Merge branch '2.3' of github.com:mixxxdj/mixxx into cleanup-headers

53 files changed, 735 insertions, 515 deletions

diff --git a/src/engine/cachingreader/cachingreader.cpp b/src/engine/cachingreader/cachingreader.cpp
index d7332eb27c..592371a686 100644
--- a/src/engine/cachingreader/cachingreader.cpp
+++ b/src/engine/cachingreader/cachingreader.cpp
@@ -40,7 +40,7 @@ const SINT kNumberOfCachedChunksInMemory = 80;
 
 } // anonymous namespace
 
-CachingReader::CachingReader(QString group,
+CachingReader::CachingReader(const QString& group,
         UserSettingsPointer config)
         : m_pConfig(config),
           // Limit the number of in-flight requests to the worker. This should
diff --git a/src/engine/cachingreader/cachingreader.h b/src/engine/cachingreader/cachingreader.h
index b46f817877..c5f5a6ee32 100644
--- a/src/engine/cachingreader/cachingreader.h
+++ b/src/engine/cachingreader/cachingreader.h
@@ -72,8 +72,8 @@ class CachingReader : public QObject {
 
   public:
     // Construct a CachingReader with the given group.
-    CachingReader(QString group,
-                  UserSettingsPointer _config);
+    CachingReader(const QString& group,
+            UserSettingsPointer _config);
     ~CachingReader() override;
 
     void process();
@@ -112,7 +112,7 @@ class CachingReader : public QObject {
     // Emitted once a new track is loaded and ready to be read from.
     void trackLoading();
     void trackLoaded(TrackPointer pTrack, int iSampleRate, int iNumSamples);
-    void trackLoadFailed(TrackPointer pTrack, QString reason);
+    void trackLoadFailed(TrackPointer pTrack, const QString& reason);
 
   private:
     const UserSettingsPointer m_pConfig;
diff --git a/src/engine/cachingreader/cachingreaderworker.cpp b/src/engine/cachingreader/cachingreaderworker.cpp
index ae5b9d8256..aefd482d04 100644
--- a/src/engine/cachingreader/cachingreaderworker.cpp
+++ b/src/engine/cachingreader/cachingreaderworker.cpp
@@ -18,7 +18,7 @@ mixxx::Logger kLogger("CachingReaderWorker");
 } // anonymous namespace
 
 CachingReaderWorker::CachingReaderWorker(
-        QString group,
+        const QString& group,
         FIFO<CachingReaderChunkReadRequest>* pChunkReadRequestFIFO,
         FIFO<ReaderStatusUpdate>* pReaderStatusFIFO)
         : m_group(group),
diff --git a/src/engine/cachingreader/cachingreaderworker.h b/src/engine/cachingreader/cachingreaderworker.h
index 78b36dd396..09801eebb8 100644
--- a/src/engine/cachingreader/cachingreaderworker.h
+++ b/src/engine/cachingreader/cachingreaderworker.h
@@ -96,7 +96,7 @@ class CachingReaderWorker : public EngineWorker {
 
   public:
     // Construct a CachingReader with the given group.
-    CachingReaderWorker(QString group,
+    CachingReaderWorker(const QString& group,
             FIFO<CachingReaderChunkReadRequest>* pChunkReadRequestFIFO,
             FIFO<ReaderStatusUpdate>* pReaderStatusFIFO);
     ~CachingReaderWorker() override = default;
@@ -114,7 +114,7 @@ class CachingReaderWorker : public EngineWorker {
     // Emitted once a new track is loaded and ready to be read from.
     void trackLoading();
     void trackLoaded(TrackPointer pTrack, int iSampleRate, int iNumSamples);
-    void trackLoadFailed(TrackPointer pTrack, QString reason);
+    void trackLoadFailed(TrackPointer pTrack, const QString& reason);
 
   private:
     const QString m_group;
diff --git a/src/engine/channels/engineaux.cpp b/src/engine/channels/engineaux.cpp
index 08748e71a7..ecba74bc13 100644
--- a/src/engine/channels/engineaux.cpp
+++ b/src/engine/channels/engineaux.cpp
@@ -42,7 +42,7 @@ bool EngineAux::isActive() {
     return m_wasActive;
 }
 
