1 2 /* 3 * Copyright 2006 The Android Open Source Project 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 #ifndef SkColorFilter_DEFINED 11 #define SkColorFilter_DEFINED 12 13 #include "SkColor.h" 14 #include "SkFlattenable.h" 15 #include "SkXfermode.h" 16 17 class SkBitmap; 18 class GrEffectRef; 19 class GrContext; 20 21 /** 22 * ColorFilters are optional objects in the drawing pipeline. When present in 23 * a paint, they are called with the "src" colors, and return new colors, which 24 * are then passed onto the next stage (either ImageFilter or Xfermode). 25 * 26 * All subclasses are required to be reentrant-safe : it must be legal to share 27 * the same instance between several threads. 28 */ 29 class SK_API SkColorFilter : public SkFlattenable { 30 public: 31 SK_DECLARE_INST_COUNT(SkColorFilter) 32 33 /** 34 * If the filter can be represented by a source color plus Mode, this 35 * returns true, and sets (if not NULL) the color and mode appropriately. 36 * If not, this returns false and ignores the parameters. 37 */ 38 virtual bool asColorMode(SkColor* color, SkXfermode::Mode* mode) const; 39 40 /** 41 * If the filter can be represented by a 5x4 matrix, this 42 * returns true, and sets the matrix appropriately. 43 * If not, this returns false and ignores the parameter. 44 */ 45 virtual bool asColorMatrix(SkScalar matrix[20]) const; 46 47 /** 48 * If the filter can be represented by per-component table, return true, 49 * and if table is not null, copy the bitmap containing the table into it. 50 * 51 * The table bitmap will be in SkBitmap::kA8_Config. Each row corresponding 52 * to each component in ARGB order. e.g. row[0] == alpha, row[1] == red, 53 * etc. To transform a color, you (logically) perform the following: 54 * 55 * a' = *table.getAddr8(a, 0); 56 * r' = *table.getAddr8(r, 1); 57 * g' = *table.getAddr8(g, 2); 58 * b' = *table.getAddr8(b, 3); 59 * 60 * The original component value is the horizontal index for a given row, 61 * and the stored value at that index is the new value for that component. 62 */ 63 virtual bool asComponentTable(SkBitmap* table) const; 64 65 /** Called with a scanline of colors, as if there was a shader installed. 66 The implementation writes out its filtered version into result[]. 67 Note: shader and result may be the same buffer. 68 @param src array of colors, possibly generated by a shader 69 @param count the number of entries in the src[] and result[] arrays 70 @param result written by the filter 71 */ 72 virtual void filterSpan(const SkPMColor src[], int count, 73 SkPMColor result[]) const = 0; 74 /** Called with a scanline of colors, as if there was a shader installed. 75 The implementation writes out its filtered version into result[]. 76 Note: shader and result may be the same buffer. 77 @param src array of colors, possibly generated by a shader 78 @param count the number of entries in the src[] and result[] arrays 79 @param result written by the filter 80 */ 81 virtual void filterSpan16(const uint16_t shader[], int count, 82 uint16_t result[]) const; 83 84 enum Flags { 85 /** If set the filter methods will not change the alpha channel of the 86 colors. 87 */ 88 kAlphaUnchanged_Flag = 0x01, 89 /** If set, this subclass implements filterSpan16(). If this flag is 90 set, then kAlphaUnchanged_Flag must also be set. 91 */ 92 kHasFilter16_Flag = 0x02 93 }; 94 95 /** Returns the flags for this filter. Override in subclasses to return 96 custom flags. 97 */ 98 virtual uint32_t getFlags() const { return 0; } 99 100 /** 101 * Apply this colorfilter to the specified SkColor. This routine handles 102 * converting to SkPMColor, calling the filter, and then converting back 103 * to SkColor. This method is not virtual, but will call filterSpan() 104 * which is virtual. 105 */ 106 SkColor filterColor(SkColor) const; 107 108 /** Create a colorfilter that uses the specified color and mode. 109 If the Mode is DST, this function will return NULL (since that 110 mode will have no effect on the result). 111 @param c The source color used with the specified mode 112 @param mode The xfermode mode that is applied to each color in 113 the colorfilter's filterSpan[16,32] methods 114 @return colorfilter object that applies the src color and mode, 115 or NULL if the mode will have no effect. 116 */ 117 static SkColorFilter* CreateModeFilter(SkColor c, SkXfermode::Mode mode); 118 119 /** Create a colorfilter that multiplies the RGB channels by one color, and 120 then adds a second color, pinning the result for each component to 121 [0..255]. The alpha components of the mul and add arguments 122 are ignored. 123 */ 124 static SkColorFilter* CreateLightingFilter(SkColor mul, SkColor add); 125 126 /** A subclass may implement this factory function to work with the GPU backend. If the return 127 is non-NULL then the caller owns a ref on the returned object. 128 */ 129 virtual GrEffectRef* asNewEffect(GrContext*) const; 130 131 SK_TO_STRING_PUREVIRT() 132 133 SK_DECLARE_FLATTENABLE_REGISTRAR_GROUP() 134 SK_DEFINE_FLATTENABLE_TYPE(SkColorFilter) 135 136 protected: 137 SkColorFilter() {} 138 SkColorFilter(SkReadBuffer& rb) : INHERITED(rb) {} 139 140 private: 141 typedef SkFlattenable INHERITED; 142 }; 143 144 #endif 145
