Mobile: BottomSheetTextControl Component: Get Text Area to Automatically Expand/Shrink with Text Entry

[SiobhyB]

Description

The BottomSheetTextControl component currently has a text area with a set height:

If a user enters a large amount of text into the text area, they need to scroll within that area to view all of it, the area doesn't automatically expand/shrink to make all text visible. Around three lines of text are visible on the screen at a time, with any more being visible upon scroll.

The current behaviour was agreed upon as part of this feedback thread and currently makes sense given that the component is currently only used for the image block's alt text settings (which doesn't generally entail that many lines of text).

However, it could be a nice enhancement for the component to automatically expand/shrink with text, especially if it goes onto be used in other places in the editor where it's expected that multiple lines of text will be used.

Step-by-step reproduction instructions

1. Open Image Block settings.
2. Tap Alt Text and confirm that a new sub sheet opens with an area to enter text.
3. Enter multiple lines of text into the area and confirm that it doesn't expand, instead you're able to scroll to view any text not visible within it.

Expected behaviour

The following feedback was provided by a colleague who tested the above steps:

I feel like the text area should expand as I type rather than creating a small scrollable area. Was most noticeable on iPad where there was room to spare, it seemed unnecessary to scroll in the small content area.

Actual behaviour

The area doesn't currently expand, with any text overflowing the view only visible on scroll. It could be a nice enhancement to change this behaviour in the future.