-void EngineAux::onInputConfigured(AudioInput input) {
+void EngineAux::onInputConfigured(const AudioInput& input) {
     if (input.getType() != AudioPath::AUXILIARY) {
         // This is an error!
         qDebug() << "WARNING: EngineAux connected to AudioInput for a non-auxiliary type!";
@@ -52,7 +52,7 @@ void EngineAux::onInputConfigured(AudioInput input) {
     m_pInputConfigured->forceSet(1.0);
 }
 
-void EngineAux::onInputUnconfigured(AudioInput input) {
+void EngineAux::onInputUnconfigured(const AudioInput& input) {
     if (input.getType() != AudioPath::AUXILIARY) {
         // This is an error!
         qDebug() << "WARNING: EngineAux connected to AudioInput for a non-auxiliary type!";
@@ -62,8 +62,8 @@ void EngineAux::onInputUnconfigured(AudioInput input) {
     m_pInputConfigured->forceSet(0.0);
 }
 
-void EngineAux::receiveBuffer(AudioInput input, const CSAMPLE* pBuffer,
-                              unsigned int nFrames) {
+void EngineAux::receiveBuffer(
+        const AudioInput& input, const CSAMPLE* pBuffer, unsigned int nFrames) {
     Q_UNUSED(input);
     Q_UNUSED(nFrames);
     m_sampleBuffer = pBuffer;
diff --git a/src/engine/channels/engineaux.h b/src/engine/channels/engineaux.h
index 296055e1f3..2362c32c0d 100644
--- a/src/engine/channels/engineaux.h
+++ b/src/engine/channels/engineaux.h
@@ -30,16 +30,17 @@ class EngineAux : public EngineChannel, public AudioDestination {
     /// the soundcard this AudioDestination was registered for! Beware, in the
     /// case of multiple soundcards, this method is not re-entrant but it may be
     /// concurrent with EngineMaster processing.
-    virtual void receiveBuffer(AudioInput input, const CSAMPLE* pBuffer,
-                               unsigned int nFrames);
+    virtual void receiveBuffer(const AudioInput& input,
+            const CSAMPLE* pBuffer,
+            unsigned int nFrames);
 
     /// Called by SoundManager whenever the aux input is connected to a
     /// soundcard input.
-    virtual void onInputConfigured(AudioInput input);
+    virtual void onInputConfigured(const AudioInput& input);
 
     /// Called by SoundManager whenever the aux input is disconnected from
     /// a soundcard input.
-    virtual void onInputUnconfigured(AudioInput input);
+    virtual void onInputUnconfigured(const AudioInput& input);
 
   private:
     QScopedPointer<ControlObject> m_pInputConfigured;
diff --git a/src/engine/channels/enginedeck.cpp b/src/engine/channels/enginedeck.cpp
index 27431078c6..8eeb3d1bad 100644
--- a/src/engine/channels/enginedeck.cpp
+++ b/src/engine/channels/enginedeck.cpp
@@ -131,7 +131,8 @@ bool EngineDeck::isActive() {
     return active;
 }
 
-void EngineDeck::receiveBuffer(AudioInput input, const CSAMPLE* pBuffer, unsigned int nFrames) {
+void EngineDeck::receiveBuffer(
+        const AudioInput& input, const CSAMPLE* pBuffer, unsigned int nFrames) {
     Q_UNUSED(input);
     Q_UNUSED(nFrames);
     // Skip receiving audio input if passthrough is not active
@@ -143,7 +144,7 @@ void EngineDeck::receiveBuffer(AudioInput input, const CSAMPLE* pBuffer, unsigne
     }
 }
 
-void EngineDeck::onInputConfigured(AudioInput input) {
+void EngineDeck::onInputConfigured(const AudioInput& input) {
     if (input.getType() != AudioPath::VINYLCONTROL) {
         // This is an error!
         qDebug() << "WARNING: EngineDeck connected to AudioInput for a non-vinylcontrol type!";
@@ -153,7 +154,7 @@ void EngineDeck::onInputConfigured(AudioInput input) {
     m_sampleBuffer =  NULL;
 }
 
