src/third_party/skia/src/effects/SkDiscretePathEffect.cpp

   1
   2 /*
   3  * Copyright 2006 The Android Open Source Project
   4  *
   5  * Use of this source code is governed by a BSD-style license that can be
   6  * found in the LICENSE file.
   7  */
   8
   9
  10 #include "SkDiscretePathEffect.h"
  11 #include "SkReadBuffer.h"
  12 #include "SkWriteBuffer.h"
  13 #include "SkPathMeasure.h"
  14 #include "SkRandom.h"
  15
  16 static void Perterb(SkPoint* p, const SkVector& tangent, SkScalar scale) {
  17     SkVector normal = tangent;
  18     normal.rotateCCW();
  19     normal.setLength(scale);
  20     *p += normal;
  21 }
  22
  23 SkDiscretePathEffect::SkDiscretePathEffect(SkScalar segLength,
  24                                            SkScalar deviation,
  25                                            uint32_t seedAssist)
  26     : fSegLength(segLength), fPerterb(deviation), fSeedAssist(seedAssist)
  27 {
  28 }
  29
  30 bool SkDiscretePathEffect::filterPath(SkPath* dst, const SkPath& src,
  31                                       SkStrokeRec* rec, const SkRect*) const {
  32     bool doFill = rec->isFillStyle();
  33
  34     SkPathMeasure   meas(src, doFill);
  35
  36     /* Caller may supply their own seed assist, which by default is 0 */
  37     uint32_t seed = fSeedAssist ^ SkScalarRoundToInt(meas.getLength());
  38
  39     SkLCGRandom     rand(seed ^ ((seed << 16) | (seed >> 16)));
  40     SkScalar        scale = fPerterb;
  41     SkPoint         p;
  42     SkVector        v;
  43
  44     do {
  45         SkScalar    length = meas.getLength();
  46
  47         if (fSegLength * (2 + doFill) > length) {
  48             meas.getSegment(0, length, dst, true);  // to short for us to mangle
  49         } else {
  50             int         n = SkScalarRoundToInt(length / fSegLength);
  51             SkScalar    delta = length / n;
  52             SkScalar    distance = 0;
  53
  54             if (meas.isClosed()) {
  55                 n -= 1;
  56                 distance += delta/2;
  57             }
  58
  59             if (meas.getPosTan(distance, &p, &v)) {
  60                 Perterb(&p, v, SkScalarMul(rand.nextSScalar1(), scale));
  61                 dst->moveTo(p);
  62             }
  63             while (--n >= 0) {
  64                 distance += delta;
  65                 if (meas.getPosTan(distance, &p, &v)) {
  66                     Perterb(&p, v, SkScalarMul(rand.nextSScalar1(), scale));
  67                     dst->lineTo(p);
  68                 }
  69             }
  70             if (meas.isClosed()) {
  71                 dst->close();
  72             }
  73         }
  74     } while (meas.nextContour());
  75     return true;
  76 }
  77
  78 SkFlattenable* SkDiscretePathEffect::CreateProc(SkReadBuffer& buffer) {
  79     SkScalar segLength = buffer.readScalar();
  80     SkScalar perterb = buffer.readScalar();
  81     uint32_t seed = buffer.readUInt();
  82     return Create(segLength, perterb, seed);
  83 }
  84
  85 void SkDiscretePathEffect::flatten(SkWriteBuffer& buffer) const {
  86     buffer.writeScalar(fSegLength);
  87     buffer.writeScalar(fPerterb);
  88     buffer.writeUInt(fSeedAssist);
  89 }
  90
  91 #ifdef SK_SUPPORT_LEGACY_DEEPFLATTENING
  92 SkDiscretePathEffect::SkDiscretePathEffect(SkReadBuffer& buffer) {
  93     fSegLength = buffer.readScalar();
  94     fPerterb = buffer.readScalar();
  95     fSeedAssist = buffer.readUInt();
  96 }
  97 #endif
  98