Question

想想我有一个位图，我已经从Media Store中的Album Art加载了它，它具有100％的透明值，如何将其更改为50或30？

您也知道我可以将图像设为黑白图像吗？

感谢

Answer 1

将alpha设置为0到255 !!

alpha设置为45将使图像透明

ViewName.getBackground（）setAlpha（65）;

Answer 2

使用以下方法：

/**
 * @param bitmap The source bitmap.
 * @param opacity a value between 0 (completely transparent) and 255 (completely
 * opaque).
 * @return The opacity-adjusted bitmap.  If the source bitmap is mutable it will be
 * adjusted and returned, otherwise a new bitmap is created.
 */
private Bitmap adjustOpacity(Bitmap bitmap, int opacity)
{
    Bitmap mutableBitmap = bitmap.copy(Bitmap.Config.ARGB_8888, true);
    Canvas canvas = new Canvas(mutableBitmap);
    int colour = (opacity & 0xFF) << 24;
    canvas.drawColor(colour, PorterDuff.Mode.DST_IN);
    return mutableBitmap;
}

这里的解释： http://blog.uncommons.org/2011/01/12/adjusting-the-opacity-of-an-android-bitmap/

如何使图像透明android

2 个答案: