java - 带圆角和透明背景的位图

Question

我正在尝试使用下面的代码对位图进行圆角处理。问题是无论我将油漆的颜色设置为什么，例如Color.TRANSPARENT ，它总是黑色的。我怎样才能真正剪裁位图的角，而不仅仅是将它们涂成黑色？

谢谢!

    public static Bitmap roundCorners(Bitmap src, int radius) {
    //Create a *mutable* location, and a canvas to draw into it
    int width = src.getWidth();
    int height = src.getHeight();
    Bitmap result = Bitmap.createBitmap(width, height, Config.ARGB_8888);
    Canvas canvas = new Canvas(result);
    Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
    RectF rect = new RectF(0, 0, width, height);
    Shader bitmapShader = new BitmapShader(src, TileMode.CLAMP, TileMode.CLAMP);
    paint.setColor(0xFF000000);
    paint.setShader(bitmapShader);
    canvas.drawRoundRect(rect, radius, radius, paint);
    return result;
}

Answer 1

有一种更简单的方法，一次即可完成。只需绘制一个圆角矩形，但在 Paint 上设置一个 BitmapShader。这将用您的位图填充圆角矩形。无需更改 xfermode 或调用 drawBitmap。