1.效果图

2.代码实现

public class ErinieShow extends RelativeLayout {
	Context context;
	RelativeLayout bg;
	MyView MyView;
	int level;
	public ErinieShow(Context context, int level) {
		super(context);
		this.context = context;
		this.level = level;
		
		bg = new RelativeLayout(context);
		MyView = new MyView(context);
		bg.addView(MyView);
		addView(bg);
		
		int[] resolution = PhoneUtil.getResolution(context);
		RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams(
				resolution[0], PhoneUtil.getFitHeight(context, 125));

		bg.setId(100001);
		bg.setLayoutParams(params);
		MyView.setLayoutParams(params);
		
		switch (level) {
		case 0:
			bg.setBackgroundResource(R.drawable.rewardlevel0);
			break;
		case 1:
			bg.setBackgroundResource(R.drawable.rewardlevel1);

			break;
		case 2:
			bg.setBackgroundResource(R.drawable.rewardlevel2);
			break;
		default:
			bg.setBackgroundResource(R.drawable.rewardlevel3);
			break;
		}
		
		MyView.init(Color.parseColor("#d3d3d3"), 30, 10);
	}
}

public class MyView extends TextView {

	private float TOUCH_TOLERANCE; // 填充距离，使线条更自然，柔和,值越小，越柔和。
	private Bitmap mBitmap;
	private Canvas mCanvas;
	private Paint mPaint;
	private Path mPath;
	private float mX, mY;
	private boolean isDraw = false;
	int time=0;
	
	public MyView(Context context) {
		super(context);
	}

	@Override
	protected void onDraw(Canvas canvas) {
		super.onDraw(canvas);
		if (isDraw) {
			mCanvas.drawPath(mPath, mPaint);
			canvas.drawBitmap(mBitmap, 0, 0, null);
		}
	}

	/**
	 * 开启檫除功能
	 * 
	 * @param bgColor
	 *            覆盖的背景颜色
	 * @param paintStrokeWidth
	 *            触点（橡皮）宽度
	 * @param touchTolerance
	 *            填充距离,值越小，越柔和。
	 */
	public void init(final int bgColor, final int paintStrokeWidth,
			float touchTolerance) {
		TOUCH_TOLERANCE = touchTolerance;
		// 设置画笔
		mPaint = new Paint();
		// mPaint.setAlpha(0);
		// 画笔划过的痕迹就变成透明色了
		mPaint.setColor(Color.BLACK); // 此处不能为透明色
		mPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DST_OUT));
		// 或者
		// mPaint.setAlpha(0);
		// mPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DST_IN));

		mPaint.setAntiAlias(true);
		mPaint.setDither(true);
		mPaint.setStyle(Paint.Style.STROKE);
		mPaint.setStrokeJoin(Paint.Join.ROUND); // 前圆角
		mPaint.setStrokeCap(Paint.Cap.ROUND); // 后圆角
		mPaint.setStrokeWidth(paintStrokeWidth); // 笔宽

		// 痕迹
		mPath = new Path();
		// 覆盖
		LayoutParams layoutParams = getLayoutParams();
		int height = layoutParams.height;
		int width;
		if (getLayoutParams().width == LayoutParams.MATCH_PARENT) {
			width = 700;
		} else {
			width = layoutParams.width;
		}

		mBitmap = Bitmap.createBitmap(width, height, Config.ARGB_8888);
		mCanvas = new Canvas(mBitmap);

		mCanvas.drawColor(bgColor);
		isDraw = true;
	}

	@Override
	public boolean onTouchEvent(MotionEvent event) {
		if (!isDraw) {
			return true;
		}
		switch (event.getAction()) {
		case MotionEvent.ACTION_DOWN: // 触点按下
			// touchDown(event.getRawX(),event.getRawY());
			touchDown(event.getX(), event.getY());
			invalidate();
			break;
		case MotionEvent.ACTION_MOVE: // 触点移动
			touchMove(event.getX(), event.getY());
			invalidate();
			break;
		case MotionEvent.ACTION_UP: // 触点弹起
			touchUp(event.getX(), event.getY());
			invalidate();
			break;
		default:
			break;
		}
		return true;
	}

	private void touchDown(float x, float y) {
		mPath.reset();
		mPath.moveTo(x, y);
		mX = x;
		mY = y;
	}

	private void touchMove(float x, float y) {
		float dx = Math.abs(x - mX);
		float dy = Math.abs(y - mY);
		if (dx >= TOUCH_TOLERANCE || dy >= TOUCH_TOLERANCE) {
			mPath.quadTo(mX, mY, (x + mX) / 2, (y + mY) / 2);
			mX = x;
			mY = y;
		}

	}

	private void touchUp(float x, float y) {
		mPath.lineTo(x, y);
		mCanvas.drawPath(mPath, mPaint);
		mPath.reset();
	}

}

源码下载http://download.csdn.net/detail/strawberry2013/7682865