reed@android.com | 8a1c16f | 2008-12-17 15:59:43 +0000 | [diff] [blame^] | 1 | /* libs/graphics/effects/Sk1DPathEffect.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 "Sk1DPathEffect.h" |
| 19 | #include "SkPathMeasure.h" |
| 20 | |
| 21 | bool Sk1DPathEffect::filterPath(SkPath* dst, const SkPath& src, SkScalar* width) |
| 22 | { |
| 23 | SkPathMeasure meas(src, false); |
| 24 | do { |
| 25 | SkScalar length = meas.getLength(); |
| 26 | SkScalar distance = this->begin(length); |
| 27 | while (distance < length) |
| 28 | { |
| 29 | SkScalar delta = this->next(dst, distance, meas); |
| 30 | if (delta <= 0) |
| 31 | break; |
| 32 | distance += delta; |
| 33 | } |
| 34 | } while (meas.nextContour()); |
| 35 | return true; |
| 36 | } |
| 37 | |
| 38 | /////////////////////////////////////////////////////////////////////////////////////////// |
| 39 | |
| 40 | SkPath1DPathEffect::SkPath1DPathEffect(const SkPath& path, SkScalar advance, |
| 41 | SkScalar phase, Style style) : fPath(path) |
| 42 | { |
| 43 | if (advance <= 0 || path.isEmpty()) |
| 44 | { |
| 45 | SkDEBUGF(("SkPath1DPathEffect can't use advance <= 0\n")); |
| 46 | fAdvance = 0; // signals we can't draw anything |
| 47 | } |
| 48 | else |
| 49 | { |
| 50 | // cleanup their phase parameter, inverting it so that it becomes an |
| 51 | // offset along the path (to match the interpretation in PostScript) |
| 52 | if (phase < 0) |
| 53 | { |
| 54 | phase = -phase; |
| 55 | if (phase > advance) |
| 56 | phase = SkScalarMod(phase, advance); |
| 57 | } |
| 58 | else |
| 59 | { |
| 60 | if (phase > advance) |
| 61 | phase = SkScalarMod(phase, advance); |
| 62 | phase = advance - phase; |
| 63 | } |
| 64 | // now catch the edge case where phase == advance (within epsilon) |
| 65 | if (phase >= advance) |
| 66 | phase = 0; |
| 67 | SkASSERT(phase >= 0); |
| 68 | |
| 69 | fAdvance = advance; |
| 70 | fInitialOffset = phase; |
| 71 | |
| 72 | if ((unsigned)style >= kStyleCount) { |
| 73 | SkDEBUGF(("SkPath1DPathEffect style enum out of range %d\n", style)); |
| 74 | } |
| 75 | fStyle = style; |
| 76 | } |
| 77 | } |
| 78 | |
| 79 | bool SkPath1DPathEffect::filterPath(SkPath* dst, const SkPath& src, SkScalar* width) |
| 80 | { |
| 81 | if (fAdvance > 0) |
| 82 | { |
| 83 | *width = -1; |
| 84 | return this->INHERITED::filterPath(dst, src, width); |
| 85 | } |
| 86 | return false; |
| 87 | } |
| 88 | |
| 89 | static void morphpoints(SkPoint dst[], const SkPoint src[], int count, |
| 90 | SkPathMeasure& meas, SkScalar dist) |
| 91 | { |
| 92 | for (int i = 0; i < count; i++) |
| 93 | { |
| 94 | SkPoint pos; |
| 95 | SkVector tangent; |
| 96 | |
| 97 | SkScalar sx = src[i].fX; |
| 98 | SkScalar sy = src[i].fY; |
| 99 | |
| 100 | meas.getPosTan(dist + sx, &pos, &tangent); |
| 101 | |
| 102 | SkMatrix matrix; |
| 103 | SkPoint pt; |
| 104 | |
| 105 | pt.set(sx, sy); |
| 106 | matrix.setSinCos(tangent.fY, tangent.fX, 0, 0); |
| 107 | matrix.preTranslate(-sx, 0); |
| 108 | matrix.postTranslate(pos.fX, pos.fY); |
| 109 | matrix.mapPoints(&dst[i], &pt, 1); |
