When transitioning between sublists, there can be a visibly observable jump in
the positioning of list items when the header container is restored to normal
size outside of sticky mode.
To avoid this problem, this leaves all headers at normal size. This creates a
new issue of a permanent gap at the top of the list for the first header, but
this can be solved by always hiding (since it can only ever appear stuck to
top).
Fixes https://github.com/vector-im/riot-web/issues/14429
this way we have a flexbox layout in the resizer with:
- the resize handle (fixed)
- the show more/less button, if any (fixed)
- the list of tiles (grabbing whatever is left)
Known issues:
* Causes scroll jumps when the button gets added to DOM
* Resize handle is invisible when there's a show more button
TODO:
* Clean up comments
* Clean up useless code (all the padding stuff isn't needed)
In this demonstration, we remove the cutting line (as it collides with the tile in a weird spot) and instead replace the tile with a placeholder when the text is about to collide with the avatar in the tile. We use a `round()` for this because through some amazing coincidence the collision happens at 0.47, which is close enough to 0.5 for people not to notice.
We now use offsets and scroll information to determine where the headers should be stuck to, still supporting the transparent background.
Some scroll jumps were originally introduced as part of the change in numbering, so they have been fixed here. By proxy, some additional scroll jump/instability should be fixed as well.
This has a lingering problem of still causing a huge number of no-op UI updates though, which will be dealt with in a future commit.
react-resizer appears to be okay at tracking state, but it often desyncs from reality. re-resizer is more maintained and more broadly used (160k downloads vs 110k), and appears to generally do a better job of tracking the cursor.
The new library has some oddities though, such as deltas, touch support (hence the polyfill), and calling handles "Enable".
For https://github.com/vector-im/riot-web/issues/14022
