| /* |
| * Copyright (C) 2010 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. |
| */ |
| |
| package android.widget; |
| |
| import android.content.Context; |
| import android.hardware.SensorManager; |
| import android.util.FloatMath; |
| import android.view.ViewConfiguration; |
| import android.view.animation.AnimationUtils; |
| import android.view.animation.Interpolator; |
| |
| /** |
| * This class encapsulates scrolling with the ability to overshoot the bounds |
| * of a scrolling operation. This class is a drop-in replacement for |
| * {@link android.widget.Scroller} in most cases. |
| */ |
| public class OverScroller { |
| private int mMode; |
| |
| private MagneticOverScroller mScrollerX; |
| private MagneticOverScroller mScrollerY; |
| |
| private final Interpolator mInterpolator; |
| |
| private static final int DEFAULT_DURATION = 250; |
| private static final int SCROLL_MODE = 0; |
| private static final int FLING_MODE = 1; |
| |
| /** |
| * Creates an OverScroller with a viscous fluid scroll interpolator. |
| * @param context |
| */ |
| public OverScroller(Context context) { |
| this(context, null); |
| } |
| |
| /** |
| * Creates an OverScroller with default edge bounce coefficients. |
| * @param context The context of this application. |
| * @param interpolator The scroll interpolator. If null, a default (viscous) interpolator will |
| * be used. |
| */ |
| public OverScroller(Context context, Interpolator interpolator) { |
| this(context, interpolator, MagneticOverScroller.DEFAULT_BOUNCE_COEFFICIENT, |
| MagneticOverScroller.DEFAULT_BOUNCE_COEFFICIENT); |
| } |
| |
| /** |
| * Creates an OverScroller. |
| * @param context The context of this application. |
| * @param interpolator The scroll interpolator. If null, a default (viscous) interpolator will |
| * be used. |
| * @param bounceCoefficientX A value between 0 and 1 that will determine the proportion of the |
| * velocity which is preserved in the bounce when the horizontal edge is reached. A null value |
| * means no bounce. |
| * @param bounceCoefficientY Same as bounceCoefficientX but for the vertical direction. |
| */ |
| public OverScroller(Context context, Interpolator interpolator, |
| float bounceCoefficientX, float bounceCoefficientY) { |
| mInterpolator = interpolator; |
| mScrollerX = new MagneticOverScroller(); |
| mScrollerY = new MagneticOverScroller(); |
| MagneticOverScroller.initializeFromContext(context); |
| |
| mScrollerX.setBounceCoefficient(bounceCoefficientX); |
| mScrollerY.setBounceCoefficient(bounceCoefficientY); |
| } |
| |
| /** |
| * |
| * Returns whether the scroller has finished scrolling. |
| * |
| * @return True if the scroller has finished scrolling, false otherwise. |
| */ |
| public final boolean isFinished() { |
| return mScrollerX.mFinished && mScrollerY.mFinished; |
| } |
| |
| /** |
| * Force the finished field to a particular value. Contrary to |
| * {@link #abortAnimation()}, forcing the animation to finished |
| * does NOT cause the scroller to move to the final x and y |
| * position. |
| * |
| * @param finished The new finished value. |
| */ |
| public final void forceFinished(boolean finished) { |
| mScrollerX.mFinished = mScrollerY.mFinished = finished; |
| } |
| |
| /** |
| * Returns the current X offset in the scroll. |
| * |
| * @return The new X offset as an absolute distance from the origin. |
| */ |
| public final int getCurrX() { |
| return mScrollerX.mCurrentPosition; |
| } |
| |
| /** |
| * Returns the current Y offset in the scroll. |
| * |
| * @return The new Y offset as an absolute distance from the origin. |
| */ |
| public final int getCurrY() { |
| return mScrollerY.mCurrentPosition; |
| } |
| |
| /** |
| * @hide |
| * Returns the current velocity. |
| * |
| * @return The original velocity less the deceleration, norm of the X and Y velocity vector. |
