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 16 class SK_API SkLayerDrawLooper : public SkDrawLooper { 17 public: 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 79 protected: 80 SkLayerDrawLooper(); 81 82 void flatten(SkWriteBuffer&) const override; 83 84 private: 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; 110 111 public: 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 */ addLayer()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