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Diffstat (limited to 'gallerycommon/src/com/android/gallery3d/common/OverScroller.java')
| -rw-r--r-- | gallerycommon/src/com/android/gallery3d/common/OverScroller.java | 958 |
1 files changed, 0 insertions, 958 deletions
diff --git a/gallerycommon/src/com/android/gallery3d/common/OverScroller.java b/gallerycommon/src/com/android/gallery3d/common/OverScroller.java deleted file mode 100644 index 1ab7953d2..000000000 --- a/gallerycommon/src/com/android/gallery3d/common/OverScroller.java +++ /dev/null @@ -1,958 +0,0 @@ -/* - * 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 com.android.gallery3d.common; - -import android.content.Context; -import android.hardware.SensorManager; -import android.util.FloatMath; -import android.util.Log; -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 final SplineOverScroller mScrollerX; - private final SplineOverScroller mScrollerY; - - private Interpolator mInterpolator; - - private final boolean mFlywheel; - - 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 and flywheel. - * @param context - */ - public OverScroller(Context context) { - this(context, null); - } - - /** - * Creates an OverScroller with flywheel enabled. - * @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, true); - } - - /** - * 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 flywheel If true, successive fling motions will keep on increasing scroll speed. - * @hide - */ - public OverScroller(Context context, Interpolator interpolator, boolean flywheel) { - mInterpolator = interpolator; - mFlywheel = flywheel; - mScrollerX = new SplineOverScroller(); - mScrollerY = new SplineOverScroller(); - - SplineOverScroller.initFromContext(context); - } - - /** - * Creates an OverScroller with flywheel enabled. - * @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. This behavior is no longer supported and this coefficient has no effect. - * @param bounceCoefficientY Same as bounceCoefficientX but for the vertical direction. This - * behavior is no longer supported and this coefficient has no effect. - * !deprecated Use {!link #OverScroller(Context, Interpolator, boolean)} instead. - */ - public OverScroller(Context context, Interpolator interpolator, - float bounceCoefficientX, float bounceCoefficientY) { - this(context, interpolator, true); - } - - /** - * 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. This behavior is no longer supported and this coefficient has no effect. - * @param bounceCoefficientY Same as bounceCoefficientX but for the vertical direction. This - * behavior is no longer supported and this coefficient has no effect. - * @param flywheel If true, successive fling motions will keep on increasing scroll speed. - * !deprecated Use {!link OverScroller(Context, Interpolator, boolean)} instead. - */ - public OverScroller(Context context, Interpolator interpolator, - float bounceCoefficientX, float bounceCoefficientY, boolean flywheel) { - this(context, interpolator, flywheel); - } - - void setInterpolator(Interpolator interpolator) { - mInterpolator = interpolator; - } - - /** - * The amount of friction applied to flings. The default value - * is {@link ViewConfiguration#getScrollFriction}. - * - * @param friction A scalar dimension-less value representing the coefficient of - * friction. - */ - public final void setFriction(float friction) { - mScrollerX.setFriction(friction); - mScrollerY.setFriction(friction); - } - - /** - * - * 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; - } - - /** - * Returns the absolute value of 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. - */ - @Deprecated - 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. - */ - @Deprecated - 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. - */ - @Deprecated - 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. - */ - @Deprecated - 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) { - // Continue a scroll or fling in progress - if (mFlywheel && !isFinished()) { - float oldVelocityX = mScrollerX.mCurrVelocity; - float oldVelocityY = mScrollerY.mCurrVelocity; - if (Math.signum(velocityX) == Math.signum(oldVelocityX) && - Math.signum(velocityY) == Math.signum(oldVelocityY)) { - velocityX += oldVelocityX; - velocityY += oldVelocityY; - } - } - - 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. Absolute value - must be positive. - */ - 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 != SplineOverScroller.SPLINE) || - (!mScrollerY.mFinished && - mScrollerY.mState != SplineOverScroller.SPLINE)); - } - - /** - * 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); - } - - /** - * @hide - */ - public boolean isScrollingInDirection(float xvel, float yvel) { - final int dx = mScrollerX.mFinal - mScrollerX.mStart; - final int dy = mScrollerY.mFinal - mScrollerY.mStart; - return !isFinished() && Math.signum(xvel) == Math.signum(dx) && - Math.signum(yvel) == Math.signum(dy); - } - - static class SplineOverScroller { - // Initial position - private int mStart; - - // Current position - private int mCurrentPosition; - - // Final position - private int mFinal; - - // Initial velocity - private int mVelocity; - - // Current velocity - private float mCurrVelocity; - - // Constant current deceleration - private float mDeceleration; - - // Animation starting time, in system milliseconds - private long mStartTime; - - // Animation duration, in milliseconds - private int mDuration; - - // Duration to complete spline component of animation - private int mSplineDuration; - - // Distance to travel along spline animation - private int mSplineDistance; - - // Whether the animation is currently in progress - private boolean mFinished; - - // The allowed overshot distance before boundary is reached. - private int mOver; - - // Fling friction - private float mFlingFriction = ViewConfiguration.getScrollFriction(); - - // Current state of the animation. - private int mState = SPLINE; - - // Constant gravity value, used in the deceleration phase. - private static final float GRAVITY = 2000.0f; - - // A device specific coefficient adjusted to physical values. - private static float PHYSICAL_COEF; - - private static float DECELERATION_RATE = (float) (Math.log(0.78) / Math.log(0.9)); - private static final float INFLEXION = 0.35f; // Tension lines cross at (INFLEXION, 1) - private static final float START_TENSION = 0.5f; - private static final float END_TENSION = 1.0f; - private static final float P1 = START_TENSION * INFLEXION; - private static final float P2 = 1.0f - END_TENSION * (1.0f - INFLEXION); - - private static final int NB_SAMPLES = 100; - private static final float[] SPLINE_POSITION = new float[NB_SAMPLES + 1]; - private static final float[] SPLINE_TIME = new float[NB_SAMPLES + 1]; - - private static final int SPLINE = 0; - private static final int CUBIC = 1; - private static final int BALLISTIC = 2; - - static { - float x_min = 0.0f; - float y_min = 0.0f; - for (int i = 0; i < NB_SAMPLES; i++) { - final float alpha = (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) * P1 + x * P2) + x * x * x; - if (Math.abs(tx - alpha) < 1E-5) break; - if (tx > alpha) x_max = x; - else x_min = x; - } - SPLINE_POSITION[i] = coef * ((1.0f - x) * START_TENSION + x) + x * x * x; - - float y_max = 1.0f; - float y, dy; - while (true) { - y = y_min + (y_max - y_min) / 2.0f; - coef = 3.0f * y * (1.0f - y); - dy = coef * ((1.0f - y) * START_TENSION + y) + y * y * y; - if (Math.abs(dy - alpha) < 1E-5) break; - if (dy > alpha) y_max = y; - else y_min = y; - } - SPLINE_TIME[i] = coef * ((1.0f - y) * P1 + y * P2) + y * y * y; - } - SPLINE_POSITION[NB_SAMPLES] = SPLINE_TIME[NB_SAMPLES] = 1.0f; - } - - static void initFromContext(Context context) { - final float ppi = context.getResources().getDisplayMetrics().density * 160.0f; - PHYSICAL_COEF = SensorManager.GRAVITY_EARTH // g (m/s^2) - * 39.37f // inch/meter - * ppi - * 0.84f; // look and feel tuning - } - - void setFriction(float friction) { - mFlingFriction = friction; - } - - SplineOverScroller() { - mFinished = true; - } - - void updateScroll(float q) { - mCurrentPosition = mStart + Math.round(q * (mFinal - mStart)); - } - - /* - * Get a signed deceleration that