a5ef39726a
Bug: chromium:954891, oss-fuzz:14079 Change-Id: Ia1ee0a15ab4bfc93e67188ff02e6aa436432a3be Reviewed-on: https://skia-review.googlesource.com/c/skia/+/211602 Commit-Queue: Jim Van Verth <jvanverth@google.com> Reviewed-by: Robert Phillips <robertphillips@google.com>
113 lines
4.9 KiB
C
113 lines
4.9 KiB
C
/*
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* Copyright 2017 Google Inc.
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*
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*/
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#ifndef SkOffsetPolygon_DEFINED
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#define SkOffsetPolygon_DEFINED
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#include <functional>
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#include "include/core/SkPoint.h"
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#include "include/private/SkTDArray.h"
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struct SkRect;
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/**
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* Generates a polygon that is inset a constant from the boundary of a given convex polygon.
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*
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* @param inputPolygonVerts Array of points representing the vertices of the original polygon.
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* It should be convex and have no coincident points.
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* @param inputPolygonSize Number of vertices in the original polygon.
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* @param inset How far we wish to inset the polygon. This should be a positive value.
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* @param insetPolygon The resulting inset polygon, if any.
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* @return true if an inset polygon exists, false otherwise.
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*/
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bool SkInsetConvexPolygon(const SkPoint* inputPolygonVerts, int inputPolygonSize,
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SkScalar inset, SkTDArray<SkPoint>* insetPolygon);
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/**
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* Generates a simple polygon (if possible) that is offset a constant distance from the boundary
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* of a given simple polygon.
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* The input polygon must be simple and have no coincident vertices or collinear edges.
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*
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* @param inputPolygonVerts Array of points representing the vertices of the original polygon.
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* @param inputPolygonSize Number of vertices in the original polygon.
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* @param bounds Bounding rectangle for the original polygon.
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* @param offset How far we wish to offset the polygon.
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* Positive values indicate insetting, negative values outsetting.
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* @param offsetPolgon The resulting offset polygon, if any.
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* @param polygonIndices The indices of the original polygon that map to the new one.
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* @return true if an offset simple polygon exists, false otherwise.
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*/
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bool SkOffsetSimplePolygon(const SkPoint* inputPolygonVerts, int inputPolygonSize,
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const SkRect& bounds, SkScalar offset, SkTDArray<SkPoint>* offsetPolygon,
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SkTDArray<int>* polygonIndices = nullptr);
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/**
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* Compute the number of points needed for a circular join when offsetting a vertex.
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* The lengths of offset0 and offset1 don't have to equal |offset| -- only the direction matters.
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* The segment lengths will be approximately four pixels.
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*
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* @param offset0 Starting offset vector direction.
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* @param offset1 Ending offset vector direction.
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* @param offset Offset value (can be negative).
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* @param rotSin Sine of rotation delta per step.
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* @param rotCos Cosine of rotation delta per step.
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* @param n Number of steps to fill out the arc.
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* @return true for success, false otherwise
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*/
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bool SkComputeRadialSteps(const SkVector& offset0, const SkVector& offset1, SkScalar offset,
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SkScalar* rotSin, SkScalar* rotCos, int* n);
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/**
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* Determine winding direction for a polygon.
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* The input polygon must be simple or the result will be meaningless.
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*
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* @param polygonVerts Array of points representing the vertices of the polygon.
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* @param polygonSize Number of vertices in the polygon.
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* @return 1 for cw, -1 for ccw, and 0 if zero signed area (either degenerate or self-intersecting).
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* The y-axis is assumed to be pointing down.
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*/
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int SkGetPolygonWinding(const SkPoint* polygonVerts, int polygonSize);
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/**
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* Determine whether a polygon is convex or not.
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*
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* @param polygonVerts Array of points representing the vertices of the polygon.
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* @param polygonSize Number of vertices in the polygon.
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* @return true if the polygon is convex, false otherwise.
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*/
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bool SkIsConvexPolygon(const SkPoint* polygonVerts, int polygonSize);
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/**
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* Determine whether a polygon is simple (i.e., not self-intersecting) or not.
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* The input polygon must have no coincident vertices or the test will fail.
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*
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* @param polygonVerts Array of points representing the vertices of the polygon.
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* @param polygonSize Number of vertices in the polygon.
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* @return true if the polygon is simple, false otherwise.
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*/
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bool SkIsSimplePolygon(const SkPoint* polygonVerts, int polygonSize);
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/**
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* Compute indices to triangulate the given polygon.
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* The input polygon must be simple (i.e. it is not self-intersecting)
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* and have no coincident vertices or collinear edges.
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*
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* @param polygonVerts Array of points representing the vertices of the polygon.
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* @param indexMap Mapping from index in the given array to the final index in the triangulation.
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* @param polygonSize Number of vertices in the polygon.
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* @param triangleIndices Indices of the resulting triangulation.
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* @return true if successful, false otherwise.
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*/
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bool SkTriangulateSimplePolygon(const SkPoint* polygonVerts, uint16_t* indexMap, int polygonSize,
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SkTDArray<uint16_t>* triangleIndices);
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// Experiment: doesn't handle really big floats (returns false), always returns true for count <= 3
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bool SkIsPolyConvex_experimental(const SkPoint[], int count);
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#endif
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