1 /*
2 * Copyright 2006 The Android Open Source Project
3 *
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
6 */
7
8
9 #include "include/core/SkPathMeasure.h"
10 #include "include/core/SkStrokeRec.h"
11 #include "include/effects/Sk1DPathEffect.h"
12 #include "src/core/SkReadBuffer.h"
13 #include "src/core/SkWriteBuffer.h"
14
15 // Since we are stepping by a float, the do/while loop might go on forever (or nearly so).
16 // Put in a governor to limit crash values from looping too long (and allocating too much ram).
17 #define MAX_REASONABLE_ITERATIONS 100000
18
onFilterPath(SkPath * dst,const SkPath & src,SkStrokeRec *,const SkRect *) const19 bool Sk1DPathEffect::onFilterPath(SkPath* dst, const SkPath& src,
20 SkStrokeRec*, const SkRect*) const {
21 SkPathMeasure meas(src, false);
22 do {
23 int governor = MAX_REASONABLE_ITERATIONS;
24 SkScalar length = meas.getLength();
25 SkScalar distance = this->begin(length);
26 while (distance < length && --governor >= 0) {
27 SkScalar delta = this->next(dst, distance, meas);
28 if (delta <= 0) {
29 break;
30 }
31 distance += delta;
32 }
33 } while (meas.nextContour());
34 return true;
35 }
36
37 ///////////////////////////////////////////////////////////////////////////////
38
SkPath1DPathEffect(const SkPath & path,SkScalar advance,SkScalar phase,Style style)39 SkPath1DPathEffect::SkPath1DPathEffect(const SkPath& path, SkScalar advance, SkScalar phase,
40 Style style) : fPath(path) {
41 SkASSERT(advance > 0 && !path.isEmpty());
42 SkASSERT((unsigned)style <= kMorph_Style);
43
44 // Make the path thread-safe.
45 fPath.updateBoundsCache();
46 (void)fPath.getGenerationID();
47
48 // cleanup their phase parameter, inverting it so that it becomes an
49 // offset along the path (to match the interpretation in PostScript)
50 if (phase < 0) {
51 phase = -phase;
52 if (phase > advance) {
53 phase = SkScalarMod(phase, advance);
54 }
55 } else {
56 if (phase > advance) {
57 phase = SkScalarMod(phase, advance);
58 }
59 phase = advance - phase;
60 }
61 // now catch the edge case where phase == advance (within epsilon)
62 if (phase >= advance) {
63 phase = 0;
64 }
65 SkASSERT(phase >= 0);
66
67 fAdvance = advance;
68 fInitialOffset = phase;
69
70 if ((unsigned)style > kMorph_Style) {
71 SkDEBUGF("SkPath1DPathEffect style enum out of range %d\n", style);
72 }
73 fStyle = style;
74 }
75
onFilterPath(SkPath * dst,const SkPath & src,SkStrokeRec * rec,const SkRect * cullRect) const76 bool SkPath1DPathEffect::onFilterPath(SkPath* dst, const SkPath& src,
77 SkStrokeRec* rec, const SkRect* cullRect) const {
78 rec->setFillStyle();
79 return this->INHERITED::onFilterPath(dst, src, rec, cullRect);
80 }
81
morphpoints(SkPoint dst[],const SkPoint src[],int count,SkPathMeasure & meas,SkScalar dist)82 static bool morphpoints(SkPoint dst[], const SkPoint src[], int count,
83 SkPathMeasure& meas, SkScalar dist) {
84 for (int i = 0; i < count; i++) {
85 SkPoint pos;
86 SkVector tangent;
87
88 SkScalar sx = src[i].fX;
89 SkScalar sy = src[i].fY;
90
91 if (!meas.getPosTan(dist + sx, &pos, &tangent)) {
92 return false;
93 }
94
95 SkMatrix matrix;
96 SkPoint pt;
97
98 pt.set(sx, sy);
99 matrix.setSinCos(tangent.fY, tangent.fX, 0, 0);
100 matrix.preTranslate(-sx, 0);
101 matrix.postTranslate(pos.fX, pos.fY);
102 matrix.mapPoints(&dst[i], &pt, 1);
103 }
104 return true;
105 }
106
107 /* TODO
108
109 Need differentially more subdivisions when the follow-path is curvy. Not sure how to
110 determine that, but we need it. I guess a cheap answer is let the caller tell us,
111 but that seems like a cop-out. Another answer is to get Rob Johnson to figure it out.