-void EngineDeck::onInputUnconfigured(AudioInput input) {
+void EngineDeck::onInputUnconfigured(const AudioInput& input) {
     if (input.getType() != AudioPath::VINYLCONTROL) {
         // This is an error!
         qDebug() << "WARNING: EngineDeck connected to AudioInput for a non-vinylcontrol type!";
diff --git a/src/engine/channels/enginedeck.h b/src/engine/channels/enginedeck.h
index f571dadb38..cc0006c9c7 100644
--- a/src/engine/channels/enginedeck.h
+++ b/src/engine/channels/enginedeck.h
@@ -62,16 +62,17 @@ class EngineDeck : public EngineChannel, public AudioDestination {
     // the soundcard this AudioDestination was registered for! Beware, in the
     // case of multiple soundcards, this method is not re-entrant but it may be
     // concurrent with EngineMaster processing.
-    virtual void receiveBuffer(AudioInput input, const CSAMPLE* pBuffer,
-                               unsigned int nFrames);
+    virtual void receiveBuffer(const AudioInput& input,
+            const CSAMPLE* pBuffer,
+            unsigned int nFrames);
 
     // Called by SoundManager whenever the passthrough input is connected to a
     // soundcard input.
-    virtual void onInputConfigured(AudioInput input);
+    virtual void onInputConfigured(const AudioInput& input);
 
     // Called by SoundManager whenever the passthrough input is disconnected
     // from a soundcard input.
-    virtual void onInputUnconfigured(AudioInput input);
+    virtual void onInputUnconfigured(const AudioInput& input);
 
     // Return whether or not passthrough is active
     bool isPassthroughActive() const;
diff --git a/src/engine/channels/enginemicrophone.cpp b/src/engine/channels/enginemicrophone.cpp
index 0e22b88d7d..884c5633d1 100644
--- a/src/engine/channels/enginemicrophone.cpp
+++ b/src/engine/channels/enginemicrophone.cpp
@@ -40,7 +40,7 @@ bool EngineMicrophone::isActive() {
     return m_wasActive;
 }
 
-void EngineMicrophone::onInputConfigured(AudioInput input) {
+void EngineMicrophone::onInputConfigured(const AudioInput& input) {
     if (input.getType() != AudioPath::MICROPHONE) {
         // This is an error!
         qWarning() << "EngineMicrophone connected to AudioInput for a non-Microphone type!";
@@ -50,7 +50,7 @@ void EngineMicrophone::onInputConfigured(AudioInput input) {
     m_pInputConfigured->forceSet(1.0);
 }
 
-void EngineMicrophone::onInputUnconfigured(AudioInput input) {
+void EngineMicrophone::onInputUnconfigured(const AudioInput& input) {
     if (input.getType() != AudioPath::MICROPHONE) {
         // This is an error!
         qWarning() << "EngineMicrophone connected to AudioInput for a non-Microphone type!";
@@ -60,8 +60,8 @@ void EngineMicrophone::onInputUnconfigured(AudioInput input) {
     m_pInputConfigured->forceSet(0.0);
 }
 
-void EngineMicrophone::receiveBuffer(AudioInput input, const CSAMPLE* pBuffer,
-                                     unsigned int nFrames) {
+void EngineMicrophone::receiveBuffer(
+        const AudioInput& input, const CSAMPLE* pBuffer, unsigned int nFrames) {
     Q_UNUSED(input);
     Q_UNUSED(nFrames);
     m_sampleBuffer = pBuffer;
diff --git a/src/engine/channels/enginemicrophone.h b/src/engine/channels/enginemicrophone.h
index e5190dc72f..b9611e7cb8 100644
--- a/src/engine/channels/enginemicrophone.h
+++ b/src/engine/channels/enginemicrophone.h
@@ -34,16 +34,17 @@ class EngineMicrophone : public EngineChannel, public AudioDestination {
     // the soundcard this AudioDestination was registered for! Beware, in the
     // case of multiple soundcards, this method is not re-entrant but it may be
     // concurrent with EngineMaster processing.
-    virtual void receiveBuffer(AudioInput input, const CSAMPLE* pBuffer,
-                               unsigned int iNumSamples);
+    virtual void receiveBuffer(const AudioInput& input,
+            const CSAMPLE* pBuffer,
+            unsigned int iNumSamples);
 
