FIX(client): Fix AudioWizard echo cancellation checkbox

The echo cancellation checkbox had two separate, but similar
problems:

1) It would never load in a checked state when you open up the
AudioWizard

2) It would also never load the correct checked state representing
the user settings when switching AudioInput or AudioOutput systems.

The first problem can be traced back to commit 0104375
where the state of qcbEcho depends on the selected element of the AudioOutput
dropdown menu, before it has been filled.

The second problem probably goes back to 2991d20 where the
enabled state of the qcbEcho checkbox was changed on changing audio systems, but
the checked state was not reloaded.

This commit refactors the code (swaps initializing input and output)
and adds a shared method to update the qcbEcho checkbox appropriately.

Fixes mumble-voip#6544

src/mumble/AudioWizard.cpp

@@ -44,26 +44,8 @@ AudioWizard::AudioWizard(QWidget *p) : QWizard(p) {
 	qcbUsage->setChecked(Global::get().s.bUsage);
 
 	// Device
-	if (AudioInputRegistrar::qmNew) {
-		foreach (AudioInputRegistrar *air, *AudioInputRegistrar::qmNew) {
-			qcbInput->addItem(air->name);
-			if (air->name == AudioInputRegistrar::current) {
-				qcbInput->setCurrentIndex(qcbInput->count() - 1);
-				EchoCancelOptionID echoCancelOptionId = firstUsableEchoCancellation(air, qcbOutput->currentText());
-				if (echoCancelOptionId != EchoCancelOptionID::DISABLED) {
-					qcbEcho->setEnabled(true);
-					qcbEcho->setChecked(Global::get().s.echoOption != EchoCancelOptionID::DISABLED);
-				}
-			}
-			QList< audioDevice > ql = air->getDeviceChoices();
-		}
-	}
-	if (qcbInput->count() < 2) {
-		qcbInput->setEnabled(false);
-	}
-
 	if (AudioOutputRegistrar::qmNew) {
-		foreach (AudioOutputRegistrar *aor, *AudioOutputRegistrar::qmNew) {
+		for (AudioOutputRegistrar *aor : *AudioOutputRegistrar::qmNew) {
 			qcbOutput->addItem(aor->name);
 			if (aor->name == AudioOutputRegistrar::current) {
 				qcbOutput->setCurrentIndex(qcbOutput->count() - 1);
@@ -73,11 +55,24 @@ AudioWizard::AudioWizard(QWidget *p) : QWizard(p) {
 			QList< audioDevice > ql = aor->getDeviceChoices();
 		}
 	}
-
 	if (qcbOutput->count() < 2) {
 		qcbOutput->setEnabled(false);
 	}
 
+	if (AudioInputRegistrar::qmNew) {
+		for (AudioInputRegistrar *air : *AudioInputRegistrar::qmNew) {
+			qcbInput->addItem(air->name);
+			if (air->name == AudioInputRegistrar::current) {
+				qcbInput->setCurrentIndex(qcbInput->count() - 1);
+				updateEchoCheckbox(air);
+			}
+			QList< audioDevice > ql = air->getDeviceChoices();
+		}
+	}
+	if (qcbInput->count() < 2) {
+		qcbInput->setEnabled(false);
+	}
+
 	qcbHighContrast->setChecked(Global::get().s.bHighContrast);
 	on_qcbHighContrast_clicked(Global::get().s.bHighContrast);
 #ifdef Q_OS_WIN
@@ -243,8 +238,7 @@ void AudioWizard::on_qcbInputDevice_activated(int) {
 		air->setDeviceChoice(qcbInputDevice->itemData(idx), Global::get().s);
 	}
 
-	EchoCancelOptionID echoCancelOptionId = firstUsableEchoCancellation(air, qcbOutput->currentText());
-	qcbEcho->setEnabled(echoCancelOptionId != EchoCancelOptionID::DISABLED);
+	updateEchoCheckbox(air);
 
 	Global::get().ai = AudioInputPtr(air->create());
 	Global::get().ai->start(QThread::HighestPriority);
@@ -284,9 +278,7 @@ void AudioWizard::on_qcbOutputDevice_activated(int) {
 		bDelay = aor->usesOutputDelay();
 	}
 
-	AudioInputRegistrar *air              = AudioInputRegistrar::qmNew->value(qcbInput->currentText());
-	EchoCancelOptionID echoCancelOptionId = firstUsableEchoCancellation(air, qcbOutput->currentText());
-	qcbEcho->setEnabled(echoCancelOptionId != EchoCancelOptionID::DISABLED);
+	updateEchoCheckbox(AudioInputRegistrar::qmNew->value(qcbInput->currentText()));
 
 	Global::get().ao = AudioOutputPtr(aor->create());
 	Global::get().ao->start(QThread::HighPriority);
@@ -767,6 +759,18 @@ void AudioWizard::on_qrbQualityCustom_clicked() {
 	restartAudio(true);
 }
 
+void AudioWizard::updateEchoCheckbox(AudioInputRegistrar *air) {
+	bool echoCancelPossible =
+		firstUsableEchoCancellation(air, qcbOutput->currentText()) != EchoCancelOptionID::DISABLED;
+
+	qcbEcho->setEnabled(echoCancelPossible);
+	if (echoCancelPossible) {
+		qcbEcho->setChecked(Global::get().s.echoOption != EchoCancelOptionID::DISABLED);
+	} else {
+		qcbEcho->setChecked(false);
+	}
+}
+
 EchoCancelOptionID AudioWizard::firstUsableEchoCancellation(AudioInputRegistrar *air, const QString outputSys) {
 	for (EchoCancelOptionID ecoid : air->echoOptions) {
 		if (air->canEcho(ecoid, outputSys)) {

src/mumble/AudioWizard.h

@@ -20,6 +20,8 @@ class AudioWizard : public QWizard, public Ui::AudioWizard {
 	Q_OBJECT
 	Q_DISABLE_COPY(AudioWizard)
 
+	void updateEchoCheckbox(AudioInputRegistrar *air);
+
 	/// Which echo cancellation is usable depends on the audio backend and the device combination.
 	/// This function will iterate through the list of available echo cancellation in the audio backend and check with
 	/// the backend whether this echo cancellation option works for current device combination.