Android 雷达扫描效果实现

在eoe看到有一篇关于雷达扫描的文章，然后看了下，很简单，但是觉得还有很多可以优化的地方，下面贴出来

package com.example.wave;

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.util.AttributeSet;
import android.widget.FrameLayout;

public class RadarView extends FrameLayout {

private int viewSize = 500;
private Paint mPaintLine;
private Paint mPaintSector;
private boolean isStart = false;
private ScanThread mThread;
private int start = 0;

private final int paintWidth = 10;

public RadarView(Context context) {
super(context);
init();
}

public RadarView(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}

private void init() {
initPaint();
mThread = new ScanThread();
setBackgroundColor(Color.TRANSPARENT);
}

private void initPaint() {
mPaintLine = new Paint();
mPaintLine.setStrokeWidth(paintWidth);
mPaintLine.setAntiAlias(true);
mPaintLine.setStyle(Style.STROKE);
mPaintLine.setColor(0xffff0000);

mPaintSector = new Paint();
mPaintSector.setColor(0x9D00ff00);
mPaintSector.setAntiAlias(true);
}

public void setViewSize(int size) {
this.viewSize = size;
mShader = new SweepGradient(viewSize >> 1, viewSize >> 1, Color.TRANSPARENT, Color.GREEN);
setMeasuredDimension(viewSize, viewSize);
}

@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
setMeasuredDimension(viewSize, viewSize);
}

public void start() {
mThread.start();
isStart = true;
}

public void stop() {
if (isStart) {
Thread.interrupted();
isStart = false;
}
}

private Shader mShader = new SweepGradient(viewSize >> 1, viewSize >> 1, Color.TRANSPARENT, Color.GREEN);
private Matrix matrix = new Matrix();

@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
int halfRadaSize = viewSize >> 1;
canvas.drawCircle(halfRadaSize, halfRadaSize, halfRadaSize >> 1, mPaintLine);
canvas.drawCircle(halfRadaSize, halfRadaSize, halfRadaSize - (paintWidth >> 1), mPaintLine);
canvas.drawLine(halfRadaSize, 0, halfRadaSize, viewSize, mPaintLine);
canvas.drawLine(0, halfRadaSize, viewSize, halfRadaSize, mPaintLine);
mPaintSector.setShader(mShader);
canvas.concat(matrix);
canvas.drawCircle(halfRadaSize, halfRadaSize, halfRadaSize - paintWidth, mPaintSector);
}

protected class ScanThread extends Thread {

int halfRadaSize = viewSize >> 1;

@Override
public void run() {
while (isStart) {
start = start + 2;
matrix.reset();
matrix.postRotate(start, halfRadaSize, halfRadaSize);
postInvalidate();
try {
Thread.sleep(10);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}
}

原文地址：http://www.eoeandroid.com/thread-550073-1-1.html