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 "SkDrawLooper.h" 12 #include "SkPaint.h" 13 #include "SkPoint.h" 14 #include "SkXfermode.h" 15 16 class SK_API SkLayerDrawLooper : public SkDrawLooper { 17 public: 18 SK_DECLARE_INST_COUNT(SkLayerDrawLooper) 19 20 SkLayerDrawLooper(); 21 virtual ~SkLayerDrawLooper(); 22 23 /** 24 * Bits specifies which aspects of the layer's paint should replace the 25 * corresponding aspects on the draw's paint. 26 * kEntirePaint_Bits means use the layer's paint completely. 27 * 0 means ignore the layer's paint... except that LayerInfo's fFlagsMask 28 * and fColorMode are always applied. 29 */ 30 enum Bits { 31 kStyle_Bit = 1 << 0, //!< use this layer's Style/stroke settings 32 kTextSkewX_Bit = 1 << 1, //!< use this layer's textskewx 33 kPathEffect_Bit = 1 << 2, //!< use this layer's patheffect 34 kMaskFilter_Bit = 1 << 3, //!< use this layer's maskfilter 35 kShader_Bit = 1 << 4, //!< use this layer's shader 36 kColorFilter_Bit = 1 << 5, //!< use this layer's colorfilter 37 kXfermode_Bit = 1 << 6, //!< use this layer's xfermode 38 39 /** 40 * Use the layer's paint entirely, with these exceptions: 41 * - We never override the draw's paint's text_encoding, since that is 42 * used to interpret the text/len parameters in draw[Pos]Text. 43 * - Flags and Color are always computed using the LayerInfo's 44 * fFlagsMask and fColorMode. 45 */ 46 kEntirePaint_Bits = -1 47 48 }; 49 typedef int32_t BitFlags; 50 51 /** 52 * Info for how to apply the layer's paint and offset. 53 * 54 * fFlagsMask selects which flags in the layer's paint should be applied. 55 * result = (draw-flags & ~fFlagsMask) | (layer-flags & fFlagsMask) 56 * In the extreme: 57 * If fFlagsMask is 0, we ignore all of the layer's flags 58 * If fFlagsMask is -1, we use all of the layer's flags 59 * 60 * fColorMode controls how we compute the final color for the layer: 61 * The layer's paint's color is treated as the SRC 62 * The draw's paint's color is treated as the DST 63 * final-color = Mode(layers-color, draws-color); 64 * Any SkXfermode::Mode will work. Two common choices are: 65 * kSrc_Mode: to use the layer's color, ignoring the draw's 66 * kDst_Mode: to just keep the draw's color, ignoring the layer's 67 */ 68 struct SK_API LayerInfo { 69 uint32_t fFlagsMask; // SkPaint::Flags 70 BitFlags fPaintBits; 71 SkXfermode::Mode fColorMode; 72 SkVector fOffset; 73 bool fPostTranslate; //!< applies to fOffset 74 75 /** 76 * Initial the LayerInfo. Defaults to settings that will draw the 77 * layer with no changes: e.g. 78 * fPaintBits == 0 79 * fColorMode == kDst_Mode 80 * fOffset == (0, 0) 81 */ 82 LayerInfo(); 83 }; 84 85 /** 86 * Call for each layer you want to add (from top to bottom). 87 * This returns a paint you can modify, but that ptr is only valid until 88 * the next call made to addLayer(). 89 */ 90 SkPaint* addLayer(const LayerInfo&); 91 92 /** 93 * This layer will draw with the original paint, at the specified offset 94 */ 95 void addLayer(SkScalar dx, SkScalar dy); 96 97 /** 98 * This layer will with the original paint and no offset. 99 */ addLayer()100 void addLayer() { this->addLayer(0, 0); } 101 102 /// Similar to addLayer, but adds a layer to the top. 103 SkPaint* addLayerOnTop(const LayerInfo&); 104 105 // overrides from SkDrawLooper 106 virtual void init(SkCanvas*); 107 virtual bool next(SkCanvas*, SkPaint* paint); 108 109 SK_DEVELOPER_TO_STRING() 110 SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkLayerDrawLooper) 111 112 protected: 113 SkLayerDrawLooper(SkFlattenableReadBuffer&); 114 virtual void flatten(SkFlattenableWriteBuffer&) const SK_OVERRIDE; 115 116 private: 117 struct Rec { 118 Rec* fNext; 119 SkPaint fPaint; 120 LayerInfo fInfo; 121 }; 122 Rec* fRecs; 123 Rec* fTopRec; 124 int fCount; 125 126 // state-machine during the init/next cycle 127 Rec* fCurrRec; 128 129 static void ApplyInfo(SkPaint* dst, const SkPaint& src, const LayerInfo&); 130 131 class MyRegistrar : public SkFlattenable::Registrar { 132 public: 133 MyRegistrar(); 134 }; 135 136 typedef SkDrawLooper INHERITED; 137 }; 138 139 #endif 140