【Android】GestuerDetectorとScrollerを組み合わせた例

package com.example.scrollerlesson;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Paint.Style;
import android.os.Handler;
import android.util.AttributeSet;
import android.view.GestureDetector;
import android.view.GestureDetector.OnGestureListener;
import android.view.MotionEvent;
import android.view.View;
import android.widget.Scroller;

public class FlingLessonView extends View {

	private static final int ANIMATION_INTERVAL = 10;
	private final Handler handler = new Handler();
	private Scroller scroller;
	private GestureDetector gestureDetector;
	
	private float currX;
	private float currY;
	
	/**
	 * @param context
	 */
	public FlingLessonView(Context context) {
		super(context);
		init(context);
	}
	
	/**
	 * @param context
	 * @param attrs
	 */
	public FlingLessonView(Context context, AttributeSet attrs) {
		super(context, attrs);
		init(context);
	}
	
	/**
	 * ビューの初期化
	 * @param context
	 */
	private void init(Context context){
		
		setLongClickable(true);
		scroller = new Scroller(context);
		gestureDetector = new GestureDetector(context,new OnGestureListener() {
			
			@Override
			public boolean onSingleTapUp(MotionEvent e) {
				// TODO Auto-generated method stub
				return false;
			}
			
			@Override
			public void onShowPress(MotionEvent e) {
				// TODO Auto-generated method stub
			}
			
			@Override
			public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX,
					float distanceY) {

				if(!scroller.isFinished())
					scroller.abortAnimation();
				
				currX = e2.getX();
				currY = e2.getY();
				
				invalidate();
				
				return true;
			}
			
			@Override
			public void onLongPress(MotionEvent e) {
				// TODO Auto-generated method stub
			}
			
			@Override
			public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX,
					float velocityY) {
				
				scroller.fling(
					(int)e2.getX(),
					(int)e2.getY(),
					(int)velocityX,
					(int)velocityY,
					0, getWidth(), 0, getHeight());

				handler.post(new Runnable() {
					
					@Override
					public void run() {
						scroller.computeScrollOffset();
						currX = scroller.getCurrX();
						currY = scroller.getCurrY();
						
						invalidate();
						
						if(!scroller.isFinished()){
							handler.postDelayed(this, ANIMATION_INTERVAL);
						}
					}
				});
				
				return true;
			}
			
			@Override
			public boolean onDown(MotionEvent e) {
				// TODO Auto-generated method stub
				return false;
			}
		});
	}
	
	private final Paint paint = new Paint();
	{
		paint.setStyle(Style.FILL);
		paint.setColor(Color.GREEN);
	}
	
	@Override
	protected void onDraw(Canvas canvas) {
		canvas.drawColor(Color.BLACK);
		canvas.drawCircle(currX, currY, 60.f, paint);
	}
	
	@Override
	public boolean onTouchEvent(MotionEvent event) {
		return 
				gestureDetector.onTouchEvent(event) ||
				super.onTouchEvent(event);
	}
}