你追我赶进度条

package com.example.androidtest;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Paint.Style;
import android.graphics.RectF;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
import android.view.animation.DecelerateInterpolator;
import android.view.animation.LinearInterpolator;
import android.widget.Scroller;

public class CircleProgress extends View {

	public CircleProgress(Context context) {
		super(context);
		init();
	}
	public CircleProgress(Context context, AttributeSet attrs) {
		super(context, attrs);
		init();
	}
	public CircleProgress(Context context, AttributeSet attrs, int defStyleAttr) {
		super(context, attrs, defStyleAttr);
		init();
	}

	private void init() {
		timer=new Scroller(getContext(),new LinearInterpolator());
		paint=new Paint();
		paint.setStrokeWidth(circleWidth);
		paint.setStyle(Style.STROKE);
		paint.setColor(Color.BLUE);
		paint.setAntiAlias(true);
		
	}

	private Scroller timer;
	private int DURATION=5000;//动画持续时间
	private Paint paint;
	private int circleWidth=50;//环的宽度
	private boolean flag;
	
	private boolean isInit;
	
	private RectF arcRectf;
	private int centerX;
	private int centerY;
	private int radius;
	@Override
	protected void onDraw(Canvas canvas) {

		if (!isInit) {
			int min=Math.min(getWidth(), getHeight())-circleWidth;
			centerX=getWidth()/2;
			centerY=getHeight()/2;
			radius=(min-circleWidth-circleWidth)/2;
			arcRectf=new RectF(centerX-radius	,centerY-radius, centerX+radius,centerY+radius);
			isInit=true;
		}
		if (flag) {
			paint.setColor(Color.RED);
			canvas.drawCircle(centerX,centerY,radius,paint);
			paint.setColor(Color.BLUE);
			canvas.drawArc(arcRectf, timer.getCurrX(),timer.getCurrY(), false, paint);

		}else{
			paint.setColor(Color.BLUE);
			canvas.drawCircle(centerX,centerY,radius,paint);
			paint.setColor(Color.RED);
			canvas.drawArc(arcRectf, timer.getCurrX(),timer.getCurrY(), false, paint);

		}
		
		
	} 
	
	@Override
	public void computeScroll() {
		if (timer.computeScrollOffset()) {
			invalidate();
		}else{
			flag=!flag;
			timer.startScroll(-90, 0, 360, 360, DURATION);
			invalidate();
		}
	}
	
	 	
}