(fix) hotcue_X_color control: color not stored in cue

[ronso0]

Fixes the hotcue color issue reported in https://mixxx.zulipchat.com/#narrow/stream/113295-controller-mapping/topic/Hotcue.20setting.20script

For some reason the valueChanged() signal is not emitted, therefore slotHotcueColorChanged() not being called and the new color not stored in the cue. The color control is reset as soon as anothe cue is set (track emits cuesUpdated() adn cues are reloaded from track, default color).
Reproducible with Qt5 and Qt6.
without this fix:
https://github.com/mixxxdj/mixxx/assets/5934199/aad6ae0f-2ea3-4825-ae77-7da8ba95b22b

For testing, use this mapping with virtual MIDI device:
load a track to deck1, click Eject on deck2
https://gist.github.com/ronso0/471efe54370a32fa9eb26a571a818dd5

[daschuer]

This is blocked to avoid endless loops. I think due to the read-only nature, slotHotcueColorChanged() is never called and can be inlined. setAndConfirm() should then only be set at the end when all other checks also have been performed successful.

[ronso0]

Please elaborate, I'm not very familiar with the contrl internals.
I see

mixxx/src/control/control.cpp

Lines 289 to 304 in 94ffc14

	void ControlDoublePrivate::setAndConfirm(double value, QObject* pSender) {
	setInner(value, pSender);
	}
	void ControlDoublePrivate::setInner(double value, QObject* pSender) {
	if (m_bIgnoreNops && get() == value) {
	return;
	}
	m_value.setValue(value);
	emit valueChanged(value, pSender);
	if (m_bTrack) {
	Stat::track(m_trackKey, static_cast<Stat::StatType>(m_trackType),
	static_cast<Stat::ComputeFlags>(m_trackFlags), value);
	}
	}

This emits valueChanged, not a value change request. Where is that blocked? I don't see how that would create an infinite loop.

slotHotcueColorChanged() is indeed never called, and we also have an unused signal hotcueColorChanged.
I'll adjust that.

[daschuer]

It is blocked here:

mixxx/src/control/controlobject.cpp

Line 50 in 94ffc14

// Only emit valueChanged() if we did not originate this change.

[ronso0]

Thanks!

[daschuer]

Thank you. LGTM