     // Called by SoundManager whenever the microphone input is connected to a
     // soundcard input.
-    virtual void onInputConfigured(AudioInput input);
+    virtual void onInputConfigured(const AudioInput& input);
 
     // Called by SoundManager whenever the microphone input is disconnected from
     // a soundcard input.
-    virtual void onInputUnconfigured(AudioInput input);
+    virtual void onInputUnconfigured(const AudioInput& input);
 
     bool isSolo();
     double getSoloDamping();
diff --git a/src/engine/controls/bpmcontrol.cpp b/src/engine/controls/bpmcontrol.cpp
index 20285ca89f..52370da16d 100644
--- a/src/engine/controls/bpmcontrol.cpp
+++ b/src/engine/controls/bpmcontrol.cpp
@@ -40,7 +40,7 @@ constexpr int kLocalBpmSpan = 4;
 constexpr SINT kSamplesPerFrame = 2;
 }
 
-BpmControl::BpmControl(QString group,
+BpmControl::BpmControl(const QString& group,
         UserSettingsPointer pConfig)
         : EngineControl(group, pConfig),
           m_tapFilter(this, kBpmTapFilterLength, kBpmTapMaxInterval),
diff --git a/src/engine/controls/bpmcontrol.h b/src/engine/controls/bpmcontrol.h
index 4257595dc5..156fdca700 100644
--- a/src/engine/controls/bpmcontrol.h
+++ b/src/engine/controls/bpmcontrol.h
@@ -22,7 +22,7 @@ class BpmControl : public EngineControl {
     Q_OBJECT
 
   public:
-    BpmControl(QString group, UserSettingsPointer pConfig);
+    BpmControl(const QString& group, UserSettingsPointer pConfig);
     ~BpmControl() override;
 
     double getBpm() const;
diff --git a/src/engine/controls/clockcontrol.cpp b/src/engine/controls/clockcontrol.cpp
index 2a374aa1b4..f48660bb4c 100644
--- a/src/engine/controls/clockcontrol.cpp
+++ b/src/engine/controls/clockcontrol.cpp
@@ -6,7 +6,7 @@
 #include "preferences/usersettings.h"
 #include "track/track.h"
 
-ClockControl::ClockControl(QString group, UserSettingsPointer pConfig)
+ClockControl::ClockControl(const QString& group, UserSettingsPointer pConfig)
         : EngineControl(group, pConfig) {
     m_pCOBeatActive = new ControlObject(ConfigKey(group, "beat_active"));
     m_pCOBeatActive->set(0.0);
diff --git a/src/engine/controls/clockcontrol.h b/src/engine/controls/clockcontrol.h
index 1a26d30d8c..87667db443 100644
--- a/src/engine/controls/clockcontrol.h
+++ b/src/engine/controls/clockcontrol.h
@@ -11,8 +11,8 @@ class ControlObject;
 class ClockControl: public EngineControl {
     Q_OBJECT
   public:
-    ClockControl(QString group,
-                 UserSettingsPointer pConfig);
+    ClockControl(const QString& group,
+            UserSettingsPointer pConfig);
 
     ~ClockControl() override;
 
diff --git a/src/engine/controls/cuecontrol.cpp b/src/engine/controls/cuecontrol.cpp
index 3a92609105..f8ac0c8e20 100644
--- a/src/engine/controls/cuecontrol.cpp
+++ b/src/engine/controls/cuecontrol.cpp
@@ -26,6 +26,7 @@ constexpr double CUE_MODE_CUP = 5.0;
 
