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