112 */
morphpath(SkPath * dst,const SkPath & src,SkPathMeasure & meas,SkScalar dist)113 static void morphpath(SkPath* dst, const SkPath& src, SkPathMeasure& meas,
114 SkScalar dist) {
115 SkPath::Iter iter(src, false);
116 SkPoint srcP[4], dstP[3];
117 SkPath::Verb verb;
118
119 while ((verb = iter.next(srcP)) != SkPath::kDone_Verb) {
120 switch (verb) {
121 case SkPath::kMove_Verb:
122 if (morphpoints(dstP, srcP, 1, meas, dist)) {
123 dst->moveTo(dstP[0]);
124 }
125 break;
126 case SkPath::kLine_Verb:
127 srcP[2] = srcP[1];
128 srcP[1].set(SkScalarAve(srcP[0].fX, srcP[2].fX),
129 SkScalarAve(srcP[0].fY, srcP[2].fY));
130 // fall through to quad
131 case SkPath::kQuad_Verb:
132 if (morphpoints(dstP, &srcP[1], 2, meas, dist)) {
133 dst->quadTo(dstP[0], dstP[1]);
134 }
135 break;
136 case SkPath::kConic_Verb:
137 if (morphpoints(dstP, &srcP[1], 2, meas, dist)) {
138 dst->conicTo(dstP[0], dstP[1], iter.conicWeight());
139 }
140 break;
141 case SkPath::kCubic_Verb:
142 if (morphpoints(dstP, &srcP[1], 3, meas, dist)) {
143 dst->cubicTo(dstP[0], dstP[1], dstP[2]);
144 }
145 break;
146 case SkPath::kClose_Verb:
147 dst->close();
148 break;
149 default:
150 SkDEBUGFAIL("unknown verb");
151 break;
152 }
153 }
154 }
155
begin(SkScalar contourLength) const156 SkScalar SkPath1DPathEffect::begin(SkScalar contourLength) const {
157 return fInitialOffset;
158 }
159
CreateProc(SkReadBuffer & buffer)160 sk_sp<SkFlattenable> SkPath1DPathEffect::CreateProc(SkReadBuffer& buffer) {
161 SkScalar advance = buffer.readScalar();
162 SkPath path;
163 buffer.readPath(&path);
164 SkScalar phase = buffer.readScalar();
165 Style style = buffer.read32LE(kLastEnum_Style);
166 return buffer.isValid() ? SkPath1DPathEffect::Make(path, advance, phase, style) : nullptr;
167 }
168
flatten(SkWriteBuffer & buffer) const169 void SkPath1DPathEffect::flatten(SkWriteBuffer& buffer) const {
170 buffer.writeScalar(fAdvance);
171 buffer.writePath(fPath);
172 buffer.writeScalar(fInitialOffset);
173 buffer.writeUInt(fStyle);
174 }
175
next(SkPath * dst,SkScalar distance,SkPathMeasure & meas) const176 SkScalar SkPath1DPathEffect::next(SkPath* dst, SkScalar distance,
177 SkPathMeasure& meas) const {
178 #if defined(IS_FUZZING_WITH_LIBFUZZER)
179 if (dst->countPoints() > 100000) {
180 return fAdvance;
181 }
182 #endif
183 switch (fStyle) {
184 case kTranslate_Style: {
185 SkPoint pos;
186 if (meas.getPosTan(distance, &pos, nullptr)) {
187 dst->addPath(fPath, pos.fX, pos.fY);
188 }
189 } break;
190 case kRotate_Style: {
191 SkMatrix matrix;
192 if (meas.getMatrix(distance, &matrix)) {
193 dst->addPath(fPath, matrix);
194 }
195 } break;
196 case kMorph_Style:
197 morphpath(dst, fPath, meas, distance);
198 break;
199 default:
200 SkDEBUGFAIL("unknown Style enum");
201 break;
202 }
203 return fAdvance;
204 }
205
206 ///////////////////////////////////////////////////////////////////////////////////////////////////
207
Make(const SkPath & path,SkScalar advance,SkScalar phase,Style style)208 sk_sp<SkPathEffect> SkPath1DPathEffect::Make(const SkPath& path, SkScalar advance, SkScalar phase,
209 Style style) {
210 if (advance <= 0 || !SkScalarIsFinite(advance) || !SkScalarIsFinite(phase) || path.isEmpty()) {
211 return nullptr;
212 }
213 return sk_sp<SkPathEffect>(new SkPath1DPathEffect(path, advance, phase, style));
214 }
215