android - 如何在位图周围制作发光效果？

Question

以下代码是我目前得到的。但是，有两个问题:

1. 我想要内部和外部发光效果，看起来类似于 Photoshop 的混合选项。但是我只设法使外部发光，如果我设置 BlurMaskFilter.Blur.INNER 或其他值，则整个图像被阻挡，而不仅仅是边缘。

2. 尽管我将“FF”设置为 alpha 值，但发光颜色仍然很暗。

   Bitmap alpha = origin.extractAlpha();
   BlurMaskFilter blurMaskFilter = new BlurMaskFilter(5, BlurMaskFilter.Blur.OUTER);
   
   Paint paint = new Paint();
   paint.setMaskFilter(blurMaskFilter);
   paint.setColor(0xffffffff);
   
   Canvas canvas = new Canvas(origin);
   canvas.drawBitmap(alpha, 0, 0, paint);
   
   return origin;
   

Answer 1

试试这个，基于 XGouchet's answer .

private void setBackgroundGlow(ImageView imgview, int imageicon,int r,int g,int b)
{
    // An added margin to the initial image
    int margin = 24;
    int halfMargin = margin / 2;
    // the glow radius
    int glowRadius = 40;

    // the glow color
    int glowColor = Color.rgb(r, g, b);

    // The original image to use
    Bitmap src = BitmapFactory.decodeResource(getResources(),imageicon);

    // extract the alpha from the source image
    Bitmap alpha = src.extractAlpha();

    // The output bitmap (with the icon + glow)
    Bitmap bmp =  Bitmap.createBitmap(src.getWidth() + margin, src.getHeight() + margin, Bitmap.Config.ARGB_8888);

    // The canvas to paint on the image
    Canvas canvas = new Canvas(bmp);

    Paint paint = new Paint();
    paint.setColor(glowColor);

    // outer glow
    paint.setMaskFilter(new BlurMaskFilter(glowRadius, Blur.OUTER));//For Inner glow set Blur.INNER
    canvas.drawBitmap(alpha, halfMargin, halfMargin, paint);

    // original icon
    canvas.drawBitmap(src, halfMargin, halfMargin, null);

    imgview.setImageBitmap(bmp);


}