| /* |
| * Copyright (C) 2013 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.internal.widget; |
| |
| import android.content.res.Resources; |
| import android.os.SystemClock; |
| import android.util.DisplayMetrics; |
| import android.view.MotionEvent; |
| import android.view.View; |
| import android.view.ViewConfiguration; |
| import android.view.animation.AccelerateInterpolator; |
| import android.view.animation.AnimationUtils; |
| import android.view.animation.Interpolator; |
| import android.widget.AbsListView; |
| |
| /** |
| * AutoScrollHelper is a utility class for adding automatic edge-triggered |
| * scrolling to Views. |
| * <p> |
| * <b>Note:</b> Implementing classes are responsible for overriding the |
| * {@link #onScrollBy} method to scroll the target view. See |
| * {@link AbsListViewAutoScroller} for an {@link android.widget.AbsListView} |
| * -specific implementation. |
| * <p> |
| * <h1>Activation</h1> Automatic scrolling starts when the user touches within |
| * an activation area. By default, activation areas are defined as the top, |
| * left, right, and bottom 20% of the host view's total area. Touching within |
| * the top activation area scrolls up, left scrolls to the left, and so on. |
| * <p> |
| * As the user touches closer to the extreme edge of the activation area, |
| * scrolling accelerates up to a maximum velocity. When using the default edge |
| * type, {@link #EDGE_TYPE_INSIDE_EXTEND}, moving outside of the view bounds |
| * will scroll at the maximum velocity. |
| * <p> |
| * The following activation properties may be configured: |
| * <ul> |
| * <li>Delay after entering activation area before auto-scrolling begins, see |
| * {@link #setActivationDelay}. Default value is |
| * {@link ViewConfiguration#getTapTimeout()} to avoid conflicting with taps. |
| * <li>Location of activation areas, see {@link #setEdgeType}. Default value is |
| * {@link #EDGE_TYPE_INSIDE_EXTEND}. |
| * <li>Size of activation areas relative to view size, see |
| * {@link #setRelativeEdges}. Default value is 20% for both vertical and |
| * horizontal edges. |
| * <li>Maximum size used to constrain relative size, see |
| * {@link #setMaximumEdges}. Default value is {@link #NO_MAX}. |
| * </ul> |
| * <h1>Scrolling</h1> When automatic scrolling is active, the helper will |
| * repeatedly call {@link #onScrollBy} to apply new scrolling offsets. |
| * <p> |
| * The following scrolling properties may be configured: |
| * <ul> |
| * <li>Acceleration ramp-up duration, see {@link #setRampUpDuration}. Default |
| * value is 2.5 seconds. |
| * <li>Target velocity relative to view size, see {@link #setRelativeVelocity}. |
| * Default value is 100% per second for both vertical and horizontal. |
| * <li>Minimum velocity used to constrain relative velocity, see |
| * {@link #setMinimumVelocity}. When set, scrolling will accelerate to the |
| * larger of either this value or the relative target value. Default value is |
| * approximately 5 centimeters or 315 dips per second. |
| * <li>Maximum velocity used to constrain relative velocity, see |
| * {@link #setMaximumVelocity}. Default value is approximately 25 centimeters or |
| * 1575 dips per second. |
| * </ul> |
| */ |
| public abstract class AutoScrollHelper implements View.OnTouchListener { |
| /** |
| * Constant passed to {@link #setRelativeEdges} or |
| * {@link #setRelativeVelocity}. Using this value ensures that the computed |
| * relative value is ignored and the absolute maximum value is always used. |
| */ |
| public static final float RELATIVE_UNSPECIFIED = 0; |
| |
| /** |
| * Constant passed to {@link #setMaximumEdges}, {@link #setMaximumVelocity}, |
| * or {@link #setMinimumVelocity}. Using this value ensures that the |
| * computed relative value is always used without constraining to a |
| * particular minimum or maximum value. |
