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per-contour variant of SkPathMeasure

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Bug: skia:8721
Change-Id: I1e79a49dee25ccc9138baf6fb2df3dc80d1ff66b
Reviewed-on: https://skia-review.googlesource.com/c/187922
Commit-Queue: Mike Reed <reed@google.com>
Reviewed-by: Kevin Lubick <kjlubick@google.com>
This commit is contained in:
Mike Reed 2019-02-06 11:40:27 -05:00 committed by Skia Commit-Bot
parent 4b261eac8c
commit cc88f3a72d
9 changed files with 870 additions and 742 deletions
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1
BUILD.gn
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@ -1093,6 +1093,7 @@ static_library("pathkit") {
sources += [
"src/core/SkAnalyticEdge.cpp",
"src/core/SkArenaAlloc.cpp",
"src/core/SkContourMeasure.cpp",
"src/core/SkCubicMap.cpp",
"src/core/SkEdge.cpp",
"src/core/SkEdgeBuilder.cpp",

1
gn/core.gni
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@ -68,6 +68,7 @@ skia_core_sources = [
"$_src/core/SkColorSpaceXformSteps.cpp",
"$_src/core/SkColorSpaceXformer.cpp",
"$_src/core/SkColorSpaceXformer.h",
"$_src/core/SkContourMeasure.cpp",
"$_src/core/SkConvertPixels.cpp",
"$_src/core/SkConvertPixels.h",
"$_src/core/SkCoreBlitters.h",

135
include/core/SkContourMeasure.h Normal file
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@ -0,0 +1,135 @@
/*
* 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 "../private/SkNoncopyable.h"
#include "../private/SkTDArray.h"
#include "SkPath.h"
#include "SkRefCnt.h"
struct SkConic;
class SK_API SkContourMeasure : public SkRefCnt {
public:
/** 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; }
private:
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 {
++seg;
} 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 : SkNoncopyable {
public:
SkContourMeasureIter();
SkContourMeasureIter(const SkPath& path, bool forceClosed, SkScalar resScale = 1);
~SkContourMeasureIter();
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();
private:
SkPath::Iter fIter;
SkPath fPath;
SkScalar fTolerance;
bool fForceClosed;
// temporary
SkTDArray<SkContourMeasure::Segment> fSegments;
SkTDArray<SkPoint> fPts; // Points used to define the segments
SkContourMeasure* buildSegments();
SkScalar compute_quad_segs(const SkPoint pts[3], SkScalar distance,
int mint, int maxt, unsigned ptIndex);
SkScalar compute_conic_segs(const SkConic& conic, SkScalar distance,
int mint, const SkPoint& minPt,
int maxt, const SkPoint& maxPt,
unsigned ptIndex);
SkScalar compute_cubic_segs(const SkPoint pts[4], SkScalar distance,
int mint, int maxt, unsigned ptIndex);
};
#endif

3
include/core/SkPath.h
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@ -1485,6 +1485,9 @@ public:
*/
bool isClosedContour() const;
// Returns the next verb, or kDone, without changing the state of the iterator
Verb peekVerb() const;
private:
const SkPoint* fPts;
const uint8_t* fVerbs;

42
include/core/SkPathMeasure.h
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@ -10,10 +10,9 @@
#include "../private/SkNoncopyable.h"
#include "../private/SkTDArray.h"
#include "SkContourMeasure.h"
#include "SkPath.h"
struct SkConic;
class SK_API SkPathMeasure : SkNoncopyable {
public:
SkPathMeasure();
@ -84,43 +83,8 @@ public:
#endif
private:
SkPath::Iter fIter;
SkPath fPath;
SkScalar fTolerance;
SkScalar fLength; // relative to the current contour
unsigned fFirstPtIndex; // relative to the current contour
bool fIsClosed; // relative to the current contour
bool fForceClosed;
#if defined(IS_FUZZING_WITH_LIBFUZZER)
int fSubdivisionsMax;
#endif
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;
};
SkTDArray<Segment> fSegments;
SkTDArray<SkPoint> fPts; // Points used to define the segments
static const Segment* NextSegment(const Segment*);
void buildSegments();
SkScalar compute_quad_segs(const SkPoint pts[3], SkScalar distance,
int mint, int maxt, unsigned ptIndex);
SkScalar compute_conic_segs(const SkConic&, SkScalar distance,
int mint, const SkPoint& minPt,
int maxt, const SkPoint& maxPt, unsigned ptIndex);
SkScalar compute_cubic_segs(const SkPoint pts[3], SkScalar distance,
int mint, int maxt, unsigned ptIndex);
const Segment* distanceToSegment(SkScalar distance, SkScalar* t);
bool quad_too_curvy(const SkPoint pts[3]);
bool conic_too_curvy(const SkPoint& firstPt, const SkPoint& midTPt,const SkPoint& lastPt);
bool cheap_dist_exceeds_limit(const SkPoint& pt, SkScalar x, SkScalar y);
bool cubic_too_curvy(const SkPoint pts[4]);
SkContourMeasureIter fIter;
sk_sp<SkContourMeasure> fContour;
};
#endif

637
src/core/SkContourMeasure.cpp Normal file
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@ -0,0 +1,637 @@
/*
* Copyright 2018 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "SkContourMeasure.h"
#include "SkPathMeasurePriv.h"
#include "SkGeometry.h"
#include "SkPath.h"
#include "SkTSearch.h"
#define kMaxTValue 0x3FFFFFFF
static inline SkScalar tValue2Scalar(int t) {
SkASSERT((unsigned)t <= kMaxTValue);
const SkScalar kMaxTReciprocal = 1.0f / kMaxTValue;
return t * kMaxTReciprocal;
}
SkScalar SkContourMeasure::Segment::getScalarT() const {
return tValue2Scalar(fTValue);
}
void SkContourMeasure_segTo(const SkPoint pts[], unsigned segType,
SkScalar startT, SkScalar stopT, SkPath* dst) {
SkASSERT(startT >= 0 && startT <= SK_Scalar1);
SkASSERT(stopT >= 0 && stopT <= SK_Scalar1);
SkASSERT(startT <= stopT);
if (startT == stopT) {
if (!dst->isEmpty()) {
/* if the dash as a zero-length on segment, add a corresponding zero-length line.
