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/*
* Copyright (C) 2008 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "SkiaInterpolator.h"
#include "include/core/SkMath.h"
#include "include/private/SkFixed.h"
#include "include/private/SkMalloc.h"
#include "include/private/SkTo.h"
#include "src/core/SkTSearch.h"
typedef int Dot14;
#define Dot14_ONE (1 << 14)
#define Dot14_HALF (1 << 13)
#define Dot14ToFloat(x) ((x) / 16384.f)
static inline Dot14 Dot14Mul(Dot14 a, Dot14 b) {
return (a * b + Dot14_HALF) >> 14;
}
static inline Dot14 eval_cubic(Dot14 t, Dot14 A, Dot14 B, Dot14 C) {
return Dot14Mul(Dot14Mul(Dot14Mul(C, t) + B, t) + A, t);
}
static inline Dot14 pin_and_convert(float x) {
if (x <= 0) {
return 0;
}
if (x >= SK_Scalar1) {
return Dot14_ONE;
}
return SkScalarToFixed(x) >> 2;
}
static float SkUnitCubicInterp(float value, float bx, float by, float cx, float cy) {
// pin to the unit-square, and convert to 2.14
Dot14 x = pin_and_convert(value);
if (x == 0) return 0;
if (x == Dot14_ONE) return SK_Scalar1;
Dot14 b = pin_and_convert(bx);
Dot14 c = pin_and_convert(cx);
// Now compute our coefficients from the control points
// t -> 3b
// t^2 -> 3c - 6b
// t^3 -> 3b - 3c + 1
Dot14 A = 3 * b;
Dot14 B = 3 * (c - 2 * b);
Dot14 C = 3 * (b - c) + Dot14_ONE;
// Now search for a t value given x
Dot14 t = Dot14_HALF;
Dot14 dt = Dot14_HALF;
for (int i = 0; i < 13; i++) {
dt >>= 1;
Dot14 guess = eval_cubic(t, A, B, C);
if (x < guess) {
t -= dt;
} else {
t += dt;
}
}
// Now we have t, so compute the coeff for Y and evaluate
b = pin_and_convert(by);
c = pin_and_convert(cy);
A = 3 * b;
B = 3 * (c - 2 * b);
C = 3 * (b - c) + Dot14_ONE;
return SkFixedToScalar(eval_cubic(t, A, B, C) << 2);
}
///////////////////////////////////////////////////////////////////////////////////////////////////
SkiaInterpolatorBase::SkiaInterpolatorBase() {
fStorage = nullptr;
fTimes = nullptr;
SkDEBUGCODE(fTimesArray = nullptr;)
}
SkiaInterpolatorBase::~SkiaInterpolatorBase() {
if (fStorage) {
sk_free(fStorage);
}
}
void SkiaInterpolatorBase::reset(int elemCount, int frameCount) {
fFlags = 0;
fElemCount = SkToU8(elemCount);
fFrameCount = SkToS16(frameCount);
fRepeat = SK_Scalar1;
if (fStorage) {
sk_free(fStorage);
fStorage = nullptr;
fTimes = nullptr;
SkDEBUGCODE(fTimesArray = nullptr);
}
}
/* Each value[] run is formatted as:
<time (in msec)>
<blend>
<data[fElemCount]>
Totaling fElemCount+2 entries per keyframe
*/
bool SkiaInterpolatorBase::getDuration(SkMSec* startTime, SkMSec* endTime) const {
if (fFrameCount == 0) {
return false;
}
if (startTime) {
*startTime = fTimes[0].fTime;
}
if (endTime) {
*endTime = fTimes[fFrameCount - 1].fTime;
}
return true;
}
float SkiaInterpolatorBase::ComputeRelativeT(SkMSec time, SkMSec prevTime, SkMSec nextTime,
const float blend[4]) {
SkASSERT(time > prevTime && time < nextTime);
float t = (float)(time - prevTime) / (float)(nextTime - prevTime);
return blend ? SkUnitCubicInterp(t, blend[0], blend[1], blend[2], blend[3]) : t;
}
SkiaInterpolatorBase::Result SkiaInterpolatorBase::timeToT(SkMSec time, float* T, int* indexPtr,
bool* exactPtr) const {
SkASSERT(fFrameCount > 0);
Result result = kNormal_Result;
if (fRepeat != SK_Scalar1) {