 /// This is the position of a fresh loaded tack without any seek
 constexpr double kDefaultLoadPosition = 0.0;
+constexpr int kNoHotCueNumber = 0;
 
 // Helper function to convert control values (i.e. doubles) into RgbColor
 // instances (or nullopt if value < 0). This happens by using the integer
@@ -41,9 +42,37 @@ inline mixxx::RgbColor::optional_t doubleToRgbColor(double value) {
     return mixxx::RgbColor::optional(colorCode);
 }
 
+/// Convert hot cue index to 1-based number
+///
+/// Works independent of if the hot cue index is either 0-based
+/// or 1..n-based.
+inline int hotcueIndexToHotcueNumber(int hotcueIndex) {
+    if (hotcueIndex >= Cue::kFirstHotCue) {
+        DEBUG_ASSERT(hotcueIndex != Cue::kNoHotCue);
+        return (hotcueIndex - Cue::kFirstHotCue) + 1; // to 1-based numbering
+    } else {
+        DEBUG_ASSERT(hotcueIndex == Cue::kNoHotCue);
+        return kNoHotCueNumber;
+    }
+}
+
+/// Convert 1-based hot cue number to hot cue index.
+///
+/// Works independent of if the hot cue index is either 0-based
+/// or 1..n-based.
+inline int hotcueNumberToHotcueIndex(int hotcueNumber) {
+    if (hotcueNumber >= 1) {
+        DEBUG_ASSERT(hotcueNumber != kNoHotCueNumber);
+        return Cue::kFirstHotCue + (hotcueNumber - 1); // from 1-based numbering
+    } else {
+        DEBUG_ASSERT(hotcueNumber == kNoHotCueNumber);
+        return Cue::kNoHotCue;
+    }
+}
+
 } // namespace
 
-CueControl::CueControl(QString group,
+CueControl::CueControl(const QString& group,
         UserSettingsPointer pConfig)
         : EngineControl(group, pConfig),
           m_pConfig(pConfig),
@@ -132,6 +161,9 @@ CueControl::CueControl(QString group,
     m_pCueIndicator = new ControlIndicator(ConfigKey(group, "cue_indicator"));
     m_pPlayIndicator = new ControlIndicator(ConfigKey(group, "play_indicator"));
 
+    m_pPlayLatched = new ControlObject(ConfigKey(group, "play_latched"));
+    m_pPlayLatched->setReadOnly();
+
     m_pIntroStartPosition = new ControlObject(ConfigKey(group, "intro_start_position"));
     m_pIntroStartPosition->set(Cue::kNoPosition);
 
@@ -220,7 +252,7 @@ CueControl::CueControl(QString group,
     m_pVinylControlMode = new ControlProxy(group, "vinylcontrol_mode");
 
     m_pHotcueFocus = new ControlObject(ConfigKey(group, "hotcue_focus"));
-    m_pHotcueFocus->set(Cue::kNoHotCue);
+    setHotcueFocusIndex(Cue::kNoHotCue);
 
     m_pHotcueFocusColorPrev = new ControlObject(ConfigKey(group, "hotcue_focus_color_prev"));
     connect(m_pHotcueFocusColorPrev,
@@ -252,6 +284,7 @@ CueControl::~CueControl() {
     delete m_pPlayStutter;
     delete m_pCueIndicator;
     delete m_pPlayIndicator;
+    delete m_pPlayLatched;
     delete m_pIntroStartPosition;
     delete m_pIntroStartEnabled;
     delete m_pIntroStartSet;
@@ -313,7 +346,7 @@ void CueControl::createControls() {
     }
 }
 