| */ |
| public float getCurrVelocity() { |
| float squaredNorm = mScrollerX.mCurrVelocity * mScrollerX.mCurrVelocity; |
| squaredNorm += mScrollerY.mCurrVelocity * mScrollerY.mCurrVelocity; |
| return FloatMath.sqrt(squaredNorm); |
| } |
| |
| /** |
| * Returns the start X offset in the scroll. |
| * |
| * @return The start X offset as an absolute distance from the origin. |
| */ |
| public final int getStartX() { |
| return mScrollerX.mStart; |
| } |
| |
| /** |
| * Returns the start Y offset in the scroll. |
| * |
| * @return The start Y offset as an absolute distance from the origin. |
| */ |
| public final int getStartY() { |
| return mScrollerY.mStart; |
| } |
| |
| /** |
| * Returns where the scroll will end. Valid only for "fling" scrolls. |
| * |
| * @return The final X offset as an absolute distance from the origin. |
| */ |
| public final int getFinalX() { |
| return mScrollerX.mFinal; |
| } |
| |
| /** |
| * Returns where the scroll will end. Valid only for "fling" scrolls. |
| * |
| * @return The final Y offset as an absolute distance from the origin. |
| */ |
| public final int getFinalY() { |
| return mScrollerY.mFinal; |
| } |
| |
| /** |
| * Returns how long the scroll event will take, in milliseconds. |
| * |
| * @return The duration of the scroll in milliseconds. |
| * |
| * @hide Pending removal once nothing depends on it |
| * @deprecated OverScrollers don't necessarily have a fixed duration. |
| * This function will lie to the best of its ability. |
| */ |
| public final int getDuration() { |
| return Math.max(mScrollerX.mDuration, mScrollerY.mDuration); |
| } |
| |
| /** |
| * Extend the scroll animation. This allows a running animation to scroll |
| * further and longer, when used with {@link #setFinalX(int)} or {@link #setFinalY(int)}. |
| * |
| * @param extend Additional time to scroll in milliseconds. |
| * @see #setFinalX(int) |
| * @see #setFinalY(int) |
| * |
| * @hide Pending removal once nothing depends on it |
| * @deprecated OverScrollers don't necessarily have a fixed duration. |
| * Instead of setting a new final position and extending |
| * the duration of an existing scroll, use startScroll |
| * to begin a new animation. |
| */ |
| public void extendDuration(int extend) { |
| mScrollerX.extendDuration(extend); |
| mScrollerY.extendDuration(extend); |
| } |
| |
| /** |
| * Sets the final position (X) for this scroller. |
| * |
| * @param newX The new X offset as an absolute distance from the origin. |
| * @see #extendDuration(int) |
| * @see #setFinalY(int) |
| * |
| * @hide Pending removal once nothing depends on it |
| * @deprecated OverScroller's final position may change during an animation. |
| * Instead of setting a new final position and extending |
| * the duration of an existing scroll, use startScroll |
| * to begin a new animation. |
| */ |
| public void setFinalX(int newX) { |
| mScrollerX.setFinalPosition(newX); |
| } |
| |
| /** |
| * Sets the final position (Y) for this scroller. |
| * |
| * @param newY The new Y offset as an absolute distance from the origin. |
| * @see #extendDuration(int) |
| * @see #setFinalX(int) |
| * |
| * @hide Pending removal once nothing depends on it |
| * @deprecated OverScroller's final position may change during an animation. |
| * Instead of setting a new final position and extending |
| * the duration of an existing scroll, use startScroll |
| * to begin a new animation. |
| */ |
| public void setFinalY(int newY) { |
| mScrollerY.setFinalPosition(newY); |
| } |
| |
| /** |
| * Call this when you want to know the new location. If it returns true, the |
| * animation is not yet finished. |
| */ |
| public boolean computeScrollOffset() { |
| if (isFinished()) { |
| return false; |
| } |
| |
| switch (mMode) { |
| case SCROLL_MODE: |
| long time = AnimationUtils.currentAnimationTimeMillis(); |
