1 /* libs/graphics/effects/SkDashPathEffect.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 "SkDashPathEffect.h"
19 #include "SkBuffer.h"
20 #include "SkPathMeasure.h"
21
is_even(int x)22 static inline int is_even(int x)
23 {
24 return (~x) << 31;
25 }
26
FindFirstInterval(const SkScalar intervals[],SkScalar phase,int32_t * index)27 static SkScalar FindFirstInterval(const SkScalar intervals[], SkScalar phase, int32_t* index)
28 {
29 int i;
30
31 for (i = 0; phase > intervals[i]; i++)
32 phase -= intervals[i];
33 *index = i;
34 return intervals[i] - phase;
35 }
36
SkDashPathEffect(const SkScalar intervals[],int count,SkScalar phase,bool scaleToFit)37 SkDashPathEffect::SkDashPathEffect(const SkScalar intervals[], int count, SkScalar phase, bool scaleToFit)
38 : fScaleToFit(scaleToFit)
39 {
40 SkASSERT(intervals);
41 SkASSERT(count > 1 && SkAlign2(count) == count);
42
43 fIntervals = (SkScalar*)sk_malloc_throw(sizeof(SkScalar) * count);
44 fCount = count;
45
46 SkScalar len = 0;
47 for (int i = 0; i < count; i++)
48 {
49 SkASSERT(intervals[i] >= 0);
50 fIntervals[i] = intervals[i];
51 len += intervals[i];
52 }
53 fIntervalLength = len;
54
55 if (len > 0) // we don't handle 0 length dash arrays
56 {
57 if (phase < 0)
58 {
59 phase = -phase;
60 if (phase > len)
61 phase = SkScalarMod(phase, len);
62 phase = len - phase;
63 }
64 else if (phase >= len)
65 phase = SkScalarMod(phase, len);
66
67 SkASSERT(phase >= 0 && phase < len);
68 fInitialDashLength = FindFirstInterval(intervals, phase, &fInitialDashIndex);
69
70 SkASSERT(fInitialDashLength >= 0);
71 SkASSERT(fInitialDashIndex >= 0 && fInitialDashIndex < fCount);
72 }
73 else
74 fInitialDashLength = -1; // signal bad dash intervals
75 }
76
~SkDashPathEffect()77 SkDashPathEffect::~SkDashPathEffect()
78 {
79 sk_free(fIntervals);
80 }
81
filterPath(SkPath * dst,const SkPath & src,SkScalar * width)82 bool SkDashPathEffect::filterPath(SkPath* dst, const SkPath& src, SkScalar* width)
83 {
84 // we do nothing if the src wants to be filled, or if our dashlength is 0
85 if (*width < 0 || fInitialDashLength < 0)
86 return false;
87
88 SkPathMeasure meas(src, false);
89 const SkScalar* intervals = fIntervals;
90
91 do {
92 bool skipFirstSegment = meas.isClosed();
93 bool addedSegment = false;
94 SkScalar length = meas.getLength();
95 int index = fInitialDashIndex;
96 SkScalar scale = SK_Scalar1;
97
98 if (fScaleToFit)
99 {
100 if (fIntervalLength >= length)
101 scale = SkScalarDiv(length, fIntervalLength);
102 else
103 {
104 SkScalar div = SkScalarDiv(length, fIntervalLength);
105 int n = SkScalarFloor(div);
106 scale = SkScalarDiv(length, n * fIntervalLength);
107 }
108 }
109
110 SkScalar distance = 0;
111 SkScalar dlen = SkScalarMul(fInitialDashLength, scale);
112
113 while (distance < length)
114 {
115 SkASSERT(dlen >= 0);
116 addedSegment = false;
117 if (is_even(index) && dlen > 0 && !skipFirstSegment)
118 {
119 addedSegment = true;
120 meas.getSegment(distance, distance + dlen, dst, true);
121 }
122 distance += dlen;
123
124 // clear this so we only respect it the first time around
125 skipFirstSegment = false;
126
127 // wrap around our intervals array if necessary
128 index += 1;
129 SkASSERT(index <= fCount);
130 if (index == fCount)
131 index = 0;
132
133 // fetch our next dlen
134 dlen = SkScalarMul(intervals[index], scale);
135 }
136
137 // extend if we ended on a segment and we need to join up with the (skipped) initial segment
138 if (meas.isClosed() && is_even(fInitialDashIndex) && fInitialDashLength > 0)
139 meas.getSegment(0, SkScalarMul(fInitialDashLength, scale), dst, !addedSegment);
140 } while (meas.nextContour());
141 return true;
142 }
143
getFactory()144 SkFlattenable::Factory SkDashPathEffect::getFactory()
145 {
146 return fInitialDashLength < 0 ? NULL : CreateProc;
147 }
148
flatten(SkFlattenableWriteBuffer & buffer)149 void SkDashPathEffect::flatten(SkFlattenableWriteBuffer& buffer)
150 {
151 SkASSERT(fInitialDashLength >= 0);
152
153 buffer.write32(fCount);
154 buffer.write32(fInitialDashIndex);
155 buffer.writeScalar(fInitialDashLength);
156 buffer.writeScalar(fIntervalLength);
157 buffer.write32(fScaleToFit);
158 buffer.writeMul4(fIntervals, fCount * sizeof(fIntervals[0]));
159 }
160
CreateProc(SkFlattenableReadBuffer & buffer)161 SkFlattenable* SkDashPathEffect::CreateProc(SkFlattenableReadBuffer& buffer)
162 {
163 return SkNEW_ARGS(SkDashPathEffect, (buffer));
164 }
165
SkDashPathEffect(SkFlattenableReadBuffer & buffer)166 SkDashPathEffect::SkDashPathEffect(SkFlattenableReadBuffer& buffer)
167 {
168 fCount = buffer.readS32();
169 fInitialDashIndex = buffer.readS32();
170 fInitialDashLength = buffer.readScalar();
171 fIntervalLength = buffer.readScalar();
172 fScaleToFit = (buffer.readS32() != 0);
173
174 fIntervals = (SkScalar*)sk_malloc_throw(sizeof(SkScalar) * fCount);
175 buffer.read(fIntervals, fCount * sizeof(fIntervals[0]));
176 }
177
178
179