1 /* 2 * Copyright 2014 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 SkPatchGrid_DEFINED 9 #define SkPatchGrid_DEFINED 10 11 #include "SkCanvas.h" 12 #include "SkPatchUtils.h" 13 #include "SkXfermode.h" 14 15 /** 16 * Class that represents a grid of patches. Adjacent patches share their corners and a color is 17 * specified at each one of them. The colors are bilinearly interpolated across the patch. 18 * 19 * This implementation defines a bidimensional array of patches. There are 3 arrays to store the 20 * control points of the patches to avoid storing repeated data since there are several points 21 * shared between adjacent patches. 22 * 23 * The array fCornerPts stores the corner control points of the patches. 24 * The array fHrzPts holds the intermidiate control points of the top and bottom curves of a patch. 25 * The array fVrtPts holds the intermidiate control points of the left and right curves of a patch. 26 * The array fCornerColors holds the corner colors in the same format as fCornerPts. 27 * The array fTexCoords holds the texture coordinates in the same format as fCornerpts. 28 * 29 * fCornerPts fHrzPts fVrtPts 30 * -------------- ------------------- -------------- 31 * | C0 | C1 | C2 | | H0 | H1 | H2 | H3 | | V0 | V1 | V2 | 32 * -------------- ------------------ --------------- 33 * | C3 | C4 | C5 | | H4 | H5 | H6 | H7 | | V4 | V5 | V6 | 34 * -------------- ------------------- -------------- 35 * | C6 | C7 | C8 | | H8 | H9 | H10| H11| | V6 | V7 | V8 | 36 * -------------- ------------------- -------------- 37 * | V9 | V10| V11| 38 * -------------- 39 * 40 * With the above configuration we would have a 2x2 grid of patches: 41 * H0 H1 H2 H3 42 * / \/ \ 43 * C0-------C1-------C2 44 * /| | |\ 45 * v0 | v1 | v2 46 * v3 | V4 | v5 47 * \| | |/ 48 * C3-H4-H5-C4-H6-H7-C5 49 * /| | |\ 50 * v6 | v7 | v8 51 * v9 | v10 | v11 52 * \| | |/ 53 * C6-------C7-------C8 54 * \ / \ / 55 * H8 H9 H10 H11 56 * 57 * When trying to get a patch at a certain position it justs builds it with the corresponding 58 * points. 59 * When adding a patch it tries to add the points at their corresponding position trying to comply 60 * with the adjacent points or overwriting them. 61 * 62 * Based the idea on the SVG2 spec for mesh gradients in which a grid of patches is build as in the 63 * the following example: 64 * <meshGradient x="100" y="100"> 65 * <meshRow> 66 * <meshPatch> 67 * <stop .../> 68 * Up to four stops in first patch. See details below. 69 * </meshPatch> 70 * <meshPatch> 71 * Any number of meshPatches in row. 72 * </meshPatch> 73 * </meshRow> 74 * <meshRow> 75 * Any number of meshRows, each with the same number of meshPatches as in the first row. 76 * </meshRow> 77 * </meshGradient> 78 */ 79 class SkPatchGrid { 80 81 public: 82 83 enum VertexType { 84 kNone_VertexType = 0X00, 85 kColors_VertexType = 0x01, 86 kTexs_VertexType = 0x02, 87 kColorsAndTexs_VertexType = 0x03 88 }; 89 90 SkPatchGrid(int rows = 0, int cols = 0, VertexType flags = kNone_VertexType, 91 SkXfermode* xfer = NULL); 92 93 ~SkPatchGrid(); 94 95 /** 96 * Add a patch at location (x,y) overwriting the previous patch and shared points so they 97 * mantain C0 connectivity. 98 * The control points must be passed in a clockwise order starting at the top left corner. 99 * The colors and texCoords are the values at the corners of the patch which will be bilerp 100 * across it, they must also be in counterclockwise order starting at the top left corner. 101 */ 102 bool setPatch(int x, int y, const SkPoint cubics[12], const SkColor colors[4], 103 const SkPoint texCoords[4]); 104 105 /** 106 * Get patch at location (x,y). If cubics, colors or texCoords is not NULL it sets patch's 107 * array with its corresponding values. 108 * The function returns false if the cubics parameter is NULL or if the (x,y) coordinates are 109 * not within the range of the grid. 110 */ 111 bool getPatch(int x, int y, SkPoint cubics[12], SkColor colors[4], SkPoint texCoords[4]) const; 112 113 /** 114 * Resets the grid of patches to contain rows and cols of patches. 115 */ 116 void reset(int rows, int cols, VertexType flags, SkXfermode* xMode); 117 118 /** 119 * Draws the grid of patches. The patches are drawn starting at patch (0,0) drawing columns, so 120 * for a 2x2 grid the order would be (0,0)->(0,1)->(1,0)->(1,1). The order follows the order 121 * of the parametric coordinates of the coons patch. 122 */ 123 void draw(SkCanvas* canvas, SkPaint& paint); 124 125 /** 126 * Get the dimensions of the grid of patches. 127 */ 128 SkISize getDimensions() const { 129 return SkISize::Make(fCols, fRows); 130 } 131 132 private: 133 int fRows, fCols; 134 VertexType fModeFlags; 135 SkPoint* fCornerPts; 136 SkColor* fCornerColors; 137 SkPoint* fTexCoords; 138 SkPoint* fHrzCtrlPts; 139 SkPoint* fVrtCtrlPts; 140 SkXfermode* fXferMode; 141 }; 142 143 144 #endif 145
