Unify stack order of elements in the waveform display

[jus]

Currently sometimes the markers are drawn behind the waveform in some display modes.

An element with greater stack order is always in front of an element with a lower stack order.
Current z-index order (example):
                              filtered Simple(GL)
Waveform 1 2
Cue 2 5
Hotcue 3 4
Loop-Marker 4 2
Loop overlay 5 1
The order is even different for Filtered GL and GLSL

We may return to a pre-1.11 like order:
*Move loop overlay move it to z-index 1 (basically making it an "underlay")
 Interested to hear other opinions here.
 Since the new waveforms leave a lot of room in between the beats, i found a loop "underlay"
 pretty useful and having displayed the waveform clearly is a big plus imo.
*Move waveform to z-index 2
*Move Loop-Marker to z-index 3
*Move Hotcues to z-index 4
*Move Cues to z-index 5

*Apply alpha value from waveform overview`s loop overlay to all other display types, currently it is different too
*Alternatively swap z-order 1 and 2 while applying multiply/overlay/source atop image composition if performance allows for better visibility.

PS. The waveform overview stack order is just fine.

[Thomas Vincent (vrince)]

I unified order in waveform-2.0_pure-gl branch but I did't see thins report before doing it. So I guess I need to check and make it compliant to what is demanded here. Should be out soon :)

[jus (jus)]

Nice.
I am not sure regarding the loops Overlay/Underlay behavior i talked about in the first post. Might be worth to try out what works best and what is the most accepted behavior.

[Thomas Vincent (vrince)]

All renderer stack are like:
Background
EndOfTrack
Preroll
MarkRange #loop
Signal
RenderMark #cues
RenderBeat #beatgrid

[Swiftb0y (swiftb0y)]

Mixxx now uses GitHub for bug tracking. This bug has been migrated to:
https://github.com/mixxxdj/mixxx/issues/6397