The stroke code will add end caps to zero length lines as appropriate */
SkPoint lastPt;
SkAssertResult(dst->getLastPt(&lastPt));
dst->lineTo(lastPt);
}
return;
}
SkPoint tmp0[7], tmp1[7];
switch (segType) {
case kLine_SegType:
if (SK_Scalar1 == stopT) {
dst->lineTo(pts[1]);
} else {
dst->lineTo(SkScalarInterp(pts[0].fX, pts[1].fX, stopT),
SkScalarInterp(pts[0].fY, pts[1].fY, stopT));
}
break;
case kQuad_SegType:
if (0 == startT) {
if (SK_Scalar1 == stopT) {
dst->quadTo(pts[1], pts[2]);
} else {
SkChopQuadAt(pts, tmp0, stopT);
dst->quadTo(tmp0[1], tmp0[2]);
}
} else {
SkChopQuadAt(pts, tmp0, startT);
if (SK_Scalar1 == stopT) {
dst->quadTo(tmp0[3], tmp0[4]);
} else {
SkChopQuadAt(&tmp0[2], tmp1, (stopT - startT) / (1 - startT));
dst->quadTo(tmp1[1], tmp1[2]);
}
}
break;
case kConic_SegType: {
SkConic conic(pts[0], pts[2], pts[3], pts[1].fX);
if (0 == startT) {
if (SK_Scalar1 == stopT) {
dst->conicTo(conic.fPts[1], conic.fPts[2], conic.fW);
} else {
SkConic tmp[2];
if (conic.chopAt(stopT, tmp)) {
dst->conicTo(tmp[0].fPts[1], tmp[0].fPts[2], tmp[0].fW);
}
}
} else {
if (SK_Scalar1 == stopT) {
SkConic tmp1[2];
if (conic.chopAt(startT, tmp1)) {
dst->conicTo(tmp1[1].fPts[1], tmp1[1].fPts[2], tmp1[1].fW);
}
} else {
SkConic tmp;
conic.chopAt(startT, stopT, &tmp);
dst->conicTo(tmp.fPts[1], tmp.fPts[2], tmp.fW);
}
}
} break;
case kCubic_SegType:
if (0 == startT) {
if (SK_Scalar1 == stopT) {
dst->cubicTo(pts[1], pts[2], pts[3]);
} else {
SkChopCubicAt(pts, tmp0, stopT);
dst->cubicTo(tmp0[1], tmp0[2], tmp0[3]);
}
} else {
SkChopCubicAt(pts, tmp0, startT);
if (SK_Scalar1 == stopT) {
dst->cubicTo(tmp0[4], tmp0[5], tmp0[6]);
} else {
SkChopCubicAt(&tmp0[3], tmp1, (stopT - startT) / (1 - startT));
dst->cubicTo(tmp1[1], tmp1[2], tmp1[3]);
}
}
break;
default:
SK_ABORT("unknown segType");
}
}
///////////////////////////////////////////////////////////////////////////////
static inline int tspan_big_enough(int tspan) {
SkASSERT((unsigned)tspan <= kMaxTValue);
return tspan >> 10;
}
// can't use tangents, since we need [0..1..................2] to be seen
// as definitely not a line (it is when drawn, but not parametrically)
// so we compare midpoints
#define CHEAP_DIST_LIMIT (SK_Scalar1/2) // just made this value up
static bool quad_too_curvy(const SkPoint pts[3], SkScalar tolerance) {
// diff = (a/4 + b/2 + c/4) - (a/2 + c/2)
// diff = -a/4 + b/2 - c/4
SkScalar dx = SkScalarHalf(pts[1].fX) -
SkScalarHalf(SkScalarHalf(pts[0].fX + pts[2].fX));
SkScalar dy = SkScalarHalf(pts[1].fY) -
SkScalarHalf(SkScalarHalf(pts[0].fY + pts[2].fY));
SkScalar dist = SkMaxScalar(SkScalarAbs(dx), SkScalarAbs(dy));
return dist > tolerance;
}
static bool conic_too_curvy(const SkPoint& firstPt, const SkPoint& midTPt,
const SkPoint& lastPt, SkScalar tolerance) {
SkPoint midEnds = firstPt + lastPt;
midEnds *= 0.5f;
SkVector dxy = midTPt - midEnds;
SkScalar dist = SkMaxScalar(SkScalarAbs(dxy.fX), SkScalarAbs(dxy.fY));
return dist > tolerance;
}
static bool cheap_dist_exceeds_limit(const SkPoint& pt, SkScalar x, SkScalar y,
SkScalar tolerance) {
SkScalar dist = SkMaxScalar(SkScalarAbs(x - pt.fX), SkScalarAbs(y - pt.fY));
// just made up the 1/2
return dist > tolerance;
}
static bool cubic_too_curvy(const SkPoint pts[4], SkScalar tolerance) {
return cheap_dist_exceeds_limit(pts[1],
SkScalarInterp(pts[0].fX, pts[3].fX, SK_Scalar1/3),
SkScalarInterp(pts[0].fY, pts[3].fY, SK_Scalar1/3), tolerance)
||
cheap_dist_exceeds_limit(pts[2],
SkScalarInterp(pts[0].fX, pts[3].fX, SK_Scalar1*2/3),
SkScalarInterp(pts[0].fY, pts[3].fY, SK_Scalar1*2/3), tolerance);
}
SkScalar SkContourMeasureIter::compute_quad_segs(const SkPoint pts[3], SkScalar distance,
int mint, int maxt, unsigned ptIndex) {
#if defined(IS_FUZZING_WITH_LIBFUZZER)
--fSubdivisionsMax;
#endif
if (tspan_big_enough(maxt - mint) && quad_too_curvy(pts, fTolerance)) {
SkPoint tmp[5];
int halft = (mint + maxt) >> 1;
SkChopQuadAtHalf(pts, tmp);
distance = this->compute_quad_segs(tmp, distance, mint, halft, ptIndex);
distance = this->compute_quad_segs(&tmp[2], distance, halft, maxt, ptIndex);
} else {
SkScalar d = SkPoint::Distance(pts[0], pts[2]);
SkScalar prevD = distance;
distance += d;
if (distance > prevD) {
SkContourMeasure::Segment* seg = fSegments.append();
seg->fDistance = distance;
seg->fPtIndex = ptIndex;
seg->fType = kQuad_SegType;
seg->fTValue = maxt;
}
}
return distance;
}
SkScalar SkContourMeasureIter::compute_conic_segs(const SkConic& conic, SkScalar distance,
int mint, const SkPoint& minPt,
int maxt, const SkPoint& maxPt,
unsigned ptIndex) {
#if defined(IS_FUZZING_WITH_LIBFUZZER)
--fSubdivisionsMax;
#endif
int halft = (mint + maxt) >> 1;
SkPoint halfPt = conic.evalAt(tValue2Scalar(halft));
if (!halfPt.isFinite()) {
return distance;
}
if (tspan_big_enough(maxt - mint) && conic_too_curvy(minPt, halfPt, maxPt, fTolerance)) {
distance = this->compute_conic_segs(conic, distance, mint, minPt, halft, halfPt, ptIndex);
distance = this->compute_conic_segs(conic, distance, halft, halfPt, maxt, maxPt, ptIndex);
} else {
SkScalar d = SkPoint::Distance(minPt, maxPt);
SkScalar prevD = distance;
distance += d;
if (distance > prevD) {
SkContourMeasure::Segment* seg = fSegments.append();
seg->fDistance = distance;
seg->fPtIndex = ptIndex;
seg->fType = kConic_SegType;
seg->fTValue = maxt;
}
}
return distance;
}
SkScalar SkContourMeasureIter::compute_cubic_segs(const SkPoint pts[4], SkScalar distance,
int mint, int maxt, unsigned ptIndex) {
#if defined(IS_FUZZING_WITH_LIBFUZZER)
--fSubdivisionsMax;
#endif
if (tspan_big_enough(maxt - mint) && cubic_too_curvy(pts, fTolerance)) {
SkPoint tmp[7];
int halft = (mint + maxt) >> 1;
SkChopCubicAtHalf(pts, tmp);
distance = this->compute_cubic_segs(tmp, distance, mint, halft, ptIndex);
distance = this->compute_cubic_segs(&tmp[3], distance, halft, maxt, ptIndex);
} else {
SkScalar d = SkPoint::Distance(pts[0], pts[3]);
SkScalar prevD = distance;
distance += d;
if (distance > prevD) {
SkContourMeasure::Segment* seg = fSegments.append();
seg->fDistance = distance;
seg->fPtIndex = ptIndex;
seg->fType = kCubic_SegType;
seg->fTValue = maxt;
}
}
return distance;
}
SkContourMeasure* SkContourMeasureIter::buildSegments() {
SkPoint pts[4];
int ptIndex = -1;
SkScalar distance = 0;
bool isClosed = fForceClosed;
bool firstMoveTo = true;
SkContourMeasure::Segment* seg;
/* Note:
* as we accumulate distance, we have to check that the result of +=
* actually made it larger, since a very small delta might be > 0, but
* still have no effect on distance (if distance >>> delta).
