RoundedPagerDrawable.java 文件源码

public static Drawable fromDrawable(Drawable drawable) {
    if (drawable == null || (drawable instanceof RoundedPagerDrawable)) {
        return drawable;
    }
    if (drawable instanceof LayerDrawable) {
        Drawable ld = (LayerDrawable) drawable;
        int num = ld.getNumberOfLayers();
        for (int i = 0; i < num; i++) {
            ld.setDrawableByLayerId(ld.getId(i), fromDrawable(ld.getDrawable(i)));
        }
        return ld;
    }
    Bitmap bm = drawableToBitmap(drawable);
    if (bm != null) {
        return new RoundedPagerDrawable(bm);
    }
    return drawable;
}