| */ |
| public static final float NO_MAX = Float.MAX_VALUE; |
| |
| /** |
| * Constant passed to {@link #setMaximumEdges}, or |
| * {@link #setMaximumVelocity}, or {@link #setMinimumVelocity}. Using this |
| * value ensures that the computed relative value is always used without |
| * constraining to a particular minimum or maximum value. |
| */ |
| public static final float NO_MIN = 0; |
| |
| /** |
| * Edge type that specifies an activation area starting at the view bounds |
| * and extending inward. Moving outside the view bounds will stop scrolling. |
| * |
| * @see #setEdgeType |
| */ |
| public static final int EDGE_TYPE_INSIDE = 0; |
| |
| /** |
| * Edge type that specifies an activation area starting at the view bounds |
| * and extending inward. After activation begins, moving outside the view |
| * bounds will continue scrolling. |
| * |
| * @see #setEdgeType |
| */ |
| public static final int EDGE_TYPE_INSIDE_EXTEND = 1; |
| |
| /** |
| * Edge type that specifies an activation area starting at the view bounds |
| * and extending outward. Moving inside the view bounds will stop scrolling. |
| * |
| * @see #setEdgeType |
| */ |
| public static final int EDGE_TYPE_OUTSIDE = 2; |
| |
| private static final int HORIZONTAL = 0; |
| private static final int VERTICAL = 1; |
| |
| /** Scroller used to control acceleration toward maximum velocity. */ |
| private final ClampedScroller mScroller = new ClampedScroller(); |
| |
| /** Interpolator used to scale velocity with touch position. */ |
| private final Interpolator mEdgeInterpolator = new AccelerateInterpolator(); |
| |
| /** The view to auto-scroll. Might not be the source of touch events. */ |
| private final View mTarget; |
| |
| /** Runnable used to animate scrolling. */ |
| private Runnable mRunnable; |
| |
| /** Edge insets used to activate auto-scrolling. */ |
| private float[] mRelativeEdges = new float[] { RELATIVE_UNSPECIFIED, RELATIVE_UNSPECIFIED }; |
| |
| /** Clamping values for edge insets used to activate auto-scrolling. */ |
| private float[] mMaximumEdges = new float[] { NO_MAX, NO_MAX }; |
| |
| /** The type of edge being used. */ |
| private int mEdgeType; |
| |
| /** Delay after entering an activation edge before auto-scrolling begins. */ |
| private int mActivationDelay; |
| |
| /** Relative scrolling velocity at maximum edge distance. */ |
| private float[] mRelativeVelocity = new float[] { RELATIVE_UNSPECIFIED, RELATIVE_UNSPECIFIED }; |
| |
| /** Clamping values used for scrolling velocity. */ |
| private float[] mMinimumVelocity = new float[] { NO_MIN, NO_MIN }; |
| |
| /** Clamping values used for scrolling velocity. */ |
| private float[] mMaximumVelocity = new float[] { NO_MAX, NO_MAX }; |
| |
| /** Whether to start activation immediately. */ |
| private boolean mSkipDelay; |
| |
| /** Whether to reset the scroller start time on the next animation. */ |
| private boolean mResetScroller; |
| |
| /** Whether the auto-scroller is active. */ |
| private boolean mActive; |
| |
| /** Whether the auto-scroller is scrolling. */ |
| private boolean mScrolling; |
| |
| /** Whether the auto-scroller is enabled. */ |
| private boolean mEnabled; |
| |
| /** Whether the auto-scroller consumes events when scrolling. */ |
| private boolean mExclusiveEnabled; |
| |
| /** Down time of the most recent down touch event. */ |
| private long mDownTime; |
| |
| // Default values. |
| private static final int DEFAULT_EDGE_TYPE = EDGE_TYPE_INSIDE_EXTEND; |
| private static final int DEFAULT_MINIMUM_VELOCITY_DIPS = 315; |
| private static final int DEFAULT_MAXIMUM_VELOCITY_DIPS = 1575; |
| private static final float DEFAULT_MAXIMUM_EDGE = NO_MAX; |
| private static final float DEFAULT_RELATIVE_EDGE = 0.2f; |
| private static final float DEFAULT_RELATIVE_VELOCITY = 1f; |
