1 /* 2 * Copyright 2006 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 #ifndef SkColorFilter_DEFINED 9 #define SkColorFilter_DEFINED 10 11 #include "SkBlendMode.h" 12 #include "SkColor.h" 13 #include "SkFlattenable.h" 14 #include "SkRefCnt.h" 15 16 class GrContext; 17 class GrColorSpaceInfo; 18 class GrFragmentProcessor; 19 class SkArenaAlloc; 20 class SkBitmap; 21 class SkColorSpace; 22 class SkColorSpaceXformer; 23 class SkRasterPipeline; 24 25 /** 26 * ColorFilters are optional objects in the drawing pipeline. When present in 27 * a paint, they are called with the "src" colors, and return new colors, which 28 * are then passed onto the next stage (either ImageFilter or Xfermode). 29 * 30 * All subclasses are required to be reentrant-safe : it must be legal to share 31 * the same instance between several threads. 32 */ 33 class SK_API SkColorFilter : public SkFlattenable { 34 public: 35 /** 36 * If the filter can be represented by a source color plus Mode, this 37 * returns true, and sets (if not NULL) the color and mode appropriately. 38 * If not, this returns false and ignores the parameters. 39 */ 40 virtual bool asColorMode(SkColor* color, SkBlendMode* bmode) const; 41 42 /** 43 * If the filter can be represented by a 5x4 matrix, this 44 * returns true, and sets the matrix appropriately. 45 * If not, this returns false and ignores the parameter. 46 */ 47 virtual bool asColorMatrix(SkScalar matrix[20]) const; 48 49 /** 50 * If the filter can be represented by per-component table, return true, 51 * and if table is not null, copy the bitmap containing the table into it. 52 * 53 * The table bitmap will be in SkBitmap::kA8_Config. Each row corresponding 54 * to each component in ARGB order. e.g. row[0] == alpha, row[1] == red, 55 * etc. To transform a color, you (logically) perform the following: 56 * 57 * a' = *table.getAddr8(a, 0); 58 * r' = *table.getAddr8(r, 1); 59 * g' = *table.getAddr8(g, 2); 60 * b' = *table.getAddr8(b, 3); 61 * 62 * The original component value is the horizontal index for a given row, 63 * and the stored value at that index is the new value for that component. 64 */ 65 virtual bool asComponentTable(SkBitmap* table) const; 66 67 void appendStages(SkRasterPipeline*, SkColorSpace*, SkArenaAlloc*, bool shaderIsOpaque) const; 68 69 enum Flags { 70 /** If set the filter methods will not change the alpha channel of the colors. 71 */ 72 kAlphaUnchanged_Flag = 1 << 0, 73 }; 74 75 /** Returns the flags for this filter. Override in subclasses to return custom flags. 76 */ getFlags()77 virtual uint32_t getFlags() const { return 0; } 78 79 SkColor filterColor(SkColor) const; 80 SkColor4f filterColor4f(const SkColor4f&) const; 81 82 /** Create a colorfilter that uses the specified color and mode. 83 If the Mode is DST, this function will return NULL (since that 84 mode will have no effect on the result). 85 @param c The source color used with the specified mode 86 @param mode The blend that is applied to each color in 87 the colorfilter's filterSpan[16,32] methods 88 @return colorfilter object that applies the src color and mode, 89 or NULL if the mode will have no effect. 90 */ 91 static sk_sp<SkColorFilter> MakeModeFilter(SkColor c, SkBlendMode mode); 92 93 /** Construct a colorfilter whose effect is to first apply the inner filter and then apply 94 * this filter, applied to the output of the inner filter. 95 * 96 * result = this(inner(...)) 97 * 98 * Due to internal limits, it is possible that this will return NULL, so the caller must 99 * always check. 