Effect chain selectors: add empty item to allow clearing the chain

src/effects/chains/quickeffectchain.cpp

@@ -11,6 +11,7 @@ QuickEffectChain::QuickEffectChain(const QString& group,
                   SignalProcessingStage::Postfader,
                   pEffectsManager,
                   pEffectsMessenger) {
+    m_isQuickEffectChain = true;
     for (int i = 0; i < kNumEffectsPerUnit; ++i) {
         addEffectSlot(formatEffectSlotGroup(group, i));
         m_effectSlots.at(i)->setEnabled(true);

src/effects/effectchain.cpp

@@ -202,7 +202,24 @@ const QString& EffectChain::presetName() const {
 
 void EffectChain::loadChainPreset(EffectChainPresetPointer pPreset) {
     slotControlClear(1);
-    VERIFY_OR_DEBUG_ASSERT(pPreset) {
+    if (!pPreset) {
+        // This may happen when a chain is cleared by selecting the empty '---'
+        // item in WEffectChainPresetSelector or in deck Quick Effect selectors
+        // in DlgPrefEq.
+        // Quick Effect chains and other chains need to be treated differently:
+        // * storing Quick Effect chain presets requires a preset name, otherwise
+        //  (empty name) will cause the default preset being loaded on next start.
+        //  Thus, we name the empty preset kNoEffectString so that the respective
+        //  item is selected in the chain preset selector and also no chain will be
+        //  loaded on next start.
+        // * storing states of regular [EffectRack1] chains doesn't require a preset
+        //  name, also they can be edited, so kNoEffectString would be incorrect
+        //  after loading an effect. Thus, if this is not a Quick Effetc chain, we
+        //  just clear the preset name which in turn clears the chain's preset
+        //  selector and chain name label.
+        m_presetName = m_isQuickEffectChain ? kNoEffectString : QString();
+        emit chainPresetChanged(m_presetName);
+        setControlLoadedPresetIndex(std::nullopt);
         return;
     }
 
@@ -349,9 +366,10 @@ void EffectChain::slotControlLoadedChainPresetRequest(double value) {
     loadChainPreset(presetAtIndex(index));
 }
 
-void EffectChain::setControlLoadedPresetIndex(uint index) {
-    // add 1 to make the ControlObject 1-indexed like other ControlObjects
-    m_pControlLoadedChainPreset->setAndConfirm(index + 1);
+void EffectChain::setControlLoadedPresetIndex(std::optional<uint> index) {
+    // add 1 to make the ControlObject 1-indexed like other ControlObjects.
+    // if the effect chain is cleared (no valid index), the CO is set 0;
+    m_pControlLoadedChainPreset->setAndConfirm(index ? *index + 1 : 0);
 }
 
 void EffectChain::slotControlNextChainPreset(double value) {

src/effects/effectchain.h

@@ -13,6 +13,7 @@
 #include "engine/channelhandle.h"
 #include "util/class.h"
 #include "util/memory.h"
+#include "util/optional.h"
 
 class ControlPushButton;
 class ControlEncoder;
@@ -90,6 +91,7 @@ class EffectChain : public QObject {
 
   protected:
     EffectSlotPointer addEffectSlot(const QString& group);
+    bool m_isQuickEffectChain = false;
 
     virtual int numPresets() const;
 
@@ -141,7 +143,7 @@ class EffectChain : public QObject {
     std::unique_ptr<ControlPushButton> m_pControlNextChainPreset;
     std::unique_ptr<ControlPushButton> m_pControlPrevChainPreset;
 
-    void setControlLoadedPresetIndex(uint index);
+    void setControlLoadedPresetIndex(std::optional<uint> index);
 
     // These COs do not affect how the effects are processed;
     // they are defined here for skins and controller mappings to communicate

src/effects/presets/effectchainpresetmanager.cpp

@@ -123,6 +123,13 @@ void EffectChainPresetManager::importPreset() {
         EffectChainPresetPointer pPreset(
                 new EffectChainPreset(doc.documentElement()));
         if (!pPreset->isEmpty() && !pPreset->name().isEmpty()) {
+            // Don't allow '---' because it is used internally for clearing effect
+            // chains and empty Quick Effect chains
+            if (pPreset->name() == kNoEffectString) {
+                pPreset->setName(pPreset->name() +
+                        QLatin1String(" (") + tr("imported") + QLatin1String(")"));
+            }
+
             while (m_effectChainPresets.contains(pPreset->name())) {
                 pPreset->setName(pPreset->name() +
                         QLatin1String(" (") + tr("duplicate") + QLatin1String(")"));
@@ -230,7 +237,8 @@ void EffectChainPresetManager::renamePreset(const QString& oldName) {
 