*
* We do this check below, and in compute_quad_segs and compute_cubic_segs
*/
fSegments.reset();
bool done = false;
#if defined(IS_FUZZING_WITH_LIBFUZZER)
fSubdivisionsMax = 10000000;
#endif
do {
if (!firstMoveTo && fIter.peekVerb() == SkPath::kMove_Verb) {
break;
}
switch (fIter.next(pts)) {
case SkPath::kMove_Verb:
ptIndex += 1;
fPts.append(1, pts);
SkASSERT(firstMoveTo);
firstMoveTo = false;
break;
case SkPath::kLine_Verb: {
SkScalar d = SkPoint::Distance(pts[0], pts[1]);
SkASSERT(d >= 0);
SkScalar prevD = distance;
distance += d;
if (distance > prevD) {
seg = fSegments.append();
seg->fDistance = distance;
seg->fPtIndex = ptIndex;
seg->fType = kLine_SegType;
seg->fTValue = kMaxTValue;
fPts.append(1, pts + 1);
ptIndex++;
}
} break;
case SkPath::kQuad_Verb: {
SkScalar prevD = distance;
distance = this->compute_quad_segs(pts, distance, 0, kMaxTValue, ptIndex);
if (distance > prevD) {
fPts.append(2, pts + 1);
ptIndex += 2;
}
} break;
case SkPath::kConic_Verb: {
const SkConic conic(pts, fIter.conicWeight());
SkScalar prevD = distance;
distance = this->compute_conic_segs(conic, distance, 0, conic.fPts[0],
kMaxTValue, conic.fPts[2], ptIndex);
if (distance > prevD) {
// we store the conic weight in our next point, followed by the last 2 pts
// thus to reconstitue a conic, you'd need to say
// SkConic(pts[0], pts[2], pts[3], weight = pts[1].fX)
fPts.append()->set(conic.fW, 0);
fPts.append(2, pts + 1);
ptIndex += 3;
}
} break;
case SkPath::kCubic_Verb: {
SkScalar prevD = distance;
distance = this->compute_cubic_segs(pts, distance, 0, kMaxTValue, ptIndex);
if (distance > prevD) {
fPts.append(3, pts + 1);
ptIndex += 3;
}
} break;
case SkPath::kClose_Verb:
isClosed = true;
break;
case SkPath::kDone_Verb:
done = true;
break;
}
#if defined(IS_FUZZING_WITH_LIBFUZZER)
if (fSubdivisionsMax < 0) {
return nullptr;
}
#endif
} while (!done);
if (!SkScalarIsFinite(distance)) {
return nullptr;
}
if (fSegments.count() == 0) {
return nullptr;
}
#if defined(IS_FUZZING_WITH_LIBFUZZER)
if (fSubdivisionsMax < 0) {
return nullptr;
}
#endif
#ifdef SK_DEBUG
{
const SkContourMeasure::Segment* seg = fSegments.begin();
const SkContourMeasure::Segment* stop = fSegments.end();
unsigned ptIndex = 0;
SkScalar distance = 0;
// limit the loop to a reasonable number; pathological cases can run for minutes
int maxChecks = 10000000; // set to INT_MAX to defeat the check
while (seg < stop) {
SkASSERT(seg->fDistance > distance);
SkASSERT(seg->fPtIndex >= ptIndex);
SkASSERT(seg->fTValue > 0);
const SkContourMeasure::Segment* s = seg;
while (s < stop - 1 && s[0].fPtIndex == s[1].fPtIndex && --maxChecks > 0) {
SkASSERT(s[0].fType == s[1].fType);
SkASSERT(s[0].fTValue < s[1].fTValue);
s += 1;
}
distance = seg->fDistance;
ptIndex = seg->fPtIndex;
seg += 1;
}
// SkDebugf("\n");
}
#endif
return new SkContourMeasure(std::move(fSegments), std::move(fPts), distance, isClosed);
}
static void compute_pos_tan(const SkPoint pts[], unsigned segType,
SkScalar t, SkPoint* pos, SkVector* tangent) {
switch (segType) {
case kLine_SegType:
if (pos) {
pos->set(SkScalarInterp(pts[0].fX, pts[1].fX, t),
SkScalarInterp(pts[0].fY, pts[1].fY, t));
}
if (tangent) {
tangent->setNormalize(pts[1].fX - pts[0].fX, pts[1].fY - pts[0].fY);
}
break;
case kQuad_SegType:
SkEvalQuadAt(pts, t, pos, tangent);
if (tangent) {
tangent->normalize();
}
break;
case kConic_SegType: {
SkConic(pts[0], pts[2], pts[3], pts[1].fX).evalAt(t, pos, tangent);
if (tangent) {
tangent->normalize();
}
} break;
case kCubic_SegType:
SkEvalCubicAt(pts, t, pos, tangent, nullptr);
if (tangent) {
tangent->normalize();
}
break;
default:
SkDEBUGFAIL("unknown segType");
}
}
////////////////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////////////////
SkContourMeasureIter::SkContourMeasureIter() {
fTolerance = CHEAP_DIST_LIMIT;
fForceClosed = false;
}
SkContourMeasureIter::SkContourMeasureIter(const SkPath& path, bool forceClosed,
SkScalar resScale) {
fPath = path.isFinite() ? path : SkPath();
fTolerance = CHEAP_DIST_LIMIT * SkScalarInvert(resScale);
fForceClosed = forceClosed;
fIter.setPath(fPath, forceClosed);
}
SkContourMeasureIter::~SkContourMeasureIter() {}
/** Assign a new path, or null to have none.
