1 /* 2 * Copyright (C) 2012 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 #ifndef ANDROID_HWUI_PATH_TESSELLATOR_H 18 #define ANDROID_HWUI_PATH_TESSELLATOR_H 19 20 #include <utils/Vector.h> 21 22 #include "Matrix.h" 23 #include "Rect.h" 24 #include "Vertex.h" 25 #include "VertexBuffer.h" 26 27 namespace android { 28 namespace uirenderer { 29 30 class PathTessellator { 31 public: 32 /** 33 * Populates scaleX and scaleY with the 'tessellation scale' of the transform - the effective X 34 * and Y scales that tessellation will take into account when generating the 1.0 pixel thick 35 * ramp. 36 * 37 * Two instances of the same shape (size, paint, etc.) will only generate the same vertices if 38 * their tessellation scales are equal. 39 */ 40 static void extractTessellationScales(const Matrix4& transform, float* scaleX, float* scaleY); 41 42 /** 43 * Populates a VertexBuffer with a tessellated approximation of the input convex path, as a single 44 * triangle strip. Note: joins are not currently supported. 45 * 46 * @param path The path to be approximated 47 * @param paint The paint the path will be drawn with, indicating AA, painting style 48 * (stroke vs fill), stroke width, stroke cap & join style, etc. 49 * @param transform The transform the path is to be drawn with, used to drive stretch-aware path 50 * vertex approximation, and correct AA ramp offsetting. 51 * @param vertexBuffer The output buffer 52 */ 53 static void tessellatePath(const SkPath& path, const SkPaint* paint, 54 const mat4& transform, VertexBuffer& vertexBuffer); 55 56 /** 57 * Populates a VertexBuffer with a tessellated approximation of points as a single triangle 58 * strip (with degenerate tris separating), respecting the shape defined by the paint cap. 59 * 60 * @param points The center vertices of the points to be drawn 61 * @param count The number of floats making up the point vertices 62 * @param paint The paint the points will be drawn with indicating AA, stroke width & cap 63 * @param transform The transform the points will be drawn with, used to drive stretch-aware path 64 * vertex approximation, and correct AA ramp offsetting 65 * @param vertexBuffer The output buffer 66 */ 67 static void tessellatePoints(const float* points, int count, const SkPaint* paint, 68 const mat4& transform, VertexBuffer& vertexBuffer); 69 70 /** 71 * Populates a VertexBuffer with a tessellated approximation of lines as a single triangle 72 * strip (with degenerate tris separating). 73 * 74 * @param points Pairs of endpoints defining the lines to be drawn 75 * @param count The number of floats making up the line vertices 76 * @param paint The paint the lines will be drawn with indicating AA, stroke width & cap 77 * @param transform The transform the points will be drawn with, used to drive stretch-aware path 78 * vertex approximation, and correct AA ramp offsetting 79 * @param vertexBuffer The output buffer 80 */ 81 static void tessellateLines(const float* points, int count, const SkPaint* paint, 82 const mat4& transform, VertexBuffer& vertexBuffer); 83 84 /** 85 * Approximates a convex, CW outline into a Vector of 2d vertices. 86 * 87 * @param path The outline to be approximated 88 * @param thresholdSquared The threshold of acceptable error (in pixels) when approximating 89 * @param outputVertices An empty Vector which will be populated with the output 90 */ 91 static bool approximatePathOutlineVertices(const SkPath &path, float thresholdSquared, 92 Vector<Vertex> &outputVertices); 93 94 private: 95 static bool approximatePathOutlineVertices(const SkPath &path, bool forceClose, 96 float sqrInvScaleX, float sqrInvScaleY, float thresholdSquared, 97 Vector<Vertex> &outputVertices); 98 99 /* 100 endpoints a & b, 101 control c 102 */ 103 static void recursiveQuadraticBezierVertices( 104 float ax, float ay, 105 float bx, float by, 106 float cx, float cy, 107 float sqrInvScaleX, float sqrInvScaleY, float thresholdSquared, 108 Vector<Vertex> &outputVertices, int depth = 0); 109 110 /* 111 endpoints p1, p2 112 control c1, c2 113 */ 114 static void recursiveCubicBezierVertices( 115 float p1x, float p1y, 116 float c1x, float c1y, 117 float p2x, float p2y, 118 float c2x, float c2y, 119 float sqrInvScaleX, float sqrInvScaleY, float thresholdSquared, 120 Vector<Vertex> &outputVertices, int depth = 0); 121 }; 122 123 }; // namespace uirenderer 124 }; // namespace android 125 126 #endif // ANDROID_HWUI_PATH_TESSELLATOR_H 127
