1 /*
2 * Copyright (C) 2008 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #include "SkiaInterpolator.h"
18
19 #include "include/core/SkMath.h"
20 #include "include/private/SkFixed.h"
21 #include "include/private/SkMalloc.h"
22 #include "include/private/SkTo.h"
23 #include "src/core/SkTSearch.h"
24
25 typedef int Dot14;
26 #define Dot14_ONE (1 << 14)
27 #define Dot14_HALF (1 << 13)
28
29 #define Dot14ToFloat(x) ((x) / 16384.f)
30
Dot14Mul(Dot14 a,Dot14 b)31 static inline Dot14 Dot14Mul(Dot14 a, Dot14 b) {
32 return (a * b + Dot14_HALF) >> 14;
33 }
34
eval_cubic(Dot14 t,Dot14 A,Dot14 B,Dot14 C)35 static inline Dot14 eval_cubic(Dot14 t, Dot14 A, Dot14 B, Dot14 C) {
36 return Dot14Mul(Dot14Mul(Dot14Mul(C, t) + B, t) + A, t);
37 }
38
pin_and_convert(float x)39 static inline Dot14 pin_and_convert(float x) {
40 if (x <= 0) {
41 return 0;
42 }
43 if (x >= SK_Scalar1) {
44 return Dot14_ONE;
45 }
46 return SkScalarToFixed(x) >> 2;
47 }
48
SkUnitCubicInterp(float value,float bx,float by,float cx,float cy)49 static float SkUnitCubicInterp(float value, float bx, float by, float cx, float cy) {
50 // pin to the unit-square, and convert to 2.14
51 Dot14 x = pin_and_convert(value);
52
53 if (x == 0) return 0;
54 if (x == Dot14_ONE) return SK_Scalar1;
55
56 Dot14 b = pin_and_convert(bx);
57 Dot14 c = pin_and_convert(cx);
58
59 // Now compute our coefficients from the control points
60 // t -> 3b
61 // t^2 -> 3c - 6b
62 // t^3 -> 3b - 3c + 1
63 Dot14 A = 3 * b;
64 Dot14 B = 3 * (c - 2 * b);
65 Dot14 C = 3 * (b - c) + Dot14_ONE;
66
67 // Now search for a t value given x
68 Dot14 t = Dot14_HALF;
69 Dot14 dt = Dot14_HALF;
70 for (int i = 0; i < 13; i++) {
71 dt >>= 1;
72 Dot14 guess = eval_cubic(t, A, B, C);
73 if (x < guess) {
74 t -= dt;
75 } else {
76 t += dt;
77 }
78 }
79
80 // Now we have t, so compute the coeff for Y and evaluate
81 b = pin_and_convert(by);
82 c = pin_and_convert(cy);
83 A = 3 * b;
84 B = 3 * (c - 2 * b);
85 C = 3 * (b - c) + Dot14_ONE;
86 return SkFixedToScalar(eval_cubic(t, A, B, C) << 2);
87 }
88
89 ///////////////////////////////////////////////////////////////////////////////////////////////////
90
SkiaInterpolatorBase()91 SkiaInterpolatorBase::SkiaInterpolatorBase() {
92 fStorage = nullptr;
93 fTimes = nullptr;
94 SkDEBUGCODE(fTimesArray = nullptr;)
95 }
96
~SkiaInterpolatorBase()97 SkiaInterpolatorBase::~SkiaInterpolatorBase() {
98 if (fStorage) {
99 sk_free(fStorage);
100 }
101 }
102
reset(int elemCount,int frameCount)103 void SkiaInterpolatorBase::reset(int elemCount, int frameCount) {
104 fFlags = 0;
105 fElemCount = SkToU8(elemCount);
106 fFrameCount = SkToS16(frameCount);
107 fRepeat = SK_Scalar1;
108 if (fStorage) {
109 sk_free(fStorage);
110 fStorage = nullptr;
111 fTimes = nullptr;
112 SkDEBUGCODE(fTimesArray = nullptr);
113 }
114 }
115
116 /* Each value[] run is formatted as:
117 <time (in msec)>
118 <blend>
119 <data[fElemCount]>
120
121 Totaling fElemCount+2 entries per keyframe
122 */
123
getDuration(SkMSec * startTime,SkMSec * endTime) const124 bool SkiaInterpolatorBase::getDuration(SkMSec* startTime, SkMSec* endTime) const {
125 if (fFrameCount == 0) {
126 return false;
127 }
128
129 if (startTime) {
130 *startTime = fTimes[0].fTime;
131 }
132 if (endTime) {
133 *endTime = fTimes[fFrameCount - 1].fTime;
134 }
135 return true;
136 }
137
ComputeRelativeT(SkMSec time,SkMSec prevTime,SkMSec nextTime,const float blend[4])138 float SkiaInterpolatorBase::ComputeRelativeT(SkMSec time, SkMSec prevTime, SkMSec nextTime,
139 const float blend[4]) {
140 SkASSERT(time > prevTime && time < nextTime);
141
142 float t = (float)(time - prevTime) / (float)(nextTime - prevTime);
143 return blend ? SkUnitCubicInterp(t, blend[0], blend[1], blend[2], blend[3]) : t;
144 }
145
timeToT(SkMSec time,float * T,int * indexPtr,bool * exactPtr) const146 SkiaInterpolatorBase::Result SkiaInterpolatorBase::timeToT(SkMSec time, float* T, int* indexPtr,
147 bool* exactPtr) const {
148 SkASSERT(fFrameCount > 0);