SkMSec startTime = 0, endTime = 0; // initialize to avoid warning
this->getDuration(&startTime, &endTime);
SkMSec totalTime = endTime - startTime;
SkMSec offsetTime = time - startTime;
endTime = SkScalarFloorToInt(fRepeat * totalTime);
if (offsetTime >= endTime) {
float fraction = SkScalarFraction(fRepeat);
offsetTime = fraction == 0 && fRepeat > 0
? totalTime
: (SkMSec)SkScalarFloorToInt(fraction * totalTime);
result = kFreezeEnd_Result;
} else {
int mirror = fFlags & kMirror;
offsetTime = offsetTime % (totalTime << mirror);
if (offsetTime > totalTime) { // can only be true if fMirror is true
offsetTime = (totalTime << 1) - offsetTime;
}
}
time = offsetTime + startTime;
}
int index = SkTSearch<SkMSec>(&fTimes[0].fTime, fFrameCount, time, sizeof(SkTimeCode));
bool exact = true;
if (index < 0) {
index = ~index;
if (index == 0) {
result = kFreezeStart_Result;
} else if (index == fFrameCount) {
if (fFlags & kReset) {
index = 0;
} else {
index -= 1;
}
result = kFreezeEnd_Result;
} else {
exact = false;
}
}
SkASSERT(index < fFrameCount);
const SkTimeCode* nextTime = &fTimes[index];
SkMSec nextT = nextTime[0].fTime;
if (exact) {
*T = 0;
} else {
SkMSec prevT = nextTime[-1].fTime;
*T = ComputeRelativeT(time, prevT, nextT, nextTime[-1].fBlend);
}
*indexPtr = index;
*exactPtr = exact;
return result;
}
SkiaInterpolator::SkiaInterpolator() {
INHERITED::reset(0, 0);
fValues = nullptr;
SkDEBUGCODE(fScalarsArray = nullptr;)
}
SkiaInterpolator::SkiaInterpolator(int elemCount, int frameCount) {
SkASSERT(elemCount > 0);
this->reset(elemCount, frameCount);
}
void SkiaInterpolator::reset(int elemCount, int frameCount) {
INHERITED::reset(elemCount, frameCount);
fStorage = sk_malloc_throw((sizeof(float) * elemCount + sizeof(SkTimeCode)) * frameCount);
fTimes = (SkTimeCode*)fStorage;
fValues = (float*)((char*)fStorage + sizeof(SkTimeCode) * frameCount);
#ifdef SK_DEBUG
fTimesArray = (SkTimeCode(*)[10])fTimes;
fScalarsArray = (float(*)[10])fValues;
#endif
}
#define SK_Fixed1Third (SK_Fixed1 / 3)
#define SK_Fixed2Third (SK_Fixed1 * 2 / 3)
static const float gIdentityBlend[4] = {0.33333333f, 0.33333333f, 0.66666667f, 0.66666667f};
bool SkiaInterpolator::setKeyFrame(int index, SkMSec time, const float values[],
const float blend[4]) {
SkASSERT(values != nullptr);
if (blend == nullptr) {
blend = gIdentityBlend;
}
bool success = ~index == SkTSearch<SkMSec>(&fTimes->fTime, index, time, sizeof(SkTimeCode));
SkASSERT(success);
if (success) {
SkTimeCode* timeCode = &fTimes[index];
timeCode->fTime = time;
memcpy(timeCode->fBlend, blend, sizeof(timeCode->fBlend));
float* dst = &fValues[fElemCount * index];
memcpy(dst, values, fElemCount * sizeof(float));
}
return success;
}
SkiaInterpolator::Result SkiaInterpolator::timeToValues(SkMSec time, float values[]) const {
float T;
int index;
bool exact;
Result result = timeToT(time, &T, &index, &exact);
if (values) {
const float* nextSrc = &fValues[index * fElemCount];
if (exact) {
memcpy(values, nextSrc, fElemCount * sizeof(float));
} else {
SkASSERT(index > 0);
const float* prevSrc = nextSrc - fElemCount;
for (int i = fElemCount - 1; i >= 0; --i) {
values[i] = SkScalarInterp(prevSrc[i], nextSrc[i], T);
}
}
}
return result;
}
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