ScrollTween.java

package com.drawbridge.utils;

import com.drawbridge.Activity;

/**
 * Animates a change between views
 * 
 * @author Alistair Stead
 * 
 */
public class ScrollTween implements Runnable
{

	private int					mStartPosition;
	private int					mFinishPosition;
	private Activity			mParent;
	private static ScrollTween	mInstance	= null;
	public boolean				mEnabled	= false;
	private TransitionType 		mTransitionType;

	public enum ScrollDirection
	{
		FORWARD, BACKWARD
	}
	
	public enum TransitionType
	{
		CUBIC, LINEAR
	}

	public static ScrollTween getInstance(Activity parent, int startPosition, int finishPosition, TransitionType mTransitionType)
	{
		if (mInstance == null)
		{
			mInstance = new ScrollTween(parent, startPosition, finishPosition, mTransitionType);
		}
		else{
			mInstance.mTransitionType = mTransitionType;
			mInstance.mParent = parent;
			mInstance.mStartPosition = startPosition;
			mInstance.mFinishPosition = finishPosition;
		}
		return mInstance;
	}

	private ScrollTween(Activity parent, int startPosition, int targetPosition, TransitionType mTransitionType) {
		this.mTransitionType = mTransitionType;
		mParent = parent;
		mStartPosition = startPosition;
		mFinishPosition = targetPosition;
		mEnabled = false;
	}

	@Override
	public void run()
	{
		long startTime = System.currentTimeMillis();
		long timeLength = 1000;
		long currentTime;
		int difference = mFinishPosition - mStartPosition;
		while((currentTime = System.currentTimeMillis()) < startTime + timeLength){
			int elapsedTime = (int) (currentTime - startTime);
			double A = difference / (8 + Math.cbrt(timeLength / 2));
			Utils.out.println("" + (int) (A * (8 + Math.cbrt(elapsedTime - (timeLength / 2)))));
			
			// Cubic transition
			int pos = 0;
			switch(mTransitionType){
			case CUBIC:
				pos = mStartPosition + (int) (A * (8 + Math.cbrt(elapsedTime - (timeLength / 2))));
				break;
			case LINEAR:
			default:
				pos = (int) (mStartPosition + (((double)elapsedTime/(double)timeLength) * difference));
				break;
			}
			
			mParent.getScrollPane().getHorizontalScrollBar().setValue(pos);
			

			try {
				Thread.sleep(25);
			} catch (InterruptedException e) {
				e.printStackTrace();
			}
		}
		Utils.out.println("start:" + mStartPosition + " end:" + mFinishPosition);
		mParent.getScrollPane().getHorizontalScrollBar().setValue(mFinishPosition);	
			

	}

}