理解Android的SurfaceView

Android中view的每一帧的刷新时间需要控制在16ms范围内（16 = 1000/60，保证刷新频率在60hz以上，一半20以上就比较流畅，60酒特表流畅），否则会有卡顿现象。
SurfaceView适用于需要频繁页面需要频繁刷新的时候，相对于View，它有两个特点。
1、双缓冲机制
2、在一个子线程执行刷新操作

public class MySurfaceView extends SurfaceView implements SurfaceHolder.Callback,Runnable{
    private SurfaceHolder mHolder;
    private boolean mIsDrawing = false;
    private Canvas mCanvas;
    private Path mPath;
    private Paint mPaint;

    public MySurfaceView(Context context) {
        super(context);
        initView();
    }

    public MySurfaceView(Context context, AttributeSet attrs) {
        super(context, attrs);
        initView();
    }

    public MySurfaceView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        initView();
    }

    private void initView() {
        mHolder = getHolder();
        mHolder.addCallback(this);
        setFocusable(true);
        setFocusableInTouchMode(true);
        this.setKeepScreenOn(true);

        mPath = new Path();
        mPaint = new Paint();
    }

    @Override
    public void surfaceCreated(SurfaceHolder holder) {
        mIsDrawing = true;
        new Thread(this).start();
    }

    @Override
    public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {

    }

    @Override
    public void surfaceDestroyed(SurfaceHolder holder) {
        mIsDrawing = false;
    }

    @Override
    public void run() {
        long start = System.currentTimeMillis();
        while (mIsDrawing) {
            draw();
        }
        long end = System.currentTimeMillis();
        if (end - start < 100) {
            try {
                Thread.sleep(100 - (end - start));
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }

    private void draw() {
        try {
            mCanvas = mHolder.lockCanvas();
            //draw sth.
            mCanvas.drawColor(Color.WHITE);
            mCanvas.drawPath(mPath, mPaint);

        } catch (Exception e) {

        } finally {
            if (mCanvas != null) {
                mHolder.unlockCanvasAndPost(mCanvas);
            }
        }
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                mPath.moveTo(event.getX(), event.getY());
                break;
            case MotionEvent.ACTION_MOVE:
                mPath.lineTo(event.getX(), event.getY());
                break;
            case MotionEvent.ACTION_UP:
                break;

        }
        return true;
    }
}