| /* |
| * Copyright 2017 Google Inc. |
| * |
| * Use of this source code is governed by a BSD-style license that can be |
| * found in the LICENSE file. |
| */ |
| |
| #ifndef SkOffsetPolygon_DEFINED |
| #define SkOffsetPolygon_DEFINED |
| |
| #include "include/core/SkPoint.h" |
| #include "include/core/SkScalar.h" |
| |
| #include <stdint.h> |
| |
| struct SkRect; |
| template <typename T> class SkTDArray; |
| |
| /** |
| * Generates a polygon that is inset a constant from the boundary of a given convex polygon. |
| * The input polygon is expected to have values clamped to the nearest 1/16th. |
| * |
| * @param inputPolygonVerts Array of points representing the vertices of the original polygon. |
| * It should be convex and have no coincident points. |
| * @param inputPolygonSize Number of vertices in the original polygon. |
| * @param inset How far we wish to inset the polygon. This should be a positive value. |
| * @param insetPolygon The resulting inset polygon, if any. |
| * @return true if an inset polygon exists, false otherwise. |
| */ |
| bool SkInsetConvexPolygon(const SkPoint* inputPolygonVerts, int inputPolygonSize, |
| SkScalar inset, SkTDArray<SkPoint>* insetPolygon); |
| |
| /** |
| * Generates a simple polygon (if possible) that is offset a constant distance from the boundary |
| * of a given simple polygon. |
| * The input polygon must be simple, have no coincident vertices or collinear edges, and have |
| * values clamped to the nearest 1/16th. |
| * |
| * @param inputPolygonVerts Array of points representing the vertices of the original polygon. |
| * @param inputPolygonSize Number of vertices in the original polygon. |
| * @param bounds Bounding rectangle for the original polygon. |
| * @param offset How far we wish to offset the polygon. |
| * Positive values indicate insetting, negative values outsetting. |
| * @param offsetPolgon The resulting offset polygon, if any. |
| * @param polygonIndices The indices of the original polygon that map to the new one. |
| * @return true if an offset simple polygon exists, false otherwise. |
| */ |
| bool SkOffsetSimplePolygon(const SkPoint* inputPolygonVerts, int inputPolygonSize, |
| const SkRect& bounds, SkScalar offset, SkTDArray<SkPoint>* offsetPolygon, |
| SkTDArray<int>* polygonIndices = nullptr); |
| |
| /** |
| * Compute the number of points needed for a circular join when offsetting a vertex. |
| * The lengths of offset0 and offset1 don't have to equal |offset| -- only the direction matters. |
| * The segment lengths will be approximately four pixels. |
| * |
| * @param offset0 Starting offset vector direction. |
| * @param offset1 Ending offset vector direction. |
| * @param offset Offset value (can be negative). |
| * @param rotSin Sine of rotation delta per step. |
| * @param rotCos Cosine of rotation delta per step. |
| * @param n Number of steps to fill out the arc. |
| * @return true for success, false otherwise |
| */ |
| bool SkComputeRadialSteps(const SkVector& offset0, const SkVector& offset1, SkScalar offset, |
| SkScalar* rotSin, SkScalar* rotCos, int* n); |
| |
| /** |
| * Determine winding direction for a polygon. |
| * The input polygon must be simple or the result will be meaningless. |
| * |
| * @param polygonVerts Array of points representing the vertices of the polygon. |
| * @param polygonSize Number of vertices in the polygon. |
| * @return 1 for cw, -1 for ccw, and 0 if zero signed area (either degenerate or self-intersecting). |
| * The y-axis is assumed to be pointing down. |
| */ |
| int SkGetPolygonWinding(const SkPoint* polygonVerts, int polygonSize); |
| |
| /** |
| * Determine whether a polygon is convex or not. |
| * |
| * @param polygonVerts Array of points representing the vertices of the polygon. |
| * @param polygonSize Number of vertices in the polygon. |
| * @return true if the polygon is convex, false otherwise. |
| */ |
| bool SkIsConvexPolygon(const SkPoint* polygonVerts, int polygonSize); |
| |
| /** |
| * Determine whether a polygon is simple (i.e., not self-intersecting) or not. |
| * The input polygon must have no coincident vertices or the test will fail. |
| * The polygon is also expected to have values clamped to the nearest 1/16th. |
| * |
| * @param polygonVerts Array of points representing the vertices of the polygon. |
| * @param polygonSize Number of vertices in the polygon. |
| * @return true if the polygon is simple, false otherwise. |
| */ |
| bool SkIsSimplePolygon(const SkPoint* polygonVerts, int polygonSize); |
| |
| /** |
| * Compute indices to triangulate the given polygon. |
| * The input polygon must be simple (i.e. it is not self-intersecting) |
| * and have no coincident vertices or collinear edges. |
| * |
| * @param polygonVerts Array of points representing the vertices of the polygon. |
| * @param indexMap Mapping from index in the given array to the final index in the triangulation. |
| * @param polygonSize Number of vertices in the polygon. |
| * @param triangleIndices Indices of the resulting triangulation. |
| * @return true if successful, false otherwise. |
| */ |
| bool SkTriangulateSimplePolygon(const SkPoint* polygonVerts, uint16_t* indexMap, int polygonSize, |
| SkTDArray<uint16_t>* triangleIndices); |
| |
| // Experiment: doesn't handle really big floats (returns false), always returns true for count <= 3 |
| bool SkIsPolyConvex_experimental(const SkPoint[], int count); |
| |
| #endif |