Allow using visible regions with projections

[danthe1st]

This is my attempt to fix #3073 in order to implement eclipse-jdt/eclipse.jdt.ui#2264

Description

ProjectionViewer currently cannot use visible regions and projections together (except by calling enableProjections() after setVisibleRegions in which case it will show a wrong region). This PR changes the implementation of visible regions to mark everything outside the visible regions as collapsed if projections are enabled. Otherwise, the existing logic is used.

Note

I have not yet written proper integration tests for this as I am interested on what people experienced with this codebase think of this implementation/I want to provide an implementation as that might make discussions easier.

I also didn't test it (much) with regions overlapping with the bounds of the visible region.

testing with JDT

To test this with JDT as requested in eclipse-jdt/eclipse.jdt.ui#2264, do the following:

• Create a workspace with eclipse.platform.ui and JDT-UI set up (I did so by creating a Target Platform and added whatever I thought was necessary until I no longer got any errors but I have no idea how to properly do that)
• Use the changes in eclipse.platform.ui
• Apply enable folding with "Only show selected Java element" eclipse-jdt/eclipse.jdt.ui#2302 with JDT-UI:
• Create an "Eclipse Application" run configuration with this version of Eclipse Platform and the patched version of JDT-UI and start it
• Enable Window > Preferences > Java > Editor > "Only show the selected Java Element"
• Make sure folding is enabled at Window > Preferences > Java > Editor > Folding
• Open a Java class
• Select elements in the outline and observe that only the "selected element" is shown in the editor and folding still works (whether it's normal folding, custom folding regions, "Extended Folding", etc shouldn't make a difference)
  

Is there a way to launch an Eclipse installation like that from the command line? If yes, @totomomo18 might want to test it.

Note

Expanding a folding region outside the currently visible region will make that folding region visible.

To Do

• Ensure that the visible region still works when typing (pretty sure that's a JDT issue but I want to be sure)
  • There's still a minor issue with that if you enter text right after the closing } of the currenly selected region.
• Still hide parts outside of visible region when using "Expand all"
  • integration test

[github-actions]

Test Results

 2 778 files  ± 0   2 778 suites  ±0   1h 35m 52s ⏱️ - 10m 45s
 7 940 tests +10   7 712 ✅ +10  228 💤 ±0  0 ❌ ±0 
23 375 runs  +30  22 629 ✅ +30  746 💤 ±0  0 ❌ ±0 

Results for commit 43f0f39. ± Comparison against base commit d2177cf.

♻️ This comment has been updated with latest results.

[iloveeclipse]

@danthe1st : thanks for PR, few things:

1. Please rebase on master
2. Please squash two commits into one
3. Please update commit message to follow commit message guidelines: https://github.com/eclipse-platform/.github/blob/main/CONTRIBUTING.md#commit-message-recommendations

[danthe1st]

@danthe1st : thanks for PR, few things:

1. Please rebase on master

2. Please squash two commits into one

3. Please update commit message to follow commit message guidelines: https://github.com/eclipse-platform/.github/blob/main/CONTRIBUTING.md#commit-message-recommendations

I'll make sure to do that once I located and fixed a remaining issue in combination with JDT (if I select a method that's within a custom folding region and enter text, it seems to show "too much" text for some reason). While I think that's an issue with JDT-UI (it only seems to happen with custom folding regions and extended folding), I want to be sure about it first (and I opened this PR before everything is finished to make it visible in advance/allow for discussion if applicable).

[danthe1st]

I have made the requested changes. However, I want to note the following:

• This has an impact on behavior(al compatibility). If some project/plugin/whatever calls enableProjections() and setVisibleRegion on some ProjectionViewer, this PR affects what is shown to the user.
• I didn't do performance testing.
• I think it would be a good idea for someone from JDT (or other projects if make use of this?) to test it before this is merged.

[danthe1st]

I am not sure why the Jenkins build seems to have issues getting tycho set up (maybe issues with https://repo.eclipse.org/?)

[merks]

Yes there are infrastructure problems again:

• https://gitlab.eclipse.org/eclipsefdn/helpdesk/-/issues/6377
• https://gitlab.eclipse.org/eclipsefdn/helpdesk/-/issues/6378

I restarted the build.

[merks]

It looks like there was a test failure:

https://ci.eclipse.org/platform/job/eclipse.platform.ui/job/PR-3074/lastCompletedBuild/testReport/

[danthe1st]

I now switched to an approach that should have fewer side effects. Instead of adding additional projection regions, I am now using the expand() and collapse() methods directly.