[keyboard] Factor out lambdas to regular slots

- Long and complicated, nested, lambdas are not convenient for reasoning.
- The debug messages from the innermost lambda have a totally useless
  function name, which makes debugging harder.

src/modules/keyboard/Config.cpp

@@ -168,54 +168,64 @@ Config::Config( QObject* parent )
         emit prettyStatusChanged();
     } );
 
-    connect( m_keyboardVariantsModel, &KeyboardVariantsModel::currentIndexChanged, [&]( int index ) {
+    connect( m_keyboardVariantsModel, &KeyboardVariantsModel::currentIndexChanged, this, &Config::xkbChanged );
-        // Set Xorg keyboard layout + variant
-        m_selectedVariant = m_keyboardVariantsModel->key( index );
-
-        if ( m_setxkbmapTimer.isActive() )
-        {
-            m_setxkbmapTimer.stop();
-            m_setxkbmapTimer.disconnect( this );
-        }
-
-        connect( &m_setxkbmapTimer, &QTimer::timeout, this, [=] {
-            m_additionalLayoutInfo = getAdditionalLayoutInfo( m_selectedLayout );
-
-            if ( !m_additionalLayoutInfo.additionalLayout.isEmpty() )
-            {
-                m_additionalLayoutInfo.groupSwitcher = xkbmap_query_grp_option();
-
-                if ( m_additionalLayoutInfo.groupSwitcher.isEmpty() )
-                {
-                    m_additionalLayoutInfo.groupSwitcher = "grp:alt_shift_toggle";
-                }
-
-                QProcess::execute( "setxkbmap",
-                                   xkbmap_layout_args( { m_additionalLayoutInfo.additionalLayout, m_selectedLayout },
-                                                       { m_additionalLayoutInfo.additionalVariant, m_selectedVariant },
-                                                       m_additionalLayoutInfo.groupSwitcher ) );
-
-
-                cDebug() << "xkbmap selection changed to: " << m_selectedLayout << '-' << m_selectedVariant << "(added "
-                         << m_additionalLayoutInfo.additionalLayout << "-" << m_additionalLayoutInfo.additionalVariant
-                         << " since current layout is not ASCII-capable)";
-            }
-            else
-            {
-                QProcess::execute( "setxkbmap", xkbmap_layout_args( m_selectedLayout, m_selectedVariant ) );
-                cDebug() << "xkbmap selection changed to: " << m_selectedLayout << '-' << m_selectedVariant;
-            }
-            m_setxkbmapTimer.disconnect( this );
-        } );
-        m_setxkbmapTimer.start( QApplication::keyboardInputInterval() );
-        emit prettyStatusChanged();
-    } );
 
     m_selectedModel = m_keyboardModelsModel->key( m_keyboardModelsModel->currentIndex() );
     m_selectedLayout = m_keyboardLayoutsModel->item( m_keyboardLayoutsModel->currentIndex() ).first;
     m_selectedVariant = m_keyboardVariantsModel->key( m_keyboardVariantsModel->currentIndex() );
 }
 
+void
+Config::xkbChanged( int index )
+{
+    // Set Xorg keyboard layout + variant
+    m_selectedVariant = m_keyboardVariantsModel->key( index );
+
+    if ( m_setxkbmapTimer.isActive() )
+    {
+        m_setxkbmapTimer.stop();
+        m_setxkbmapTimer.disconnect( this );
+    }
+
+    connect( &m_setxkbmapTimer, &QTimer::timeout, this, &Config::xkbApply );
+
+    m_setxkbmapTimer.start( QApplication::keyboardInputInterval() );
+    emit prettyStatusChanged();
+}
+
+void
+Config::xkbApply()
+{
+    m_additionalLayoutInfo = getAdditionalLayoutInfo( m_selectedLayout );
+
+    if ( !m_additionalLayoutInfo.additionalLayout.isEmpty() )
+    {
+        m_additionalLayoutInfo.groupSwitcher = xkbmap_query_grp_option();
+
+        if ( m_additionalLayoutInfo.groupSwitcher.isEmpty() )
+        {
+            m_additionalLayoutInfo.groupSwitcher = "grp:alt_shift_toggle";
+        }
+
+        QProcess::execute( "setxkbmap",
+                           xkbmap_layout_args( { m_additionalLayoutInfo.additionalLayout, m_selectedLayout },
+                                               { m_additionalLayoutInfo.additionalVariant, m_selectedVariant },
+                                               m_additionalLayoutInfo.groupSwitcher ) );
+
+
+        cDebug() << "xkbmap selection changed to: " << m_selectedLayout << '-' << m_selectedVariant << "(added "
+                 << m_additionalLayoutInfo.additionalLayout << "-" << m_additionalLayoutInfo.additionalVariant
+                 << " since current layout is not ASCII-capable)";
+    }
+    else
+    {
+        QProcess::execute( "setxkbmap", xkbmap_layout_args( m_selectedLayout, m_selectedVariant ) );
+        cDebug() << "xkbmap selection changed to: " << m_selectedLayout << '-' << m_selectedVariant;
+    }
+    m_setxkbmapTimer.disconnect( this );
+}
+
+
 KeyboardModelsModel*
 Config::keyboardModels() const
 {

src/modules/keyboard/Config.h

@@ -76,6 +76,18 @@ private:
     void guessLayout( const QStringList& langParts );
     void updateVariants( const QPersistentModelIndex& currentItem, QString currentVariant = QString() );
 
+    /* These two methods are used in tandem to apply changes to the
+     * keyboard layout. This introduces a slight delay between selecting
+     * a keyboard, and applying it to the system -- so that if you
+     * scroll through or down-arrow through the list of keyboards,
+     * you don't get buried under xkbset processes.
+     *
+     * xkbChanged() is called when the selection changes, and triggers
+     * a delayed call to xkbApply() which does the actual work.
+     */
+    void xkbChanged( int index );
+    void xkbApply();
+
     KeyboardModelsModel* m_keyboardModelsModel;
     KeyboardLayoutModel* m_keyboardLayoutsModel;
     KeyboardVariantsModel* m_keyboardVariantsModel;