opening preferences resets deck eq knobs

[RJ Skerry-Ryan]

Something is likely doing engine-changing work in the slotUpdate call.

[Owen Williams (ywwg)]

This is because applySelections() is getting called when the prefs window opens, and reloading the EQ effects resets the knobs.

The thing to do would be to check that the currently-loaded effect matches the configured effect, but I can't figure out how to get the id of an instantiated effect. the getId method is static per-GroupEffectProcessor, and that isn't exposed in the parent classes because you can't have static virtual methods. I think the solution is to make getId not static, then I can do a crazy call in dlgprefeq like:

QString current_effect = m_pEQEffectRack->getEffectChainSlot(deck)->getEffectSlot(0)->getEffect()->getEngineEffect()->getId();

(obviously checking for null pointers along the way)

[Daniel Schürmann (daschuer)]

> This is because applySelections() is getting called when the prefs window opens, and reloading the EQ effects resets the knobs.

Why not fixing that? This seams to be an issue for all preference panes.

[RJ Skerry-Ryan (rryan)]

Right -- engine changing work should not be done in slotUpdate.

The way preferences functions are designed to work:

slotUpdate -> update the GUI widgets to match internal engine state
slotApply -> take the GUI widget state and apply them to the engine
slotCancel -> all changes to the GUI widget state since that last slotUpdate call are reverted (typically not implemented since the next slotUpdate will revert them)
slotResetToDefaults -> change GUI widgets to the defaults.

slotShow -> preferences dialog is shown (for starting timers e.g. the waveform measurement timer)
slotHide -> preferences dialog is hidden (for stopping timers, etc.)

DlgPrefEq is kind of an odd ball here since changes made affect the engine instantly (they don't need the user to hit apply). However, we should still not do engine changing work in slotUpdate.

[Owen Williams (ywwg)]

If we want to update the gui widgets to match internal engine state, then there needs to be some way to introspect a loaded effect to figure out what it is. If you have any guidance on the issue I raised above (static method problems) let me know, otherwise I will just barrel ahead with an attempt.

[RJ Skerry-Ryan (rryan)]

Whoops, I didn't read your comment that closely -- you can get the ID from the manifest with something similar to what you posted:

m_pEQEffectRack->getEffectChainSlot(deck)->getEffectSlot(0)->getEffect()->getManifest().id()

[Owen Williams (ywwg)]

https://github.com/mixxxdj/mixxx/pull/459

[Swiftb0y (swiftb0y)]

Mixxx now uses GitHub for bug tracking. This bug has been migrated to:
https://github.com/mixxxdj/mixxx/issues/7781