will reduce the velocity. - */ - static private float getDeceleration(int velocity) { - return velocity > 0 ? -GRAVITY : GRAVITY; - } - - /* - * Modifies mDuration to the duration it takes to get from start to newFinal using the - * spline interpolation. The previous duration was needed to get to oldFinal. - */ - private void adjustDuration(int start, int oldFinal, int newFinal) { - final int oldDistance = oldFinal - start; - final int newDistance = newFinal - start; - final float x = Math.abs((float) newDistance / oldDistance); - final int index = (int) (NB_SAMPLES * x); - if (index < NB_SAMPLES) { - final float x_inf = (float) index / NB_SAMPLES; - final float x_sup = (float) (index + 1) / NB_SAMPLES; - final float t_inf = SPLINE_TIME[index]; - final float t_sup = SPLINE_TIME[index + 1]; - final float timeCoef = t_inf + (x - x_inf) / (x_sup - x_inf) * (t_sup - t_inf); - mDuration *= timeCoef; - } - } - - 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 finish() { - mCurrentPosition = mFinal; - // Not reset since WebView relies on this value for fast fling. - // TODO: restore when WebView uses the fast fling implemented in this class. - // 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; - } - - boolean springback(int start, int min, int max) { - mFinished = true; - - mStart = mFinal = start; - mVelocity = 0; - - mStartTime = AnimationUtils.currentAnimationTimeMillis(); - mDuration = 0; - - if (start < min) { - startSpringback(start, min, 0); - } else if (start > max) { - startSpringback(start, max, 0); - } - - return !mFinished; - } - - private void startSpringback(int start, int end, int velocity) { - // mStartTime has been set - mFinished = false; - mState = CUBIC; - mStart = start; - mFinal = end; - final int delta = start - end; - mDeceleration = getDeceleration(delta); - // TODO take velocity into account - mVelocity = -delta; // only sign is used - mOver = Math.abs(delta); - mDuration = (int) (1000.0 * Math.sqrt(-2.0 * delta / mDeceleration)); - } - - void fling(int start, int velocity, int min, int max, int over) { - mOver = over; - mFinished = false; - mCurrVelocity = mVelocity = velocity; - mDuration = mSplineDuration = 0; - mStartTime = AnimationUtils.currentAnimationTimeMillis(); - mCurrentPosition = mStart = start; - - if (start > max || start < min) { - startAfterEdge(start, min, max, velocity); - return; - } - - mState = SPLINE; - double totalDistance = 0.0; - - if (velocity != 0) { - mDuration = mSplineDuration = getSplineFlingDuration(velocity); - totalDistance = getSplineFlingDistance(velocity); - } - - mSplineDistance = (int) (totalDistance * Math.signum(velocity)); - mFinal = start + mSplineDistance; - - // Clamp to a valid final position - if (mFinal < min) { - adjustDuration(mStart, mFinal, min); - mFinal = min; - } - - if (mFinal > max) { - adjustDuration(mStart, mFinal, max); - mFinal = max; - } - } - - private double getSplineDeceleration(int velocity) { - return Math.log(INFLEXION * Math.abs(velocity) / (mFlingFriction * PHYSICAL_COEF)); - } - - private double getSplineFlingDistance(int velocity) { - final double l = getSplineDeceleration(velocity); - final double decelMinusOne = DECELERATION_RATE - 1.0; - return mFlingFriction * PHYSICAL_COEF * Math.exp(DECELERATION_RATE / decelMinusOne * l); - } - - /* Returns the duration, expressed in milliseconds */ - private int getSplineFlingDuration(int velocity) { - final double l = getSplineDeceleration(velocity); - final double decelMinusOne = DECELERATION_RATE - 1.0; - return (int) (1000.0 * Math.exp(l / decelMinusOne)); - } - - private void fitOnBounceCurve(int start, int end, int velocity) { - // Simulate a bounce that started from edge - final float durationToApex = - velocity / mDeceleration; - final float distanceToApex = velocity * velocity / 2.0f / Math.abs(mDeceleration); - final float distanceToEdge = Math.abs(end - start); - final float totalDuration = (float) Math.sqrt( - 2.0 * (distanceToApex + distanceToEdge) / Math.abs(mDeceleration)); - mStartTime -= (int) (1000.0f * (totalDuration - durationToApex)); - mStart = end; - mVelocity = (int) (- mDeceleration * totalDuration); - } - - private void startBounceAfterEdge(int start, int end, int velocity) { - mDeceleration = getDeceleration(velocity == 0 ? start - end : velocity); - fitOnBounceCurve(start, end, velocity); - onEdgeReached(); - } - - private void startAfterEdge(int start, int min, int max, int velocity) { - if (start > min && start < max) { - Log.e("OverScroller", "startAfterEdge called from a valid position"); - mFinished = true; - return; - } - final boolean positive = start > max; - final int edge = positive ? max : min; - final int overDistance = start - edge; - boolean keepIncreasing = overDistance * velocity >= 0; - if (keepIncreasing) { - // Will result in a bounce or a to_boundary depending on velocity. - startBounceAfterEdge(start, edge, velocity); - } else { - final double totalDistance = getSplineFlingDistance(velocity); - if (totalDistance > Math.abs(overDistance)) { - fling(start, velocity, positive ? min : start, positive ? start : max, mOver); - } else { - startSpringback(start, edge, velocity); - } - } - } - - void notifyEdgeReached(int start, int end, int over) { - // mState is used to detect successive notifications - if (mState == SPLINE) { - mOver = over; - mStartTime = AnimationUtils.currentAnimationTimeMillis(); - // We were in fling/scroll mode before: current velocity is such that distance to - // edge is increasing. This ensures that startAfterEdge will not start a new fling. - startAfterEdge(start, end, end, (int) mCurrVelocity); - } - } - - private void onEdgeReached() { - // mStart, mVelocity and mStartTime were adjusted to their values when edge was reached. - float distance = mVelocity * mVelocity / (2.0f * Math.abs(mDeceleration)); - final float sign = Math.signum(mVelocity); - - if (distance > mOver) { - // Default deceleration is not sufficient to slow us down before boundary - mDeceleration = - sign * mVelocity * mVelocity / (2.0f * mOver); - distance = mOver; - } - - mOver = (int) distance; - mState = BALLISTIC; - mFinal = mStart + (int) (mVelocity > 0 ? distance : -distance); - mDuration = - (int) (1000.0f * mVelocity / mDeceleration); - } - - boolean continueWhenFinished() { - switch (mState) { - case SPLINE: - // Duration from start to null velocity - if (mDuration < mSplineDuration) { - // If the animation was clamped, we reached the edge - mStart = mFinal; - // TODO Better compute speed when edge was reached - mVelocity = (int) mCurrVelocity; - mDeceleration = getDeceleration(mVelocity); - mStartTime += mDuration; - onEdgeReached(); - } else { - // Normal stop, no need to continue - return false; - } - break; - case BALLISTIC: - mStartTime += mDuration; - startSpringback(mFinal, mStart, 0); - break; - case CUBIC: - return false; - } - - 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 currentTime = time - mStartTime; - - if (currentTime > mDuration) { - return false; - } - - double distance = 0.0; - switch (mState) { - case SPLINE: { - final float t = (float) currentTime / mSplineDuration; - final int index = (int) (NB_SAMPLES * t); - float distanceCoef = 1.f; - float velocityCoef = 0.f; - if (index < NB_SAMPLES) { - final float t_inf = (float) index / NB_SAMPLES; - final float t_sup = (float) (index + 1) / NB_SAMPLES; - final float d_inf = SPLINE_POSITION[index]; - final float d_sup = SPLINE_POSITION[index + 1]; - velocityCoef = (d_sup - d_inf) / (t_sup - t_inf); - distanceCoef = d_inf + (t - t_inf) * velocityCoef; - } - - distance = distanceCoef * mSplineDistance; - mCurrVelocity = velocityCoef * mSplineDistance / mSplineDuration * 1000.0f; - break; - } - - case BALLISTIC: { - final float t = currentTime / 1000.0f; - mCurrVelocity = mVelocity + mDeceleration * t; - distance = mVelocity * t + mDeceleration * t * t / 2.0f; - break; - } - - case CUBIC: { - final float t = (float) (currentTime) / mDuration; - final float t2 = t * t; - final float sign = Math.signum(mVelocity); - distance = sign * mOver * (3.0f * t2 - 2.0f * t * t2); - mCurrVelocity = sign * mOver * 6.0f * (- t + t2); - break; - } - } - - mCurrentPosition = mStart + (int) Math.round(distance); - - return true; - } - } -} |