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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 <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
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