libs/hwui/SkiaInterpolator.cpp - platform/frameworks/base - Git at Google

 /*
  * 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;
 }
	/*
	* 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;
	}