Changes to scrolling physics (d348bb4f) · Commits · e / os / android_frameworks_base

api/current.xml

+14 −0

Original line number	Diff line number	Diff line
		@@ -239966,6 +239966,20 @@
		<parameter name="interpolator" type="android.view.animation.Interpolator">
		</parameter>
		</constructor>
		<constructor name="Scroller"
		type="android.widget.Scroller"
		static="false"
		final="false"
		deprecated="not deprecated"
		visibility="public"
		>
		<parameter name="context" type="android.content.Context">
		</parameter>
		<parameter name="interpolator" type="android.view.animation.Interpolator">
		</parameter>
		<parameter name="flywheel" type="boolean">
		</parameter>
		</constructor>
		<method name="abortAnimation"
		return="void"
		abstract="false"

core/java/android/widget/AbsListView.java

+83 −46

Original line number	Diff line number	Diff line
		@@ -2543,6 +2543,7 @@ public abstract class AbsListView extends AdapterView<ListAdapter> implements Te
		mMotionCorrection = 0;
		motionPosition = findMotionRow(y);
		reportScrollStateChange(OnScrollListener.SCROLL_STATE_TOUCH_SCROLL);
		mFlingRunnable.flywheelTouch();
		}
		}
		}
		@@ -2715,6 +2716,9 @@ public abstract class AbsListView extends AdapterView<ListAdapter> implements Te
		} else {
		mTouchMode = TOUCH_MODE_REST;
		reportScrollStateChange(OnScrollListener.SCROLL_STATE_IDLE);
		if (mFlingRunnable != null) {
		mFlingRunnable.endFling();
		}
		}
		}
		} else {
		@@ -2758,7 +2762,7 @@ public abstract class AbsListView extends AdapterView<ListAdapter> implements Te
		case MotionEvent.ACTION_CANCEL: {
		mTouchMode = TOUCH_MODE_REST;
		setPressed(false);
		View motionView = this.getChildAt(mMotionPosition - mFirstPosition);
		View motionView = getChildAt(mMotionPosition - mFirstPosition);
		if (motionView != null) {
		motionView.setPressed(false);
		}
		@@ -2946,6 +2950,30 @@ public abstract class AbsListView extends AdapterView<ListAdapter> implements Te
		*/
		private int mLastFlingY;

		private final Runnable mCheckFlywheel = new Runnable() {
		public void run() {
		final int activeId = mActivePointerId;
		final VelocityTracker vt = mVelocityTracker;
		final Scroller scroller = mScroller;
		if (vt == null \|\| activeId == INVALID_POINTER) {
		return;
		}

		vt.computeCurrentVelocity(1000, mMaximumVelocity);
		final float yvel = -vt.getYVelocity(activeId);

		if (scroller.isScrollingInDirection(0, yvel)) {
		// Keep the fling alive a little longer
		postDelayed(this, FLYWHEEL_TIMEOUT);
		} else {
		endFling();
		mTouchMode = TOUCH_MODE_SCROLL;
		}
		}
		};

		private static final int FLYWHEEL_TIMEOUT = 40; // milliseconds

		FlingRunnable() {
		mScroller = new Scroller(getContext());
		}
		@@ -2978,29 +3006,42 @@ public abstract class AbsListView extends AdapterView<ListAdapter> implements Te
		post(this);
		}

		private void endFling() {
		void endFling() {
		mTouchMode = TOUCH_MODE_REST;

		removeCallbacks(this);
		removeCallbacks(mCheckFlywheel);
		if (mPositionScroller != null) {
		removeCallbacks(mPositionScroller);
		}

		reportScrollStateChange(OnScrollListener.SCROLL_STATE_IDLE);
		clearScrollingCache();
		mScroller.abortAnimation();
		}

		void flywheelTouch() {
		postDelayed(mCheckFlywheel, FLYWHEEL_TIMEOUT);
		}

		public void run() {
		switch (mTouchMode) {
		default:
		endFling();
		return;

		case TOUCH_MODE_FLING: {
		case TOUCH_MODE_SCROLL:
		if (mScroller.isFinished()) {
		return;
		}
		// Fall through
		case TOUCH_MODE_FLING:
		if (mItemCount == 0 \|\| getChildCount() == 0) {
		endFling();
		return;
		}

		break;
		}
		final Scroller scroller = mScroller;
		boolean more = scroller.computeScrollOffset();
		final int y = scroller.getCurrY();
		@@ -3045,17 +3086,13 @@ public abstract class AbsListView extends AdapterView<ListAdapter> implements Te
		Debug.stopMethodTracing();
		mFlingProfilingStarted = false;
		}
		}

		if (mFlingStrictSpan != null) {
		mFlingStrictSpan.finish();
		mFlingStrictSpan = null;
		}
		}
		break;
		}
		}

