Merge pull request #13312 from ronso0/startup-no-sound-IO-fix

(fix) Sound config: fix UX when applying config with missing/busy devices

src/preferences/dialog/dlgpreferences.cpp

@@ -428,6 +428,9 @@ void DlgPreferences::slotButtonPressed(QAbstractButton* pButton) {
     case QDialogButtonBox::AcceptRole:
         // Same as Apply but close the dialog
         emit applyPreferences();
+        // TODO Unfortunately this will accept() even if DlgPrefSound threw a warning
+        // due to inaccessible device(s) or inapplicable samplerate.
+        // https://github.com/mixxxdj/mixxx/issues/6077
         accept();
         break;
     case QDialogButtonBox::RejectRole:

src/preferences/dialog/dlgprefsound.cpp

@@ -120,6 +120,9 @@ DlgPrefSound::DlgPrefSound(QWidget* pParent,
     headDelaySpinBox->setValue(m_pHeadDelay->get());
     boothDelaySpinBox->setValue(m_pBoothDelay->get());
 
+    // TODO These settings are applied immediately via ControlProxies.
+    // While this is handy for testing the delays, it breaks the rule to
+    // apply only in slotApply(). Add hint to UI?
     connect(latencyCompensationSpinBox,
             QOverload<double>::of(&QDoubleSpinBox::valueChanged),
             this,
@@ -263,18 +266,12 @@ DlgPrefSound::DlgPrefSound(QWidget* pParent,
                             MIXXX_WIKI_HARDWARE_COMPATIBILITY_URL)));
 }
 
-/// Slot called when the preferences dialog is opened or this pane is
-/// selected.
+/// Slot called when the preferences dialog is opened.
 void DlgPrefSound::slotUpdate() {
-    // this is unfortunate, because slotUpdate is called every time
-    // we change to this pane, we lose changed and unapplied settings
-    // every time. There's no real way around this, just another argument
-    // for a prefs rewrite -- bkgood
     m_bSkipConfigClear = true;
     loadSettings();
     checkLatencyCompensation();
     m_bSkipConfigClear = false;
-    m_settingsModified = false;
 }
 
 /// Slot called when the Apply or OK button is pressed.
@@ -386,6 +383,10 @@ void DlgPrefSound::connectSoundItem(DlgPrefSoundItem* pItem) {
             &DlgPrefSoundItem::selectedChannelsChanged,
             this,
             &DlgPrefSound::deviceChannelsChanged);
+    connect(pItem,
+            &DlgPrefSoundItem::configuredDeviceNotFound,
+            this,
+            &DlgPrefSound::configuredDeviceNotFound);
     connect(this, &DlgPrefSound::loadPaths, pItem, &DlgPrefSoundItem::loadPath);
     connect(this, &DlgPrefSound::writePaths, pItem, &DlgPrefSoundItem::writePath);
     if (pItem->isInput()) {
@@ -678,6 +679,18 @@ void DlgPrefSound::settingChanged() {
     m_settingsModified = true;
 }
 
+/// Slot called when a device from the config can not be selected, i.e. is
+/// currently not available. This may happen during startup when MixxxMainWindow
+/// opens this page to allow users to make adjustments in case configured
+/// devices are busy/missing.
+/// The issue is that the visual state (combobox(es) with 'None') does not match
+/// the untouched config state. This set the modified flag so slotApply() will
+/// apply the (seemingly) unchanged configuration if users simply click Apply/Okay
+/// because they are okay to continue without these devices.
+void DlgPrefSound::configuredDeviceNotFound() {
+    m_settingsModified = true;
+}
+
 void DlgPrefSound::deviceChanged() {
     if (m_loading) {
         return;

src/preferences/dialog/dlgprefsound.h

@@ -70,6 +70,7 @@ class DlgPrefSound : public DlgPreferencePage, public Ui::DlgPrefSoundDlg  {
     void settingChanged();
     void deviceChanged();
     void deviceChannelsChanged();
+    void configuredDeviceNotFound();
     void queryClicked();
 
   private:

src/preferences/dialog/dlgprefsounditem.cpp

@@ -246,14 +246,18 @@ SoundDevicePointer DlgPrefSoundItem::getDevice() const {
     return SoundDevicePointer();
 }
 
-/// Selects a device in the device combo box given a SoundDevice
-/// internal name, or selects "None" if the device isn't found.
+/// Selects a device in the device combo box given a SoundDevice' internal name,
+/// or selects "None" if the device is nullptr or isn't found.
+/// Called only internally via DlPrefSound::loadPaths()
 void DlgPrefSoundItem::setDevice(const SoundDeviceId& device) {
     int index = deviceComboBox->findData(QVariant::fromValue(device));
-    //qDebug() << "DlgPrefSoundItem::setDevice" << device;
     if (index == -1) {
         deviceComboBox->setCurrentIndex(0); // None
         emit selectedDeviceChanged();
+        if (device != SoundDeviceId()) {
+            // Notify DlgPrefSound that the device that can't be found.
+            emit configuredDeviceNotFound();
+        }
     } else {
         m_emitSettingChanged = false;
         deviceComboBox->setCurrentIndex(index);

src/preferences/dialog/dlgprefsounditem.h

@@ -36,6 +36,7 @@ class DlgPrefSoundItem : public QWidget, public Ui::DlgPrefSoundItem {
   signals:
     void selectedDeviceChanged();
     void selectedChannelsChanged();
+    void configuredDeviceNotFound();
 
   public slots:
     void refreshDevices(const QList<SoundDevicePointer>& devices);