149 Result result = kNormal_Result;
150 if (fRepeat != SK_Scalar1) {
151 SkMSec startTime = 0, endTime = 0; // initialize to avoid warning
152 this->getDuration(&startTime, &endTime);
153 SkMSec totalTime = endTime - startTime;
154 SkMSec offsetTime = time - startTime;
155 endTime = SkScalarFloorToInt(fRepeat * totalTime);
156 if (offsetTime >= endTime) {
157 float fraction = SkScalarFraction(fRepeat);
158 offsetTime = fraction == 0 && fRepeat > 0
159 ? totalTime
160 : (SkMSec)SkScalarFloorToInt(fraction * totalTime);
161 result = kFreezeEnd_Result;
162 } else {
163 int mirror = fFlags & kMirror;
164 offsetTime = offsetTime % (totalTime << mirror);
165 if (offsetTime > totalTime) { // can only be true if fMirror is true
166 offsetTime = (totalTime << 1) - offsetTime;
167 }
168 }
169 time = offsetTime + startTime;
170 }
171
172 int index = SkTSearch<SkMSec>(&fTimes[0].fTime, fFrameCount, time, sizeof(SkTimeCode));
173
174 bool exact = true;
175
176 if (index < 0) {
177 index = ~index;
178 if (index == 0) {
179 result = kFreezeStart_Result;
180 } else if (index == fFrameCount) {
181 if (fFlags & kReset) {
182 index = 0;
183 } else {
184 index -= 1;
185 }
186 result = kFreezeEnd_Result;
187 } else {
188 exact = false;
189 }
190 }
191 SkASSERT(index < fFrameCount);
192 const SkTimeCode* nextTime = &fTimes[index];
193 SkMSec nextT = nextTime[0].fTime;
194 if (exact) {
195 *T = 0;
196 } else {
197 SkMSec prevT = nextTime[-1].fTime;
198 *T = ComputeRelativeT(time, prevT, nextT, nextTime[-1].fBlend);
199 }
200 *indexPtr = index;
201 *exactPtr = exact;
202 return result;
203 }
204
SkiaInterpolator()205 SkiaInterpolator::SkiaInterpolator() {
206 INHERITED::reset(0, 0);
207 fValues = nullptr;
208 SkDEBUGCODE(fScalarsArray = nullptr;)
209 }
210
SkiaInterpolator(int elemCount,int frameCount)211 SkiaInterpolator::SkiaInterpolator(int elemCount, int frameCount) {
212 SkASSERT(elemCount > 0);
213 this->reset(elemCount, frameCount);
214 }
215
reset(int elemCount,int frameCount)216 void SkiaInterpolator::reset(int elemCount, int frameCount) {
217 INHERITED::reset(elemCount, frameCount);
218 fStorage = sk_malloc_throw((sizeof(float) * elemCount + sizeof(SkTimeCode)) * frameCount);
219 fTimes = (SkTimeCode*)fStorage;
220 fValues = (float*)((char*)fStorage + sizeof(SkTimeCode) * frameCount);
221 #ifdef SK_DEBUG
222 fTimesArray = (SkTimeCode(*)[10])fTimes;
223 fScalarsArray = (float(*)[10])fValues;
224 #endif
225 }
226
227 #define SK_Fixed1Third (SK_Fixed1 / 3)
228 #define SK_Fixed2Third (SK_Fixed1 * 2 / 3)
229
230 static const float gIdentityBlend[4] = {0.33333333f, 0.33333333f, 0.66666667f, 0.66666667f};
231
setKeyFrame(int index,SkMSec time,const float values[],const float blend[4])232 bool SkiaInterpolator::setKeyFrame(int index, SkMSec time, const float values[],
233 const float blend[4]) {
234 SkASSERT(values != nullptr);
235
236 if (blend == nullptr) {
237 blend = gIdentityBlend;
238 }
239
240 bool success = ~index == SkTSearch<SkMSec>(&fTimes->fTime, index, time, sizeof(SkTimeCode));
241 SkASSERT(success);
242 if (success) {
243 SkTimeCode* timeCode = &fTimes[index];
244 timeCode->fTime = time;
245 memcpy(timeCode->fBlend, blend, sizeof(timeCode->fBlend));
246 float* dst = &fValues[fElemCount * index];
247 memcpy(dst, values, fElemCount * sizeof(float));
248 }
249 return success;
250 }
251
timeToValues(SkMSec time,float values[]) const252 SkiaInterpolator::Result SkiaInterpolator::timeToValues(SkMSec time, float values[]) const {
253 float T;
254 int index;
255 bool exact;
256 Result result = timeToT(time, &T, &index, &exact);
257 if (values) {
258 const float* nextSrc = &fValues[index * fElemCount];
259
260 if (exact) {
261 memcpy(values, nextSrc, fElemCount * sizeof(float));
262 } else {
263 SkASSERT(index > 0);
264
265 const float* prevSrc = nextSrc - fElemCount;
266
267 for (int i = fElemCount - 1; i >= 0; --i) {
268 values[i] = SkScalarInterp(prevSrc[i], nextSrc[i], T);
269 }
270 }
271 }
272 return result;
273 }
274