		}
		}

core/java/android/widget/Scroller.java

+85 −16

Original line number	Diff line number	Diff line
		@@ -18,6 +18,8 @@ package android.widget;

		import android.content.Context;
		import android.hardware.SensorManager;
		import android.os.Build;
		import android.util.FloatMath;
		import android.view.ViewConfiguration;
		import android.view.animation.AnimationUtils;
		import android.view.animation.Interpolator;
		@@ -54,6 +56,7 @@ public class Scroller {
		private float mViscousFluidNormalize;
		private boolean mFinished;
		private Interpolator mInterpolator;
		private boolean mFlywheel;

		private float mCoeffX = 0.0f;
		private float mCoeffY = 1.0f;
		@@ -63,9 +66,37 @@ public class Scroller {
		private static final int SCROLL_MODE = 0;
		private static final int FLING_MODE = 1;

		private static float DECELERATION_RATE = (float) (Math.log(0.75) / Math.log(0.9));
		private static float ALPHA = 400; // pixels / seconds
		private static float START_TENSION = 0.4f; // Tension at start: (0.4 * total T, 1.0 * Distance)
		private static float END_TENSION = 1.0f - START_TENSION;
		private static final int NB_SAMPLES = 100;
		private static final float[] SPLINE = new float[NB_SAMPLES + 1];


		private float mDeceleration;
		private final float mPpi;

		static {
		float x_min = 0.0f;
		for (int i = 0; i <= NB_SAMPLES; i++) {
		final float t = (float) i / NB_SAMPLES;
		float x_max = 1.0f;
		float x, tx, coef;
		while (true) {
		x = x_min + (x_max - x_min) / 2.0f;
		coef = 3.0f * x * (1.0f - x);
		tx = coef * ((1.0f - x) * START_TENSION + x * END_TENSION) + x * x * x;
		if (Math.abs(tx - t) < 1E-5) break;
		if (tx > t) x_max = x;
		else x_min = x;
		}
		final float d = coef + x * x * x;
		SPLINE[i] = d;
		}
		SPLINE[NB_SAMPLES] = 1.0f;
		}

		/**
		* Create a Scroller with the default duration and interpolator.
		*/
		@@ -73,22 +104,28 @@ public class Scroller {
		this(context, null);
		}

		public Scroller(Context context, Interpolator interpolator) {
		this(context, interpolator,
		context.getApplicationInfo().targetSdkVersion >= Build.VERSION_CODES.HONEYCOMB);
		}

		/**
		* Create a Scroller with the specified interpolator. If the interpolator is
		* null, the default (viscous) interpolator will be used.
		*/
		public Scroller(Context context, Interpolator interpolator) {
		public Scroller(Context context, Interpolator interpolator, boolean flywheel) {
		mFinished = true;
		mInterpolator = interpolator;
		mPpi = context.getResources().getDisplayMetrics().density * 160.0f;
		mDeceleration = computeDeceleration(ViewConfiguration.getScrollFriction());
		mFlywheel = flywheel;
		}

		/**
		* The amount of friction applied to flings. The default value
		* is {@link ViewConfiguration#getScrollFriction}.
		*
		* @return A scalar dimensionless value representing the coefficient of
		* @param friction A scalar dimension-less value representing the coefficient of
		* friction.
		*/
		public final void setFriction(float friction) {
		@@ -210,7 +247,7 @@ public class Scroller {
		if (timePassed < mDuration) {
		switch (mMode) {
		case SCROLL_MODE:
		float x = (float)timePassed * mDurationReciprocal;
		float x = timePassed * mDurationReciprocal;

		if (mInterpolator == null)
		x = viscousFluid(x);
		@@ -221,16 +258,20 @@ public class Scroller {
		mCurrY = mStartY + Math.round(x * mDeltaY);
		break;
		case FLING_MODE:
		float timePassedSeconds = timePassed / 1000.0f;
		float distance = (mVelocity * timePassedSeconds)
		- (mDeceleration * timePassedSeconds * timePassedSeconds / 2.0f);

