| /* |
| * 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 <functional> |
| |
| #include "SkTDArray.h" |
| #include "SkPoint.h" |
| |
| /** |
| * Generates a polygon that is inset a given distance from the boundary of a given convex polygon. |
| * |
| * @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 insetDistanceFunc How far we wish to inset the polygon for a given index in the array. |
| * This should return 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, |
| std::function<SkScalar(int index)> insetDistanceFunc, |
| SkTDArray<SkPoint>* insetPolygon); |
| |
| inline bool SkInsetConvexPolygon(const SkPoint* inputPolygonVerts, int inputPolygonSize, |
| SkScalar inset, SkTDArray<SkPoint>* insetPolygon) { |
| return SkInsetConvexPolygon(inputPolygonVerts, inputPolygonSize, |
| [inset](int) { return inset; }, |
| insetPolygon); |
| } |
| |
| /** |
| * Generates a simple polygon (if possible) that is offset a given distance from the boundary of a |
| * given simple polygon. |
| * |
| * @param inputPolygonVerts Array of points representing the vertices of the original polygon. |
| * @param inputPolygonSize Number of vertices in the original polygon. |
| * @param offset How far we wish to offset the polygon. |
| * Positive value means inset, negative value means outset. |
| * @param offsetPolgon The resulting offset polygon, if any. |
| * @return true if an offset simple polygon exists, false otherwise. |
| */ |
| bool SkOffsetSimplePolygon(const SkPoint* inputPolygonVerts, int inputPolygonSize, |
| SkScalar offset, SkTDArray<SkPoint>* offsetPolygon); |
| |
| /** |
| * Offset a segment by the given distance at each point. |
| * Uses the outer tangents of two circles centered on each endpoint. |
| * See: https://en.wikipedia.org/wiki/Tangent_lines_to_circles |
| * |
| * @param p0 First endpoint. |
| * @param p1 Second endpoint. |
| * @param d0 Offset distance from first endpoint. |
| * @param d1 Offset distance from second endpoint. |
| * @param side Indicates whether we want to offset to the left (1) or right (-1) side of segment. |
| * @param offset0 First endpoint of offset segment. |
| * @param offset1 Second endpoint of offset segment. |
| * @return true if an offset segment exists, false otherwise. |
| */ |
| bool SkOffsetSegment(const SkPoint& p0, const SkPoint& p1, SkScalar d0, SkScalar d1, |
| int side, SkPoint* offset0, SkPoint* offset1); |
| |
| #endif |