add checkbox to hide unenabled controllers in preferences

adds a checkbox in preferences > controllers to hide controllers
that are not enabled, making it easier for users with many controllers
to find the ones they actually use.

the checkbox state is persisted in the config and the controller list
visibility is updated efficiently using setHidden() to avoid expensive
widget rebuilding.

implementation:
- added checkbox ui element "hide controllers that are not enabled"
- persists state in [controller]/hide_unenabled_controllers config key
- uses lightweight updatecontrollervisibility() method to toggle tree
  item visibility instead of destroying/rebuilding all widgets
- matches controllers correctly using controller pages in sync with tree
  items
- updates visibility automatically when controller enabled state changes
- added controller() getter to dlgprefcontroller for proper matching

fixes #14275

Author: Milkii Brewster

src/controllers/defs_controllers.h

@@ -32,3 +32,6 @@ const auto kMidiThroughPortPrefix = QLatin1String("MIDI Through Port");
 const ConfigKey kMidiThroughCfgKey =
         ConfigKey(QStringLiteral("[Controller]"), QStringLiteral("midi_through_enabled"));
 #endif
+
+const ConfigKey kHideUnenabledControllersCfgKey =
+        ConfigKey(QStringLiteral("[Controller]"), QStringLiteral("hide_unenabled_controllers"));

src/controllers/dlgprefcontroller.h

@@ -38,6 +38,10 @@ class DlgPrefController : public DlgPreferencePage {
     QUrl helpUrl() const override;
     void keyPressEvent(QKeyEvent* pEvent) override;
 
+    Controller* controller() const {
+        return m_pController;
+    }
+
   public slots:
     /// Called when the preference dialog (not this page) is shown to the user.
     void slotUpdate() override;

src/controllers/dlgprefcontrollers.cpp

@@ -44,6 +44,18 @@ DlgPrefControllers::DlgPrefControllers(DlgPreferences* pPreferences,
             this,
             &DlgPrefControllers::rescanControllers);
 
+    // Hide unenabled controllers checkbox
+    checkBox_hideUnenabled->setChecked(
+            m_pConfig->getValue(kHideUnenabledControllersCfgKey, false));
+    connect(checkBox_hideUnenabled,
+#if QT_VERSION >= QT_VERSION_CHECK(6, 7, 0)
+            &QCheckBox::checkStateChanged,
+#else
+            &QCheckBox::stateChanged,
+#endif
+            this,
+            &DlgPrefControllers::slotHideUnenabledChanged);
+
 #ifdef __PORTMIDI__
     checkBox_midithrough->setChecked(m_pConfig->getValue(kMidiThroughCfgKey, false));
     connect(checkBox_midithrough,
@@ -256,6 +268,32 @@ void DlgPrefControllers::setupControllerWidgets() {
         temp.setBold(pController->isOpen());
         pControllerTreeItem->setFont(0, temp);
     }
+
+    // Update visibility based on checkbox state
+    updateControllerVisibility();
+}
+
+void DlgPrefControllers::updateControllerVisibility() {
+    bool hideUnenabled = m_pConfig->getValue(kHideUnenabledControllersCfgKey, false);
+
+    // Use the controller pages to match tree items with controllers
+    // since they are built together and always in sync
+    for (int i = 0; i < m_controllerTreeItems.size() && i < m_controllerPages.size(); ++i) {
+        QTreeWidgetItem* pTreeItem = m_controllerTreeItems.at(i);
+        DlgPrefController* pControllerDlg = m_controllerPages.at(i);
+
+        if (pTreeItem && pControllerDlg && pControllerDlg->controller()) {
+            Controller* pController = pControllerDlg->controller();
+
+            if (!hideUnenabled) {
+                // Show all controllers
+                pTreeItem->setHidden(false);
+            } else {
+                // Hide if controller is not open/enabled
+                pTreeItem->setHidden(!pController->isOpen());
+            }
+        }
+    }
 }
 
 void DlgPrefControllers::slotHighlightDevice(DlgPrefController* pControllerDlg, bool enabled) {
@@ -273,8 +311,26 @@ void DlgPrefControllers::slotHighlightDevice(DlgPrefController* pControllerDlg,
     QFont temp = pControllerTreeItem->font(0);
     temp.setBold(enabled);
     pControllerTreeItem->setFont(0, temp);
+
+    // Update visibility in case the checkbox is checked and this controller's state changed
+    bool hideUnenabled = m_pConfig->getValue(kHideUnenabledControllersCfgKey, false);
+    if (hideUnenabled) {
+        pControllerTreeItem->setHidden(!enabled);
+    }
 }
 
+#if QT_VERSION >= QT_VERSION_CHECK(6, 7, 0)
+void DlgPrefControllers::slotHideUnenabledChanged(Qt::CheckState state) {
+    m_pConfig->setValue(kHideUnenabledControllersCfgKey, state != Qt::Unchecked);
+    updateControllerVisibility();
+}
+#else
+void DlgPrefControllers::slotHideUnenabledChanged(bool checked) {
+    m_pConfig->setValue(kHideUnenabledControllersCfgKey, checked);
+    updateControllerVisibility();
+}
+#endif
+
 #ifdef __PORTMIDI__
 #if QT_VERSION >= QT_VERSION_CHECK(6, 7, 0)
 void DlgPrefControllers::slotMidiThroughChanged(Qt::CheckState state) {

src/controllers/dlgprefcontrollers.h

@@ -41,6 +41,11 @@ class DlgPrefControllers : public DlgPreferencePage, public Ui::DlgPrefControlle
 
   private slots:
     void rescanControllers();
+#if QT_VERSION >= QT_VERSION_CHECK(6, 7, 0)
+    void slotHideUnenabledChanged(Qt::CheckState state);
+#else
+    void slotHideUnenabledChanged(bool checked);
+#endif
 #ifdef __PORTMIDI__
 #if QT_VERSION >= QT_VERSION_CHECK(6, 7, 0)
     void slotMidiThroughChanged(Qt::CheckState state);
@@ -53,6 +58,7 @@ class DlgPrefControllers : public DlgPreferencePage, public Ui::DlgPrefControlle
   private:
     void destroyControllerWidgets();
     void setupControllerWidgets();
+    void updateControllerVisibility();
     void openLocalFile(const QString& file);
 
     DlgPreferences* m_pDlgPreferences;

src/controllers/dlgprefcontrollersdlg.ui

@@ -70,6 +70,20 @@
        </widget>
       </item>
 
+      <item>
+       <widget class="QCheckBox" name="checkBox_hideUnenabled">
+        <property name="sizePolicy">
+         <sizepolicy hsizetype="Minimum" vsizetype="Fixed">
+          <horstretch>0</horstretch>
+          <verstretch>0</verstretch>
+         </sizepolicy>
+        </property>
+        <property name="text">
+         <string>Hide controllers that are not enabled</string>
+        </property>
+       </widget>
+      </item>
+
       <item>
        <widget class="Line" name="line_midithrough">
         <property name="orientation">
@@ -224,6 +238,7 @@
   </layout>
  </widget>
  <tabstops>
+  checkBox_hideUnenabled
   checkBox_midithrough
   btnOpenUserMappings
  </tabstops>