libs/hwui/effects/StretchEffect.cpp - android_frameworks_base - Gitiles

 /*
  * Copyright (C) 2021 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 "StretchEffect.h"
 #include <SkImageFilter.h>
 #include <SkRefCnt.h>
 #include <SkRuntimeEffect.h>
 #include <SkString.h>
 #include <SkSurface.h>
 #include <include/effects/SkImageFilters.h>

 #include <memory>

 namespace android::uirenderer {

 static const SkString stretchShader = SkString(R"(
     uniform shader uContentTexture;

     // multiplier to apply to scale effect
     uniform float uMaxStretchIntensity;

     // Maximum percentage to stretch beyond bounds  of target
     uniform float uStretchAffectedDistX;
     uniform float uStretchAffectedDistY;

     // Distance stretched as a function of the normalized overscroll times
     // scale intensity
     uniform float uDistanceStretchedX;
     uniform float uDistanceStretchedY;
     uniform float uInverseDistanceStretchedX;
     uniform float uInverseDistanceStretchedY;
     uniform float uDistDiffX;

     // Difference between the peak stretch amount and overscroll amount normalized
     uniform float uDistDiffY;

     // Horizontal offset represented as a ratio of pixels divided by the target width
     uniform float uScrollX;
     // Vertical offset represented as a ratio of pixels divided by the target height
     uniform float uScrollY;

     // Normalized overscroll amount in the horizontal direction
     uniform float uOverscrollX;

     // Normalized overscroll amount in the vertical direction
     uniform float uOverscrollY;
     uniform float viewportWidth; // target height in pixels
     uniform float viewportHeight; // target width in pixels

     // uInterpolationStrength is the intensity of the interpolation.
     // if uInterpolationStrength is 0, then the stretch is constant for all the
     // uStretchAffectedDist. if uInterpolationStrength is 1, then stretch intensity
     // is interpolated based on the pixel position in the uStretchAffectedDist area;
     // The closer we are from the scroll anchor point, the more it stretches,
     // and the other way around.
     uniform float uInterpolationStrength;

     float easeIn(float t, float d) {
         return t * d;
     }

     float computeOverscrollStart(
         float inPos,
         float overscroll,
         float uStretchAffectedDist,
         float uInverseStretchAffectedDist,
         float distanceStretched,
         float interpolationStrength
     ) {
         float offsetPos = uStretchAffectedDist - inPos;
         float posBasedVariation = mix(
                 1. ,easeIn(offsetPos, uInverseStretchAffectedDist), interpolationStrength);
         float stretchIntensity = overscroll * posBasedVariation;
         return distanceStretched - (offsetPos / (1. + stretchIntensity));
     }

     float computeOverscrollEnd(
         float inPos,
         float overscroll,
         float reverseStretchDist,
         float uStretchAffectedDist,
         float uInverseStretchAffectedDist,
         float distanceStretched,
         float interpolationStrength,
         float viewportDimension
     ) {
         float offsetPos = inPos - reverseStretchDist;
         float posBasedVariation = mix(
                 1. ,easeIn(offsetPos, uInverseStretchAffectedDist), interpolationStrength);
         float stretchIntensity = (-overscroll) * posBasedVariation;
         return viewportDimension - (distanceStretched - (offsetPos / (1. + stretchIntensity)));
     }

     // Prefer usage of return values over out parameters as it enables
     // SKSL to properly inline method calls and works around potential GPU
     // driver issues on Wembly. See b/182566543 for details
     float computeOverscroll(
         float inPos,
         float overscroll,
         float uStretchAffectedDist,
         float uInverseStretchAffectedDist,
         float distanceStretched,
         float distanceDiff,
         float interpolationStrength,
         float viewportDimension
     ) {
       if (overscroll > 0) {
         if (inPos <= uStretchAffectedDist) {
             return computeOverscrollStart(
               inPos,
               overscroll,
               uStretchAffectedDist,
               uInverseStretchAffectedDist,
               distanceStretched,
               interpolationStrength
             );
         } else {
             return distanceDiff + inPos;
         }
       } else if (overscroll < 0) {
         float stretchAffectedDist = viewportDimension - uStretchAffectedDist;
         if (inPos >= stretchAffectedDist) {
             return computeOverscrollEnd(
               inPos,
               overscroll,
               stretchAffectedDist,
               uStretchAffectedDist,
               uInverseStretchAffectedDist,
               distanceStretched,
               interpolationStrength,
               viewportDimension
             );
         } else {
             return -distanceDiff + inPos;
         }
       } else {
         return inPos;
       }
     }