100 */ 101 sk_sp<SkColorFilter> makeComposed(sk_sp<SkColorFilter> inner) const; 102 103 // DEPRECATED, call makeComposed instead MakeComposeFilter(sk_sp<SkColorFilter> outer,sk_sp<SkColorFilter> inner)104 static sk_sp<SkColorFilter> MakeComposeFilter(sk_sp<SkColorFilter> outer, 105 sk_sp<SkColorFilter> inner) { 106 return outer ? outer->makeComposed(inner) : inner; 107 } 108 109 /** Construct a color filter that transforms a color by a 4x5 matrix. The matrix is in row- 110 * major order and the translation column is specified in unnormalized, 0...255, space. 111 */ 112 static sk_sp<SkColorFilter> MakeMatrixFilterRowMajor255(const SkScalar array[20]); 113 114 /** Construct a colorfilter that applies the srgb gamma curve to the RGB channels */ 115 static sk_sp<SkColorFilter> MakeLinearToSRGBGamma(); 116 117 /** Construct a colorfilter that applies the inverse of the srgb gamma curve to the 118 * RGB channels 119 */ 120 static sk_sp<SkColorFilter> MakeSRGBToLinearGamma(); 121 122 #if SK_SUPPORT_GPU 123 /** 124 * A subclass may implement this factory function to work with the GPU backend. It returns 125 * a GrFragmentProcessor that implemets the color filter in GPU shader code. 126 * 127 * The fragment processor receives a premultiplied input color and produces a premultiplied 128 * output color. 129 * 130 * A null return indicates that the color filter isn't implemented for the GPU backend. 131 */ 132 virtual std::unique_ptr<GrFragmentProcessor> asFragmentProcessor( 133 GrContext*, const GrColorSpaceInfo& dstColorSpaceInfo) const; 134 #endif 135 affectsTransparentBlack()136 bool affectsTransparentBlack() const { 137 return this->filterColor(0) != 0; 138 } 139 140 SK_TO_STRING_PUREVIRT() 141 SK_DECLARE_FLATTENABLE_REGISTRAR_GROUP()142 SK_DECLARE_FLATTENABLE_REGISTRAR_GROUP() 143 SK_DEFINE_FLATTENABLE_TYPE(SkColorFilter) 144 145 protected: 146 SkColorFilter() {} 147 makeColorSpace(SkColorSpaceXformer * xformer)148 sk_sp<SkColorFilter> makeColorSpace(SkColorSpaceXformer* xformer) const { 149 return this->onMakeColorSpace(xformer); 150 } onMakeColorSpace(SkColorSpaceXformer *)151 virtual sk_sp<SkColorFilter> onMakeColorSpace(SkColorSpaceXformer*) const { 152 return sk_ref_sp(const_cast<SkColorFilter*>(this)); 153 } 154 155 /** 156 * If this subclass can optimally createa composition with the inner filter, return it as 157 * a new filter (which the caller must unref() when it is done). If no such optimization 158 * is known, return NULL. 159 * 160 * e.g. result(color) == this_filter(inner(color)) 161 */ onMakeComposed(sk_sp<SkColorFilter>)162 virtual sk_sp<SkColorFilter> onMakeComposed(sk_sp<SkColorFilter>) const { return nullptr; } 163 164 private: 165 /* 166 * Returns 1 if this is a single filter (not a composition of other filters), otherwise it 167 * reutrns the number of leaf-node filters in a composition. This should be the same value 168 * as the number of GrFragmentProcessors returned by asFragmentProcessors's array parameter. 169 * 170 * e.g. compose(filter, compose(compose(filter, filter), filter)) --> 4 171 */ privateComposedFilterCount()172 virtual int privateComposedFilterCount() const { return 1; } 173 174 virtual void onAppendStages(SkRasterPipeline*, SkColorSpace*, SkArenaAlloc*, 175 bool shaderIsOpaque) const = 0; 176 177 friend class SkColorSpaceXformer; 178 friend class SkComposeColorFilter; 179 180 typedef SkFlattenable INHERITED; 181 }; 182 183 #endif 184