Allow anyone (not just SCM) to hook into quick diff provider

[alexr00]

Why this would be useful: microsoft/vscode-pull-request-github#392

We'll also need to determine what should happen when there are multiple quick diff providers on the same range.

[alexr00]

@laurentlb FYI in case you would also find this useful.

[alexr00]

Here's what it looks like:

[justanotheranonymoususer]

Will it also allow to show gutter markers? If yes, perhaps #167306 can be implemented with an extension

[alexr00]

Yes, this shows gutter markers.

[eamodio]

@alexr00 I've tried out this proposal (thrilled about it BTW) and I've run into an issue where it doesn't seem like the quickdiff is removed from the editor properly when disposed. I am currently turning on the feature by calling registerQuickDiffProvider on-demand (in response to a user action) and want to turn it back off when they toggle it back off, but even when disposing the returned disposable it doesn't clear it from the document.

Also minor, but why is there a label both on the registerQuickDiffProvider call and on the provider itself?

[eamodio]

Playing with this some more (in today's insiders), it seems dispose works more reliably, but still not 100%.

[alexr00]

@eamodio there was a dispose that wasn't happening. It is fixed in insiders, though if you're not seeing it work 100% then I'll need to investigate further.

Also minor, but why is there a label both on the registerQuickDiffProvider call and on the provider itself?

This will likely be deduplicated.

[sergei-dyshel]

Is provideOriginalResource should be called for existing editors at the moment of registration?

I have the following sequence of events (vscode 1.76):

1. Text editor is showed.
2. Extension loads and calls registerQuickDiffProvider.
3. Newly registered quick diff doesn't show.
4. I close and reopen the editor.
5. Quick diff is properly displayed in the editor.

[eamodio]

@alexr00 Any chance this could land soon? I would love to get this in.

[alexr00]

@eamodio do you have any other feedback on the API?

Adding to February to revisit then.

[eamodio]

Not really it seems to work well as is. I have a branch with it implemented for the File Changes annotations in GitLens: https://github.com/gitkraken/vscode-gitlens/tree/feature/gutter-changes

Thanks!

[starball5]

We'll also need to determine what should happen when there are multiple quick diff providers on the same range.

Related? #196759

[alexr00]

Moving back to the backlog as we're not going to get to #196759 this month.

[gjsjohnmurray]

@alexr00 are there any plans to finalize this API?

[alexr00]

We don't have a plan to finalize it. Tentatively assigning to October to see if we have time then.