使用SurfaceView模擬寫字板

MSurfaceView:

public class MSurfaceView extends SurfaceView implements SurfaceHolder.Callback, Runnable {

    private SurfaceHolder mHolder;
    private Canvas mCanvas;
    private boolean mIsDrawing;


    Path path = new Path();
    Paint paint = new Paint();
    float x, y;


    public MSurfaceView(Context context) {
        this(context, null);
    }

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

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


        paint.setColor(Color.RED);
        paint.setStyle(Paint.Style.STROKE);
        paint.setStrokeWidth(2);
    }


    @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 startTime = System.currentTimeMillis();
        while (mIsDrawing) {
            draw();
            
            x++;
            y = (float) (100 * Math.sin(x * 2 * Math.PI / 180) + 400);
            path.lineTo(x, y);

            long endTime = System.currentTimeMillis();
            if (endTime - startTime < 100) {
                try {
                    Thread.sleep(100 - (endTime - startTime));
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }
    }


    private void draw() {

        try {
            //get canvas
            mCanvas = mHolder.lockCanvas();

            //draw...
            mCanvas.drawColor(Color.WHITE);
            mCanvas.drawPath(path, paint);

        } catch (Exception e) {
        } finally {
            //submit
            if (mCanvas != null) {
                mHolder.unlockCanvasAndPost(mCanvas);
            }
        }
    }

@Override
public boolean onTouchEvent(MotionEvent event) {

    int x = (int) event.getX();
    int y = (int) event.getY();

    switch (event.getAction()) {
        case MotionEvent.ACTION_DOWN:
            path.moveTo(x, y);
            break;
        case MotionEvent.ACTION_MOVE:
            path.lineTo(x, y);
            break;
        case MotionEvent.ACTION_UP:
            break;
    }

    return true;
}

 }