| private static final int DEFAULT_ACTIVATION_DELAY = ViewConfiguration.getTapTimeout(); |
| private static final int DEFAULT_RAMP_UP_DURATION = 2500; |
| // TODO: RAMP_DOWN_DURATION of 500ms? |
| |
| /** |
| * Creates a new helper for scrolling the specified target view. |
| * <p> |
| * The resulting helper may be configured by chaining setter calls and |
| * should be set as a touch listener on the target view. |
| * <p> |
| * By default, the helper is disabled and will not respond to touch events |
| * until it is enabled using {@link #setEnabled}. |
| * |
| * @param target The view to automatically scroll. |
| */ |
| public AutoScrollHelper(View target) { |
| mTarget = target; |
| |
| final DisplayMetrics metrics = Resources.getSystem().getDisplayMetrics(); |
| final int maxVelocity = (int) (DEFAULT_MAXIMUM_VELOCITY_DIPS * metrics.density + 0.5f); |
| final int minVelocity = (int) (DEFAULT_MINIMUM_VELOCITY_DIPS * metrics.density + 0.5f); |
| setMaximumVelocity(maxVelocity, maxVelocity); |
| setMinimumVelocity(minVelocity, minVelocity); |
| |
| setEdgeType(DEFAULT_EDGE_TYPE); |
| setMaximumEdges(DEFAULT_MAXIMUM_EDGE, DEFAULT_MAXIMUM_EDGE); |
| setRelativeEdges(DEFAULT_RELATIVE_EDGE, DEFAULT_RELATIVE_EDGE); |
| setRelativeVelocity(DEFAULT_RELATIVE_VELOCITY, DEFAULT_RELATIVE_VELOCITY); |
| setActivationDelay(DEFAULT_ACTIVATION_DELAY); |
| setRampUpDuration(DEFAULT_RAMP_UP_DURATION); |
| |
| mEnabled = true; |
| } |
| |
| /** |
| * Sets whether the scroll helper is enabled and should respond to touch |
| * events. |
| * |
| * @param enabled Whether the scroll helper is enabled. |
| * @return The scroll helper, which may used to chain setter calls. |
| */ |
| public AutoScrollHelper setEnabled(boolean enabled) { |
| if (!enabled) { |
| stop(true); |
| } |
| |
| mEnabled = enabled; |
| return this; |
| } |
| |
| /** |
| * @return True if this helper is enabled and responding to touch events. |
| */ |
| public boolean isEnabled() { |
| return mEnabled; |
| } |
| |
| /** |
| * Enables or disables exclusive handling of touch events during scrolling. |
| * By default, exclusive handling is disabled and the target view receives |
| * all touch events. |
| * <p> |
| * When enabled, {@link #onTouch} will return true if the helper is |
| * currently scrolling and false otherwise. |
| * |
| * @param enabled True to exclusively handle touch events during scrolling, |
| * false to allow the target view to receive all touch events. |
| * @see #isExclusiveEnabled() |
| * @see #onTouch(View, MotionEvent) |
| */ |
| public void setExclusiveEnabled(boolean enabled) { |
| mExclusiveEnabled = enabled; |
| } |
| |
| /** |
| * Indicates whether the scroll helper handles touch events exclusively |
| * during scrolling. |
| * |
| * @return True if exclusive handling of touch events during scrolling is |
| * enabled, false otherwise. |
| * @see #setExclusiveEnabled(boolean) |
| */ |
| public boolean isExclusiveEnabled() { |
| return mExclusiveEnabled; |
| } |
| |
| /** |
| * Sets the absolute maximum scrolling velocity. |
| * <p> |
| * If relative velocity is not specified, scrolling will always reach the |
| * same maximum velocity. If both relative and maximum velocities are |
| * specified, the maximum velocity will be used to clamp the calculated |
| * relative velocity. |
| * |
| * @param horizontalMax The maximum horizontal scrolling velocity, or |
| * {@link #NO_MAX} to leave the relative value unconstrained. |
| * @param verticalMax The maximum vertical scrolling velocity, or |
| * {@link #NO_MAX} to leave the relative value unconstrained. |
| * @return The scroll helper, which may used to chain setter calls. |
| */ |
| public AutoScrollHelper setMaximumVelocity(float horizontalMax, float verticalMax) { |
| mMaximumVelocity[HORIZONTAL] = horizontalMax / 1000f; |
| mMaximumVelocity[VERTICAL] = verticalMax / 1000f; |
| return this; |
| } |
| |