*/
void SkContourMeasureIter::reset(const SkPath& path, bool forceClosed, SkScalar resScale) {
if (path.isFinite()) {
fPath = path;
} else {
fPath.reset();
}
fForceClosed = forceClosed;
fIter.setPath(fPath, forceClosed);
fSegments.reset();
fPts.reset();
}
sk_sp<SkContourMeasure> SkContourMeasureIter::next() {
while (fIter.peekVerb() != SkPath::kDone_Verb) {
auto cm = this->buildSegments();
if (cm) {
return sk_sp<SkContourMeasure>(cm);
}
}
return nullptr;
}
///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
SkContourMeasure::SkContourMeasure(SkTDArray<Segment>&& segs, SkTDArray<SkPoint>&& pts, SkScalar length, bool isClosed)
: fSegments(std::move(segs))
, fPts(std::move(pts))
, fLength(length)
, fIsClosed(isClosed)
{}
template <typename T, typename K>
int SkTKSearch(const T base[], int count, const K& key) {
SkASSERT(count >= 0);
if (count <= 0) {
return ~0;
}
SkASSERT(base != nullptr); // base may be nullptr if count is zero
unsigned lo = 0;
unsigned hi = count - 1;
while (lo < hi) {
unsigned mid = (hi + lo) >> 1;
if (base[mid].fDistance < key) {
lo = mid + 1;
} else {
hi = mid;
}
}
if (base[hi].fDistance < key) {
hi += 1;
hi = ~hi;
} else if (key < base[hi].fDistance) {
hi = ~hi;
}
return hi;
}
const SkContourMeasure::Segment* SkContourMeasure::distanceToSegment( SkScalar distance,
SkScalar* t) const {
SkDEBUGCODE(SkScalar length = ) this->length();
SkASSERT(distance >= 0 && distance <= length);
const Segment* seg = fSegments.begin();
int count = fSegments.count();
int index = SkTKSearch<Segment, SkScalar>(seg, count, distance);
// don't care if we hit an exact match or not, so we xor index if it is negative
index ^= (index >> 31);
seg = &seg[index];
// now interpolate t-values with the prev segment (if possible)
SkScalar startT = 0, startD = 0;
// check if the prev segment is legal, and references the same set of points
if (index > 0) {
startD = seg[-1].fDistance;
if (seg[-1].fPtIndex == seg->fPtIndex) {
SkASSERT(seg[-1].fType == seg->fType);
startT = seg[-1].getScalarT();
}
}
SkASSERT(seg->getScalarT() > startT);
SkASSERT(distance >= startD);
SkASSERT(seg->fDistance > startD);
*t = startT + (seg->getScalarT() - startT) * (distance - startD) / (seg->fDistance - startD);
return seg;
}
bool SkContourMeasure::getPosTan(SkScalar distance, SkPoint* pos, SkVector* tangent) const {
if (SkScalarIsNaN(distance)) {
return false;
}
const SkScalar length = this->length();
SkASSERT(length > 0 && fSegments.count() > 0);
// pin the distance to a legal range
if (distance < 0) {
distance = 0;
} else if (distance > length) {
distance = length;
}
SkScalar t;
const Segment* seg = this->distanceToSegment(distance, &t);
if (SkScalarIsNaN(t)) {
return false;
}
compute_pos_tan(&fPts[seg->fPtIndex], seg->fType, t, pos, tangent);
return true;
}
bool SkContourMeasure::getMatrix(SkScalar distance, SkMatrix* matrix, MatrixFlags flags) const {
SkPoint position;
SkVector tangent;
if (this->getPosTan(distance, &position, &tangent)) {
if (matrix) {
if (flags & kGetTangent_MatrixFlag) {
matrix->setSinCos(tangent.fY, tangent.fX, 0, 0);
} else {
matrix->reset();
}
if (flags & kGetPosition_MatrixFlag) {
matrix->postTranslate(position.fX, position.fY);
}
}
return true;
}
return false;
}
bool SkContourMeasure::getSegment(SkScalar startD, SkScalar stopD, SkPath* dst,
bool startWithMoveTo) const {
SkASSERT(dst);
SkScalar length = this->length(); // ensure we have built our segments
if (startD < 0) {
startD = 0;
}
if (stopD > length) {
stopD = length;
}
if (!(startD <= stopD)) { // catch NaN values as well
return false;
}
if (!fSegments.count()) {
return false;
}
SkPoint p;
SkScalar startT, stopT;
const Segment* seg = this->distanceToSegment(startD, &startT);
if (!SkScalarIsFinite(startT)) {
return false;
}
const Segment* stopSeg = this->distanceToSegment(stopD, &stopT);
if (!SkScalarIsFinite(stopT)) {
return false;
}
SkASSERT(seg <= stopSeg);
if (startWithMoveTo) {
compute_pos_tan(&fPts[seg->fPtIndex], seg->fType, startT, &p, nullptr);
dst->moveTo(p);
}
if (seg->fPtIndex == stopSeg->fPtIndex) {
SkContourMeasure_segTo(&fPts[seg->fPtIndex], seg->fType, startT, stopT, dst);
} else {
do {
SkContourMeasure_segTo(&fPts[seg->fPtIndex], seg->fType, startT, SK_Scalar1, dst);
seg = SkContourMeasure::Segment::Next(seg);
startT = 0;
} while (seg->fPtIndex < stopSeg->fPtIndex);
SkContourMeasure_segTo(&fPts[seg->fPtIndex], seg->fType, 0, stopT, dst);
}
return true;
}

7
src/core/SkPath.cpp
View File

@ -1959,6 +1959,13 @@ bool SkPath::Iter::isClosedContour() const {
return false;
}
SkPath::Verb SkPath::Iter::peekVerb() const {
if (fVerbs == nullptr || fVerbs == fVerbStop) {
return kDone_Verb;
}
return (Verb)fVerbs[-1];
}
SkPath::Verb SkPath::Iter::autoClose(SkPoint pts[2]) {
SkASSERT(pts);
if (fLastPt != fMoveTo) {

722
src/core/SkPathMeasure.cpp
View File

@ -5,733 +5,49 @@
* found in the LICENSE file.
*/
#include "SkPathMeasure.h"
#include "SkPathMeasurePriv.h"
#include "SkGeometry.h"
#include "SkPath.h"
#include "SkTSearch.h"
#include "SkContourMeasure.h"
#define kMaxTValue 0x3FFFFFFF
SkPathMeasure::SkPathMeasure() {}
static inline SkScalar tValue2Scalar(int t) {
SkASSERT((unsigned)t <= kMaxTValue);
const SkScalar kMaxTReciprocal = 1.0f / kMaxTValue;
return t * kMaxTReciprocal;
}
SkScalar SkPathMeasure::Segment::getScalarT() const {
return tValue2Scalar(fTValue);
}
const SkPathMeasure::Segment* SkPathMeasure::NextSegment(const Segment* seg) {
unsigned ptIndex = seg->fPtIndex;
do {
++seg;
} while (seg->fPtIndex == ptIndex);
return seg;
}
void SkPathMeasure_segTo(const SkPoint pts[], unsigned segType,
SkScalar startT, SkScalar stopT, SkPath* dst) {
SkASSERT(startT >= 0 && startT <= SK_Scalar1);
SkASSERT(stopT >= 0 && stopT <= SK_Scalar1);
SkASSERT(startT <= stopT);
if (startT == stopT) {
if (!dst->isEmpty()) {
/* if the dash as a zero-length on segment, add a corresponding zero-length line.
