Merge "Use spring animation for stretch overscroll" into sc-dev (73046dc2) · Commits · e / os / android_frameworks_base

core/java/android/widget/EdgeEffect.java

+102 −37

Original line number	Diff line number	Diff line
		@@ -102,6 +102,28 @@ public class EdgeEffect {
		*/
		public static final int TYPE_STRETCH = 1;

		/**
		* The velocity threshold before the spring animation is considered settled.
		* The idea here is that velocity should be less than 1 pixel per frame (~16ms).
		*/
		private static final double VELOCITY_THRESHOLD = 1.0 / 0.016;

		/**
		* The value threshold before the spring animation is considered close enough to
		* the destination to be settled. This should be around 1 pixel.
		*/
		private static final double VALUE_THRESHOLD = 1;

		/**
		* The natural frequency of the stretch spring.
		*/
		private static final double NATURAL_FREQUENCY = 14.4222;

		/**
		* The damping ratio of the stretch spring.
		*/
		private static final double DAMPING_RATIO = 0.875;

		/** @hide */
		@IntDef({TYPE_GLOW, TYPE_STRETCH})
		@Retention(RetentionPolicy.SOURCE)
		@@ -145,13 +167,12 @@ public class EdgeEffect {
		@UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.R, trackingBug = 170729553)
		private float mGlowScaleY;
		private float mDistance;
		private float mVelocity; // only for stretch animations

		private float mGlowAlphaStart;
		private float mGlowAlphaFinish;
		private float mGlowScaleYStart;
		private float mGlowScaleYFinish;
		private float mDistanceStart;
		private float mDistanceFinish;

		private long mStartTime;
		private float mDuration;
		@@ -273,6 +294,8 @@ public class EdgeEffect {
		*/
		public void finish() {
		mState = STATE_IDLE;
		mDistance = 0;
		mVelocity = 0;
		}

		/**
		@@ -327,7 +350,8 @@ public class EdgeEffect {
		mDuration = PULL_TIME;

		mPullDistance += deltaDistance;
		mDistanceStart = mDistanceFinish = mDistance = Math.max(0f, mPullDistance);
		mDistance = Math.max(0f, mPullDistance);
		mVelocity = 0;

		final float absdd = Math.abs(deltaDistance);
		mGlowAlpha = mGlowAlphaStart = Math.min(MAX_ALPHA,
		@@ -421,11 +445,10 @@ public class EdgeEffect {
		mState = STATE_RECEDE;
		mGlowAlphaStart = mGlowAlpha;
		mGlowScaleYStart = mGlowScaleY;
		mDistanceStart = mDistance;

		mGlowAlphaFinish = 0.f;
		mGlowScaleYFinish = 0.f;
		mDistanceFinish = 0.f;
		mVelocity = 0.f;

		mStartTime = AnimationUtils.currentAnimationTimeMillis();
		mDuration = RECEDE_TIME;
		@@ -442,7 +465,14 @@ public class EdgeEffect {
		* @param velocity Velocity at impact in pixels per second.
		*/
		public void onAbsorb(int velocity) {
		if (mEdgeEffectType == TYPE_STRETCH) {
		mState = STATE_RECEDE;
		mVelocity = velocity / mHeight;
		mDistance = 0;
		mStartTime = AnimationUtils.currentAnimationTimeMillis();
		} else {
		mState = STATE_ABSORB;
		mVelocity = 0;
		velocity = Math.min(Math.max(MIN_VELOCITY, Math.abs(velocity)), MAX_VELOCITY);

		mStartTime = AnimationUtils.currentAnimationTimeMillis();
		@@ -452,20 +482,19 @@ public class EdgeEffect {
		// nearly invisible.
		mGlowAlphaStart = GLOW_ALPHA_START;
		mGlowScaleYStart = Math.max(mGlowScaleY, 0.f);
		mDistanceStart = mDistance;

		// Growth for the size of the glow should be quadratic to properly
		// respond
		// to a user's scrolling speed. The faster the scrolling speed, the more
		// intense the effect should be for both the size and the saturation.
		mGlowScaleYFinish = Math.min(0.025f + (velocity * (velocity / 100) * 0.00015f) / 2, 1.f);
		mGlowScaleYFinish = Math.min(0.025f + (velocity * (velocity / 100) * 0.00015f) / 2,
		1.f);
		// Alpha should change for the glow as well as size.
		mGlowAlphaFinish = Math.max(
		mGlowAlphaStart, Math.min(velocity * VELOCITY_GLOW_FACTOR * .00001f, MAX_ALPHA));
		mGlowAlphaStart,
		Math.min(velocity * VELOCITY_GLOW_FACTOR * .00001f, MAX_ALPHA));
		mTargetDisplacement = 0.5f;

		// Use glow values to estimate the absorption for stretch distance.
		mDistanceFinish = calculateDistanceFromGlowValues(mGlowScaleYFinish, mGlowAlphaFinish);
		}
		}