| /** |
| * Sets the absolute minimum scrolling velocity. |
| * <p> |
| * If both relative and minimum velocities are specified, the minimum |
| * velocity will be used to clamp the calculated relative velocity. |
| * |
| * @param horizontalMin The minimum horizontal scrolling velocity, or |
| * {@link #NO_MIN} to leave the relative value unconstrained. |
| * @param verticalMin The minimum vertical scrolling velocity, or |
| * {@link #NO_MIN} to leave the relative value unconstrained. |
| * @return The scroll helper, which may used to chain setter calls. |
| */ |
| public AutoScrollHelper setMinimumVelocity(float horizontalMin, float verticalMin) { |
| mMinimumVelocity[HORIZONTAL] = horizontalMin / 1000f; |
| mMinimumVelocity[VERTICAL] = verticalMin / 1000f; |
| return this; |
| } |
| |
| /** |
| * Sets the target scrolling velocity relative to the host view's |
| * dimensions. |
| * <p> |
| * If both relative and maximum velocities are specified, the maximum |
| * velocity will be used to clamp the calculated relative velocity. |
| * |
| * @param horizontal The target horizontal velocity as a fraction of the |
| * host view width per second, or {@link #RELATIVE_UNSPECIFIED} |
| * to ignore. |
| * @param vertical The target vertical velocity as a fraction of the host |
| * view height per second, or {@link #RELATIVE_UNSPECIFIED} to |
| * ignore. |
| * @return The scroll helper, which may used to chain setter calls. |
| */ |
| public AutoScrollHelper setRelativeVelocity(float horizontal, float vertical) { |
| mRelativeVelocity[HORIZONTAL] = horizontal / 1000f; |
| mRelativeVelocity[VERTICAL] = vertical / 1000f; |
| return this; |
| } |
| |
| /** |
| * Sets the activation edge type, one of: |
| * <ul> |
| * <li>{@link #EDGE_TYPE_INSIDE} for edges that respond to touches inside |
| * the bounds of the host view. If touch moves outside the bounds, scrolling |
| * will stop. |
| * <li>{@link #EDGE_TYPE_INSIDE_EXTEND} for inside edges that continued to |
| * scroll when touch moves outside the bounds of the host view. |
| * <li>{@link #EDGE_TYPE_OUTSIDE} for edges that only respond to touches |
| * that move outside the bounds of the host view. |
| * </ul> |
| * |
| * @param type The type of edge to use. |
| * @return The scroll helper, which may used to chain setter calls. |
| */ |
| public AutoScrollHelper setEdgeType(int type) { |
| mEdgeType = type; |
| return this; |
| } |
| |
| /** |
| * Sets the activation edge size relative to the host view's dimensions. |
| * <p> |
| * If both relative and maximum edges are specified, the maximum edge will |
| * be used to constrain the calculated relative edge size. |
| * |
| * @param horizontal The horizontal edge size as a fraction of the host view |
| * width, or {@link #RELATIVE_UNSPECIFIED} to always use the |
| * maximum value. |
| * @param vertical The vertical edge size as a fraction of the host view |
| * height, or {@link #RELATIVE_UNSPECIFIED} to always use the |
| * maximum value. |
| * @return The scroll helper, which may used to chain setter calls. |
| */ |
| public AutoScrollHelper setRelativeEdges(float horizontal, float vertical) { |
| mRelativeEdges[HORIZONTAL] = horizontal; |
| mRelativeEdges[VERTICAL] = vertical; |
| return this; |
| } |
| |
| /** |
| * Sets the absolute maximum edge size. |
| * <p> |
| * If relative edge size is not specified, activation edges will always be |
| * the maximum edge size. If both relative and maximum edges are specified, |
| * the maximum edge will be used to constrain the calculated relative edge |
| * size. |
| * |
| * @param horizontalMax The maximum horizontal edge size in pixels, or |
| * {@link #NO_MAX} to use the unconstrained calculated relative |
| * value. |
| * @param verticalMax The maximum vertical edge size in pixels, or |
| * {@link #NO_MAX} to use the unconstrained calculated relative |