The stroke code will add end caps to zero length lines as appropriate */
SkPoint lastPt;
SkAssertResult(dst->getLastPt(&lastPt));
dst->lineTo(lastPt);
}
return;
}
SkPoint tmp0[7], tmp1[7];
switch (segType) {
case kLine_SegType:
if (SK_Scalar1 == stopT) {
dst->lineTo(pts[1]);
} else {
dst->lineTo(SkScalarInterp(pts[0].fX, pts[1].fX, stopT),
SkScalarInterp(pts[0].fY, pts[1].fY, stopT));
}
break;
case kQuad_SegType:
if (0 == startT) {
if (SK_Scalar1 == stopT) {
dst->quadTo(pts[1], pts[2]);
} else {
SkChopQuadAt(pts, tmp0, stopT);
dst->quadTo(tmp0[1], tmp0[2]);
}
} else {
SkChopQuadAt(pts, tmp0, startT);
if (SK_Scalar1 == stopT) {
dst->quadTo(tmp0[3], tmp0[4]);
} else {
SkChopQuadAt(&tmp0[2], tmp1, (stopT - startT) / (1 - startT));
dst->quadTo(tmp1[1], tmp1[2]);
}
}
break;
case kConic_SegType: {
SkConic conic(pts[0], pts[2], pts[3], pts[1].fX);
if (0 == startT) {
if (SK_Scalar1 == stopT) {
dst->conicTo(conic.fPts[1], conic.fPts[2], conic.fW);
} else {
SkConic tmp[2];
if (conic.chopAt(stopT, tmp)) {
dst->conicTo(tmp[0].fPts[1], tmp[0].fPts[2], tmp[0].fW);
}
}
} else {
if (SK_Scalar1 == stopT) {
SkConic tmp1[2];
if (conic.chopAt(startT, tmp1)) {
dst->conicTo(tmp1[1].fPts[1], tmp1[1].fPts[2], tmp1[1].fW);
}
} else {
SkConic tmp;
conic.chopAt(startT, stopT, &tmp);
dst->conicTo(tmp.fPts[1], tmp.fPts[2], tmp.fW);
}
}
} break;
case kCubic_SegType:
if (0 == startT) {
if (SK_Scalar1 == stopT) {
dst->cubicTo(pts[1], pts[2], pts[3]);
} else {
SkChopCubicAt(pts, tmp0, stopT);
dst->cubicTo(tmp0[1], tmp0[2], tmp0[3]);
}
} else {
SkChopCubicAt(pts, tmp0, startT);
if (SK_Scalar1 == stopT) {
dst->cubicTo(tmp0[4], tmp0[5], tmp0[6]);
} else {
SkChopCubicAt(&tmp0[3], tmp1, (stopT - startT) / (1 - startT));
dst->cubicTo(tmp1[1], tmp1[2], tmp1[3]);
}
}
break;
default:
SK_ABORT("unknown segType");
}
}
///////////////////////////////////////////////////////////////////////////////
static inline int tspan_big_enough(int tspan) {
SkASSERT((unsigned)tspan <= kMaxTValue);
return tspan >> 10;
}
// can't use tangents, since we need [0..1..................2] to be seen
// as definitely not a line (it is when drawn, but not parametrically)
// so we compare midpoints
#define CHEAP_DIST_LIMIT (SK_Scalar1/2) // just made this value up
bool SkPathMeasure::quad_too_curvy(const SkPoint pts[3]) {
// diff = (a/4 + b/2 + c/4) - (a/2 + c/2)
// diff = -a/4 + b/2 - c/4
SkScalar dx = SkScalarHalf(pts[1].fX) -
SkScalarHalf(SkScalarHalf(pts[0].fX + pts[2].fX));
SkScalar dy = SkScalarHalf(pts[1].fY) -
SkScalarHalf(SkScalarHalf(pts[0].fY + pts[2].fY));
SkScalar dist = SkMaxScalar(SkScalarAbs(dx), SkScalarAbs(dy));
return dist > fTolerance;
}
bool SkPathMeasure::conic_too_curvy(const SkPoint& firstPt, const SkPoint& midTPt,
const SkPoint& lastPt) {
SkPoint midEnds = firstPt + lastPt;
midEnds *= 0.5f;
SkVector dxy = midTPt - midEnds;
SkScalar dist = SkMaxScalar(SkScalarAbs(dxy.fX), SkScalarAbs(dxy.fY));
return dist > fTolerance;
}
bool SkPathMeasure::cheap_dist_exceeds_limit(const SkPoint& pt,
SkScalar x, SkScalar y) {
SkScalar dist = SkMaxScalar(SkScalarAbs(x - pt.fX), SkScalarAbs(y - pt.fY));
// just made up the 1/2
return dist > fTolerance;
}
bool SkPathMeasure::cubic_too_curvy(const SkPoint pts[4]) {
return cheap_dist_exceeds_limit(pts[1],
SkScalarInterp(pts[0].fX, pts[3].fX, SK_Scalar1/3),
SkScalarInterp(pts[0].fY, pts[3].fY, SK_Scalar1/3))
||
cheap_dist_exceeds_limit(pts[2],
SkScalarInterp(pts[0].fX, pts[3].fX, SK_Scalar1*2/3),
SkScalarInterp(pts[0].fY, pts[3].fY, SK_Scalar1*2/3));
}
static SkScalar quad_folded_len(const SkPoint pts[3]) {
SkScalar t = SkFindQuadMaxCurvature(pts);
SkPoint pt = SkEvalQuadAt(pts, t);
SkVector a = pts[2] - pt;
SkScalar result = a.length();
if (0 != t && 1 != t) {
SkVector b = pts[0] - pt;
result += b.length();
}
SkASSERT(SkScalarIsFinite(result));
return result;
}
/* from http://www.malczak.linuxpl.com/blog/quadratic-bezier-curve-length/ */
/* This works -- more needs to be done to see if it is performant on all platforms.
To use this to measure parts of quads requires recomputing everything -- perhaps
a chop-like interface can start from a larger measurement and get two new measurements
with one call here.