		/**
		@@ -573,8 +602,8 @@ public class EdgeEffect {
		canvas.drawCircle(centerX, centerY, mRadius, mPaint);
		canvas.restoreToCount(count);
		} else if (canvas instanceof RecordingCanvas) {
		if (mState != STATE_PULL) {
		update();
		if (mState == STATE_RECEDE) {
		updateSpring();
		}
		RecordingCanvas recordingCanvas = (RecordingCanvas) canvas;
		if (mTmpMatrix == null) {
		@@ -631,7 +660,7 @@ public class EdgeEffect {
		}

		boolean oneLastFrame = false;
		if (mState == STATE_RECEDE && mDistance == 0) {
		if (mState == STATE_RECEDE && mDistance == 0 && mVelocity == 0) {
		mState = STATE_IDLE;
		oneLastFrame = true;
		}
		@@ -668,7 +697,7 @@ public class EdgeEffect {

		mGlowAlpha = mGlowAlphaStart + (mGlowAlphaFinish - mGlowAlphaStart) * interp;
		mGlowScaleY = mGlowScaleYStart + (mGlowScaleYFinish - mGlowScaleYStart) * interp;
		mDistance = mDistanceStart + (mDistanceFinish - mDistanceStart) * interp;
		mDistance = calculateDistanceFromGlowValues(mGlowScaleY, mGlowAlpha);
		mDisplacement = (mDisplacement + mTargetDisplacement) / 2;

		if (t >= 1.f - EPSILON) {
		@@ -680,12 +709,10 @@ public class EdgeEffect {

		mGlowAlphaStart = mGlowAlpha;
		mGlowScaleYStart = mGlowScaleY;
		mDistanceStart = mDistance;

		// After absorb, the glow should fade to nothing.
		mGlowAlphaFinish = 0.f;
		mGlowScaleYFinish = 0.f;
		mDistanceFinish = 0.f;
		break;
		case STATE_PULL:
		mState = STATE_PULL_DECAY;
		@@ -694,12 +721,10 @@ public class EdgeEffect {

		mGlowAlphaStart = mGlowAlpha;
		mGlowScaleYStart = mGlowScaleY;
		mDistanceStart = mDistance;

		// After pull, the glow should fade to nothing.
		mGlowAlphaFinish = 0.f;
		mGlowScaleYFinish = 0.f;
		mDistanceFinish = 0.f;
		break;
		case STATE_PULL_DECAY:
		mState = STATE_RECEDE;
		@@ -711,6 +736,35 @@ public class EdgeEffect {
		}
		}

		private void updateSpring() {
		final long time = AnimationUtils.currentAnimationTimeMillis();
		final float deltaT = (time - mStartTime) / 1000f; // Convert from millis to seconds
		if (deltaT < 0.001f) {
		return; // Must have at least 1 ms difference
		}
		final double mDampedFreq = NATURAL_FREQUENCY * Math.sqrt(1 - DAMPING_RATIO * DAMPING_RATIO);

		// We're always underdamped, so we can use only those equations:
		double cosCoeff = mDistance;
		double sinCoeff = (1 / mDampedFreq) * (DAMPING_RATIO * NATURAL_FREQUENCY
		* mDistance + mVelocity);
		double distance = Math.pow(Math.E, -DAMPING_RATIO * NATURAL_FREQUENCY * deltaT)
		* (cosCoeff * Math.cos(mDampedFreq * deltaT)
		+ sinCoeff * Math.sin(mDampedFreq * deltaT));
		double velocity = distance * (-NATURAL_FREQUENCY) * DAMPING_RATIO
		+ Math.pow(Math.E, -DAMPING_RATIO * NATURAL_FREQUENCY * deltaT)
		* (-mDampedFreq * cosCoeff * Math.sin(mDampedFreq * deltaT)
		+ mDampedFreq * sinCoeff * Math.cos(mDampedFreq * deltaT));
		mDistance = (float) distance;
		mVelocity = (float) velocity;
		mStartTime = time;
		if (isAtEquilibrium()) {
		mState = STATE_IDLE;
		mDistance = 0;
		mVelocity = 0;
		}
		}

		/**
		* @return The estimated pull distance as calculated from mGlowScaleY.
		*/
		@@ -726,4 +780,15 @@ public class EdgeEffect {
		}
		return alpha / PULL_DISTANCE_ALPHA_GLOW_FACTOR;
		}

		/**
		* @return true if the spring used for calculating the stretch animation is
		* considered at rest or false if it is still animating.
		*/
		private boolean isAtEquilibrium() {
		double velocity = mVelocity * mHeight; // in pixels/second
		double displacement = mDistance * mHeight; // in pixels
		return Math.abs(velocity) < VELOCITY_THRESHOLD
		&& Math.abs(displacement) < VALUE_THRESHOLD;
		}
		}