     QString newName;
     QString errorText;
-    while (newName.isEmpty() || m_effectChainPresets.contains(newName)) {
+    while (newName.isEmpty() || m_effectChainPresets.contains(newName) ||
+            newName == kNoEffectString) {
         bool okay = false;
         newName = QInputDialog::getText(nullptr,
                 tr("Rename effect chain preset"),
@@ -251,6 +259,8 @@ void EffectChainPresetManager::renamePreset(const QString& oldName) {
                     tr("An effect chain preset named \"%1\" already exists.")
                             .arg(newName) +
                     QStringLiteral("\n");
+        } else if (newName == kNoEffectString) {
+            errorText = tr("Invalid name \"%1\"").arg(newName) + QStringLiteral("\n");
         } else {
             errorText = QString();
         }
@@ -371,7 +381,7 @@ void EffectChainPresetManager::savePreset(EffectChainPointer pChainSlot) {
 void EffectChainPresetManager::savePreset(EffectChainPresetPointer pPreset) {
     QString name;
     QString errorText;
-    while (name.isEmpty() || m_effectChainPresets.contains(name)) {
+    while (name.isEmpty() || m_effectChainPresets.contains(name) || name == kNoEffectString) {
         bool okay = false;
         name = QInputDialog::getText(nullptr,
                 tr("Save preset for effect chain"),
@@ -391,6 +401,8 @@ void EffectChainPresetManager::savePreset(EffectChainPresetPointer pPreset) {
                     tr("An effect chain preset named \"%1\" already exists.")
                             .arg(name) +
                     QStringLiteral("\n");
+        } else if (name == kNoEffectString) {
+            errorText = tr("Invalid name \"%1\"").arg(name) + QStringLiteral("\n");
         } else {
             errorText = QString();
         }
@@ -444,6 +456,12 @@ void EffectChainPresetManager::importUserPresets() {
         EffectChainPresetPointer pEffectChainPreset = loadPresetFromFile(
                 savedPresetsPath + kFolderDelimiter + filePath);
         if (pEffectChainPreset && !pEffectChainPreset->isEmpty()) {
+            // Don't allow '---' because it is used internally for clearing effect
+            // chains and empty Quick Effect chains
+            if (pEffectChainPreset->name() == kNoEffectString) {
+                pEffectChainPreset->setName(pEffectChainPreset->name() +
+                        QLatin1String(" (") + tr("imported") + QLatin1String(")"));
+            }
             m_effectChainPresets.insert(
                     pEffectChainPreset->name(), pEffectChainPreset);
         }
@@ -678,9 +696,20 @@ EffectsXmlData EffectChainPresetManager::readEffectsXml(
         QDomElement presetNameElement = quickEffectNodeList.at(i).toElement();
         if (!presetNameElement.isNull()) {
             QString deckGroup = presetNameElement.attribute(QStringLiteral("group"));
-            auto pPreset = m_effectChainPresets.value(presetNameElement.text());
-            if (pPreset != nullptr) {
-                quickEffectPresets.insert(deckGroup, pPreset);
+            QString presetName = presetNameElement.text();
+            if (presetName == kNoEffectString) {
+                // kNoEffectString is not allowed as preset name (import,
+                // export, save as new), it can only be set by selecting
+                // kNoEffectString in the Quick Effect slot preset selector
+                // (skin & EQ preferences).
+                // Thus, it's safe to use kNoEffectString to explicitly load
+                // an empty preset.
+                quickEffectPresets.insert(deckGroup, nullptr);
+            } else { // any name incl. empty string
+                auto pPreset = m_effectChainPresets.value(presetName);
+                if (pPreset != nullptr) {
+                    quickEffectPresets.insert(deckGroup, pPreset);
+                }
             }
         }
     }

src/preferences/dialog/dlgprefeq.cpp

@@ -297,23 +297,21 @@ void DlgPrefEQ::populateDeckQuickEffectBoxList(
     int deck = 0;
     for (QComboBox* box : boxList) {
         box->clear();
-        int currentIndex = -1; // Nothing selected
+
+        // Add empty item at the top: no effect
+        box->addItem(kNoEffectString);
+        // Note: now there's an index offset (items vs. actual presets).
+        // Compensate with a nullptr in slotQuickEffectChangedOnDeck().
 