-void CueControl::attachCue(CuePointer pCue, HotcueControl* pControl) {
+void CueControl::attachCue(const CuePointer& pCue, HotcueControl* pControl) {
     VERIFY_OR_DEBUG_ASSERT(pControl) {
         return;
     }
@@ -355,7 +388,7 @@ void CueControl::trackLoaded(TrackPointer pNewTrack) {
         m_pOutroStartEnabled->forceSet(0.0);
         m_pOutroEndPosition->set(Cue::kNoPosition);
         m_pOutroEndEnabled->forceSet(0.0);
-        m_pHotcueFocus->set(Cue::kNoHotCue);
+        setHotcueFocusIndex(Cue::kNoHotCue);
         m_pLoadedTrack.reset();
         m_usedSeekOnLoadPosition.setValue(kDefaultLoadPosition);
     }
@@ -644,15 +677,16 @@ void CueControl::quantizeChanged(double v) {
 void CueControl::hotcueSet(HotcueControl* pControl, double value) {
     //qDebug() << "CueControl::hotcueSet" << value;
 
-    if (value == 0) {
+    if (value <= 0) {
         return;
     }
 
     QMutexLocker lock(&m_mutex);
-    if (!m_pLoadedTrack)
+    if (!m_pLoadedTrack) {
         return;
+    }
 
-    int hotcue = pControl->getHotcueNumber();
+    int hotcueIndex = pControl->getHotcueIndex();
     // Note: the cue is just detached from the hotcue control
     // It remains in the database for later use
     // TODO: find a rule, that allows us to delete the cue as well
@@ -662,14 +696,14 @@ void CueControl::hotcueSet(HotcueControl* pControl, double value) {
     CuePointer pCue(m_pLoadedTrack->createAndAddCue());
     double cuePosition = getQuantizedCurrentPosition();
     pCue->setStartPosition(cuePosition);
-    pCue->setHotCue(hotcue);
+    pCue->setHotCue(hotcueIndex);
     pCue->setLabel();
     pCue->setType(mixxx::CueType::HotCue);
 
     const ColorPalette hotcueColorPalette =
             m_colorPaletteSettings.getHotcueColorPalette();
     if (getConfig()->getValue(ConfigKey("[Controls]", "auto_hotcue_colors"), false)) {
-        pCue->setColor(hotcueColorPalette.colorForHotcueIndex(hotcue));
+        pCue->setColor(hotcueColorPalette.colorForHotcueIndex(hotcueIndex));
     } else {
         int hotcueDefaultColorIndex = m_pConfig->getValue(ConfigKey("[Controls]", "HotcueDefaultColorIndex"), -1);
         if (hotcueDefaultColorIndex < 0 || hotcueDefaultColorIndex >= hotcueColorPalette.size()) {
@@ -693,7 +727,7 @@ void CueControl::hotcueSet(HotcueControl* pControl, double value) {
 }
 
 void CueControl::hotcueGoto(HotcueControl* pControl, double value) {
-    if (value == 0) {
+    if (value <= 0) {
         return;
     }
 
@@ -716,7 +750,7 @@ void CueControl::hotcueGoto(HotcueControl* pControl, double value) {
 }
 
 void CueControl::hotcueGotoAndStop(HotcueControl* pControl, double value) {
-    if (value == 0) {
+    if (value <= 0) {
         return;
     }
 
@@ -732,14 +766,19 @@ void CueControl::hotcueGotoAndStop(HotcueControl* pControl, double value) {
     if (pCue) {
         double position = pCue->getPosition();
         if (position != Cue::kNoPosition) {
-            m_pPlay->set(0.0);
-            seekExact(position);
+            if (!m_iCurrentlyPreviewingHotcues && !m_bPreviewing) {
+                m_pPlay->set(0.0);
+                seekExact(position);
+            } else {
+                // this becomes a play latch command if we are previewing
+                m_pPlay->set(0.0);
+            }
         }
     }
 }
 
 void CueControl::hotcueGotoAndPlay(HotcueControl* pControl, double value) {
-    if (value == 0) {
+    if (value <= 0) {
         return;
     }
 
@@ -784,7 +823,7 @@ void CueControl::hotcueActivate(HotcueControl* pControl, double value) {
     lock.unlock();
 
     if (pCue) {
-        if (value != 0) {
+        if (value > 0) {
             if (pCue->getPosition() == Cue::kNoPosition) {
                 hotcueSet(pControl, value);
             } else {
@@ -801,7 +840,7 @@ void CueControl::hotcueActivate(HotcueControl* pControl, double value) {
         }<