1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
|
/*
* 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 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<SkScalar(const SkPoint&)> insetDistanceFunc,
SkTDArray<SkPoint>* 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<SkPoint>* 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<SkScalar(const SkPoint&)> offsetDistanceFunc,
SkTDArray<SkPoint>* offsetPolygon,
SkTDArray<int>* 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<SkPoint>* offsetPolygon,
SkTDArray<int>* 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
|