| // Any scroller can be used for time, since they were started |
| // together in scroll mode. We use X here. |
| final long elapsedTime = time - mScrollerX.mStartTime; |
| |
| final int duration = mScrollerX.mDuration; |
| if (elapsedTime < duration) { |
| float q = (float) (elapsedTime) / duration; |
| |
| if (mInterpolator == null) |
| q = Scroller.viscousFluid(q); |
| else |
| q = mInterpolator.getInterpolation(q); |
| |
| mScrollerX.updateScroll(q); |
| mScrollerY.updateScroll(q); |
| } else { |
| abortAnimation(); |
| } |
| break; |
| |
| case FLING_MODE: |
| if (!mScrollerX.mFinished) { |
| if (!mScrollerX.update()) { |
| if (!mScrollerX.continueWhenFinished()) { |
| mScrollerX.finish(); |
| } |
| } |
| } |
| |
| if (!mScrollerY.mFinished) { |
| if (!mScrollerY.update()) { |
| if (!mScrollerY.continueWhenFinished()) { |
| mScrollerY.finish(); |
| } |
| } |
| } |
| |
| break; |
| } |
| |
| return true; |
| } |
| |
| /** |
| * Start scrolling by providing a starting point and the distance to travel. |
| * The scroll will use the default value of 250 milliseconds for the |
| * duration. |
| * |
| * @param startX Starting horizontal scroll offset in pixels. Positive |
| * numbers will scroll the content to the left. |
| * @param startY Starting vertical scroll offset in pixels. Positive numbers |
| * will scroll the content up. |
| * @param dx Horizontal distance to travel. Positive numbers will scroll the |
| * content to the left. |
| * @param dy Vertical distance to travel. Positive numbers will scroll the |
| * content up. |
| */ |
| public void startScroll(int startX, int startY, int dx, int dy) { |
| startScroll(startX, startY, dx, dy, DEFAULT_DURATION); |
| } |
| |
| /** |
| * Start scrolling by providing a starting point and the distance to travel. |
| * |
| * @param startX Starting horizontal scroll offset in pixels. Positive |
| * numbers will scroll the content to the left. |
| * @param startY Starting vertical scroll offset in pixels. Positive numbers |
| * will scroll the content up. |
| * @param dx Horizontal distance to travel. Positive numbers will scroll the |
| * content to the left. |
| * @param dy Vertical distance to travel. Positive numbers will scroll the |
| * content up. |
| * @param duration Duration of the scroll in milliseconds. |
| */ |
| public void startScroll(int startX, int startY, int dx, int dy, int duration) { |
| mMode = SCROLL_MODE; |
| mScrollerX.startScroll(startX, dx, duration); |
| mScrollerY.startScroll(startY, dy, duration); |
| } |
| |
| /** |
| * Call this when you want to 'spring back' into a valid coordinate range. |
| * |
| * @param startX Starting X coordinate |
| * @param startY Starting Y coordinate |
| * @param minX Minimum valid X value |
| * @param maxX Maximum valid X value |
| * @param minY Minimum valid Y value |
| * @param maxY Minimum valid Y value |
| * @return true if a springback was initiated, false if startX and startY were |
| * already within the valid range. |
| */ |
| public boolean springback(int startX, int startY, int minX, int maxX, int minY, int maxY) { |
| mMode = FLING_MODE; |
| |
| // Make sure both methods are called. |
| final boolean spingbackX = mScrollerX.springback(startX, minX, maxX); |
| final boolean spingbackY = mScrollerY.springback(startY, minY, maxY); |
| return spingbackX || spingbackY; |
| } |
| |
| public void fling(int startX, int startY, int velocityX, int velocityY, |
| int minX, int maxX, int minY, int maxY) { |
| fling(startX, startY, velocityX, velocityY, minX, maxX, minY, maxY, 0, 0); |
| } |
| |
| /** |
| * Start scrolling based on a fling gesture. The distance traveled will |
| * depend on the initial velocity of the fling. |
| * |
| * @param startX Starting point of the scroll (X) |
| * @param startY Starting point of the scroll (Y) |
