Fix 13060 loop gradient

[m0dB]

Fixes #13060

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After

[daschuer]

LGTM and I can confirm the issue is fixed.
I have not understand how to be honest ..

[daschuer]

Oh, this needs also to go to 2.4. I will cherry pick it manually.

[m0dB]

LGTM and I can confirm the issue is fixed. I have not understand how to be honest ..

The textures for the markers are drawn centered around the position in the waveform (This is not ideal, as this means the left side of e.g. a hot cue marker image is just transparency. It doesn't really matter for a signal digit hot cue, but it becomes a bit ridiculous with longer labels). The bug was that I used the x position of that texture also for the gradient, instead of the center position.

(The implementation with the centered image with transparency is carried over from the legacy implementation, I might improve this in a separate PR)

[m0dB]

Oh, this needs also to go to 2.4. I will cherry pick it manually.

Oh, my bad! It was my intention to fix this on 2.4 but somehow I did it on main. Thanks for taking care of this!