package com.mm.android.deviceaddmodule.mobilecommon.widget.antistatic.spinnerwheel;
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import android.content.Context;
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import android.os.Handler;
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import android.os.Message;
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import android.view.GestureDetector;
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import android.view.GestureDetector.SimpleOnGestureListener;
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import android.view.MotionEvent;
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import android.view.animation.Interpolator;
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import android.widget.Scroller;
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/**
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* Scroller class handles scrolling events and updates the spinnerwheel
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*/
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public abstract class WheelScroller {
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/**
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* Scrolling listener interface
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*/
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public interface ScrollingListener {
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/**
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* Scrolling callback called when scrolling is performed.
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* @param distance the distance to scroll
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*/
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void onScroll(int distance);
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/**
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* This callback is invoked when scroller has been touched
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*/
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void onTouch();
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/**
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* This callback is invoked when touch is up
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*/
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void onTouchUp();
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/**
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* Starting callback called when scrolling is started
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*/
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void onStarted();
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/**
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* Finishing callback called after justifying
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*/
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void onFinished();
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/**
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* Justifying callback called to justify a view when scrolling is ended
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*/
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void onJustify();
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}
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/** Scrolling duration */
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private static final int SCROLLING_DURATION = 400;
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/** Minimum delta for scrolling */
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public static final int MIN_DELTA_FOR_SCROLLING = 1;
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// Listener
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private ScrollingListener listener;
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// Context
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private Context context;
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// Scrolling
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private GestureDetector gestureDetector;
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protected Scroller scroller;
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private int lastScrollPosition;
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private float lastTouchedPosition;
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private boolean isScrollingPerformed;
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/**
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* Constructor
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* @param context the current context
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* @param listener the scrolling listener
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*/
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public WheelScroller(Context context, ScrollingListener listener) {
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gestureDetector = new GestureDetector(context, new SimpleOnGestureListener() {
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public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {
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// Do scrolling in onTouchEvent() since onScroll() are not call immediately
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// when user touch and move the spinnerwheel
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return true;
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}
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public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
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lastScrollPosition = 0;
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scrollerFling(lastScrollPosition, (int) velocityX, (int) velocityY);
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setNextMessage(MESSAGE_SCROLL);
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return true;
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}
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// public boolean onDown(MotionEvent motionEvent);
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});
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gestureDetector.setIsLongpressEnabled(false);
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scroller = new Scroller(context);
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this.listener = listener;
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this.context = context;
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}
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/**
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* Set the the specified scrolling interpolator
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* @param interpolator the interpolator
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*/
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public void setInterpolator(Interpolator interpolator) {
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scroller.forceFinished(true);
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scroller = new Scroller(context, interpolator);
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}
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/**
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* Scroll the spinnerwheel
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* @param distance the scrolling distance
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* @param time the scrolling duration
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*/
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public void scroll(int distance, int time) {
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scroller.forceFinished(true);
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lastScrollPosition = 0;
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scrollerStartScroll(distance, time != 0 ? time : SCROLLING_DURATION);
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setNextMessage(MESSAGE_SCROLL);
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startScrolling();
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}
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/**
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* Stops scrolling
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*/
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public void stopScrolling() {
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scroller.forceFinished(true);
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}
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/**
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* Handles Touch event
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* @param event the motion event
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* @return
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*/
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public boolean onTouchEvent(MotionEvent event) {
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switch (event.getAction()) {
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case MotionEvent.ACTION_DOWN:
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lastTouchedPosition = getMotionEventPosition(event);
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scroller.forceFinished(true);
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clearMessages();
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listener.onTouch();
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break;
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case MotionEvent.ACTION_UP:
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if (scroller.isFinished())
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listener.onTouchUp();
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break;
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case MotionEvent.ACTION_MOVE:
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// perform scrolling
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int distance = (int)(getMotionEventPosition(event) - lastTouchedPosition);
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if (distance != 0) {
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startScrolling();
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listener.onScroll(distance);
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lastTouchedPosition = getMotionEventPosition(event);
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}
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break;
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}
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if (!gestureDetector.onTouchEvent(event) && event.getAction() == MotionEvent.ACTION_UP) {
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justify();
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}
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return true;
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}
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// Messages
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private static final int MESSAGE_SCROLL = 0;
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private static final int MESSAGE_JUSTIFY = 1;
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/**
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* Set next message to queue. Clears queue before.
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*
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* @param message the message to set
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*/
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private void setNextMessage(int message) {
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clearMessages();
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animationHandler.sendEmptyMessage(message);
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}
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/**
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* Clears messages from queue
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*/
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private void clearMessages() {
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animationHandler.removeMessages(MESSAGE_SCROLL);
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animationHandler.removeMessages(MESSAGE_JUSTIFY);
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}
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// animation handler
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private Handler animationHandler = new Handler() {
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public void handleMessage(Message msg) {
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scroller.computeScrollOffset();
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int currPosition = getCurrentScrollerPosition();
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int delta = lastScrollPosition - currPosition;
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lastScrollPosition = currPosition;
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if (delta != 0) {
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listener.onScroll(delta);
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}
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// scrolling is not finished when it comes to final Y
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// so, finish it manually
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if (Math.abs(currPosition - getFinalScrollerPosition()) < MIN_DELTA_FOR_SCROLLING) {
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// currPosition = getFinalScrollerPosition();
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scroller.forceFinished(true);
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}
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if (!scroller.isFinished()) {
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animationHandler.sendEmptyMessage(msg.what);
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} else if (msg.what == MESSAGE_SCROLL) {
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justify();
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} else {
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finishScrolling();
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}
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}
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};
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/**
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* Justifies spinnerwheel
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*/
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private void justify() {
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listener.onJustify();
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setNextMessage(MESSAGE_JUSTIFY);
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}
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/**
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* Starts scrolling
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*/
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private void startScrolling() {
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if (!isScrollingPerformed) {
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isScrollingPerformed = true;
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listener.onStarted();
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}
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}
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/**
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* Finishes scrolling
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*/
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protected void finishScrolling() {
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if (isScrollingPerformed) {
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listener.onFinished();
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isScrollingPerformed = false;
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}
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}
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protected abstract int getCurrentScrollerPosition();
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protected abstract int getFinalScrollerPosition();
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protected abstract float getMotionEventPosition(MotionEvent event);
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protected abstract void scrollerStartScroll(int distance, int time);
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protected abstract void scrollerFling(int position, int velocityX, int velocityY);
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}
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