java Android位图：中心裁剪+创建位图的圆形

Question

我希望能够将一个矩形图像中心裁剪成一个圆形。我已经设法做到了，但我相信还有更有效的方法吗？这是我的代码：

中心作物：

    int sourceWidth = source.getWidth();
    int sourceHeight = source.getHeight();

    // Compute the scaling factors to fit the new height and width, respectively.
    // To cover the final image, the final scaling will be the bigger
    // of these two.

    int newWidth = 300;
    int newHeight  = 300;

    float xScale = (float) newWidth / sourceWidth;
    float yScale = (float) newHeight / sourceHeight;
    float scale = Math.max(xScale, yScale);

    // Now get the size of the source bitmap when scaled
    float scaledWidth = scale * sourceWidth;
    float scaledHeight = scale * sourceHeight;

    // Let's find out the upper left coordinates if the scaled bitmap
    // should be centered in the new size give by the parameters
    float left = (newWidth - scaledWidth) / 2;
    float top = (newHeight - scaledHeight) / 2;

    // The target rectangle for the new, scaled version of the source bitmap will now
    // be
    RectF targetRect = new RectF(left, top, left + scaledWidth, top + scaledHeight);

    // Finally, we create a new bitmap of the specified size and draw our new,
    // scaled bitmap onto it.
    Bitmap dest = Bitmap.createBitmap(newWidth, newHeight, source.getConfig());
   Canvas canvas = new Canvas(dest);
    canvas.drawBitmap(source, null, targetRect, null);

一旦我创建了这个新的中间裁剪位图，我现在想把它做成圆形。我将位图从上面传递到以下方法：

    public Bitmap getRoundedBitmap(Bitmap bitmap) {
    final Bitmap output = Bitmap.createBitmap(bitmap.getWidth(), bitmap.getHeight(), Bitmap.Config.ARGB_8888);
    final Canvas canvas = new Canvas(output);

    final int color = Color.RED;
    final Paint paint = new Paint();
    final Rect rect = new Rect(0, 0, bitmap.getWidth(), bitmap.getHeight());
    final RectF rectF = new RectF(rect);

    paint.setAntiAlias(true);
    canvas.drawARGB(0, 0, 0, 0);
    paint.setColor(color);
    canvas.drawOval(rectF, paint);
    paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_IN));
    canvas.drawBitmap(bitmap, rect, rect, paint);
    bitmap.recycle();
    return output;
    }

有可能把这些方法结合起来吗？我对位图操作相当陌生。谢谢

创建另一个位图，然后在getRoundedBitmap（）方法中进行操作似乎是不必要的

Answer 1

这个答案可能会对您有所帮助（它显示了RoundedImageView类的代码）：https://stackoverflow.com/a/16208548/1370336