1 /*
2 * Copyright 2008 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 #include "SkInterpolator.h"
9
10 #include "SkFixed.h"
11 #include "SkMath.h"
12 #include "SkMalloc.h"
13 #include "SkTSearch.h"
14
SkInterpolatorBase()15 SkInterpolatorBase::SkInterpolatorBase() {
16 fStorage = nullptr;
17 fTimes = nullptr;
18 SkDEBUGCODE(fTimesArray = nullptr;)
19 }
20
~SkInterpolatorBase()21 SkInterpolatorBase::~SkInterpolatorBase() {
22 if (fStorage) {
23 sk_free(fStorage);
24 }
25 }
26
reset(int elemCount,int frameCount)27 void SkInterpolatorBase::reset(int elemCount, int frameCount) {
28 fFlags = 0;
29 fElemCount = SkToU8(elemCount);
30 fFrameCount = SkToS16(frameCount);
31 fRepeat = SK_Scalar1;
32 if (fStorage) {
33 sk_free(fStorage);
34 fStorage = nullptr;
35 fTimes = nullptr;
36 SkDEBUGCODE(fTimesArray = nullptr);
37 }
38 }
39
40 /* Each value[] run is formated as:
41 <time (in msec)>
42 <blend>
43 <data[fElemCount]>
44
45 Totaling fElemCount+2 entries per keyframe
46 */
47
getDuration(SkMSec * startTime,SkMSec * endTime) const48 bool SkInterpolatorBase::getDuration(SkMSec* startTime, SkMSec* endTime) const {
49 if (fFrameCount == 0) {
50 return false;
51 }
52
53 if (startTime) {
54 *startTime = fTimes[0].fTime;
55 }
56 if (endTime) {
57 *endTime = fTimes[fFrameCount - 1].fTime;
58 }
59 return true;
60 }
61
ComputeRelativeT(SkMSec time,SkMSec prevTime,SkMSec nextTime,const SkScalar blend[4])62 SkScalar SkInterpolatorBase::ComputeRelativeT(SkMSec time, SkMSec prevTime,
63 SkMSec nextTime, const SkScalar blend[4]) {
64 SkASSERT(time > prevTime && time < nextTime);
65
66 SkScalar t = (SkScalar)(time - prevTime) / (SkScalar)(nextTime - prevTime);
67 return blend ?
68 SkUnitCubicInterp(t, blend[0], blend[1], blend[2], blend[3]) : t;
69 }
70
timeToT(SkMSec time,SkScalar * T,int * indexPtr,bool * exactPtr) const71 SkInterpolatorBase::Result SkInterpolatorBase::timeToT(SkMSec time, SkScalar* T,
72 int* indexPtr, bool* exactPtr) const {
73 SkASSERT(fFrameCount > 0);
74 Result result = kNormal_Result;
75 if (fRepeat != SK_Scalar1) {
76 SkMSec startTime = 0, endTime = 0; // initialize to avoid warning
77 this->getDuration(&startTime, &endTime);
78 SkMSec totalTime = endTime - startTime;
79 SkMSec offsetTime = time - startTime;
80 endTime = SkScalarFloorToInt(fRepeat * totalTime);
81 if (offsetTime >= endTime) {
82 SkScalar fraction = SkScalarFraction(fRepeat);
83 offsetTime = fraction == 0 && fRepeat > 0 ? totalTime :
84 (SkMSec) SkScalarFloorToInt(fraction * totalTime);
85 result = kFreezeEnd_Result;
86 } else {
87 int mirror = fFlags & kMirror;
88 offsetTime = offsetTime % (totalTime << mirror);
89 if (offsetTime > totalTime) { // can only be true if fMirror is true
90 offsetTime = (totalTime << 1) - offsetTime;
91 }
92 }
93 time = offsetTime + startTime;
94 }
95
96 int index = SkTSearch<SkMSec>(&fTimes[0].fTime, fFrameCount, time,
97 sizeof(SkTimeCode));
98
99 bool exact = true;
100
101 if (index < 0) {
102 index = ~index;
103 if (index == 0) {
104 result = kFreezeStart_Result;
105 } else if (index == fFrameCount) {
106 if (fFlags & kReset) {
107 index = 0;
108 } else {
109 index -= 1;
110 }
111 result = kFreezeEnd_Result;
112 } else {
113 exact = false;
114 }
115 }
116 SkASSERT(index < fFrameCount);
117 const SkTimeCode* nextTime = &fTimes[index];
118 SkMSec nextT = nextTime[0].fTime;
119 if (exact) {
120 *T = 0;
121 } else {
122 SkMSec prevT = nextTime[-1].fTime;
123 *T = ComputeRelativeT(time, prevT, nextT, nextTime[-1].fBlend);
124 }
125 *indexPtr = index;
126 *exactPtr = exact;
127 return result;
128 }
129
130
SkInterpolator()131 SkInterpolator::SkInterpolator() {
132 INHERITED::reset(0, 0);
133 fValues = nullptr;
134 SkDEBUGCODE(fScalarsArray = nullptr;)
135 }
136
SkInterpolator(int elemCount,int frameCount)137 SkInterpolator::SkInterpolator(int elemCount, int frameCount) {
138 SkASSERT(elemCount > 0);
139 this->reset(elemCount, frameCount);
140 }
141
