code掃描雷達

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.RectF;
import android.graphics.SweepGradient;
import android.os.Handler;
import android.os.Message;
import android.util.AttributeSet;
import android.view.View;


/**
 * Created by glory on 2015/9/24.
 */
public class ScanningView extends View {
    private static final int MSG_RUN = 1;
    private Paint mCirclePaint;
    private Paint mArcPaint;
    private Paint mBgPain;
    private RectF mRectf;
    private int mSweep;
    public ScanningView(Context context, AttributeSet attrs) {
        super(context, attrs);
        mCirclePaint = new Paint(Paint.ANTI_ALIAS_FLAG);
        mCirclePaint.setColor(Color.parseColor("#33ff00"));
        mCirclePaint.setStyle(Paint.Style.STROKE);
        mCirclePaint.setStrokeWidth(2.f);

        mArcPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
        mArcPaint.setColor(Color.GRAY);
        mArcPaint.setStyle(Paint.Style.FILL);

        mBgPain = new Paint(Paint.ANTI_ALIAS_FLAG);
        mBgPain.setColor(Color.parseColor("#00ff00"));
        mBgPain.setStyle(Paint.Style.FILL);

        mRectf = new RectF();
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        int size = getMeasuredWidth();
        setMeasuredDimension(size, size);
        mRectf.set(0, 0, getMeasuredWidth(), getMeasuredHeight());
        mArcPaint.setShader(new SweepGradient(size/2,size/2,Color.parseColor("#00ff00"),Color.parseColor("#006600")));
    }

    @Override
    protected void onDraw(Canvas canvas) {
        int centerX = getMeasuredWidth()/2;
        int centerY = getMeasuredHeight()/2;

        canvas.save();
        canvas.rotate(mSweep, centerX, centerY);
        canvas.drawArc(mRectf, 0, 360, true, mBgPain);
        canvas.drawArc(mRectf, 0, mSweep, true, mArcPaint);
        canvas.restore();
        canvas.drawCircle(centerX, centerY, centerX / 3, mCirclePaint);
        canvas.drawCircle(centerX, centerY, (centerX *2)/ 3, mCirclePaint);
        canvas.drawCircle(centerX, centerY, centerX, mCirclePaint);
    }
    public void start(){
        mHandler.removeMessages(MSG_RUN);//防止產生多次消息
        mHandler.sendEmptyMessage(MSG_RUN);
    }
    private Handler mHandler = new Handler(){
        @Override
        public void handleMessage(Message msg) {
            if(msg.what == MSG_RUN){
                mSweep +=1;
                if(mSweep>360){ mSweep = 0;}
                postInvalidate();
                sendEmptyMessage(MSG_RUN);
            }
        }
    };
}