| * value. |
| * @return The scroll helper, which may used to chain setter calls. |
| */ |
| public AutoScrollHelper setMaximumEdges(float horizontalMax, float verticalMax) { |
| mMaximumEdges[HORIZONTAL] = horizontalMax; |
| mMaximumEdges[VERTICAL] = verticalMax; |
| return this; |
| } |
| |
| /** |
| * Sets the delay after entering an activation edge before activation of |
| * auto-scrolling. By default, the activation delay is set to |
| * {@link ViewConfiguration#getTapTimeout()}. |
| * <p> |
| * Specifying a delay of zero will start auto-scrolling immediately after |
| * the touch position enters an activation edge. |
| * |
| * @param delayMillis The activation delay in milliseconds. |
| * @return The scroll helper, which may used to chain setter calls. |
| */ |
| public AutoScrollHelper setActivationDelay(int delayMillis) { |
| mActivationDelay = delayMillis; |
| return this; |
| } |
| |
| /** |
| * Sets the amount of time after activation of auto-scrolling that is takes |
| * to reach target velocity for the current touch position. |
| * <p> |
| * Specifying a duration greater than zero prevents sudden jumps in |
| * velocity. |
| * |
| * @param durationMillis The ramp-up duration in milliseconds. |
| * @return The scroll helper, which may used to chain setter calls. |
| */ |
| public AutoScrollHelper setRampUpDuration(int durationMillis) { |
| mScroller.setDuration(durationMillis); |
| return this; |
| } |
| |
| /** |
| * Handles touch events by activating automatic scrolling, adjusting scroll |
| * velocity, or stopping. |
| * <p> |
| * If {@link #isExclusiveEnabled()} is false, always returns false so that |
| * the host view may handle touch events. Otherwise, returns true when |
| * automatic scrolling is active and false otherwise. |
| */ |
| @Override |
| public boolean onTouch(View v, MotionEvent event) { |
| if (!mEnabled) { |
| return false; |
| } |
| |
| final int action = event.getActionMasked(); |
| switch (action) { |
| case MotionEvent.ACTION_DOWN: |
| mDownTime = event.getDownTime(); |
| case MotionEvent.ACTION_MOVE: |
| final float xValue = getEdgeValue(mRelativeEdges[HORIZONTAL], v.getWidth(), |
| mMaximumEdges[HORIZONTAL], event.getX()); |
| final float yValue = getEdgeValue(mRelativeEdges[VERTICAL], v.getHeight(), |
| mMaximumEdges[VERTICAL], event.getY()); |
| final float maxVelX = constrain(mRelativeVelocity[HORIZONTAL] * mTarget.getWidth(), |
| mMinimumVelocity[HORIZONTAL], mMaximumVelocity[HORIZONTAL]); |
| final float maxVelY = constrain(mRelativeVelocity[VERTICAL] * mTarget.getHeight(), |
| mMinimumVelocity[VERTICAL], mMaximumVelocity[VERTICAL]); |
| mScroller.setTargetVelocity(xValue * maxVelX, yValue * maxVelY); |
| |
| if ((xValue != 0 || yValue != 0) && !mActive) { |
| mActive = true; |
| mResetScroller = true; |
| if (mRunnable == null) { |
| mRunnable = new AutoScrollRunnable(); |
| } |
| if (mSkipDelay) { |
| mTarget.postOnAnimation(mRunnable); |
| } else { |
| mSkipDelay = true; |
| mTarget.postOnAnimationDelayed(mRunnable, mActivationDelay); |
| } |
| } |
| break; |
| case MotionEvent.ACTION_UP: |
| case MotionEvent.ACTION_CANCEL: |
| stop(true); |
| break; |
| } |
| |
| return mExclusiveEnabled && mScrolling; |
| } |
| |
| /** |
| * Override this method to scroll the target view by the specified number |
| * of pixels. |
| * <p> |
| * Returns whether the target view was able to scroll the requested amount. |
| * |
| * @param deltaX The amount to scroll in the X direction, in pixels. |
| * @param deltaY The amount to scroll in the Y direction, in pixels. |
| * @return true if the target view was able to scroll the requested amount. |
| */ |
| public abstract boolean onScrollBy(int deltaX, int deltaY); |
| |
| /** |
| * Returns the interpolated position of a touch point relative to an edge |
| * defined by its relative inset, its maximum absolute inset, and the edge |