*/
static SkScalar compute_quad_len(const SkPoint pts[3]) {
SkPoint a,b;
a.fX = pts[0].fX - 2 * pts[1].fX + pts[2].fX;
a.fY = pts[0].fY - 2 * pts[1].fY + pts[2].fY;
SkScalar A = 4 * (a.fX * a.fX + a.fY * a.fY);
if (0 == A) {
a = pts[2] - pts[0];
return a.length();
}
b.fX = 2 * (pts[1].fX - pts[0].fX);
b.fY = 2 * (pts[1].fY - pts[0].fY);
SkScalar B = 4 * (a.fX * b.fX + a.fY * b.fY);
SkScalar C = b.fX * b.fX + b.fY * b.fY;
SkScalar Sabc = 2 * SkScalarSqrt(A + B + C);
SkScalar A_2 = SkScalarSqrt(A);
SkScalar A_32 = 2 * A * A_2;
SkScalar C_2 = 2 * SkScalarSqrt(C);
SkScalar BA = B / A_2;
if (0 == BA + C_2) {
return quad_folded_len(pts);
}
SkScalar J = A_32 * Sabc + A_2 * B * (Sabc - C_2);
SkScalar K = 4 * C * A - B * B;
SkScalar L = (2 * A_2 + BA + Sabc) / (BA + C_2);
if (L <= 0) {
return quad_folded_len(pts);
}
SkScalar M = SkScalarLog(L);
SkScalar result = (J + K * M) / (4 * A_32);
SkASSERT(SkScalarIsFinite(result));
return result;
}
SkScalar SkPathMeasure::compute_quad_segs(const SkPoint pts[3],
SkScalar distance, int mint, int maxt, unsigned ptIndex) {
#if defined(IS_FUZZING_WITH_LIBFUZZER)
--fSubdivisionsMax;
#endif
if (tspan_big_enough(maxt - mint) && quad_too_curvy(pts)) {
SkPoint tmp[5];
int halft = (mint + maxt) >> 1;
SkChopQuadAtHalf(pts, tmp);
distance = this->compute_quad_segs(tmp, distance, mint, halft, ptIndex);
distance = this->compute_quad_segs(&tmp[2], distance, halft, maxt, ptIndex);
} else {
SkScalar d = SkPoint::Distance(pts[0], pts[2]);
SkScalar prevD = distance;
distance += d;
if (distance > prevD) {
Segment* seg = fSegments.append();
seg->fDistance = distance;
seg->fPtIndex = ptIndex;
seg->fType = kQuad_SegType;
seg->fTValue = maxt;
}
}
return distance;
}
SkScalar SkPathMeasure::compute_conic_segs(const SkConic& conic, SkScalar distance,
int mint, const SkPoint& minPt,
int maxt, const SkPoint& maxPt, unsigned ptIndex) {
#if defined(IS_FUZZING_WITH_LIBFUZZER)
--fSubdivisionsMax;
#endif
int halft = (mint + maxt) >> 1;
SkPoint halfPt = conic.evalAt(tValue2Scalar(halft));
if (!halfPt.isFinite()) {
return distance;
}
if (tspan_big_enough(maxt - mint) && conic_too_curvy(minPt, halfPt, maxPt)) {
distance = this->compute_conic_segs(conic, distance, mint, minPt, halft, halfPt, ptIndex);
distance = this->compute_conic_segs(conic, distance, halft, halfPt, maxt, maxPt, ptIndex);
} else {
SkScalar d = SkPoint::Distance(minPt, maxPt);
SkScalar prevD = distance;
distance += d;
if (distance > prevD) {
Segment* seg = fSegments.append();
seg->fDistance = distance;
seg->fPtIndex = ptIndex;
seg->fType = kConic_SegType;
seg->fTValue = maxt;
}
}
return distance;
}
SkScalar SkPathMeasure::compute_cubic_segs(const SkPoint pts[4],
SkScalar distance, int mint, int maxt, unsigned ptIndex) {
#if defined(IS_FUZZING_WITH_LIBFUZZER)
--fSubdivisionsMax;
#endif
if (tspan_big_enough(maxt - mint) && cubic_too_curvy(pts)) {
SkPoint tmp[7];
int halft = (mint + maxt) >> 1;
SkChopCubicAtHalf(pts, tmp);
distance = this->compute_cubic_segs(tmp, distance, mint, halft, ptIndex);
distance = this->compute_cubic_segs(&tmp[3], distance, halft, maxt, ptIndex);
} else {
SkScalar d = SkPoint::Distance(pts[0], pts[3]);
SkScalar prevD = distance;
distance += d;
if (distance > prevD) {
Segment* seg = fSegments.append();
seg->fDistance = distance;
seg->fPtIndex = ptIndex;
seg->fType = kCubic_SegType;
seg->fTValue = maxt;
}
}
return distance;
}
void SkPathMeasure::buildSegments() {
SkPoint pts[4];
unsigned ptIndex = fFirstPtIndex;
SkScalar distance = 0;
bool isClosed = fForceClosed;
bool firstMoveTo = ptIndex == (unsigned) -1;
Segment* seg;
/* Note:
* as we accumulate distance, we have to check that the result of +=
* actually made it larger, since a very small delta might be > 0, but
* still have no effect on distance (if distance >>> delta).
