Android get background color of parent view if no background color set

Question

I have a a TextView for which I have not set a background color yet. I would like go the background color, but when I do ((ColorDrawable) mTextView.getBackground()).getColor() I obviously get a null pointer exception.

How would I traverse the view hierarchy of the TextView to find the most recent background color in the hierarchy that the TextView uses as background as a result.

And how would I determine the background color if no background color has been set in the hierarchy? And how would I determine that situation? How can I tell that no background has been set?

I basically have difficulty to determine the background color of a view when it has not been set explicitly.

Answer 1

I don't know how generally applicable this is but it does the trick for me:

int getBackgroundColor(View view, int fallbackColor) {
    if (view.getBackground() instanceof ColorDrawable) {
        return ((ColorDrawable) view.getBackground()).getColor();
    } else {
        if (view.getParent() instanceof View)
            return getBackgroundColor((View) view.getParent(), fallbackColor);
        else
            return fallbackColor;
    }
}

It tries to cast the background as ColorDrawable and if that fails it tries again on its parent, recursively. If the parent is not a View, the specified fallback color is returned.

Now for some Kotlin poetry:

tailrec fun View.getBackgroundColor(): Int? =
    (background as? ColorDrawable)?.color
        ?: (parent as? View)?.getBackgroundColor()