FlyoutMenuView.java 文件源码

Bitmap createButtonShadowBitmap() {
    int shadowRadius = (int) buttonElevation * 2;
    int bitmapRadius = buttonRadius + (shadowRadius / 2);
    int bitmapSize = bitmapRadius * 2;
    Bitmap shadowBitmap = Bitmap.createBitmap(bitmapSize, bitmapSize, Bitmap.Config.ARGB_8888);
    shadowBitmap.eraseColor(0x0);

    int colors[] = {
            ColorUtils.setAlphaComponent(SHADOW_COLOR, SHADOW_ALPHA),
            ColorUtils.setAlphaComponent(SHADOW_COLOR, 0)
    };

    float stops[] = {
            (float) (buttonRadius - (shadowRadius / 2)) / (float) bitmapRadius,
            1f
    };

    Paint paint = new Paint();
    paint.setAntiAlias(true);
    paint.setShader(new RadialGradient(bitmapRadius, bitmapRadius, bitmapRadius, colors, stops, Shader.TileMode.CLAMP));

    Canvas canvas = new Canvas(shadowBitmap);
    canvas.drawRect(0, 0, bitmapSize, bitmapSize, paint);

    return shadowBitmap;
}