Android使用SurfaceView实现墨迹天气的风车效果
SurfaceView也是继承自View，它和我们以前接触到的View（Button、TextView等）最大的不同是，SurfaceView可以有一个单独的线程进行绘制，这个线程区别于UI线程（主线程），因此SurfaceView绘制并不占用主线程资源。
SurfaceView实现通常是自定义，继承SurfaceView并实现SurfaceHolder.Callback接口。使用SurfaceView，所有的绘图工作必须得在Surface 被创建之后才能开始，所以Callback 中的surfaceCreated 和surfaceDestroyed 就成了绘图处理代码的边界。
实现SurfaceHolder.Callback接口需要重写的方法：
//在surface的大小发生改变时激发
（1）public void surfaceChanged(SurfaceHolder holder,int format,int width,int height){}
//在创建时激发，一般在这里调用画图的线程。
（2）public void surfaceCreated(SurfaceHolder holder){}
//销毁时激发，一般在这里将画图的线程停止、释放。
（3）public void surfaceDestroyed(SurfaceHolder holder) {}
SurfaceHolder有几个重要方法：
// 锁定画布，一般在锁定后就可以通过其返回的画布对象Canvas，在其上面画图等操作了。
(1)、abstract Canvas lockCanvas();
// 锁定画布的某个区域进行画图等..因为画完图后，会调用下面的unlockCanvasAndPost来改变显示内容。
// 相对部分内存要求比较高的游戏来说，可以不用重画dirty外的其它区域的像素，可以提高速度。
(2)、abstract Canvas lockCanvas(Rect dirty);
// 结束锁定画图，并提交改变。(3)、abstract void unlockCanvasAndPost(Canvas canvas);
//给SurfaceView当前的持有者一个回调对象。
(4)、abstract void addCallback(SurfaceHolder.Callback callback);
下面使用SurfaceView实现墨迹天气的风车效果：
public class WindmillView extends SurfaceView implements
SurfaceHolder.Callback, Runnable {
private SurfaceHolder holder;
private boolean isRunning = true;
/**
* 屏幕的像素
*/
private int screenWidth;
private int screenHeiht;
private Bitmap windPoint;
/**
* 风车图片
*/
private Bitmap Windmill;
/**
* 背景图片
*/
private Bitmap viewBg;
public WindmillView(Context context) {
super(context);
this.setLayoutParams(new LayoutParams(LayoutParams.MATCH_PARENT,
LayoutParams.MATCH_PARENT));
holder = getHolder();
holder.addCallback(this);
holder.setFormat(PixelFormat.RGBA_8888); // 顶层绘制SurfaceView设成透明
getViewSize(context);
LoadWindmillImage();
}
private void LoadWindmillImage() {
viewBg = BitmapFactory.decodeResource(getResources(), R.drawable.bg_na);
Windmill = BitmapFactory.decodeResource(getResources(),
R.drawable.na_windmill);
windPoint = BitmapFactory.decodeResource(getResources(),
R.drawable.na_point);
float percent = percentumW();
Log.v("icers", screenWidth + "");
int _witdh = (int) (250 / percent);//250是风车基点左侧像素
Log.v("icers", _witdh + "");
Windmill = Bitmap.createScaledBitmap(Windmill, _witdh * 2, _witdh * 2,
true);
}
// 获取屏幕的分辨率
private void getViewSize(Context context) {
DisplayMetrics metrics = new DisplayMetrics();
WindowManager windowManager = (WindowManager) context
.getSystemService(Context.WINDOW_SERVICE);
windowManager.getDefaultDisplay().getMetrics(metrics);
this.screenHeiht = metrics.heightPixels;
this.screenWidth = metrics.widthPixels;
Log.d("Windmill", "Windmill:"+screenHeiht+"|"+screenWidth);
}
/**
* 获取背景图和风车的比率 ，从而根据这个比例改变各个手机上面的风车图片大小
*
*
* @return
*/
private float percentumW() {
float bg_width = viewBg.getWidth();
return bg_width/screenWidth ;
}
/**
* 获取背景图和风车的比率 ，从而根据这个比例改变各个手机上面的风车图片大小
*
*
* @return
*/
private float percentumH() {
float bg_height = viewBg.getHeight();
return bg_height/(screenHeiht);
}
@Override
public void run() {
float rotate = 0;// 旋转角度变量
while (isRunning) {
Log.i("icer", "Running");
Canvas canvas = null;
synchronized (this) {
try {
canvas = holder.lockCanvas();
if (canvas != null) {
Paint paint = new Paint();
paint.setAntiAlias(true);
// 对图片抗锯齿
paint.setFilterBitmap(true);
RectF rect = new RectF(0, 0, screenWidth, screenHeiht
);
canvas.drawBitmap(viewBg, null, rect, paint);
Matrix matrix = new Matrix();
matrix.postRotate((rotate += 2) % 360f,
Windmill.getWidth() / 2,
Windmill.getHeight() / 2);
int _dy = (int) (500 /percentumH()); //500是风车基点到背景定点的像素
matrix.postTranslate(0, (_dy - (Windmill.getHeight()/2)));
canvas.drawBitmap(Windmill, matrix, paint);
int _dx = (int) (250 / percentumW());//250是风车基点左侧像素
canvas.drawBitmap(windPoint,_dx-windPoint.getWidth()/2,_dy-windPoint.getHeight()/2,paint);
Thread.sleep(3);
}
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} finally {
if (canvas != null) {
holder.unlockCanvasAndPost(canvas);
}
}
}
}
}
public void setRunning(boolean state) {
isRunning = state;
}
@Override
public void surfaceChanged(SurfaceHolder arg0, int arg1, int arg2, int arg3) {
// TODO Auto-generated method stub
}
@Override
public void surfaceCreated(SurfaceHolder arg0) {
new Thread(this).start();
}
@Override
public void surfaceDestroyed(SurfaceHolder arg0) {
// TODO Auto-generated method stub
isRunning = false;
}
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,WindowManager.LayoutParams.FLAG_FULLSCREEN);
requestWindowFeature(Window.FEATURE_NO_TITLE);
WindmillView view=new WindmillView(this);
setContentView(view);
} 整个过程：继承SurfaceView并实现SurfaceHolder.Callback接口 ----> SurfaceView.getHolder()获得SurfaceHolder对象 ---->SurfaceHolder.lockCanvas()获得Canvas对象并锁定画布----> Canvas绘画 ---->SurfaceHolder.unlockCanvasAndPost(Canvas canvas)结束锁定画图，并提交改变，将图形显示。
/**
参考：
http://www.cnblogs.com/plokmju/p/android_SurfaceView.html
http://developer.android.com/reference/android/view/SurfaceView.html
http://blog.csdn.net/luoshengyang/article/details/8661317
http://blog.csdn.net/hellogv/article/details/5986835
http://developer.android.com/reference/android/view/SurfaceHolder.html
