Small quicks with custom backgrounds for waveform & waveform overview

[jus]

New in trunk is the <BgPixmap> key which allows to set custom backgrounds for waveform & waveform overview (*.png).

1. If a skin has <BgPixmap> set and you switch to a skin that has no <BgPixmap> , the <BgPixmap> is not deleted. It shows up on the waveform background of all other skins .

2. If you use <BgPixmap> on the waveform overview and use the "eject" control (either by keyboard or midi) , the <BgPixmap> is deleted for the waveform overview. This does not happen with <BgPixmap> on the main waveform.

[RJ Skerry-Ryan (rryan)]

feel free to directly assign waveform bugs to me so that I don't lose track of them :)

[jus (jus)]

Addition:
1.<BgPixmap> does not allow transparent images or images alpha channel, shows image on top of <BgColor> instead
Transparency is very useful for skin scaling and would make work easier.
2. The waveform overview <BgPixmap> turns white on track load if the image is transparent or the image has alpha channel

[RJ Skerry-Ryan (rryan)]

From the original post:

1) Fixed in trunk
2) Fixed in 1.9 (was a more general problem than bgpixmap, also happened for bgcolor)

For the addition:

1) transparency is sadly difficult for the waveform displays because Qt would need to draw what is under the QGLWidget, and then pass that into the OpenGL as a texture. I don't think it's possible given our current setup.

Transparency is now possible for the waveform overviews in trunk. You have to remove the BgColor to make it work. If you supply a BgColor it means "paint the background of the overview to this color" so it prevents transparency. Also in 1.9 I fixed it so that if BgColor is not provided, the background is treated as transparent.

2) White on track load -- this was happening in 1.9 even without the BgPixmap. I fixed it there.

[Swiftb0y (swiftb0y)]

Mixxx now uses GitHub for bug tracking. This bug has been migrated to:
https://github.com/mixxxdj/mixxx/issues/5841