| * interpolator. |
| * |
| * @param relativeValue The size of the inset relative to the total size. |
| * @param size Total size. |
| * @param maxValue The maximum size of the inset, used to clamp (relative * |
| * total). |
| * @param current Touch position within within the total size. |
| * @return Interpolated value of the touch position within the edge. |
| */ |
| private float getEdgeValue(float relativeValue, float size, float maxValue, float current) { |
| // For now, leading and trailing edges are always the same size. |
| final float edgeSize = constrain(relativeValue * size, NO_MIN, maxValue); |
| final float valueLeading = constrainEdgeValue(current, edgeSize); |
| final float valueTrailing = constrainEdgeValue(size - current, edgeSize); |
| final float value = (valueTrailing - valueLeading); |
| final float interpolated; |
| if (value < 0) { |
| interpolated = -mEdgeInterpolator.getInterpolation(-value); |
| } else if (value > 0) { |
| interpolated = mEdgeInterpolator.getInterpolation(value); |
| } else { |
| return 0; |
| } |
| |
| return constrain(interpolated, -1, 1); |
| } |
| |
| private float constrainEdgeValue(float current, float leading) { |
| if (leading == 0) { |
| return 0; |
| } |
| |
| switch (mEdgeType) { |
| case EDGE_TYPE_INSIDE: |
| case EDGE_TYPE_INSIDE_EXTEND: |
| if (current < leading) { |
| if (current >= 0) { |
| // Movement up to the edge is scaled. |
| return 1f - current / leading; |
| } else if (mActive && (mEdgeType == EDGE_TYPE_INSIDE_EXTEND)) { |
| // Movement beyond the edge is always maximum. |
| return 1f; |
| } |
| } |
| break; |
| case EDGE_TYPE_OUTSIDE: |
| if (current < 0) { |
| // Movement beyond the edge is scaled. |
| return current / -leading; |
| } |
| break; |
| } |
| |
| return 0; |
| } |
| |
| private static float constrain(float value, float min, float max) { |
| if (value > max) { |
| return max; |
| } else if (value < min) { |
| return min; |
| } else { |
| return value; |
| } |
| } |
| |
| /** |
| * Stops auto-scrolling immediately, optionally reseting the auto-scrolling |
| * delay. |
| * |
| * @param reset Whether to reset the auto-scrolling delay. |
| */ |
| private void stop(boolean reset) { |
| mActive = false; |
| mScrolling = false; |
| mSkipDelay = !reset; |
| |
| if (mRunnable != null) { |
| mTarget.removeCallbacks(mRunnable); |
| } |
| } |
| |
| /** |
| * Sends a {@link MotionEvent#ACTION_CANCEL} event to the target view, |
| * canceling any ongoing touch events. |
| */ |
| private void cancelTargetTouch() { |
| final MotionEvent cancel = MotionEvent.obtain( |
| mDownTime, SystemClock.uptimeMillis(), MotionEvent.ACTION_CANCEL, 0, 0, 0); |
| cancel.setAction(MotionEvent.ACTION_CANCEL); |
| mTarget.onTouchEvent(cancel); |
| cancel.recycle(); |
| } |
| |
| private class AutoScrollRunnable implements Runnable { |
| @Override |
| public void run() { |
| if (!mActive) { |
| return; |
| } |
| |
| if (mResetScroller) { |
| mResetScroller = false; |
| mScroller.start(); |
| } |
| |
| final View target = mTarget; |
| final ClampedScroller scroller = mScroller; |
| scroller.computeScrollDelta(); |
| |
| final int deltaX = scroller.getDeltaX(); |
| final int deltaY = scroller.getDeltaY(); |
| if ((deltaX != 0 || deltaY != 0 || !scroller.isFinished()) |
| && onScrollBy(deltaX, deltaY)) { |
| // Update whether we're actively scrolling. |
| final boolean scrolling = (deltaX != 0 || deltaY != 0); |
| if (mScrolling != scrolling) { |
| mScrolling = scrolling; |
| |
| // If we just started actively scrolling, make sure any down |
| // or move events send to the target view are canceled. |
| if (mExclusiveEnabled && scrolling) { |
| cancelTargetTouch(); |
| } |
| } |
| |
| // Keep going until the scroller has permanently stopped or the |
| // view can't scroll any more. If the user moves their finger |