| * @param velocityX Initial velocity of the fling (X) measured in pixels per |
| * second. |
| * @param velocityY Initial velocity of the fling (Y) measured in pixels per |
| * second |
| * @param minX Minimum X value. The scroller will not scroll past this point |
| * unless overX > 0. If overfling is allowed, it will use minX as |
| * a springback boundary. |
| * @param maxX Maximum X value. The scroller will not scroll past this point |
| * unless overX > 0. If overfling is allowed, it will use maxX as |
| * a springback boundary. |
| * @param minY Minimum Y value. The scroller will not scroll past this point |
| * unless overY > 0. If overfling is allowed, it will use minY as |
| * a springback boundary. |
| * @param maxY Maximum Y value. The scroller will not scroll past this point |
| * unless overY > 0. If overfling is allowed, it will use maxY as |
| * a springback boundary. |
| * @param overX Overfling range. If > 0, horizontal overfling in either |
| * direction will be possible. |
| * @param overY Overfling range. If > 0, vertical overfling in either |
| * direction will be possible. |
| */ |
| public void fling(int startX, int startY, int velocityX, int velocityY, |
| int minX, int maxX, int minY, int maxY, int overX, int overY) { |
| mMode = FLING_MODE; |
| mScrollerX.fling(startX, velocityX, minX, maxX, overX); |
| mScrollerY.fling(startY, velocityY, minY, maxY, overY); |
| } |
| |
| /** |
| * Notify the scroller that we've reached a horizontal boundary. |
| * Normally the information to handle this will already be known |
| * when the animation is started, such as in a call to one of the |
| * fling functions. However there are cases where this cannot be known |
| * in advance. This function will transition the current motion and |
| * animate from startX to finalX as appropriate. |
| * |
| * @param startX Starting/current X position |
| * @param finalX Desired final X position |
| * @param overX Magnitude of overscroll allowed. This should be the maximum |
| * desired distance from finalX. Absolute value - must be positive. |
| */ |
| public void notifyHorizontalEdgeReached(int startX, int finalX, int overX) { |
| mScrollerX.notifyEdgeReached(startX, finalX, overX); |
| } |
| |
| /** |
| * Notify the scroller that we've reached a vertical boundary. |
| * Normally the information to handle this will already be known |
| * when the animation is started, such as in a call to one of the |
| * fling functions. However there are cases where this cannot be known |
| * in advance. This function will animate a parabolic motion from |
| * startY to finalY. |
| * |
| * @param startY Starting/current Y position |
| * @param finalY Desired final Y position |
| * @param overY Magnitude of overscroll allowed. This should be the maximum |
| * desired distance from finalY. |
| */ |
| public void notifyVerticalEdgeReached(int startY, int finalY, int overY) { |
| mScrollerY.notifyEdgeReached(startY, finalY, overY); |
| } |
| |
| /** |
| * Returns whether the current Scroller is currently returning to a valid position. |
| * Valid bounds were provided by the |
| * {@link #fling(int, int, int, int, int, int, int, int, int, int)} method. |
| * |
| * One should check this value before calling |
| * {@link #startScroll(int, int, int, int)} as the interpolation currently in progress |
| * to restore a valid position will then be stopped. The caller has to take into account |
| * the fact that the started scroll will start from an overscrolled position. |
| * |
| * @return true when the current position is overscrolled and in the process of |
| * interpolating back to a valid value. |
| */ |
| public boolean isOverscrolled() { |
| return ((!mScrollerX.mFinished && |
| mScrollerX.mState != MagneticOverScroller.TO_EDGE) || |
| (!mScrollerY.mFinished && |
