hwui's own impl for interpolator
Bug: 184822190
Test: make
Change-Id: Ib041ad8207417ea5dfa09b50412234e5cf7daf80
diff --git a/libs/hwui/SkiaInterpolator.cpp b/libs/hwui/SkiaInterpolator.cpp
new file mode 100644
index 0000000..0695dd1
--- /dev/null
+++ b/libs/hwui/SkiaInterpolator.cpp
@@ -0,0 +1,273 @@
+/*
+ * 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;
+}
