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。

代码下载
/**

* @author 张兴业

*  http://blog.csdn.net/xyz_lmn

*  iOS入门群：83702688

*  android开发进阶群：241395671

*  我的新浪微博：@张兴业TBOW

*/

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