ColorMatrixColorFilter不适用于alpha android

Question

我正在尝试存储具有Alpha值的位图以及RGB所有颜色和阴影应用，除了具有值＆gt;的Alpha效果。 ColorMatrix中的1.0。

以下是我的代码

Bitmap bm = BitmapFactory.decodeFile(imagePath).copy(Config.ARGB_8888, true);

    final Bitmap b = Bitmap.createBitmap(bm.getWidth(), bm.getHeight(),
            Bitmap.Config.ARGB_8888);
    b.eraseColor(Color.argb(0, 0, 0, 0));
    final Canvas c = new Canvas(b);

    float redValue = ((float) red) / 255;
    float greenValue = ((float) green) / 255;
    float blueValue = ((float) blue) / 255;
    float alphaValue = ((float) alpha) / 255;

    ColorMatrix cm = new ColorMatrix();

    cm.set(new float[] { redValue, 0, 0, 0,0,
            0, greenValue, 0, 0, 0,
            0, 0, blueValue, 0, 0,
            0, 0, 0, alphaValue, 0 });

    Log.e("cm","cm::"+cm.toString());

    Paint p = new Paint();

    p.setColorFilter(new ColorMatrixColorFilter(cm));
    c.drawBitmap(bm, 0, 0, p);

return b;

您的建议/帮助将不胜感激