reed@android.com | 8a1c16f | 2008-12-17 15:59:43 +0000 | [diff] [blame^] | 1 | /* libs/graphics/effects/SkDiscretePathEffect.cpp |
| 2 | ** |
| 3 | ** Copyright 2006, The Android Open Source Project |
| 4 | ** |
| 5 | ** Licensed under the Apache License, Version 2.0 (the "License"); |
| 6 | ** you may not use this file except in compliance with the License. |
| 7 | ** You may obtain a copy of the License at |
| 8 | ** |
| 9 | ** http://www.apache.org/licenses/LICENSE-2.0 |
| 10 | ** |
| 11 | ** Unless required by applicable law or agreed to in writing, software |
| 12 | ** distributed under the License is distributed on an "AS IS" BASIS, |
| 13 | ** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 14 | ** See the License for the specific language governing permissions and |
| 15 | ** limitations under the License. |
| 16 | */ |
| 17 | |
| 18 | #include "SkDiscretePathEffect.h" |
| 19 | #include "SkBuffer.h" |
| 20 | #include "SkPathMeasure.h" |
| 21 | #include "SkRandom.h" |
| 22 | |
| 23 | static void Perterb(SkPoint* p, const SkVector& tangent, SkScalar scale) |
| 24 | { |
| 25 | SkVector normal = tangent; |
| 26 | normal.rotateCCW(); |
| 27 | normal.setLength(scale); |
| 28 | *p += normal; |
| 29 | } |
| 30 | |
| 31 | |
| 32 | SkDiscretePathEffect::SkDiscretePathEffect(SkScalar segLength, SkScalar deviation) |
| 33 | : fSegLength(segLength), fPerterb(deviation) |
| 34 | { |
| 35 | } |
| 36 | |
| 37 | bool SkDiscretePathEffect::filterPath(SkPath* dst, const SkPath& src, SkScalar* width) |
| 38 | { |
| 39 | bool doFill = *width < 0; |
| 40 | |
| 41 | SkPathMeasure meas(src, doFill); |
| 42 | uint32_t seed = SkScalarRound(meas.getLength()); |
| 43 | SkRandom rand(seed ^ ((seed << 16) | (seed >> 16))); |
| 44 | SkScalar scale = fPerterb; |
| 45 | SkPoint p; |
| 46 | SkVector v; |
| 47 | |
| 48 | do { |
| 49 | SkScalar length = meas.getLength(); |
| 50 | |
| 51 | if (fSegLength * (2 + doFill) > length) |
| 52 | { |
| 53 | meas.getSegment(0, length, dst, true); // to short for us to mangle |
| 54 | } |
| 55 | else |
| 56 | { |
| 57 | int n = SkScalarRound(SkScalarDiv(length, fSegLength)); |
| 58 | SkScalar delta = length / n; |
| 59 | SkScalar distance = 0; |
| 60 | |
| 61 | if (meas.isClosed()) |
| 62 | { |
| 63 | n -= 1; |
| 64 | distance += delta/2; |
| 65 | } |
| 66 | meas.getPosTan(distance, &p, &v); |
| 67 | Perterb(&p, v, SkScalarMul(rand.nextSScalar1(), scale)); |
| 68 | dst->moveTo(p); |
| 69 | while (--n >= 0) |
| 70 | { |
| 71 | distance += delta; |
| 72 | meas.getPosTan(distance, &p, &v); |
| 73 | Perterb(&p, v, SkScalarMul(rand.nextSScalar1(), scale)); |
| 74 | dst->lineTo(p); |
| 75 | } |
| 76 | if (meas.isClosed()) |
| 77 | dst->close(); |
| 78 | } |
| 79 | } while (meas.nextContour()); |
| 80 | return true; |
| 81 | } |
| 82 | |
| 83 | SkFlattenable::Factory SkDiscretePathEffect::getFactory() |
| 84 | { |
| 85 | return CreateProc; |
| 86 | } |
| 87 | |
| 88 | SkFlattenable* SkDiscretePathEffect::CreateProc(SkFlattenableReadBuffer& buffer) |
| 89 | { |
| 90 | return SkNEW_ARGS(SkDiscretePathEffect, (buffer)); |
| 91 | } |
| 92 | |
| 93 | void SkDiscretePathEffect::flatten(SkFlattenableWriteBuffer& buffer) |
| 94 | { |
| 95 | buffer.writeScalar(fSegLength); |
| 96 | buffer.writeScalar(fPerterb); |
| 97 | } |
| 98 | |
| 99 | SkDiscretePathEffect::SkDiscretePathEffect(SkFlattenableReadBuffer& buffer) |
| 100 | { |
| 101 | fSegLength = buffer.readScalar(); |
| 102 | fPerterb = buffer.readScalar(); |
| 103 | } |
| 104 | |
| 105 | |