		mCurrX = mStartX + Math.round(distance * mCoeffX);
		final float t = (float) timePassed / mDuration;
		final int index = (int) (NB_SAMPLES * t);
		final float t_inf = (float) index / NB_SAMPLES;
		final float t_sup = (float) (index + 1) / NB_SAMPLES;
		final float d_inf = SPLINE[index];
		final float d_sup = SPLINE[index + 1];
		final float distanceCoef = d_inf + (t - t_inf) / (t_sup - t_inf) * (d_sup - d_inf);

		mCurrX = mStartX + Math.round(distanceCoef * (mFinalX - mStartX));
		// Pin to mMinX <= mCurrX <= mMaxX
		mCurrX = Math.min(mCurrX, mMaxX);
		mCurrX = Math.max(mCurrX, mMinX);

		mCurrY = mStartY + Math.round(distance * mCoeffY);
		mCurrY = mStartY + Math.round(distanceCoef * (mFinalY - mStartY));
		// Pin to mMinY <= mCurrY <= mMaxY
		mCurrY = Math.min(mCurrY, mMaxY);
		mCurrY = Math.max(mCurrY, mMinY);
		@@ -292,7 +333,7 @@ public class Scroller {
		mFinalY = startY + dy;
		mDeltaX = dx;
		mDeltaY = dy;
		mDurationReciprocal = 1.0f / (float) mDuration;
		mDurationReciprocal = 1.0f / mDuration;
		// This controls the viscous fluid effect (how much of it)
		mViscousFluidScale = 8.0f;
		// must be set to 1.0 (used in viscousFluid())
		@@ -321,14 +362,34 @@ public class Scroller {
		*/
		public void fling(int startX, int startY, int velocityX, int velocityY,
		int minX, int maxX, int minY, int maxY) {
		// Continue a scroll or fling in progress
		if (mFlywheel && !mFinished) {
		float oldVel = getCurrVelocity();

		float dx = (float) (mFinalX - mStartX);
		float dy = (float) (mFinalY - mStartY);
		float hyp = FloatMath.sqrt(dx * dx + dy * dy);

		float ndx = dx / hyp;
		float ndy = dy / hyp;

		float oldVelocityX = ndx * oldVel;
		float oldVelocityY = ndy * oldVel;
		if (Math.signum(velocityX) == Math.signum(oldVelocityX) &&
		Math.signum(velocityY) == Math.signum(oldVelocityY)) {
		velocityX += oldVelocityX;
		velocityY += oldVelocityY;
		}
		}

		mMode = FLING_MODE;
		mFinished = false;

		float velocity = (float)Math.hypot(velocityX, velocityY);
		float velocity = FloatMath.sqrt(velocityX * velocityX + velocityY * velocityY);

		mVelocity = velocity;
		mDuration = (int) (1000 * velocity / mDeceleration); // Duration is in
		// milliseconds
		final double l = Math.log(START_TENSION * velocity / ALPHA);
		mDuration = (int) (1000.0 * Math.exp(l / (DECELERATION_RATE - 1.0)));
		mStartTime = AnimationUtils.currentAnimationTimeMillis();
		mStartX = startX;
		mStartY = startY;
		@@ -336,14 +397,14 @@ public class Scroller {
		mCoeffX = velocity == 0 ? 1.0f : velocityX / velocity;
		mCoeffY = velocity == 0 ? 1.0f : velocityY / velocity;

		int totalDistance = (int) ((velocity * velocity) / (2 * mDeceleration));
		int totalDistance =
		(int) (ALPHA * Math.exp(DECELERATION_RATE / (DECELERATION_RATE - 1.0) * l));

		mMinX = minX;
		mMaxX = maxX;
		mMinY = minY;
		mMaxY = maxY;


		mFinalX = startX + Math.round(totalDistance * mCoeffX);
		// Pin to mMinX <= mFinalX <= mMaxX
		mFinalX = Math.min(mFinalX, mMaxX);
		@@ -395,7 +456,7 @@ public class Scroller {
		public void extendDuration(int extend) {
		int passed = timePassed();
		mDuration = passed + extend;
		mDurationReciprocal = 1.0f / (float)mDuration;
		mDurationReciprocal = 1.0f / mDuration;
		mFinished = false;
		}

		@@ -433,4 +494,12 @@ public class Scroller {
		mDeltaY = mFinalY - mStartY;
		mFinished = false;
		}

		/**
		* @hide
		*/
		public boolean isScrollingInDirection(float xvel, float yvel) {
		return !mFinished && Math.signum(xvel) == Math.signum(mFinalX - mStartX) &&
		Math.signum(yvel) == Math.signum(mFinalY - mStartY);
		}
		}