Android - How to make an icon glow on touch?

问题

How to get this blue glow effect over an icon? Is there any quick way of doing it? I really don't want to use photoshop for this effect.

Any help would be really appreciated.

回答1:

If you want to generate the glow programatically, here's how you can do. My advice, generate it just once at the beggining of your activity, then create a StateListDrawable using it, as said in the comment :

    // An added margin to the initial image
    int margin = 24;
    int halfMargin = margin / 2;

    // the glow radius
    int glowRadius = 16;

    // the glow color
    int glowColor = Color.rgb(0, 192, 255);

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

    // 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));
    canvas.drawBitmap(alpha, halfMargin, halfMargin, paint);

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

    ((ImageView) findViewById(R.id.bmpImg)).setImageBitmap(bmp);

来源：https://stackoverflow.com/questions/12157412/android-how-to-make-an-icon-glow-on-touch