| mScrollerY.mState != MagneticOverScroller.TO_EDGE)); |
| } |
| |
| /** |
| * Stops the animation. Contrary to {@link #forceFinished(boolean)}, |
| * aborting the animating causes the scroller to move to the final x and y |
| * positions. |
| * |
| * @see #forceFinished(boolean) |
| */ |
| public void abortAnimation() { |
| mScrollerX.finish(); |
| mScrollerY.finish(); |
| } |
| |
| /** |
| * Returns the time elapsed since the beginning of the scrolling. |
| * |
| * @return The elapsed time in milliseconds. |
| * |
| * @hide |
| */ |
| public int timePassed() { |
| final long time = AnimationUtils.currentAnimationTimeMillis(); |
| final long startTime = Math.min(mScrollerX.mStartTime, mScrollerY.mStartTime); |
| return (int) (time - startTime); |
| } |
| |
| static class MagneticOverScroller { |
| // Initial position |
| int mStart; |
| |
| // Current position |
| int mCurrentPosition; |
| |
| // Final position |
| int mFinal; |
| |
| // Initial velocity |
| int mVelocity; |
| |
| // Current velocity |
| float mCurrVelocity; |
| |
| // Constant current deceleration |
| float mDeceleration; |
| |
| // Animation starting time, in system milliseconds |
| long mStartTime; |
| |
| // Animation duration, in milliseconds |
| int mDuration; |
| |
| // Whether the animation is currently in progress |
| boolean mFinished; |
| |
| // Constant gravity value, used to scale deceleration |
| static float GRAVITY; |
| |
| static void initializeFromContext(Context context) { |
| final float ppi = context.getResources().getDisplayMetrics().density * 160.0f; |
| GRAVITY = SensorManager.GRAVITY_EARTH // g (m/s^2) |
| * 39.37f // inch/meter |
| * ppi // pixels per inch |
| * ViewConfiguration.getScrollFriction(); |
| } |
| |
| private static final int TO_EDGE = 0; |
| private static final int TO_BOUNDARY = 1; |
| private static final int TO_BOUNCE = 2; |
| |
| private int mState = TO_EDGE; |
| |
| // The allowed overshot distance before boundary is reached. |
| private int mOver; |
| |
| // Duration in milliseconds to go back from edge to edge. Springback is half of it. |
| private static final int OVERSCROLL_SPRINGBACK_DURATION = 200; |
| |
| // Oscillation period |
| private static final float TIME_COEF = |
| 1000.0f * (float) Math.PI / OVERSCROLL_SPRINGBACK_DURATION; |
| |
| // If the velocity is smaller than this value, no bounce is triggered |
| // when the edge limits are reached (would result in a zero pixels |
| // displacement anyway). |
| private static final float MINIMUM_VELOCITY_FOR_BOUNCE = Float.MAX_VALUE;//140.0f; |
| |
| // Proportion of the velocity that is preserved when the edge is reached. |
| private static final float DEFAULT_BOUNCE_COEFFICIENT = 0.16f; |
| |
| private float mBounceCoefficient = DEFAULT_BOUNCE_COEFFICIENT; |
| |
| MagneticOverScroller() { |
| mFinished = true; |
| } |
| |
| void updateScroll(float q) { |
| mCurrentPosition = mStart + Math.round(q * (mFinal - mStart)); |
| } |
| |
| /* |
| * Get a signed deceleration that will reduce the velocity. |
| */ |
| static float getDeceleration(int velocity) { |
| return velocity > 0 ? -GRAVITY : GRAVITY; |
| } |
| |
| /* |
| * Returns the time (in milliseconds) it will take to go from start to end. |
| */ |
| static int computeDuration(int start, int end, float initialVelocity, float deceleration) { |
| final int distance = start - end; |
| final float discriminant = initialVelocity * initialVelocity - 2.0f * deceleration |
| * distance; |
| if (discriminant >= 0.0f) { |
| float delta = (float) Math.sqrt(discriminant); |
| if (deceleration < 0.0f) { |
| delta = -delta; |
| } |
| return (int) (1000.0f * (-initialVelocity - delta) / deceleration); |
| } |
| |
| // End position can not be reached |
| return 0; |
| } |
| |
| void startScroll(int start, int distance, int duration) { |
| mFinished = false; |
| |
| mStart = start; |