| 110 | } |
| 111 | } |
| 112 | |
| 113 | /* TODO |
| 114 | |
| 115 | Need differentially more subdivisions when the follow-path is curvy. Not sure how to |
| 116 | determine that, but we need it. I guess a cheap answer is let the caller tell us, |
| 117 | but that seems like a cop-out. Another answer is to get Rob Johnson to figure it out. |
| 118 | */ |
| 119 | static void morphpath(SkPath* dst, const SkPath& src, SkPathMeasure& meas, SkScalar dist) |
| 120 | { |
| 121 | SkPath::Iter iter(src, false); |
| 122 | SkPoint srcP[4], dstP[3]; |
| 123 | SkPath::Verb verb; |
| 124 | |
| 125 | while ((verb = iter.next(srcP)) != SkPath::kDone_Verb) |
| 126 | { |
| 127 | switch (verb) { |
| 128 | case SkPath::kMove_Verb: |
| 129 | morphpoints(dstP, srcP, 1, meas, dist); |
| 130 | dst->moveTo(dstP[0]); |
| 131 | break; |
| 132 | case SkPath::kLine_Verb: |
| 133 | srcP[2] = srcP[1]; |
| 134 | srcP[1].set(SkScalarAve(srcP[0].fX, srcP[2].fX), |
| 135 | SkScalarAve(srcP[0].fY, srcP[2].fY)); |
| 136 | // fall through to quad |
| 137 | case SkPath::kQuad_Verb: |
| 138 | morphpoints(dstP, &srcP[1], 2, meas, dist); |
| 139 | dst->quadTo(dstP[0], dstP[1]); |
| 140 | break; |
| 141 | case SkPath::kCubic_Verb: |
| 142 | morphpoints(dstP, &srcP[1], 3, meas, dist); |
| 143 | dst->cubicTo(dstP[0], dstP[1], dstP[2]); |
| 144 | break; |
| 145 | case SkPath::kClose_Verb: |
| 146 | dst->close(); |
| 147 | break; |
| 148 | default: |
| 149 | SkASSERT(!"unknown verb"); |
| 150 | break; |
| 151 | } |
| 152 | } |
| 153 | } |
| 154 | |
| 155 | SkPath1DPathEffect::SkPath1DPathEffect(SkFlattenableReadBuffer& buffer) |
| 156 | { |
| 157 | fAdvance = buffer.readScalar(); |
| 158 | if (fAdvance > 0) { |
| 159 | fPath.unflatten(buffer); |
| 160 | fInitialOffset = buffer.readScalar(); |
| 161 | fStyle = (Style) buffer.readU8(); |
| 162 | } |
| 163 | } |
| 164 | |
| 165 | SkScalar SkPath1DPathEffect::begin(SkScalar contourLength) |
| 166 | { |
| 167 | return fInitialOffset; |
| 168 | } |
| 169 | |
| 170 | void SkPath1DPathEffect::flatten(SkFlattenableWriteBuffer& buffer) |
| 171 | { |
| 172 | buffer.writeScalar(fAdvance); |
| 173 | if (fAdvance > 0) { |
| 174 | fPath.flatten(buffer); |
| 175 | buffer.writeScalar(fInitialOffset); |
| 176 | buffer.write8(fStyle); |
| 177 | } |
| 178 | } |
| 179 | |
| 180 | SkScalar SkPath1DPathEffect::next(SkPath* dst, SkScalar distance, SkPathMeasure& meas) |
| 181 | { |
| 182 | switch (fStyle) { |
| 183 | case kTranslate_Style: |
| 184 | { |
| 185 | SkPoint pos; |
| 186 | meas.getPosTan(distance, &pos, NULL); |
| 187 | dst->addPath(fPath, pos.fX, pos.fY); |
| 188 | } |
| 189 | break; |
| 190 | case kRotate_Style: |
| 191 | { |
| 192 | SkMatrix matrix; |
| 193 | meas.getMatrix(distance, &matrix); |
| 194 | dst->addPath(fPath, matrix); |
| 195 | } |
| 196 | break; |
| 197 | case kMorph_Style: |
| 198 | morphpath(dst, fPath, meas, distance); |
| 199 | break; |
| 200 | default: |
| 201 | SkASSERT(!"unknown Style enum"); |
| 202 | break; |
| 203 | } |
| 204 | return fAdvance; |
| 205 | } |
| 206 | |