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* Copyright 2018 Google Inc.
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
#ifndef SkContourMeasure_DEFINED
#define SkContourMeasure_DEFINED
#include "include/core/SkPath.h"
#include "include/core/SkRefCnt.h"
#include "include/private/SkTDArray.h"
struct SkConic;
class SK_API SkContourMeasure : public SkRefCnt {
/** Return the length of the contour.
SkScalar length() const { return fLength; }
/** Pins distance to 0 <= distance <= length(), and then computes the corresponding
* position and tangent.
bool SK_WARN_UNUSED_RESULT getPosTan(SkScalar distance, SkPoint* position,
SkVector* tangent) const;
enum MatrixFlags {
kGetPosition_MatrixFlag = 0x01,
kGetTangent_MatrixFlag = 0x02,
kGetPosAndTan_MatrixFlag = kGetPosition_MatrixFlag | kGetTangent_MatrixFlag
/** Pins distance to 0 <= distance <= getLength(), and then computes
the corresponding matrix (by calling getPosTan).
Returns false if there is no path, or a zero-length path was specified, in which case
matrix is unchanged.
bool SK_WARN_UNUSED_RESULT getMatrix(SkScalar distance, SkMatrix* matrix,
MatrixFlags flags = kGetPosAndTan_MatrixFlag) const;
/** Given a start and stop distance, return in dst the intervening segment(s).
If the segment is zero-length, return false, else return true.
startD and stopD are pinned to legal values (0..getLength()). If startD > stopD
then return false (and leave dst untouched).
Begin the segment with a moveTo if startWithMoveTo is true
bool SK_WARN_UNUSED_RESULT getSegment(SkScalar startD, SkScalar stopD, SkPath* dst,
bool startWithMoveTo) const;
/** Return true if the contour is closed()
bool isClosed() const { return fIsClosed; }
struct Segment {
SkScalar fDistance; // total distance up to this point
unsigned fPtIndex; // index into the fPts array
unsigned fTValue : 30;
unsigned fType : 2; // actually the enum SkSegType
// See SkPathMeasurePriv.h
SkScalar getScalarT() const;
static const Segment* Next(const Segment* seg) {
unsigned ptIndex = seg->fPtIndex;
do {
} while (seg->fPtIndex == ptIndex);
return seg;
const SkTDArray<Segment> fSegments;
const SkTDArray<SkPoint> fPts; // Points used to define the segments
const SkScalar fLength;
const bool fIsClosed;
SkContourMeasure(SkTDArray<Segment>&& segs, SkTDArray<SkPoint>&& pts,
SkScalar length, bool isClosed);
~SkContourMeasure() override {}
const Segment* distanceToSegment(SkScalar distance, SkScalar* t) const;
friend class SkContourMeasureIter;
class SK_API SkContourMeasureIter {
* Initialize the Iter with a path.
* The parts of the path that are needed are copied, so the client is free to modify/delete
* the path after this call.
* resScale controls the precision of the measure. values > 1 increase the
* precision (and possibly slow down the computation).
SkContourMeasureIter(const SkPath& path, bool forceClosed, SkScalar resScale = 1);
* Reset the Iter with a path.
* The parts of the path that are needed are copied, so the client is free to modify/delete
* the path after this call.
void reset(const SkPath& path, bool forceClosed, SkScalar resScale = 1);
* Iterates through contours in path, returning a contour-measure object for each contour
* in the path. Returns null when it is done.
* This only returns non-zero length contours, where a contour is the segments between
* a kMove_Verb and either ...
* - the next kMove_Verb
* - kClose_Verb (1 or more)
* - kDone_Verb
* If it encounters a zero-length contour, it is skipped.
sk_sp<SkContourMeasure> next();
class Impl;
std::unique_ptr<Impl> fImpl;