| mFinal = start + distance; |
| |
| mStartTime = AnimationUtils.currentAnimationTimeMillis(); |
| mDuration = duration; |
| |
| // Unused |
| mDeceleration = 0.0f; |
| mVelocity = 0; |
| } |
| |
| void fling(int start, int velocity, int min, int max) { |
| mFinished = false; |
| |
| mStart = start; |
| mStartTime = AnimationUtils.currentAnimationTimeMillis(); |
| |
| mVelocity = velocity; |
| |
| mDeceleration = getDeceleration(velocity); |
| |
| // A start from an invalid position immediately brings back to a valid position |
| if (mStart < min) { |
| mDuration = 0; |
| mFinal = min; |
| return; |
| } |
| |
| if (mStart > max) { |
| mDuration = 0; |
| mFinal = max; |
| return; |
| } |
| |
| // Duration are expressed in milliseconds |
| mDuration = (int) (-1000.0f * velocity / mDeceleration); |
| |
| mFinal = start - Math.round((velocity * velocity) / (2.0f * mDeceleration)); |
| |
| // Clamp to a valid final position |
| if (mFinal < min) { |
| mFinal = min; |
| mDuration = computeDuration(mStart, min, mVelocity, mDeceleration); |
| } |
| |
| if (mFinal > max) { |
| mFinal = max; |
| mDuration = computeDuration(mStart, max, mVelocity, mDeceleration); |
| } |
| } |
| |
| void finish() { |
| mCurrentPosition = mFinal; |
| // Not reset since WebView relies on this value for fast fling. |
| // mCurrVelocity = 0.0f; |
| mFinished = true; |
| } |
| |
| void setFinalPosition(int position) { |
| mFinal = position; |
| mFinished = false; |
| } |
| |
| void extendDuration(int extend) { |
| final long time = AnimationUtils.currentAnimationTimeMillis(); |
| final int elapsedTime = (int) (time - mStartTime); |
| mDuration = elapsedTime + extend; |
| mFinished = false; |
| } |
| |
| void setBounceCoefficient(float coefficient) { |
| mBounceCoefficient = coefficient; |
| } |
| |
| boolean springback(int start, int min, int max) { |
| mFinished = true; |
| |
| mStart = start; |
| mVelocity = 0; |
| |
| mStartTime = AnimationUtils.currentAnimationTimeMillis(); |
| mDuration = 0; |
| |
| if (start < min) { |
| startSpringback(start, min, false); |
| } else if (start > max) { |
| startSpringback(start, max, true); |
| } |
| |
| return !mFinished; |
| } |
| |
| private void startSpringback(int start, int end, boolean positive) { |
| mFinished = false; |
| mState = TO_BOUNCE; |
| mStart = mFinal = end; |
| mDuration = OVERSCROLL_SPRINGBACK_DURATION; |
| mStartTime -= OVERSCROLL_SPRINGBACK_DURATION / 2; |
| mVelocity = (int) (Math.abs(end - start) * TIME_COEF * (positive ? 1.0 : -1.0f)); |
| } |
| |
| void fling(int start, int velocity, int min, int max, int over) { |
| mState = TO_EDGE; |
| mOver = over; |
| |
| mFinished = false; |
| |
| mStart = start; |
| mStartTime = AnimationUtils.currentAnimationTimeMillis(); |
| |
| mVelocity = velocity; |
| |
| mDeceleration = getDeceleration(velocity); |
| |
| // Duration are expressed in milliseconds |
| mDuration = (int) (-1000.0f * velocity / mDeceleration); |
| |
| mFinal = start - Math.round((velocity * velocity) / (2.0f * mDeceleration)); |
| |
| // Clamp to a valid final position |
| if (mFinal < min) { |
| mFinal = min; |
| mDuration = computeDuration(mStart, min, mVelocity, mDeceleration); |
| } |
| |
| if (mFinal > max) { |
| mFinal = max; |
| mDuration = computeDuration(mStart, max, mVelocity, mDeceleration); |
| } |
| |
| if (start > max) { |
| if (start >= max + over) { |
| springback(max + over, min, max); |
| } else { |
| if (velocity <= 0) { |
| springback(start, min, max); |
| } else { |
| long time = AnimationUtils.currentAnimationTimeMillis(); |
| final double durationSinceEdge = |
| Math.atan((start-max) * TIME_COEF / velocity) / TIME_COEF; |
| mStartTime = (int) (time - 1000.0f * durationSinceEdge); |
| |
| // Simulate a bounce that started from edge |
| mStart = max; |
| |
| mVelocity = (int) (velocity / Math.cos(durationSinceEdge * TIME_COEF)); |
