<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.RadarViewandroid:layout_width="match_parent"android:layout_height="match_parent" /><ImageViewandroid:layout_width="wrap_content"android:layout_height="wrap_content"android:layout_centerInParent="true"android:src="@drawable/circle_photo" /></RelativeLayout>

RadarViewpackage 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() {@Overridepublic void run() {start = start + 1;matrix = new Matrix();// 參數：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();// 繼續循環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*/@Overrideprotected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {// 設置鋪滿setMeasuredDimension(w, h);}@Overrideprotected 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canvas.concat(matrix); // 前置動畫canvas.drawCircle(w / 2, h / 2, w * 7 / 10, mPaintCircle);}}