Android Bit地图 圆角

Button mView = (Button)findViewById(R.id.mView);				Bitmap myCoolBitmap = ((BitmapDrawable) getResources().getDrawable(				R.drawable.icon)).getBitmap();		int w = myCoolBitmap.getWidth(), h = myCoolBitmap.getHeight();				Bitmap rounder = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);		Canvas canvas = new Canvas(rounder);		Paint xferPaint = new Paint(Paint.ANTI_ALIAS_FLAG);		xferPaint.setColor(Color.RED);		canvas.drawRoundRect(new RectF(0, 0, w, h), 20.0f, 20.0f, xferPaint);		xferPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DST_IN));		canvas.drawBitmap(myCoolBitmap, 0, 0, null);		canvas.drawBitmap(rounder, 0, 0, xferPaint);				Drawable drawable = new BitmapDrawable(rounder);  		mView.setBackgroundDrawable(drawable);

public Bitmap getRoundedCornerBitmap(Bitmap bitmap) {		// 创建一个指定宽度和高度的空位图对象		Bitmap output = Bitmap.createBitmap(bitmap.getWidth(),				bitmap.getHeight(), Config.ARGB_8888);		// 用该位图创建画布		Canvas canvas = new Canvas(output);		// 画笔对象		final Paint paint = new Paint();		// 画笔的颜色		final int color = 0xff424242;		// 矩形区域对象		final Rect rect = new Rect(0, 0, bitmap.getWidth(), bitmap.getHeight());		// 未知		final RectF rectF = new RectF(rect);		// 拐角的半径		final float roundPx = 30;		// 消除锯齿		paint.setAntiAlias(true);		// 画布背景色		canvas.drawARGB(0, 0, 0, 0);		// 设置画笔颜色		paint.setColor(color);		// 绘制圆角矩形		canvas.drawRoundRect(rectF, roundPx, roundPx, paint);		// 未知		paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN));		// 把该图片绘制在该圆角矩形区域中		canvas.drawBitmap(bitmap, rect, rect, paint);		// 最终在画布上呈现的就是该圆角矩形图片，然后我们返回该Bitmap对象		return output;	}