Enhance Annotation Layer Changes: Relative zOrder Updates

[arianizadi]

Motivation and context

Closes #9064
The current method of moving objects in CVAT using absolute placements (sending them directly to the front or back) can be disorienting and unpredictable. When repeatedly moving an object backward, it can continue to shift unexpectedly, making it difficult to track and control its position accurately.

This update introduces a relative movement approach, allowing users to adjust an object’s z-order one layer at a time. Instead of jumping directly to the back or front, users can precisely move objects step-by-step, ensuring greater accuracy and control over the annotation layout. This prevents unwanted drastic changes and makes object layering more intuitive and predictable.

By constraining the movement within minZLayer and maxZLayer, this solution also prevents objects from going out of bounds, further improving usability.

How has this been tested?

I had tested by rebuilding and using the functionality for my semantic segmentation tasks. Just by testing the keybinds and buttons in multiple images.

Checklist

• I submit my changes into the develop branch
• I have created a changelog fragment
• I have updated the documentation accordingly
• I have added tests to cover my changes
• I have linked related issues (see GitHub docs)

License

• I submit my code changes under the same MIT License that covers the project.
  Feel free to contact the maintainers if that's a concern.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[arianizadi]

Would this kind of change need a test? I did not find any tests for the previous implementation.

[klakhov]

Hi,
Moving objects between layers could be a useful feature. However, I don’t think we should completely remove the To Background and To Foreground functions. What do you think about adding additional shortcuts or buttons to support moving objects between layers?

An e2e test would be much appreciated. You can find basic tests for z order here

[arianizadi]

That makes sense. I will try to fix that and write the tests. Thank you!