| |
| onEdgeReached(); |
| } |
| } |
| } else { |
| if (start < min) { |
| if (start <= min - over) { |
| springback(min - over, min, max); |
| } else { |
| if (velocity >= 0) { |
| springback(start, min, max); |
| } else { |
| long time = AnimationUtils.currentAnimationTimeMillis(); |
| final double durationSinceEdge = |
| Math.atan((start-min) * TIME_COEF / velocity) / TIME_COEF; |
| mStartTime = (int) (time - 1000.0f * durationSinceEdge); |
| |
| // Simulate a bounce that started from edge |
| mStart = min; |
| |
| mVelocity = (int) (velocity / Math.cos(durationSinceEdge * TIME_COEF)); |
| |
| onEdgeReached(); |
| } |
| |
| } |
| } |
| } |
| } |
| |
| void notifyEdgeReached(int start, int end, int over) { |
| mDeceleration = getDeceleration(mVelocity); |
| |
| // Local time, used to compute edge crossing time. |
| float timeCurrent = mCurrVelocity / mDeceleration; |
| final int distance = end - start; |
| float timeEdge = -(float) Math.sqrt((2.0f * distance / mDeceleration) |
| + (timeCurrent * timeCurrent)); |
| |
| mVelocity = (int) (mDeceleration * timeEdge); |
| |
| // Simulate a symmetric bounce that started from edge |
| mStart = end; |
| |
| mOver = over; |
| |
| long time = AnimationUtils.currentAnimationTimeMillis(); |
| mStartTime = (int) (time - 1000.0f * (timeCurrent - timeEdge)); |
| |
| onEdgeReached(); |
| } |
| |
| private void onEdgeReached() { |
| // mStart, mVelocity and mStartTime were adjusted to their values when edge was reached. |
| final float distance = mVelocity / TIME_COEF; |
| |
| if (Math.abs(distance) < mOver) { |
| // Spring force will bring us back to final position |
| mState = TO_BOUNCE; |
| mFinal = mStart; |
| mDuration = OVERSCROLL_SPRINGBACK_DURATION; |
| } else { |
| // Velocity is too high, we will hit the boundary limit |
| mState = TO_BOUNDARY; |
| int over = mVelocity > 0 ? mOver : -mOver; |
| mFinal = mStart + over; |
| mDuration = (int) (1000.0f * Math.asin(over / distance) / TIME_COEF); |
| } |
| } |
| |
| boolean continueWhenFinished() { |
| switch (mState) { |
| case TO_EDGE: |
| // Duration from start to null velocity |
| int duration = (int) (-1000.0f * mVelocity / mDeceleration); |
| if (mDuration < duration) { |
| // If the animation was clamped, we reached the edge |
| mStart = mFinal; |
| // Speed when edge was reached |
| mVelocity = (int) (mVelocity + mDeceleration * mDuration / 1000.0f); |
| mStartTime += mDuration; |
| onEdgeReached(); |
| } else { |
| // Normal stop, no need to continue |
| return false; |
| } |
| break; |
| case TO_BOUNDARY: |
| mStartTime += mDuration; |
| startSpringback(mFinal, mFinal - (mVelocity > 0 ? mOver:-mOver), mVelocity > 0); |
| break; |
| case TO_BOUNCE: |
| //mVelocity = (int) (mVelocity * BOUNCE_COEFFICIENT); |
| mVelocity = (int) (mVelocity * mBounceCoefficient); |
| if (Math.abs(mVelocity) < MINIMUM_VELOCITY_FOR_BOUNCE) { |
| return false; |
| } |
| mStartTime += mDuration; |
| break; |
| } |
| |
| update(); |
| return true; |
| } |
| |
| /* |
| * Update the current position and velocity for current time. Returns |
| * true if update has been done and false if animation duration has been |
| * reached. |
| */ |
| boolean update() { |
| final long time = AnimationUtils.currentAnimationTimeMillis(); |
| final long duration = time - mStartTime; |
| |
| if (duration > mDuration) { |
| return false; |
| } |
| |
| double distance; |
| final float t = duration / 1000.0f; |
| if (mState == TO_EDGE) { |
| mCurrVelocity = mVelocity + mDeceleration * t; |
| distance = mVelocity * t + mDeceleration * t * t / 2.0f; |
| } else { |
| final float d = t * TIME_COEF; |
| mCurrVelocity = mVelocity * (float)Math.cos(d); |
| distance = mVelocity / TIME_COEF * Math.sin(d); |
| } |
| |
| mCurrentPosition = mStart + (int) distance; |
| return true; |
| } |
| } |
| } |