AutoDJ: handle "enabled" CO change requests like clicks on the GUI bu…

…tton

otherwise, if AutoDJ refuses to start because of unmet conditions, no error messages are shown
and the CO remains in 'enabled' state.

src/library/autodj/autodjprocessor.cpp

@@ -145,8 +145,8 @@ AutoDJProcessor::AutoDJProcessor(
     m_pEnabledAutoDJ = new ControlPushButton(
             ConfigKey("[AutoDJ]", "enabled"));
     m_pEnabledAutoDJ->setButtonMode(ControlPushButton::TOGGLE);
-    connect(m_pEnabledAutoDJ, &ControlObject::valueChanged,
-            this, &AutoDJProcessor::controlEnable);
+    m_pEnabledAutoDJ->connectValueChangeRequest(this,
+            &AutoDJProcessor::autoDJStateChangeRequest);
 
     // TODO(rryan) listen to signals from PlayerManager and add/remove as decks
     // are created.

src/library/autodj/autodjprocessor.h

@@ -203,6 +203,7 @@ class AutoDJProcessor : public QObject {
   signals:
     void loadTrackToPlayer(TrackPointer pTrack, const QString& group, bool play);
     void autoDJStateChanged(AutoDJProcessor::AutoDJState state);
+    void autoDJStateChangeRequest(bool enable);
     void transitionTimeChanged(int time);
     void randomTrackRequested(int tracksToAdd);
 

src/library/autodj/dlgautodj.cpp

@@ -88,6 +88,12 @@ DlgAutoDJ::DlgAutoDJ(
             &QPushButton::clicked,
             this,
             &DlgAutoDJ::toggleAutoDJButton);
+    // Connect the 'enabled' ControlPushButton to the same slot so we can show
+    // potential error messages here
+    connect(m_pAutoDJProcessor,
+            &AutoDJProcessor::autoDJStateChangeRequest,
+            this,
+            &DlgAutoDJ::toggleAutoDJButton);
 
     setupActionButton(pushButtonFadeNow, &DlgAutoDJ::fadeNowButton, tr("Fade"));
     setupActionButton(pushButtonSkipNext, &DlgAutoDJ::skipNextButton, tr("Skip"));