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/*
* Copyright 2006 The Android Open Source Project
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "SkDiscretePathEffect.h"
#include "SkFlattenableBuffers.h"
#include "SkPathMeasure.h"
#include "SkRandom.h"
static void Perterb(SkPoint* p, const SkVector& tangent, SkScalar scale) {
SkVector normal = tangent;
normal.rotateCCW();
normal.setLength(scale);
*p += normal;
}
SkDiscretePathEffect::SkDiscretePathEffect(SkScalar segLength, SkScalar deviation)
: fSegLength(segLength), fPerterb(deviation)
{
}
bool SkDiscretePathEffect::filterPath(SkPath* dst, const SkPath& src,
SkStrokeRec* rec, const SkRect*) const {
bool doFill = rec->isFillStyle();
SkPathMeasure meas(src, doFill);
uint32_t seed = SkScalarRound(meas.getLength());
SkRandom rand(seed ^ ((seed << 16) | (seed >> 16)));
SkScalar scale = fPerterb;
SkPoint p;
SkVector v;
do {
SkScalar length = meas.getLength();
if (fSegLength * (2 + doFill) > length) {
meas.getSegment(0, length, dst, true); // to short for us to mangle
} else {
int n = SkScalarRound(SkScalarDiv(length, fSegLength));
SkScalar delta = length / n;
SkScalar distance = 0;
if (meas.isClosed()) {
n -= 1;
distance += delta/2;
}
if (meas.getPosTan(distance, &p, &v)) {
Perterb(&p, v, SkScalarMul(rand.nextSScalar1(), scale));
dst->moveTo(p);
}
while (--n >= 0) {
distance += delta;
if (meas.getPosTan(distance, &p, &v)) {
Perterb(&p, v, SkScalarMul(rand.nextSScalar1(), scale));
dst->lineTo(p);
}
}
if (meas.isClosed()) {
dst->close();
}
}
} while (meas.nextContour());
return true;
}
void SkDiscretePathEffect::flatten(SkFlattenableWriteBuffer& buffer) const {
this->INHERITED::flatten(buffer);
buffer.writeScalar(fSegLength);
buffer.writeScalar(fPerterb);
}
SkDiscretePathEffect::SkDiscretePathEffect(SkFlattenableReadBuffer& buffer) {
fSegLength = buffer.readScalar();
fPerterb = buffer.readScalar();
}
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