SkGradientShader.h revision 83f23d87f1d67e6e73873e1ef7cda621c43703a0
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 SkGradientShader_DEFINED 9#define SkGradientShader_DEFINED 10 11#include "SkShader.h" 12 13/** \class SkGradientShader 14 15 SkGradientShader hosts factories for creating subclasses of SkShader that 16 render linear and radial gradients. 17*/ 18class SK_API SkGradientShader { 19public: 20 enum Flags { 21 /** By default gradients will interpolate their colors in unpremul space 22 * and then premultiply each of the results. By setting this flag, the 23 * gradients will premultiply their colors first, and then interpolate 24 * between them. 25 */ 26 kInterpolateColorsInPremul_Flag = 1 << 0, 27 }; 28 29 /** Returns a shader that generates a linear gradient between the two 30 specified points. 31 <p /> 32 CreateLinear returns a shader with a reference count of 1. 33 The caller should decrement the shader's reference count when done with the shader. 34 It is an error for count to be < 2. 35 @param pts The start and end points for the gradient. 36 @param colors The array[count] of colors, to be distributed between the two points 37 @param pos May be NULL. array[count] of SkScalars, or NULL, of the relative position of 38 each corresponding color in the colors array. If this is NULL, 39 the the colors are distributed evenly between the start and end point. 40 If this is not null, the values must begin with 0, end with 1.0, and 41 intermediate values must be strictly increasing. 42 @param count Must be >=2. The number of colors (and pos if not NULL) entries. 43 @param mode The tiling mode 44 */ 45 static SkShader* CreateLinear(const SkPoint pts[2], 46 const SkColor colors[], const SkScalar pos[], int count, 47 SkShader::TileMode mode, 48 uint32_t flags, const SkMatrix* localMatrix); 49 50 static SkShader* CreateLinear(const SkPoint pts[2], 51 const SkColor colors[], const SkScalar pos[], int count, 52 SkShader::TileMode mode) { 53 return CreateLinear(pts, colors, pos, count, mode, 0, NULL); 54 } 55 56 /** Returns a shader that generates a radial gradient given the center and radius. 57 <p /> 58 CreateRadial returns a shader with a reference count of 1. 59 The caller should decrement the shader's reference count when done with the shader. 60 It is an error for colorCount to be < 2, or for radius to be <= 0. 61 @param center The center of the circle for this gradient 62 @param radius Must be positive. The radius of the circle for this gradient 63 @param colors The array[count] of colors, to be distributed between the center and edge of the circle 64 @param pos May be NULL. The array[count] of SkScalars, or NULL, of the relative position of 65 each corresponding color in the colors array. If this is NULL, 66 the the colors are distributed evenly between the center and edge of the circle. 67 If this is not null, the values must begin with 0, end with 1.0, and 68 intermediate values must be strictly increasing. 69 @param count Must be >= 2. The number of colors (and pos if not NULL) entries 70 @param mode The tiling mode 71 */ 72 static SkShader* CreateRadial(const SkPoint& center, SkScalar radius, 73 const SkColor colors[], const SkScalar pos[], int count, 74 SkShader::TileMode mode, 75 uint32_t flags, const SkMatrix* localMatrix); 76 77 static SkShader* CreateRadial(const SkPoint& center, SkScalar radius, 78 const SkColor colors[], const SkScalar pos[], int count, 79 SkShader::TileMode mode) { 80 return CreateRadial(center, radius, colors, pos, count, mode, 0, NULL); 81 } 82 83 /** Returns a shader that generates a radial gradient given the start position, start radius, end position and end radius. 84 <p /> 85 CreateTwoPointRadial returns a shader with a reference count of 1. 86 The caller should decrement the shader's reference count when done with the shader. 87 It is an error for colorCount to be < 2, for startRadius or endRadius to be < 0, or for 88 startRadius to be equal to endRadius. 89 @param start The center of the start circle for this gradient 90 @param startRadius Must be positive. The radius of the start circle for this gradient. 91 @param end The center of the end circle for this gradient 92 @param endRadius Must be positive. The radius of the end circle for this gradient. 93 @param colors The array[count] of colors, to be distributed between the center and edge of the circle 94 @param pos May be NULL. The array[count] of SkScalars, or NULL, of the relative position of 95 each corresponding color in the colors array. If this is NULL, 96 the the colors are distributed evenly between the center and edge of the circle. 97 If this is not null, the values must begin with 0, end with 1.0, and 98 intermediate values must be strictly increasing. 99 @param count Must be >= 2. The number of colors (and pos if not NULL) entries 100 @param mode The tiling mode 101 */ 102 static SkShader* CreateTwoPointRadial(const SkPoint& start, SkScalar startRadius, 103 const SkPoint& end, SkScalar endRadius, 104 const SkColor colors[], const SkScalar pos[], int count, 105 SkShader::TileMode mode, 106 uint32_t flags, const SkMatrix* localMatrix); 107 108 static SkShader* CreateTwoPointRadial(const SkPoint& start, SkScalar startRadius, 109 const SkPoint& end, SkScalar endRadius, 110 const SkColor colors[], const SkScalar pos[], int count, 111 SkShader::TileMode mode) { 112 return CreateTwoPointRadial(start, startRadius, end, endRadius, colors, pos, count, mode, 113 0, NULL); 114 } 115 116 /** 117 * Returns a shader that generates a conical gradient given two circles, or 118 * returns NULL if the inputs are invalid. The gradient interprets the 119 * two circles according to the following HTML spec. 120 * http://dev.w3.org/html5/2dcontext/#dom-context-2d-createradialgradient 121 */ 122 static SkShader* CreateTwoPointConical(const SkPoint& start, SkScalar startRadius, 123 const SkPoint& end, SkScalar endRadius, 124 const SkColor colors[], const SkScalar pos[], int count, 125 SkShader::TileMode mode, 126 uint32_t flags, const SkMatrix* localMatrix); 127 128 static SkShader* CreateTwoPointConical(const SkPoint& start, SkScalar startRadius, 129 const SkPoint& end, SkScalar endRadius, 130 const SkColor colors[], const SkScalar pos[], int count, 131 SkShader::TileMode mode) { 132 return CreateTwoPointConical(start, startRadius, end, endRadius, colors, pos, count, mode, 133 0, NULL); 134 } 135 136 /** Returns a shader that generates a sweep gradient given a center. 137 <p /> 138 CreateSweep returns a shader with a reference count of 1. 139 The caller should decrement the shader's reference count when done with the shader. 140 It is an error for colorCount to be < 2. 141 @param cx The X coordinate of the center of the sweep 142 @param cx The Y coordinate of the center of the sweep 143 @param colors The array[count] of colors, to be distributed around the center. 144 @param pos May be NULL. The array[count] of SkScalars, or NULL, of the relative position of 145 each corresponding color in the colors array. If this is NULL, 146 the the colors are distributed evenly between the center and edge of the circle. 147 If this is not null, the values must begin with 0, end with 1.0, and 148 intermediate values must be strictly increasing. 149 @param count Must be >= 2. The number of colors (and pos if not NULL) entries 150 */ 151 static SkShader* CreateSweep(SkScalar cx, SkScalar cy, 152 const SkColor colors[], const SkScalar pos[], int count, 153 uint32_t flags, const SkMatrix* localMatrix); 154 155 static SkShader* CreateSweep(SkScalar cx, SkScalar cy, 156 const SkColor colors[], const SkScalar pos[], int count) { 157 return CreateSweep(cx, cy, colors, pos, count, 0, NULL); 158 } 159 160 SK_DECLARE_FLATTENABLE_REGISTRAR_GROUP() 161}; 162 163#endif 164