*
* We do this check below, and in compute_quad_segs and compute_cubic_segs
*/
fSegments.reset();
bool done = false;
#if defined(IS_FUZZING_WITH_LIBFUZZER)
fSubdivisionsMax = 10000000;
#endif
do {
switch (fIter.next(pts)) {
case SkPath::kMove_Verb:
ptIndex += 1;
fPts.append(1, pts);
if (!firstMoveTo) {
done = true;
break;
}
firstMoveTo = false;
break;
case SkPath::kLine_Verb: {
SkScalar d = SkPoint::Distance(pts[0], pts[1]);
SkASSERT(d >= 0);
SkScalar prevD = distance;
distance += d;
if (distance > prevD) {
seg = fSegments.append();
seg->fDistance = distance;
seg->fPtIndex = ptIndex;
seg->fType = kLine_SegType;
seg->fTValue = kMaxTValue;
fPts.append(1, pts + 1);
ptIndex++;
}
} break;
case SkPath::kQuad_Verb: {
SkScalar prevD = distance;
if (false) {
SkScalar length = compute_quad_len(pts);
if (length) {
distance += length;
Segment* seg = fSegments.append();
seg->fDistance = distance;
seg->fPtIndex = ptIndex;
seg->fType = kQuad_SegType;
seg->fTValue = kMaxTValue;
}
} else {
distance = this->compute_quad_segs(pts, distance, 0, kMaxTValue, ptIndex);
}
if (distance > prevD) {
fPts.append(2, pts + 1);
ptIndex += 2;
}
} break;
case SkPath::kConic_Verb: {
const SkConic conic(pts, fIter.conicWeight());
SkScalar prevD = distance;
distance = this->compute_conic_segs(conic, distance, 0, conic.fPts[0],
kMaxTValue, conic.fPts[2], ptIndex);
if (distance > prevD) {
// we store the conic weight in our next point, followed by the last 2 pts
// thus to reconstitue a conic, you'd need to say
// SkConic(pts[0], pts[2], pts[3], weight = pts[1].fX)
fPts.append()->set(conic.fW, 0);
fPts.append(2, pts + 1);
ptIndex += 3;
}
} break;
case SkPath::kCubic_Verb: {
SkScalar prevD = distance;
distance = this->compute_cubic_segs(pts, distance, 0, kMaxTValue, ptIndex);
if (distance > prevD) {
fPts.append(3, pts + 1);
ptIndex += 3;
}
} break;
case SkPath::kClose_Verb:
isClosed = true;
break;
case SkPath::kDone_Verb:
done = true;
break;
}
#if defined(IS_FUZZING_WITH_LIBFUZZER)
if (fSubdivisionsMax < 0) {
fLength = 0;
return;
}
#endif
} while (!done);
fLength = distance;
fIsClosed = isClosed;
fFirstPtIndex = ptIndex;
#ifdef SK_DEBUG
{
const Segment* seg = fSegments.begin();
const Segment* stop = fSegments.end();
unsigned ptIndex = 0;
SkScalar distance = 0;
// limit the loop to a reasonable number; pathological cases can run for minutes
int maxChecks = 10000000; // set to INT_MAX to defeat the check
while (seg < stop) {
SkASSERT(seg->fDistance > distance);
SkASSERT(seg->fPtIndex >= ptIndex);
SkASSERT(seg->fTValue > 0);
const Segment* s = seg;
while (s < stop - 1 && s[0].fPtIndex == s[1].fPtIndex && --maxChecks > 0) {
SkASSERT(s[0].fType == s[1].fType);
SkASSERT(s[0].fTValue < s[1].fTValue);
s += 1;
}
distance = seg->fDistance;
ptIndex = seg->fPtIndex;
seg += 1;
}
// SkDebugf("\n");
}
#endif
}
static void compute_pos_tan(const SkPoint pts[], unsigned segType,
SkScalar t, SkPoint* pos, SkVector* tangent) {
switch (segType) {
case kLine_SegType:
if (pos) {
pos->set(SkScalarInterp(pts[0].fX, pts[1].fX, t),
SkScalarInterp(pts[0].fY, pts[1].fY, t));
}
if (tangent) {
tangent->setNormalize(pts[1].fX - pts[0].fX, pts[1].fY - pts[0].fY);
}
break;
case kQuad_SegType:
SkEvalQuadAt(pts, t, pos, tangent);
if (tangent) {
tangent->normalize();
}
break;
case kConic_SegType: {
SkConic(pts[0], pts[2], pts[3], pts[1].fX).evalAt(t, pos, tangent);
if (tangent) {
tangent->normalize();
}
} break;
case kCubic_SegType:
SkEvalCubicAt(pts, t, pos, tangent, nullptr);
if (tangent) {
tangent->normalize();
}
break;
default:
SkDEBUGFAIL("unknown segType");
}
}
////////////////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////////////////
SkPathMeasure::SkPathMeasure() {
fTolerance = CHEAP_DIST_LIMIT;
fLength = -1; // signal we need to compute it
fForceClosed = false;
fFirstPtIndex = -1;
}
SkPathMeasure::SkPathMeasure(const SkPath& path, bool forceClosed, SkScalar resScale) {
fPath = path.isFinite() ? path : SkPath();
fTolerance = CHEAP_DIST_LIMIT * SkScalarInvert(resScale);
fLength = -1; // signal we need to compute it
fForceClosed = forceClosed;
fFirstPtIndex = -1;
fIter.setPath(fPath, forceClosed);
SkPathMeasure::SkPathMeasure(const SkPath& path, bool forceClosed, SkScalar resScale)
: fIter(path, forceClosed, resScale)
{
fContour = fIter.next();
}
SkPathMeasure::~SkPathMeasure() {}
/** Assign a new path, or null to have none.
*/
void SkPathMeasure::setPath(const SkPath* path, bool forceClosed) {
if (path && path->isFinite()) {
fPath = *path;
} else {
fPath.reset();
}
fLength = -1; // signal we need to compute it
fForceClosed = forceClosed;
fFirstPtIndex = -1;
fIter.setPath(fPath, forceClosed);
fSegments.reset();
fPts.reset();
fIter.reset(path ? *path : SkPath(), forceClosed);
fContour = fIter.next();
}
SkScalar SkPathMeasure::getLength() {
if (fLength < 0) {
this->buildSegments();
}
if (SkScalarIsNaN(fLength)) {
fLength = 0;
fSegments.reset(); // may contain inf or NaN, which will fail later
}
SkASSERT(fLength >= 0);
return fLength;
return fContour ? fContour->length() : 0;
}
template <typename T, typename K>
int SkTKSearch(const T base[], int count, const K& key) {
SkASSERT(count >= 0);
if (count <= 0) {
return ~0;
}
SkASSERT(base != nullptr); // base may be nullptr if count is zero
unsigned lo = 0;
unsigned hi = count - 1;
while (lo < hi) {
unsigned mid = (hi + lo) >> 1;
if (base[mid].fDistance < key) {
lo = mid + 1;
} else {
hi = mid;
}
}
if (base[hi].fDistance < key) {
hi += 1;
hi = ~hi;
} else if (key < base[hi].fDistance) {
hi = ~hi;
}
return hi;
bool SkPathMeasure::getPosTan(SkScalar distance, SkPoint* position, SkVector* tangent) {
return fContour && fContour->getPosTan(distance, position, tangent);
}
const SkPathMeasure::Segment* SkPathMeasure::distanceToSegment(
SkScalar distance, SkScalar* t) {
SkDEBUGCODE(SkScalar length = ) this->getLength();
SkASSERT(distance >= 0 && distance <= length);
const Segment* seg = fSegments.begin();
int count = fSegments.count();
int index = SkTKSearch<Segment, SkScalar>(seg, count, distance);
// don't care if we hit an exact match or not, so we xor index if it is negative
index ^= (index >> 31);
seg = &seg[index];
// now interpolate t-values with the prev segment (if possible)
SkScalar startT = 0, startD = 0;
// check if the prev segment is legal, and references the same set of points
