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 /* * 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 "SkTDArray.h" #include "SkPoint.h" /** * Generates a polygon that is inset a variable distance (controlled by offsetDistanceFunc) * 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 position. * 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 insetDistanceFunc, SkTDArray* insetPolygon); /** * Generates a polygon that is inset a constant 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 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. */ inline bool SkInsetConvexPolygon(const SkPoint* inputPolygonVerts, int inputPolygonSize, SkScalar inset, SkTDArray* insetPolygon) { return SkInsetConvexPolygon(inputPolygonVerts, inputPolygonSize, [inset](const SkPoint&) { return inset; }, insetPolygon); } /** * Generates a simple polygon (if possible) that is offset a variable distance (controlled by * offsetDistanceFunc) 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 offsetDistanceFunc How far we wish to offset the polygon for a given position. * 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, std::function offsetDistanceFunc, SkTDArray* offsetPolygon, SkTDArray* polygonIndices = nullptr); /** * Generates a simple polygon (if possible) that is offset a constant 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 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. */ inline bool SkOffsetSimplePolygon(const SkPoint* inputPolygonVerts, int inputPolygonSize, SkScalar offset, SkTDArray* offsetPolygon, SkTDArray* polygonIndices = nullptr) { return SkOffsetSimplePolygon(inputPolygonVerts, inputPolygonSize, [offset](const SkPoint&) { return offset; }, offsetPolygon, polygonIndices); } /** * 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