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/* libs/graphics/effects/SkDiscretePathEffect.cpp
**
** Copyright 2006, The Android Open Source Project
**
** Licensed under the Apache License, Version 2.0 (the "License");
** you may not use this file except in compliance with the License.
** You may obtain a copy of the License at
**
** http://www.apache.org/licenses/LICENSE-2.0
**
** Unless required by applicable law or agreed to in writing, software
** distributed under the License is distributed on an "AS IS" BASIS,
** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
** See the License for the specific language governing permissions and
** limitations under the License.
*/
#include "SkDiscretePathEffect.h"
#include "SkBuffer.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,
SkScalar* width) {
bool doFill = *width < 0;
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;
}
meas.getPosTan(distance, &p, &v);
Perterb(&p, v, SkScalarMul(rand.nextSScalar1(), scale));
dst->moveTo(p);
while (--n >= 0) {
distance += delta;
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;
}
SkFlattenable::Factory SkDiscretePathEffect::getFactory() {
return CreateProc;
}
SkFlattenable* SkDiscretePathEffect::CreateProc(SkFlattenableReadBuffer& buffer) {
return SkNEW_ARGS(SkDiscretePathEffect, (buffer));
}
void SkDiscretePathEffect::flatten(SkFlattenableWriteBuffer& buffer) {
buffer.writeScalar(fSegLength);
buffer.writeScalar(fPerterb);
}
SkDiscretePathEffect::SkDiscretePathEffect(SkFlattenableReadBuffer& buffer) {
fSegLength = buffer.readScalar();
fPerterb = buffer.readScalar();
}
///////////////////////////////////////////////////////////////////////////////
static SkFlattenable::Registrar gReg("SkDiscretePathEffect",
SkDiscretePathEffect::CreateProc);
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