<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@drawable/photo" >
<com.lgl.radarsearch.RadarView
android:layout_width="match_parent"
android:layout_height="match_parent" />
<ImageView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerInParent="true"
android:src="@drawable/circle_photo" />
</RelativeLayout>

RadarView
package com.lgl.radarsearch;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.graphics.Paint.Style;
import android.graphics.Shader;
import android.graphics.SweepGradient;
import android.os.Handler;
import android.util.AttributeSet;
import android.view.View;
/**
* 雷達搜索
* 
* @author LGL
*
*/
public class RadarView extends View {
/**
* 思路：我們首先初始化畫筆，并且獲取到控件的寬高，在onMeasure()中設置鋪滿，然后在onDraw()方法中繪制四個靜態(tài)圓和一個漸變圓，
* 我們通過Matrix矩陣來讓他不停的旋轉就達到我們想要的效果了
*/
private Paint mPaintLine, mPaintCircle;
private int w, h;
// 動畫
private Matrix matrix;
// 旋轉角度
private int start;
// Handler定時動畫
private Handler handler = new Handler();
private Runnable run = new Runnable() {
@Override
public void run() {
start = start + 1;
matrix = new Matrix();
// 參數(shù)：旋轉角度，圍繞點坐標的x,y坐標點
matrix.postRotate(start, w / 2, h / 2);
// 刷新重繪
RadarView.this.invalidate();
// 繼續(xù)循環(huán)
handler.postDelayed(run, 60);
}
};
public RadarView(Context context, AttributeSet attrs) {
super(context, attrs);
initView();
// 獲取高寬
w = context.getResources().getDisplayMetrics().widthPixels;
h = context.getResources().getDisplayMetrics().heightPixels;
// 一致旋轉
handler.post(run);
}
private void initView() {
mPaintLine = new Paint();
mPaintLine.setColor(Color.WHITE);
mPaintLine.setAntiAlias(true);
mPaintLine.setStyle(Style.STROKE);
mPaintCircle = new Paint();
mPaintCircle.setColor(Color.RED);
mPaintCircle.setAntiAlias(true);
matrix = new Matrix();
}
/**
* 測量
* 
* @author LGL
*/
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
// 設置鋪滿
setMeasuredDimension(w, h);
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
// 畫四個圓形
canvas.drawCircle(w / 2, h / 2, w / 2, mPaintLine);
canvas.drawCircle(w / 2, h / 2, w / 3, mPaintLine);
canvas.drawCircle(w / 2, h / 2, w * 7 / 10, mPaintLine);
canvas.drawCircle(w / 2, h / 2, w / 4, mPaintLine);
// 繪制漸變圓
Shader mShader = new SweepGradient(w / 2, h / 2, Color.TRANSPARENT,
Color.parseColor("#AAAAAAAA"));
// 繪制時漸變
mPaintCircle.setShader(mShader);
// 增加旋轉動畫，使用矩陣實現(xiàn)
canvas.concat(matrix); // 前置動畫
canvas.drawCircle(w / 2, h / 2, w * 7 / 10, mPaintCircle);
}
}