Prevent editor "jumping" by using placeholders for Code Minings

[vogella]

@tobiasmelcher asked for improvement suggestions for code minings. Here is one:

Description: Currently, when opening a file, Code Minings are calculated asynchronously and injected into the editor upon completion. If this calculation takes more than a few milliseconds, the source code shifts downward unexpectedly while the user is trying to read or edit.

Suggested Improvement: Implement layout reservation or placeholders. If possible, the Code Mining provider should immediately return an empty placeholder of a fixed height. This ensures the space is already allocated, allowing the content to fade in once the calculation is finished without moving the rest of the source code.

If the current architecture doesn't allow for pre-allocating vertical space, please feel free to close this.

[HeikoKlare]

We would also be very interested in this kind of enhancement, as the lazy calculation of the code minings and the consequential "jumping" code (both in terms of added lines as well as in terms of in-line annotations) is something that significantly limits usability of the nice code mining feature.

[tobiasmelcher]

How should a code mining provider implementation instantly return the locations where to place the code minings without doing the heavy calculation work? If they already know where to place the minings they could also immediately return the text to be shown.

Is it about showing the code minings for the Java editor? What if we would calculate the code minings always in the main thread? There would be then no flickering. We could try it out and check if the Java code mining provider implementation is fast enough.

[vogella]

Some code mininig implementations will always return a value, for example reference reference counts if null is allowed. In this case they could already return a placeholder like "Calculating" and update them once the calculation is done.

Using the main thread should not be done, as big workspaces require a long, long time to calculate some of the code minings and we should not block the ui during the calculation.

[tobiasmelcher]

Thanks a lot for clarification. Now, I got it. Proposal makes absolutely sense.