         QString deckGroupName = PlayerManager::groupForDeck(deck);
         QString unitGroup = QuickEffectChain::formatEffectChainGroup(deckGroupName);
         EffectChainPointer pChain = m_pEffectsManager->getEffectChain(unitGroup);
-
-        // Add empty item at the top: no effect
-        box->addItem(kNoEffectString);
-        int i = 1;
         for (const auto& pChainPreset : presetList) {
             box->addItem(pChainPreset->name());
-            if (pChain->presetName() == pChainPreset->name()) {
-                currentIndex = i;
-            }
-            ++i;
         }
-        box->setCurrentIndex(currentIndex);
+
+        // Nothing selected (-1) if preset name was not found
+        box->setCurrentIndex(box->findText(pChain->presetName()));
         ++deck;
     }
 }
@@ -490,10 +488,15 @@ void DlgPrefEQ::slotQuickEffectChangedOnDeck(int effectIndex) {
     QString deckGroupName = PlayerManager::groupForDeck(deckNumber);
     QString unitGroup = QuickEffectChain::formatEffectChainGroup(deckGroupName);
     EffectChainPointer pChain = m_pEffectsManager->getEffectChain(unitGroup);
-    QList<EffectChainPresetPointer> presetList =
-            m_pChainPresetManager->getQuickEffectPresetsSorted();
-    if (pChain && effectIndex > 0 && effectIndex <= presetList.size()) {
-        pChain->loadChainPreset(presetList[effectIndex - 1]);
+    QList<EffectChainPresetPointer> presetList;
+    // add nullptr for empty kNoEffectString item so combobox effectIndex
+    // matches index in presetList
+    presetList.append(nullptr);
+    // add available Quick Effect chains
+    presetList.append(m_pChainPresetManager->getQuickEffectPresetsSorted());
+
+    if (pChain && effectIndex > -1 && effectIndex <= presetList.size()) {
+        pChain->loadChainPreset(presetList[effectIndex]);
     }
 }
 

src/widget/weffectchainpresetselector.cpp

@@ -63,6 +63,10 @@ void WEffectChainPresetSelector::populate() {
 
     QFontMetrics metrics(font());
 
+    // This is used to clear the effect chain
+    addItem(kNoEffectString, kNoEffectString);
+    setItemData(0, QVariant(tr("No effect chain loaded.")), Qt::ToolTipRole);
+
     QList<EffectChainPresetPointer> presetList;
     if (m_bQuickEffectChain) {
         presetList = m_pEffectsManager->getChainPresetManager()->getQuickEffectPresetsSorted();
@@ -76,15 +80,16 @@ void WEffectChainPresetSelector::populate() {
                 Qt::ElideMiddle,
                 view()->width() - 2);
         addItem(elidedDisplayName, QVariant(pChainPreset->name()));
-        setItemData(i, pChainPreset->name(), Qt::ToolTipRole);
+        setItemData(i + 1, pChainPreset->name(), Qt::ToolTipRole);
     }
 
     slotChainPresetChanged(m_pChain->presetName());
     blockSignals(false);
 }
 
 void WEffectChainPresetSelector::slotEffectChainPresetSelected(int index) {
-    Q_UNUSED(index);
+    // If kNoEffectString was selected the chain will be cleared.
+    // See EffectChain::loadChainPreset for details.
     m_pChain->loadChainPreset(
             m_pChainPresetManager->getPreset(currentData().toString()));
     setBaseTooltip(itemData(index, Qt::ToolTipRole).toString());
@@ -96,8 +101,12 @@ void WEffectChainPresetSelector::slotEffectChainPresetSelected(int index) {
 }
 
 void WEffectChainPresetSelector::slotChainPresetChanged(const QString& name) {
-    setCurrentIndex(findData(name));
-    setBaseTooltip(name);
+    // This is called by signal EffectChain::chainPresetChanged(name) emitted by
+    // EffectChain::loadChainPreset. See that slot for details about the preset
+    // names being emitted for different chain types.
+    int newIndex = findData(name);
+    setCurrentIndex(newIndex);
+    setBaseTooltip(itemData(newIndex, Qt::ToolTipRole).toString());
 }
 
 bool WEffectChainPresetSelector::event(QEvent* pEvent) {