     vec4 main(vec2 coord) {
         float inU = coord.x;
         float inV = coord.y;
         float outU;
         float outV;

         inU += uScrollX;
         inV += uScrollY;
         outU = computeOverscroll(
             inU,
             uOverscrollX,
             uStretchAffectedDistX,
             uInverseDistanceStretchedX,
             uDistanceStretchedX,
             uDistDiffX,
             uInterpolationStrength,
             viewportWidth
         );
         outV = computeOverscroll(
             inV,
             uOverscrollY,
             uStretchAffectedDistY,
             uInverseDistanceStretchedY,
             uDistanceStretchedY,
             uDistDiffY,
             uInterpolationStrength,
             viewportHeight
         );
         coord.x = outU;
         coord.y = outV;
         return uContentTexture.eval(coord);
     })");

 static const float ZERO = 0.f;
 static const float INTERPOLATION_STRENGTH_VALUE = 0.7f;
 static const char CONTENT_TEXTURE[] = "uContentTexture";

 sk_sp<SkShader> StretchEffect::getShader(float width, float height,
                                          const sk_sp<SkImage>& snapshotImage,
                                          const SkMatrix* matrix) const {
     if (isEmpty()) {
         return nullptr;
     }

     float normOverScrollDistX = mStretchDirection.x();
     float normOverScrollDistY = mStretchDirection.y();
     float distanceStretchedX = width / (1 + abs(normOverScrollDistX));
     float distanceStretchedY = height / (1 + abs(normOverScrollDistY));
     float inverseDistanceStretchedX = 1.f / width;
     float inverseDistanceStretchedY = 1.f / height;
     float diffX = distanceStretchedX - width;
     float diffY = distanceStretchedY - height;

     if (mBuilder == nullptr) {
         mBuilder = std::make_unique<SkRuntimeShaderBuilder>(getStretchEffect());
     }

     mBuilder->child(CONTENT_TEXTURE) =
             snapshotImage->makeShader(SkTileMode::kClamp, SkTileMode::kClamp,
                                       SkSamplingOptions(SkFilterMode::kLinear), matrix);
     mBuilder->uniform("uInterpolationStrength").set(&INTERPOLATION_STRENGTH_VALUE, 1);
     mBuilder->uniform("uStretchAffectedDistX").set(&width, 1);
     mBuilder->uniform("uStretchAffectedDistY").set(&height, 1);
     mBuilder->uniform("uDistanceStretchedX").set(&distanceStretchedX, 1);
     mBuilder->uniform("uDistanceStretchedY").set(&distanceStretchedY, 1);
     mBuilder->uniform("uInverseDistanceStretchedX").set(&inverseDistanceStretchedX, 1);
     mBuilder->uniform("uInverseDistanceStretchedY").set(&inverseDistanceStretchedY, 1);
     mBuilder->uniform("uDistDiffX").set(&diffX, 1);
     mBuilder->uniform("uDistDiffY").set(&diffY, 1);
     mBuilder->uniform("uOverscrollX").set(&normOverScrollDistX, 1);
     mBuilder->uniform("uOverscrollY").set(&normOverScrollDistY, 1);
     mBuilder->uniform("uScrollX").set(&ZERO, 1);
     mBuilder->uniform("uScrollY").set(&ZERO, 1);
     mBuilder->uniform("viewportWidth").set(&width, 1);
     mBuilder->uniform("viewportHeight").set(&height, 1);

     auto result = mBuilder->makeShader();
     mBuilder->child(CONTENT_TEXTURE) = nullptr;
     return result;
 }

 sk_sp<SkRuntimeEffect> StretchEffect::getStretchEffect() {
     const static SkRuntimeEffect::Result instance = SkRuntimeEffect::MakeForShader(stretchShader);
     return instance.effect;
 }

 /**
  * Helper method that maps the input texture position to the stretch position
  * based on the given overscroll value that represents an overscroll from
  * either the top or left
  * @param overscroll current overscroll value
  * @param input normalized input position (can be x or y) on the input texture
  * @return stretched position of the input normalized from 0 to 1
  */
 float reverseMapStart(float overscroll, float input) {
     float numerator = (-input * overscroll * overscroll) -
         (2 * input * overscroll) - input;
     float denominator = 1.f + (.3f * overscroll) +
         (.7f * input * overscroll * overscroll) + (.7f * input * overscroll);
     return -(numerator / denominator);
 }

