Fix EmphasisAPI Leaking Layers, Fix Emphasis Drawing

[thecoolwinter]

Description

• Fixes an emphasis manager bug where it could leak layers without removing their CALayers when replacing flash emphases with other emphases.
• Updates the emphasis drawing code to correctly draw underlines.
• Updates the roundedPathForRange to correctly handle emphases that span multiple line fragments.

During the last point, I discovered that the emphasis manager doesn't correctly draw the text on emphases that span multiple line fragments. This makes sense, as right now it's just using a CATextLayer that has no knowledge of line breaks.

In the future, that text layer should be replaced by a custom layer that draws the text using knowledge of existing line fragments positions. However, I think the issues this PR fixes are too important to wait until that can be done.

Also note that that change will be critical to drag and drop, so it will absolutely be done and I have a branch somewhere with some of that work already completed.

Related Issues

• feat: Find in Editor CodeEditSourceEditor#295

Checklist

• I read and understood the contributing guide as well as the code of conduct
• The issues this PR addresses are related to each other
• My changes generate no new warnings
• My code builds and runs on my machine
• My changes are all related to the related issue above
• I documented my code

Screenshots

Screen recording showing the text layer bug mentioned above, as well as the fixed multi-fragment drawing, and the fixed leak.

Prior to this, when switching from flash to any other emphasis type, there was a good chance one of the new emphases would be kept. This was due to the emphasis manager assuming that the emphasis being flashed was kept around after the animation delay. This has been fixed in this PR.

Screen.Recording.2025-04-07.at.12.11.10.PM.mov