if (index > 0) {
startD = seg[-1].fDistance;
if (seg[-1].fPtIndex == seg->fPtIndex) {
SkASSERT(seg[-1].fType == seg->fType);
startT = seg[-1].getScalarT();
}
}
SkASSERT(seg->getScalarT() > startT);
SkASSERT(distance >= startD);
SkASSERT(seg->fDistance > startD);
*t = startT + (seg->getScalarT() - startT) * (distance - startD) / (seg->fDistance - startD);
return seg;
bool SkPathMeasure::getMatrix(SkScalar distance, SkMatrix* matrix, MatrixFlags flags) {
return fContour && fContour->getMatrix(distance, matrix, (SkContourMeasure::MatrixFlags)flags);
}
bool SkPathMeasure::getPosTan(SkScalar distance, SkPoint* pos, SkVector* tangent) {
SkScalar length = this->getLength(); // call this to force computing it
int count = fSegments.count();
if (count == 0 || length == 0 || SkScalarIsNaN(distance)) {
return false;
}
// pin the distance to a legal range
if (distance < 0) {
distance = 0;
} else if (distance > length) {
distance = length;
}
SkScalar t;
const Segment* seg = this->distanceToSegment(distance, &t);
if (SkScalarIsNaN(t)) {
return false;
}
compute_pos_tan(&fPts[seg->fPtIndex], seg->fType, t, pos, tangent);
return true;
}
bool SkPathMeasure::getMatrix(SkScalar distance, SkMatrix* matrix,
MatrixFlags flags) {
SkPoint position;
SkVector tangent;
if (this->getPosTan(distance, &position, &tangent)) {
if (matrix) {
if (flags & kGetTangent_MatrixFlag) {
matrix->setSinCos(tangent.fY, tangent.fX, 0, 0);
} else {
matrix->reset();
}
if (flags & kGetPosition_MatrixFlag) {
matrix->postTranslate(position.fX, position.fY);
}
}
return true;
}
return false;
}
bool SkPathMeasure::getSegment(SkScalar startD, SkScalar stopD, SkPath* dst,
bool startWithMoveTo) {
SkASSERT(dst);
SkScalar length = this->getLength(); // ensure we have built our segments
if (startD < 0) {
startD = 0;
}
if (stopD > length) {
stopD = length;
}
if (!(startD <= stopD)) { // catch NaN values as well
return false;
}
if (!fSegments.count()) {
return false;
}
SkPoint p;
SkScalar startT, stopT;
const Segment* seg = this->distanceToSegment(startD, &startT);
if (!SkScalarIsFinite(startT)) {
return false;
}
const Segment* stopSeg = this->distanceToSegment(stopD, &stopT);
if (!SkScalarIsFinite(stopT)) {
return false;
}
SkASSERT(seg <= stopSeg);
if (startWithMoveTo) {
compute_pos_tan(&fPts[seg->fPtIndex], seg->fType, startT, &p, nullptr);
dst->moveTo(p);
}
if (seg->fPtIndex == stopSeg->fPtIndex) {
SkPathMeasure_segTo(&fPts[seg->fPtIndex], seg->fType, startT, stopT, dst);
} else {
do {
SkPathMeasure_segTo(&fPts[seg->fPtIndex], seg->fType, startT, SK_Scalar1, dst);
seg = SkPathMeasure::NextSegment(seg);
startT = 0;
} while (seg->fPtIndex < stopSeg->fPtIndex);
SkPathMeasure_segTo(&fPts[seg->fPtIndex], seg->fType, 0, stopT, dst);
}
return true;
bool SkPathMeasure::getSegment(SkScalar startD, SkScalar stopD, SkPath* dst, bool startWithMoveTo) {
return fContour && fContour->getSegment(startD, stopD, dst, startWithMoveTo);
}
bool SkPathMeasure::isClosed() {
(void)this->getLength(); // make sure we measure the current contour
return fIsClosed;
return fContour && fContour->isClosed();
}
/** Move to the next contour in the path. Return true if one exists, or false if
we're done with the path.
*/
bool SkPathMeasure::nextContour() {
(void)this->getLength(); // make sure we measure the current contour
#if defined(IS_FUZZING_WITH_LIBFUZZER)
if (fSubdivisionsMax < 0) {
return false;
}
#endif
fLength = -1; // now signal that we should build the next set of segments
return this->getLength() > 0;
fContour = fIter.next();
return !!fContour;
}
///////////////////////////////////////////////////////////////////////////////
///////////////////////////////////////////////////////////////////////////////
#ifdef SK_DEBUG
void SkPathMeasure::dump() {
SkDebugf("pathmeas: length=%g, segs=%d\n", fLength, fSegments.count());
for (int i = 0; i < fSegments.count(); i++) {
const Segment* seg = &fSegments[i];
SkDebugf("pathmeas: seg[%d] distance=%g, point=%d, t=%g, type=%d\n",
i, seg->fDistance, seg->fPtIndex, seg->getScalarT(),
seg->fType);
}
}
void SkPathMeasure::dump() {}
#endif

64
tests/PathMeasureTest.cpp
View File

@ -227,3 +227,67 @@ DEF_TEST(PathMeasure_nextctr, reporter) {
// only expect 1 contour, even if we didn't explicitly call getLength() ourselves
REPORTER_ASSERT(reporter, !meas.nextContour());
}
#include "SkContourMeasure.h"
static void test_90_degrees(sk_sp<SkContourMeasure> cm, SkScalar radius,
skiatest::Reporter* reporter) {
SkPoint pos;
SkVector tan;
SkScalar distance = cm->length() / 4;
bool success = cm->getPosTan(distance, &pos, &tan);
REPORTER_ASSERT(reporter, success);
REPORTER_ASSERT(reporter, SkScalarNearlyEqual(pos.fX, 0));
REPORTER_ASSERT(reporter, SkScalarNearlyEqual(pos.fY, radius));
REPORTER_ASSERT(reporter, SkScalarNearlyEqual(tan.fX, -1));
REPORTER_ASSERT(reporter, SkScalarNearlyEqual(tan.fY, 0));
}
static void test_empty_contours(skiatest::Reporter* reporter) {
SkPath path;
path.moveTo(0, 0).lineTo(100, 100).lineTo(200, 100);
path.moveTo(2, 2).moveTo(3, 3); // zero-length(s)
path.moveTo(4, 4).close().close().close(); // zero-length
path.moveTo(5, 5).lineTo(5, 5); // zero-length
path.moveTo(5, 5).lineTo(5, 5).close(); // zero-length
path.moveTo(5, 5).lineTo(5, 5).close().close(); // zero-length
path.moveTo(6, 6).lineTo(7, 7);
path.moveTo(10, 10); // zero-length
SkContourMeasureIter fact(path, false);
// given the above construction, we expect only 2 contours (the rest are "empty")
REPORTER_ASSERT(reporter, fact.next());
REPORTER_ASSERT(reporter, fact.next());
REPORTER_ASSERT(reporter, !fact.next());
}
DEF_TEST(contour_measure, reporter) {
SkPath path;
path.addCircle(0, 0, 100);
path.addCircle(0, 0, 10);
SkContourMeasureIter fact(path, false);
path.reset(); // we should not need the path avert we created the factory
auto cm0 = fact.next();
auto cm1 = fact.next();
REPORTER_ASSERT(reporter, cm0->isClosed());
REPORTER_ASSERT(reporter, SkScalarNearlyEqual(cm0->length(), 200 * SK_ScalarPI, 1.5f));
test_90_degrees(cm0, 100, reporter);
REPORTER_ASSERT(reporter, cm1->isClosed());
REPORTER_ASSERT(reporter, SkScalarNearlyEqual(cm1->length(), 20 * SK_ScalarPI, 0.5f));
test_90_degrees(cm1, 10, reporter);
auto cm2 = fact.next();
REPORTER_ASSERT(reporter, !cm2);
test_empty_contours(reporter);
}