 /**
  * Helper method that maps the input texture position to the stretch position
  * based on the given overscroll value that represents an overscroll from
  * either the bottom or right
  * @param overscroll current overscroll value
  * @param input normalized input position (can be x or y) on the input texture
  * @return stretched position of the input normalized from 0 to 1
  */
 float reverseMapEnd(float overscroll, float input) {
     float numerator = (.3f * overscroll * overscroll) -
         (.3f * input * overscroll * overscroll) +
         (1.3f * input * overscroll) - overscroll - input;
     float denominator = (.7f * input * overscroll * overscroll) -
         (.7f * input * overscroll) - (.7f * overscroll * overscroll) +
         overscroll - 1.f;
     return numerator / denominator;
 }

 /**
   * Calculates the normalized stretch position given the normalized input
   * position. This handles calculating the overscroll from either the
   * top or left vs bottom or right depending on the sign of the given overscroll
   * value
   *
   * @param overscroll unit vector of overscroll from -1 to 1 indicating overscroll
   * from the bottom or right vs top or left respectively
   * @param normalizedInput the
   * @return
   */
 float computeReverseOverscroll(float overscroll, float normalizedInput) {
     float distanceStretched = 1.f / (1.f + abs(overscroll));
     float distanceDiff = distanceStretched - 1.f;
     if (overscroll > 0) {
         float output = reverseMapStart(overscroll, normalizedInput);
         if (output <= 1.0f) {
             return output;
         } else if (output >= distanceStretched){
             return output - distanceDiff;
         }
     }

     if (overscroll < 0) {
         float output = reverseMapEnd(overscroll, normalizedInput);
         if (output >= 0.f) {
             return output;
         } else if (output < 0.f){
             return output + distanceDiff;
         }
     }
     return normalizedInput;
 }

 float StretchEffect::computeStretchedPositionX(float normalizedX) const {
   return computeReverseOverscroll(mStretchDirection.x(), normalizedX);
 }

 float StretchEffect::computeStretchedPositionY(float normalizedY) const {
   return computeReverseOverscroll(mStretchDirection.y(), normalizedY);
 }

 } // namespace android::uirenderer
	/*
	* Copyright (C) 2021 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 "StretchEffect.h"
	#include <SkImageFilter.h>
	#include <SkRefCnt.h>
	#include <SkRuntimeEffect.h>
	#include <SkString.h>
	#include <SkSurface.h>
	#include <include/effects/SkImageFilters.h>

	#include <memory>

	namespace android::uirenderer {

	static const SkString stretchShader = SkString(R"(
	uniform shader uContentTexture;

	// multiplier to apply to scale effect
	uniform float uMaxStretchIntensity;

	// Maximum percentage to stretch beyond bounds of target
	uniform float uStretchAffectedDistX;
	uniform float uStretchAffectedDistY;

	// Distance stretched as a function of the normalized overscroll times
	// scale intensity
	uniform float uDistanceStretchedX;
	uniform float uDistanceStretchedY;
	uniform float uInverseDistanceStretchedX;
	uniform float uInverseDistanceStretchedY;
	uniform float uDistDiffX;

	// Difference between the peak stretch amount and overscroll amount normalized
	uniform float uDistDiffY;

	// Horizontal offset represented as a ratio of pixels divided by the target width
	uniform float uScrollX;
	// Vertical offset represented as a ratio of pixels divided by the target height
	uniform float uScrollY;

	// Normalized overscroll amount in the horizontal direction
	uniform float uOverscrollX;

	// Normalized overscroll amount in the vertical direction
	uniform float uOverscrollY;
	uniform float viewportWidth; // target height in pixels
	uniform float viewportHeight; // target width in pixels

