SkGradientShader.h revision 9c9005a347e9996f357bd79591bd34f74f8bbc66
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 13class SkUnitMapper; 14 15/** \class SkGradientShader 16 17 SkGradientShader hosts factories for creating subclasses of SkShader that 18 render linear and radial gradients. 19*/ 20class SK_API SkGradientShader { 21public: 22 enum Flags { 23 /** By default gradients will interpolate their colors in unpremul space 24 * and then premultiply each of the results. By setting this flag, the 25 * gradients will premultiply their colors first, and then interpolate 26 * between them. 27 */ 28 kInterpolateColorsInPremul_Flag = 1 << 0, 29 }; 30 31 /** Returns a shader that generates a linear gradient between the two 32 specified points. 33 <p /> 34 CreateLinear returns a shader with a reference count of 1. 35 The caller should decrement the shader's reference count when done with the shader. 36 It is an error for count to be < 2. 37 @param pts The start and end points for the gradient. 38 @param colors The array[count] of colors, to be distributed between the two points 39 @param pos May be NULL. array[count] of SkScalars, or NULL, of the relative position of 40 each corresponding color in the colors array. If this is NULL, 41 the the colors are distributed evenly between the start and end point. 42 If this is not null, the values must begin with 0, end with 1.0, and 43 intermediate values must be strictly increasing. 44 @param count Must be >=2. The number of colors (and pos if not NULL) entries. 45 @param mode The tiling mode 46 @param mapper May be NULL. Callback to modify the spread of the colors. 47 */ 48 static SkShader* CreateLinear(const SkPoint pts[2], 49 const SkColor colors[], const SkScalar pos[], int count, 50 SkShader::TileMode mode, 51 SkUnitMapper* mapper = NULL, 52 uint32_t flags = 0, 53 const SkMatrix* localMatrix = NULL); 54 55 /** Returns a shader that generates a radial gradient given the center and radius. 56 <p /> 57 CreateRadial returns a shader with a reference count of 1. 58 The caller should decrement the shader's reference count when done with the shader. 59 It is an error for colorCount to be < 2, or for radius to be <= 0. 60 @param center The center of the circle for this gradient 61 @param radius Must be positive. The radius of the circle for this gradient 62 @param colors The array[count] of colors, to be distributed between the center and edge of the circle 63 @param pos May be NULL. The array[count] of SkScalars, or NULL, of the relative position of 64 each corresponding color in the colors array. If this is NULL, 65 the the colors are distributed evenly between the center and edge of the circle. 66 If this is not null, the values must begin with 0, end with 1.0, and 67 intermediate values must be strictly increasing. 68 @param count Must be >= 2. The number of colors (and pos if not NULL) entries 69 @param mode The tiling mode 70 @param mapper May be NULL. Callback to modify the spread of the colors. 71 */ 72 static SkShader* CreateRadial(const SkPoint& center, SkScalar radius, 73 const SkColor colors[], const SkScalar pos[], int count, 74 SkShader::TileMode mode, 75 SkUnitMapper* mapper = NULL, 76 uint32_t flags = 0, 77 const SkMatrix* localMatrix = NULL); 78 79 /** Returns a shader that generates a radial gradient given the start position, start radius, end position and end radius. 80 <p /> 81 CreateTwoPointRadial returns a shader with a reference count of 1. 82 The caller should decrement the shader's reference count when done with the shader. 83 It is an error for colorCount to be < 2, for startRadius or endRadius to be < 0, or for 84 startRadius to be equal to endRadius. 85 @param start The center of the start circle for this gradient 86 @param startRadius Must be positive. The radius of the start circle for this gradient. 87 @param end The center of the end circle for this gradient 88 @param endRadius Must be positive. The radius of the end circle for this gradient. 89 @param colors The array[count] of colors, to be distributed between the center and edge of the circle 90 @param pos May be NULL. The array[count] of SkScalars, or NULL, of the relative position of 91 each corresponding color in the colors array. If this is NULL, 92 the the colors are distributed evenly between the center and edge of the circle. 93 If this is not null, the values must begin with 0, end with 1.0, and 94 intermediate values must be strictly increasing. 95 @param count Must be >= 2. The number of colors (and pos if not NULL) entries 96 @param mode The tiling mode 97 @param mapper May be NULL. Callback to modify the spread of the colors. 98 */ 99 static SkShader* CreateTwoPointRadial(const SkPoint& start, 100 SkScalar startRadius, 101 const SkPoint& end, 102 SkScalar endRadius, 103 const SkColor colors[], 104 const SkScalar pos[], int count, 105 SkShader::TileMode mode, 106 SkUnitMapper* mapper = NULL, 107 uint32_t flags = 0, 108 const SkMatrix* localMatrix = NULL); 109 110 /** 111 * Returns a shader that generates a conical gradient given two circles, or 112 * returns NULL if the inputs are invalid. The gradient interprets the 113 * two circles according to the following HTML spec. 114 * http://dev.w3.org/html5/2dcontext/#dom-context-2d-createradialgradient 115 */ 116 static SkShader* CreateTwoPointConical(const SkPoint& start, 117 SkScalar startRadius, 118 const SkPoint& end, 119 SkScalar endRadius, 120 const SkColor colors[], 121 const SkScalar pos[], int count, 122 SkShader::TileMode mode, 123 SkUnitMapper* mapper = NULL, 124 uint32_t flags = 0, 125 const SkMatrix* localMatrix = NULL); 126 127 /** Returns a shader that generates a sweep gradient given a center. 128 <p /> 129 CreateSweep returns a shader with a reference count of 1. 130 The caller should decrement the shader's reference count when done with the shader. 131 It is an error for colorCount to be < 2. 132 @param cx The X coordinate of the center of the sweep 133 @param cx The Y coordinate of the center of the sweep 134 @param colors The array[count] of colors, to be distributed around the center. 135 @param pos May be NULL. The array[count] of SkScalars, or NULL, of the relative position of 136 each corresponding color in the colors array. If this is NULL, 137 the the colors are distributed evenly between the center and edge of the circle. 138 If this is not null, the values must begin with 0, end with 1.0, and 139 intermediate values must be strictly increasing. 140 @param count Must be >= 2. The number of colors (and pos if not NULL) entries 141 @param mapper May be NULL. Callback to modify the spread of the colors. 142 */ 143 static SkShader* CreateSweep(SkScalar cx, SkScalar cy, 144 const SkColor colors[], const SkScalar pos[], 145 int count, SkUnitMapper* mapper = NULL, 146 uint32_t flags = 0, 147 const SkMatrix* localMatrix = NULL); 148 149 SK_DECLARE_FLATTENABLE_REGISTRAR_GROUP() 150}; 151 152#endif 153