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 SkLayerDrawLooper_DEFINED
9#define SkLayerDrawLooper_DEFINED
10
11#include "include/core/SkBlendMode.h"
12#include "include/core/SkDrawLooper.h"
13#include "include/core/SkPaint.h"
14#include "include/core/SkPoint.h"
15
16class SK_API SkLayerDrawLooper : public SkDrawLooper {
17public:
18 ~SkLayerDrawLooper() override;
19
20 /**
21 * Bits specifies which aspects of the layer's paint should replace the
22 * corresponding aspects on the draw's paint.
23 * kEntirePaint_Bits means use the layer's paint completely.
24 * 0 means ignore the layer's paint... except for fColorMode, which is
25 * always applied.
26 */
27 enum Bits {
28 kStyle_Bit = 1 << 0, //!< use this layer's Style/stroke settings
29 kPathEffect_Bit = 1 << 2, //!< use this layer's patheffect
30 kMaskFilter_Bit = 1 << 3, //!< use this layer's maskfilter
31 kShader_Bit = 1 << 4, //!< use this layer's shader
32 kColorFilter_Bit = 1 << 5, //!< use this layer's colorfilter
33 kXfermode_Bit = 1 << 6, //!< use this layer's xfermode
34
35 // unsupported kTextSkewX_Bit = 1 << 1,
36
37 /**
38 * Use the layer's paint entirely, with these exceptions:
39 * - We never override the draw's paint's text_encoding, since that is
40 * used to interpret the text/len parameters in draw[Pos]Text.
41 * - Color is always computed using the LayerInfo's fColorMode.
42 */
43 kEntirePaint_Bits = -1
44
45 };
46 typedef int32_t BitFlags;
47
48 /**
49 * Info for how to apply the layer's paint and offset.
50 *
51 * fColorMode controls how we compute the final color for the layer:
52 * The layer's paint's color is treated as the SRC
53 * The draw's paint's color is treated as the DST
54 * final-color = Mode(layers-color, draws-color);
55 * Any SkBlendMode will work. Two common choices are:
56 * kSrc: to use the layer's color, ignoring the draw's
57 * kDst: to just keep the draw's color, ignoring the layer's
58 */
59 struct SK_API LayerInfo {
60 BitFlags fPaintBits;
61 SkBlendMode fColorMode;
62 SkVector fOffset;
63 bool fPostTranslate; //!< applies to fOffset
64
65 /**
66 * Initial the LayerInfo. Defaults to settings that will draw the
67 * layer with no changes: e.g.
68 * fPaintBits == 0
69 * fColorMode == kDst_Mode
70 * fOffset == (0, 0)
71 */
72 LayerInfo();
73 };
74
75 SkDrawLooper::Context* makeContext(SkArenaAlloc*) const override;
76
77 bool asABlurShadow(BlurShadowRec* rec) const override;
78
79protected:
80 SkLayerDrawLooper();
81
82 void flatten(SkWriteBuffer&) const override;
83
84private:
85 SK_FLATTENABLE_HOOKS(SkLayerDrawLooper)
86
87 struct Rec {
88 Rec* fNext;
89 SkPaint fPaint;
90 LayerInfo fInfo;
91 };
92 Rec* fRecs;
93 int fCount;
94
95 // state-machine during the init/next cycle
96 class LayerDrawLooperContext : public SkDrawLooper::Context {
97 public:
98 explicit LayerDrawLooperContext(const SkLayerDrawLooper* looper);
99
100 protected:
101 bool next(Info*, SkPaint* paint) override;
102
103 private:
104 Rec* fCurrRec;
105
106 static void ApplyInfo(SkPaint* dst, const SkPaint& src, const LayerInfo&);
107 };
108
109 typedef SkDrawLooper INHERITED;
110
111public:
112 class SK_API Builder {
113 public:
114 Builder();
115 ~Builder();
116
117 /**
118 * Call for each layer you want to add (from top to bottom).
119 * This returns a paint you can modify, but that ptr is only valid until
120 * the next call made to addLayer().
121 */
122 SkPaint* addLayer(const LayerInfo&);
123
124 /**
125 * This layer will draw with the original paint, at the specified offset
126 */
127 void addLayer(SkScalar dx, SkScalar dy);
128
129 /**
130 * This layer will with the original paint and no offset.
131 */
132 void addLayer() { this->addLayer(0, 0); }
133
134 /// Similar to addLayer, but adds a layer to the top.
135 SkPaint* addLayerOnTop(const LayerInfo&);
136
137 /**
138 * Pass list of layers on to newly built looper and return it. This will
139 * also reset the builder, so it can be used to build another looper.
140 */
141 sk_sp<SkDrawLooper> detach();
142
143 private:
144 Rec* fRecs;
145 Rec* fTopRec;
146 int fCount;
147 };
148};
149
150#endif
151