	// uInterpolationStrength is the intensity of the interpolation.
	// if uInterpolationStrength is 0, then the stretch is constant for all the
	// uStretchAffectedDist. if uInterpolationStrength is 1, then stretch intensity
	// is interpolated based on the pixel position in the uStretchAffectedDist area;
	// The closer we are from the scroll anchor point, the more it stretches,
	// and the other way around.
	uniform float uInterpolationStrength;

	float easeIn(float t, float d) {
	return t * d;
	}

	float computeOverscrollStart(
	float inPos,
	float overscroll,
	float uStretchAffectedDist,
	float uInverseStretchAffectedDist,
	float distanceStretched,
	float interpolationStrength
	) {
	float offsetPos = uStretchAffectedDist - inPos;
	float posBasedVariation = mix(
	1. ,easeIn(offsetPos, uInverseStretchAffectedDist), interpolationStrength);
	float stretchIntensity = overscroll * posBasedVariation;
	return distanceStretched - (offsetPos / (1. + stretchIntensity));
	}

	float computeOverscrollEnd(
	float inPos,
	float overscroll,
	float reverseStretchDist,
	float uStretchAffectedDist,
	float uInverseStretchAffectedDist,
	float distanceStretched,
	float interpolationStrength,
	float viewportDimension
	) {
	float offsetPos = inPos - reverseStretchDist;
	float posBasedVariation = mix(
	1. ,easeIn(offsetPos, uInverseStretchAffectedDist), interpolationStrength);
	float stretchIntensity = (-overscroll) * posBasedVariation;
	return viewportDimension - (distanceStretched - (offsetPos / (1. + stretchIntensity)));
	}

	// Prefer usage of return values over out parameters as it enables
	// SKSL to properly inline method calls and works around potential GPU
	// driver issues on Wembly. See b/182566543 for details
	float computeOverscroll(
	float inPos,
	float overscroll,
	float uStretchAffectedDist,
	float uInverseStretchAffectedDist,
	float distanceStretched,
	float distanceDiff,
	float interpolationStrength,
	float viewportDimension
	) {
	if (overscroll > 0) {
	if (inPos <= uStretchAffectedDist) {
	return computeOverscrollStart(
	inPos,
	overscroll,
	uStretchAffectedDist,
	uInverseStretchAffectedDist,
	distanceStretched,
	interpolationStrength
	);
	} else {
	return distanceDiff + inPos;
	}
	} else if (overscroll < 0) {
	float stretchAffectedDist = viewportDimension - uStretchAffectedDist;
	if (inPos >= stretchAffectedDist) {
	return computeOverscrollEnd(
	inPos,
	overscroll,
	stretchAffectedDist,
	uStretchAffectedDist,
	uInverseStretchAffectedDist,
	distanceStretched,
	interpolationStrength,
	viewportDimension
	);
	} else {
	return -distanceDiff + inPos;
	}
	} else {
	return inPos;
	}
	}

	vec4 main(vec2 coord) {
	float inU = coord.x;
	float inV = coord.y;
	float outU;
	float outV;

	inU += uScrollX;
	inV += uScrollY;
	outU = computeOverscroll(
	inU,
	uOverscrollX,
	uStretchAffectedDistX,
	uInverseDistanceStretchedX,
	uDistanceStretchedX,
	uDistDiffX,
	uInterpolationStrength,
	viewportWidth
	);
	outV = computeOverscroll(
	inV,
	uOverscrollY,
	uStretchAffectedDistY,
	uInverseDistanceStretchedY,
	uDistanceStretchedY,
	uDistDiffY,
	uInterpolationStrength,
	viewportHeight
	);
	coord.x = outU;
	coord.y = outV;
	return uContentTexture.eval(coord);
	})");

	static const float ZERO = 0.f;
	static const float INTERPOLATION_STRENGTH_VALUE = 0.7f;
	static const char CONTENT_TEXTURE[] = "uContentTexture";

	sk_sp<SkShader> StretchEffect::getShader(float width, float height,
	const sk_sp<SkImage>& snapshotImage,
	const SkMatrix* matrix) const {
	if (isEmpty()) {
	return nullptr;
	}

	float normOverScrollDistX = mStretchDirection.x();
	float normOverScrollDistY = mStretchDirection.y();
	float distanceStretchedX = width / (1 + abs(normOverScrollDistX));
	float distanceStretchedY = height / (1 + abs(normOverScrollDistY));
	float inverseDistanceStretchedX = 1.f / width;
	float inverseDistanceStretchedY = 1.f / height;
	float diffX = distanceStretchedX - width;
	float diffY = distanceStretchedY - height;

	if (mBuilder == nullptr) {
	mBuilder = std::make_unique<SkRuntimeShaderBuilder>(getStretchEffect());
	}