| // again, we'll repost the animation. |
| target.postOnAnimation(this); |
| } else { |
| stop(false); |
| } |
| } |
| } |
| |
| /** |
| * Scroller whose velocity follows the curve of an {@link Interpolator} and |
| * is clamped to the interpolated 0f value before starting and the |
| * interpolated 1f value after a specified duration. |
| */ |
| private static class ClampedScroller { |
| private final Interpolator mInterpolator = new AccelerateInterpolator(); |
| |
| private int mDuration; |
| private float mTargetVelocityX; |
| private float mTargetVelocityY; |
| |
| private long mStartTime; |
| private long mDeltaTime; |
| private int mDeltaX; |
| private int mDeltaY; |
| |
| /** |
| * Creates a new ramp-up scroller that reaches full velocity after a |
| * specified duration. |
| */ |
| public ClampedScroller() { |
| reset(); |
| } |
| |
| public void setDuration(int durationMillis) { |
| mDuration = durationMillis; |
| } |
| |
| /** |
| * Starts the scroller at the current animation time. |
| */ |
| public void start() { |
| mStartTime = AnimationUtils.currentAnimationTimeMillis(); |
| mDeltaTime = mStartTime; |
| } |
| |
| /** |
| * Returns whether the scroller is finished, which means that its |
| * acceleration is zero. |
| * |
| * @return Whether the scroller is finished. |
| */ |
| public boolean isFinished() { |
| if (mTargetVelocityX == 0 && mTargetVelocityY == 0) { |
| return true; |
| } |
| final long currentTime = AnimationUtils.currentAnimationTimeMillis(); |
| final long elapsedSinceStart = currentTime - mStartTime; |
| return elapsedSinceStart > mDuration; |
| } |
| |
| /** |
| * Stops the scroller and resets its values. |
| */ |
| public void reset() { |
| mStartTime = -1; |
| mDeltaTime = -1; |
| mDeltaX = 0; |
| mDeltaY = 0; |
| } |
| |
| /** |
| * Computes the current scroll deltas. This usually only be called after |
| * starting the scroller with {@link #start()}. |
| * |
| * @see #getDeltaX() |
| * @see #getDeltaY() |
| */ |
| public void computeScrollDelta() { |
| final long currentTime = AnimationUtils.currentAnimationTimeMillis(); |
| final long elapsedSinceStart = currentTime - mStartTime; |
| final float value; |
| if (mStartTime < 0) { |
| value = 0f; |
| } else if (elapsedSinceStart < mDuration) { |
| value = (float) elapsedSinceStart / mDuration; |
| } else { |
| value = 1f; |
| } |
| |
| final float scale = mInterpolator.getInterpolation(value); |
| final long elapsedSinceDelta = currentTime - mDeltaTime; |
| |
| mDeltaTime = currentTime; |
| mDeltaX = (int) (elapsedSinceDelta * scale * mTargetVelocityX); |
| mDeltaY = (int) (elapsedSinceDelta * scale * mTargetVelocityY); |
| } |
| |
| /** |
| * Sets the target velocity for this scroller. |
| * |
| * @param x The target X velocity in pixels per millisecond. |
| * @param y The target Y velocity in pixels per millisecond. |
| */ |
| public void setTargetVelocity(float x, float y) { |
| mTargetVelocityX = x; |
| mTargetVelocityY = y; |
| } |
| |
| /** |
| * The distance traveled in the X-coordinate computed by the last call |
| * to {@link #computeScrollDelta()}. |
| */ |
| public int getDeltaX() { |
| return mDeltaX; |
| } |
| |
| /** |
| * The distance traveled in the Y-coordinate computed by the last call |
| * to {@link #computeScrollDelta()}. |
| */ |
| public int getDeltaY() { |
| return mDeltaY; |
| } |
| } |
| |
| /** |
| * Implementation of {@link AutoScrollHelper} that knows how to scroll |
| * generic {@link AbsListView}s. |
| */ |
| public static class AbsListViewAutoScroller extends AutoScrollHelper { |
| private final AbsListView mTarget; |
| |
| public AbsListViewAutoScroller(AbsListView target) { |
| super(target); |
| mTarget = target; |
| } |
| |
| @Override |
| public boolean onScrollBy(int deltaX, int deltaY) { |
| return mTarget.scrollListBy(deltaY); |
| } |
| } |
| } |
