Android仿微信雷达辐射搜索好友(逻辑清晰实现简单)

<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;
/**
* 雷达搜索
* 
* @author LGL
*
*/
public class RadarView extends View {
/**
* 思路：我们首先初始化画笔，并且获取到控件的宽高，在onMeasure()中设置铺满，然后在onDraw()方法中绘制四个静态圆和一个渐变圆，
* 我们通过Matrix矩阵来让他不停的旋转就达到我们想要的效果了
*/
private Paint mPaintLine, mPaintCircle;
private int w, h;
// 动画
private Matrix matrix;
// 旋转角度
private int start;
// Handler定时动画
private Handler handler = new Handler();
private Runnable run = new Runnable() {
@Override
public void run() {
start = start + 1;
matrix = new Matrix();
// 参数：旋转角度，围绕点坐标的x,y坐标点
matrix.postRotate(start, w / 2, h / 2);
// 刷新重绘
RadarView.this.invalidate();
// 继续循环
handler.postDelayed(run, 60);
}
};
public RadarView(Context context, AttributeSet attrs) {
super(context, attrs);
initView();
// 获取高宽
w = context.getResources().getDisplayMetrics().widthPixels;
h = context.getResources().getDisplayMetrics().heightPixels;
// 一致旋转
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();
}
/**
* 测量
* 
* @author LGL
*/
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
// 设置铺满
setMeasuredDimension(w, h);
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
// 画四个圆形
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);
// 绘制渐变圆
Shader mShader = new SweepGradient(w / 2, h / 2, Color.TRANSPARENT,
Color.parseColor("#AAAAAAAA"));
// 绘制时渐变
mPaintCircle.setShader(mShader);
// 增加旋转动画，使用矩阵实现
canvas.concat(matrix); // 前置动画
canvas.drawCircle(w / 2, h / 2, w * 7 / 10, mPaintCircle);
}
}