	mBuilder->child(CONTENT_TEXTURE) =
	snapshotImage->makeShader(SkTileMode::kClamp, SkTileMode::kClamp,
	SkSamplingOptions(SkFilterMode::kLinear), matrix);
	mBuilder->uniform("uInterpolationStrength").set(&INTERPOLATION_STRENGTH_VALUE, 1);
	mBuilder->uniform("uStretchAffectedDistX").set(&width, 1);
	mBuilder->uniform("uStretchAffectedDistY").set(&height, 1);
	mBuilder->uniform("uDistanceStretchedX").set(&distanceStretchedX, 1);
	mBuilder->uniform("uDistanceStretchedY").set(&distanceStretchedY, 1);
	mBuilder->uniform("uInverseDistanceStretchedX").set(&inverseDistanceStretchedX, 1);
	mBuilder->uniform("uInverseDistanceStretchedY").set(&inverseDistanceStretchedY, 1);
	mBuilder->uniform("uDistDiffX").set(&diffX, 1);
	mBuilder->uniform("uDistDiffY").set(&diffY, 1);
	mBuilder->uniform("uOverscrollX").set(&normOverScrollDistX, 1);
	mBuilder->uniform("uOverscrollY").set(&normOverScrollDistY, 1);
	mBuilder->uniform("uScrollX").set(&ZERO, 1);
	mBuilder->uniform("uScrollY").set(&ZERO, 1);
	mBuilder->uniform("viewportWidth").set(&width, 1);
	mBuilder->uniform("viewportHeight").set(&height, 1);

	auto result = mBuilder->makeShader();
	mBuilder->child(CONTENT_TEXTURE) = nullptr;
	return result;
	}

	sk_sp<SkRuntimeEffect> StretchEffect::getStretchEffect() {
	const static SkRuntimeEffect::Result instance = SkRuntimeEffect::MakeForShader(stretchShader);
	return instance.effect;
	}

	/**
	* Helper method that maps the input texture position to the stretch position
	* based on the given overscroll value that represents an overscroll from
	* either the top or left
	* @param overscroll current overscroll value
	* @param input normalized input position (can be x or y) on the input texture
	* @return stretched position of the input normalized from 0 to 1
	*/
	float reverseMapStart(float overscroll, float input) {
	float numerator = (-input * overscroll * overscroll) -
	(2 * input * overscroll) - input;
	float denominator = 1.f + (.3f * overscroll) +
	(.7f * input * overscroll * overscroll) + (.7f * input * overscroll);
	return -(numerator / denominator);
	}

	/**
	* Helper method that maps the input texture position to the stretch position
	* based on the given overscroll value that represents an overscroll from
	* either the bottom or right
	* @param overscroll current overscroll value
	* @param input normalized input position (can be x or y) on the input texture
	* @return stretched position of the input normalized from 0 to 1
	*/
	float reverseMapEnd(float overscroll, float input) {
	float numerator = (.3f * overscroll * overscroll) -
	(.3f * input * overscroll * overscroll) +
	(1.3f * input * overscroll) - overscroll - input;
	float denominator = (.7f * input * overscroll * overscroll) -
	(.7f * input * overscroll) - (.7f * overscroll * overscroll) +
	overscroll - 1.f;
	return numerator / denominator;
	}

	/**
	* Calculates the normalized stretch position given the normalized input
	* position. This handles calculating the overscroll from either the
	* top or left vs bottom or right depending on the sign of the given overscroll
	* value
	*
	* @param overscroll unit vector of overscroll from -1 to 1 indicating overscroll
	* from the bottom or right vs top or left respectively
	* @param normalizedInput the
	* @return
	*/
	float computeReverseOverscroll(float overscroll, float normalizedInput) {
	float distanceStretched = 1.f / (1.f + abs(overscroll));
	float distanceDiff = distanceStretched - 1.f;
	if (overscroll > 0) {
	float output = reverseMapStart(overscroll, normalizedInput);
	if (output <= 1.0f) {
	return output;
	} else if (output >= distanceStretched){
	return output - distanceDiff;
	}
	}

	if (overscroll < 0) {
	float output = reverseMapEnd(overscroll, normalizedInput);
	if (output >= 0.f) {
	return output;
	} else if (output < 0.f){
	return output + distanceDiff;
	}
	}
	return normalizedInput;
	}

	float StretchEffect::computeStretchedPositionX(float normalizedX) const {
	return computeReverseOverscroll(mStretchDirection.x(), normalizedX);
	}

	float StretchEffect::computeStretchedPositionY(float normalizedY) const {
	return computeReverseOverscroll(mStretchDirection.y(), normalizedY);
	}

	} // namespace android::uirenderer