commit 63506828a3cd79509256482c45e82c10a86d782d
author Ben Rohlfs <brohlfs@google.com> Thu Nov 03 11:17:26 2022 +0100
committer Ben Rohlfs <brohlfs@google.com> Mon Nov 07 13:38:29 2022 +0100
tree 228bb4426358c95207fc6297564382b141499d3c
parent f7f040e78c80180b77434108d49cfce7839d0432

Fix diff layers for lit based rendering

The diff layer API allows layers to manipulate the DOM directly, and
this API is hard to change. So at least for now we have to maintain
this API also for the new lit based rendering.

Direct DOM manipulation does not work well with the Lit controlled DOM
rendering, which is written and optimized for a rendering process
without external manipulation. So what we are doing is that we initiate
the diff layer manipulations for each diff row in `updated()`. And once
the layer annotations are complete, we mark the component as "dirty"
using a new `layersApplied` field.

When a diff row is being re-rendered we have to ensure that all parts
of the DOM are removed and re-constructed, if some layer may have
touched them. The easiest way to do that is to remove those DOM parts
in one rendering pass and then initiate another rendering pass to
bring them back. Btw, `gr-app-element` is doing something similar
with its `invalidateChangeViewCache` field.

Unfortunately layers can theoretically affect the content cells and
the line number cells. In reality only the coverage layer affects the
line number cells, and there is no good reason for this being a diff
layer at all. Otherwise we could have moved this logic of
remove+re-construct into `gr-diff-text`. That would have a been a bit
simpler.

Release-Notes: skip
Change-Id: I5280d843fe72ae096a12c1e081e213f8bdb7343f