalar sigma, SkScalar dx, SkScalar dy,
54                     uint32_t flags);
55
56    virtual void flatten(SkWriteBuffer&) const SK_OVERRIDE;
57
58    virtual bool asABlurShadow(BlurShadowRec*) const SK_OVERRIDE;
59
60private:
61    SkMaskFilter*   fBlur;
62    SkColorFilter*  fColorFilter;
63    SkScalar        fDx, fDy, fSigma;
64    SkColor         fBlurColor;
65    uint32_t        fBlurFlags;
66
67    enum State {
68        kBeforeEdge,
69        kAfterEdge,
70        kDone
71    };
72
73    class BlurDrawLooperContext : public SkDrawLooper::Context {
74    public:
75        explicit BlurDrawLooperContext(const SkBlurDrawLooper* looper);
76
77        virtual bool next(SkCanvas* canvas, SkPaint* paint) SK_OVERRIDE;
78
79    private:
80        const SkBlurDrawLooper* fLooper;
81        State fState;
82    };
83
84    void init(SkScalar sigma, SkScalar dx, SkScalar dy, SkColor color, uint32_t flags);
85    void initEffects();
86
87    typedef SkDrawLooper INHERITED;
88};
89
90#endif
91