reset(int elemCount,int frameCount)142 void SkInterpolator::reset(int elemCount, int frameCount) {
143 INHERITED::reset(elemCount, frameCount);
144 fStorage = sk_malloc_throw((sizeof(SkScalar) * elemCount +
145 sizeof(SkTimeCode)) * frameCount);
146 fTimes = (SkTimeCode*) fStorage;
147 fValues = (SkScalar*) ((char*) fStorage + sizeof(SkTimeCode) * frameCount);
148 #ifdef SK_DEBUG
149 fTimesArray = (SkTimeCode(*)[10]) fTimes;
150 fScalarsArray = (SkScalar(*)[10]) fValues;
151 #endif
152 }
153
154 #define SK_Fixed1Third (SK_Fixed1/3)
155 #define SK_Fixed2Third (SK_Fixed1*2/3)
156
157 static const SkScalar gIdentityBlend[4] = {
158 0.33333333f, 0.33333333f, 0.66666667f, 0.66666667f
159 };
160
setKeyFrame(int index,SkMSec time,const SkScalar values[],const SkScalar blend[4])161 bool SkInterpolator::setKeyFrame(int index, SkMSec time,
162 const SkScalar values[], const SkScalar blend[4]) {
163 SkASSERT(values != nullptr);
164
165 if (blend == nullptr) {
166 blend = gIdentityBlend;
167 }
168
169 bool success = ~index == SkTSearch<SkMSec>(&fTimes->fTime, index, time,
170 sizeof(SkTimeCode));
171 SkASSERT(success);
172 if (success) {
173 SkTimeCode* timeCode = &fTimes[index];
174 timeCode->fTime = time;
175 memcpy(timeCode->fBlend, blend, sizeof(timeCode->fBlend));
176 SkScalar* dst = &fValues[fElemCount * index];
177 memcpy(dst, values, fElemCount * sizeof(SkScalar));
178 }
179 return success;
180 }
181
timeToValues(SkMSec time,SkScalar values[]) const182 SkInterpolator::Result SkInterpolator::timeToValues(SkMSec time,
183 SkScalar values[]) const {
184 SkScalar T;
185 int index;
186 bool exact;
187 Result result = timeToT(time, &T, &index, &exact);
188 if (values) {
189 const SkScalar* nextSrc = &fValues[index * fElemCount];
190
191 if (exact) {
192 memcpy(values, nextSrc, fElemCount * sizeof(SkScalar));
193 } else {
194 SkASSERT(index > 0);
195
196 const SkScalar* prevSrc = nextSrc - fElemCount;
197
198 for (int i = fElemCount - 1; i >= 0; --i) {
199 values[i] = SkScalarInterp(prevSrc[i], nextSrc[i], T);
200 }
201 }
202 }
203 return result;
204 }
205
206 ///////////////////////////////////////////////////////////////////////////////
207
208 typedef int Dot14;
209 #define Dot14_ONE (1 << 14)
210 #define Dot14_HALF (1 << 13)
211
212 #define Dot14ToFloat(x) ((x) / 16384.f)
213
Dot14Mul(Dot14 a,Dot14 b)214 static inline Dot14 Dot14Mul(Dot14 a, Dot14 b) {
215 return (a * b + Dot14_HALF) >> 14;
216 }
217
eval_cubic(Dot14 t,Dot14 A,Dot14 B,Dot14 C)218 static inline Dot14 eval_cubic(Dot14 t, Dot14 A, Dot14 B, Dot14 C) {
219 return Dot14Mul(Dot14Mul(Dot14Mul(C, t) + B, t) + A, t);
220 }
221
pin_and_convert(SkScalar x)222 static inline Dot14 pin_and_convert(SkScalar x) {
223 if (x <= 0) {
224 return 0;
225 }
226 if (x >= SK_Scalar1) {
227 return Dot14_ONE;
228 }
229 return SkScalarToFixed(x) >> 2;
230 }
231
SkUnitCubicInterp(SkScalar value,SkScalar bx,SkScalar by,SkScalar cx,SkScalar cy)232 SkScalar SkUnitCubicInterp(SkScalar value, SkScalar bx, SkScalar by,
233 SkScalar cx, SkScalar cy) {
234 // pin to the unit-square, and convert to 2.14
235 Dot14 x = pin_and_convert(value);
236
237 if (x == 0) return 0;
238 if (x == Dot14_ONE) return SK_Scalar1;
239
240 Dot14 b = pin_and_convert(bx);
241 Dot14 c = pin_and_convert(cx);
242
243 // Now compute our coefficients from the control points
244 // t -> 3b
245 // t^2 -> 3c - 6b
246 // t^3 -> 3b - 3c + 1
247 Dot14 A = 3*b;
248 Dot14 B = 3*(c - 2*b);
249 Dot14 C = 3*(b - c) + Dot14_ONE;
250
251 // Now search for a t value given x
252 Dot14 t = Dot14_HALF;
253 Dot14 dt = Dot14_HALF;
254 for (int i = 0; i < 13; i++) {
255 dt >>= 1;
256 Dot14 guess = eval_cubic(t, A, B, C);
257 if (x < guess) {
258 t -= dt;
259 } else {
260 t += dt;
261 }
262 }
263
264 // Now we have t, so compute the coeff for Y and evaluate
265 b = pin_and_convert(by);
266 c = pin_and_convert(cy);
267 A = 3*b;
268 B = 3*(c - 2*b);
269 C = 3*(b - c) + Dot14_ONE;
270 return SkFixedToScalar(eval_cubic(t, A, B, C) << 2);
271 }
272