android - Animate MaxLines and Ellipsize

Question

I have textview which contains a part of a text. When the user clicks the arrow, the textview resizes so the full text is shown. See the images below for an example:

The TextView has a wrap_content height, and when collapsed a maxLines="4".

The onClick of the arrow contains this code:

        if (isExpanded) {
            btnToggle.setImageDrawable(getResources().getDrawable(
                    R.drawable.arrow_down));
            tvText.setMaxLines(4);
            tvText.setEllipsize(TruncateAt.END);
        } else {
            btnToggle.setImageDrawable(getResources().getDrawable(
                    R.drawable.arrow_up));
            tvText.setMaxLines(Integer.MAX_VALUE);
            tvText.setEllipsize(null);
        }
        isExpanded = !isExpanded;

This code works, but it is not animated. I need to animate the expansion, so the TextView animates to it's full height. I can't find anything about animating properties like MaxLines. Who can help me out?

Answer 1

You can achieve this using an ObjectAnimator

ObjectAnimator animation = ObjectAnimator.ofInt(
        tvText,
        "maxLines", 
        25);
animation.setDuration(4000);
animation.start();

This will increase the "maxLines" property of the "tvText" TextView from whatever it initially is set to, to 25, over the period of 4000 milliseconds.

See more here and here.