先上效果图(没有录成gif格式~其实是旋转的很漂亮。)
image.png
雷达效果原先是自定义View来实现的，但是由于要不停的刷新，会造成轻微的卡顿，所以又使用自定义SurfaceView重写了一遍，对SurfaceView不了解的可以先学习一下。
SurfaceView推荐文章：http://blog.csdn.net/android_cmos/article/details/68955134
实现思路：
1:画内外圆
2：画水平坐标线
3：画半圆弧
4:通过Paint.setShader()设置着色器，使用SweepGradient实现颜色渐变。
思路很清晰,下面上代码
public class CanvasView extends SurfaceView implements SurfaceHolder.Callback, Runnable {
private SurfaceHolder mHolder;
private Canvas canvas;
private int viewSize = 800;
private Paint mPaintLine;
private Paint mPaint;
private float start = 0;
private Random random;
public List<PointPaint> list;
//两个随机点
private Paint mPointPaint1, mPointPaint2;
private final int paintWidth = 3;
private Paint mPaintC, mPaintCC;
//初始化角度渐变 从透明-绿色
private Shader mShader = new SweepGradient(viewSize >> 1, viewSize >> 1,
Color.TRANSPARENT, Color.GREEN);
private Matrix matrix = new Matrix();
//两个随机点坐标值
private int x1, x2;
private int y1, y2;
//不断改变的值 用于透明度
private int change1;
private int change2;
//是否重置位置 即是否随机点坐标
private boolean flag_reset1 = false;
private boolean flag_reset2 = false;
//是否开始反方向变化 从透明度255-0
private boolean isReverse1 = false;
private boolean isReverse2 = false;
private int halfsize = viewSize >> 1;
private Paint p = new Paint();
private boolean isRotate = true;
public CanvasView(Context context) {
super(context);
init();
}
public CanvasView(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
public CanvasView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
init();
}
@Override
public void surfaceCreated(SurfaceHolder aSurfaceHolder) {
new Thread(this).start();
}
@Override
public void surfaceChanged(SurfaceHolder aSurfaceHolder, int aI, int aI1, int aI2) {
}
@Override
public void surfaceDestroyed(SurfaceHolder aSurfaceHolder) {
}
@Override
public void run() {
while (true) {
draw();
}
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
setMeasuredDimension(viewSize + 10, viewSize + 10);
}
private void init() {
setZOrderOnTop(true);
setBackgroundColor(Color.TRANSPARENT);
mHolder = getHolder();
mHolder.setFormat(PixelFormat.TRANSLUCENT);
mHolder.addCallback(this);
setFocusable(true);
setFocusableInTouchMode(true);
this.setKeepScreenOn(true);
list = new ArrayList<>();
initPaint();
random = new Random();
}
private void initPaint() {
mPaintLine = new Paint();
mPaintLine.setStrokeWidth(paintWidth >> 1);
mPaintLine.setAntiAlias(true);
mPaintLine.setStyle(Paint.Style.STROKE);
mPaintLine.setColor(0x880000ff);
mPaintLine.setStrokeCap(Paint.Cap.ROUND);
mPaintCC = new Paint();
mPaintCC.setStrokeWidth(paintWidth);
mPaintCC.setAntiAlias(true);
mPaintCC.setStyle(Paint.Style.STROKE);
mPaintCC.setColor(0xaa000000);
mPaintCC.setStrokeCap(Paint.Cap.ROUND);
mPaintC = new Paint();
mPaintC.setStrokeWidth(paintWidth >> 1);
mPaintC.setAntiAlias(true);
mPaintC.setStyle(Paint.Style.STROKE);
mPaintC.setColor(0X87872300);
mPaintC.setStrokeCap(Paint.Cap.ROUND);
mPaint = new Paint();
mPaint.setColor(0x9D00ff00);
mPaint.setAntiAlias(true);
mPointPaint1 = new Paint();
mPointPaint1.setStrokeWidth(2);
mPointPaint1.setColor(Color.RED);
mPointPaint1.setAntiAlias(true);
mPointPaint1.setAlpha(0);
mPointPaint2 = new Paint();
mPointPaint2.setStrokeWidth(2);
mPointPaint2.setColor(Color.RED);
// mPointPaint2.setColor(0xffff0000);
mPointPaint2.setAntiAlias(true);
mPointPaint2.setAlpha(0);
flag_reset1 = true;
flag_reset2 = true;
isReverse1 = false;
}
private void draw() {
canvas = mHolder.lockCanvas();
//清屏
p.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.CLEAR));
canvas.drawPaint(p);
p.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC));
// canvas.save();
int radius = viewSize >> 1;
//画内圆
canvas.drawCircle(radius, radius, radius >> 1, mPaintC);
//画外圆
canvas.drawCircle(radius, radius, radius - (paintWidth >> 1), mPaintCC);
canvas.drawLine(0, radius, viewSize, radius, mPaintLine);
canvas.drawLine(radius, 0, radius, viewSize, mPaintLine);
mPaint.setShader(mShader);
//设置矩阵
canvas.concat(matrix);
//第二种
canvas.drawArc(new RectF(0, 0, viewSize, viewSize), 0, 180, true, mPaint);
// canvas.restore();
//画随机点
int centerx = radius;
int centery = radius;
// canvas.save();
// canvas.scale(0.5f + change1 / 360, 0.5f + change1 / 360);
// canvas.restore();
//画随机点
if (!isReverse1 && flag_reset1) {
int a = random.nextInt(360);
int d = random.nextInt(radius);
x1 = (int) (centerx + d * (Math.cos(a * Math.PI / 180)));
y1 = (int) (centery + d * (Math.sin(a * Math.PI / 180)));
flag_reset1 = false;
}
if (!isReverse2 && flag_reset2) {
int a = random.nextInt(360);
int d = random.nextInt(radius);
x2 = (int) (centerx + d * (Math.cos(a * Math.PI / 180)));
y2 = (int) (centery + d * (Math.sin(a * Math.PI / 180)));
flag_reset2 = false;
}
if (list.size() > 0) {
for (int i = 0; i < list.size(); i++) {
//if(list.get(i).getT()!=null){
//计算x,y值
x1 = list.get(i).getX();
y1 = list.get(i).getY();
if (i == list.size() - 1) {
canvas.drawCircle(400 + 4 * x1, 400 + 4 * y1, 8, mPointPaint2);
} else {
canvas.drawCircle(400 + 4 * x1, 400 + 4 * y1, 8, mPointPaint1);
}
}
}
isRotate = false;
if (change1 < 0) {
isReverse1 = false;
change1 = 0;
flag_reset1 = true;
}
if (change2 < 0) {
isReverse2 = false;
change2 = 0;
flag_reset2 = true;
}
//正方向下的 增值
if (!isReverse2) change2 += 2;
if (!isReverse1) change1 += 4;
//正方向
if (change1 >= 255) {
isReverse1 = true;
change1 = 255;
}
if (change2 >= 255) {
isReverse2 = true;
change2 = 255;
}
if (isReverse1) change1 -= 8;
if (isReverse2) change2 -= 4;
mPointPaint1.setAlpha(change1);
mPointPaint2.setAlpha(change2);
if (start >= 360) start = 0;
start += 2;
matrix.reset();
matrix.postRotate(start, halfsize, halfsize);
mHolder.unlockCanvasAndPost(canvas);
}
}
xml
<com.example.aml.clearn.view.CanvasView
android:layout_width="100dp"
android:layout_height="100dp"
android:background="@android:color/transparent"/>
结束。
笔者能力有限，不足之处欢迎指出。
