Add two keyboard actions for focusing on next/prev in split view mode

This commit adds two keyboard action for focusing on next or previous
view in split view tab.

The default shortcuts are `ctrl-F11` for next view and `ctrl=shift-F11`
for previous view. I find these shortcuts more useful in some situations
than the currently available shortcuts for moving the focus
up/down/left/right. The order of the views in the list is the one
returned by `ViewSplitter::findChildren<TerminalDisplay *>`, so it
does not correlate exactly to their positions.

src/ViewManager.cpp

@@ -279,6 +279,18 @@ void ViewManager::setupActions()
     collection->addAction(QStringLiteral("focus-view-right"), action);
     _multiSplitterOnlyActions << action;
 
+    action = new QAction(i18nc("@action Shortcut entry", "Focus Next Terminal"), this);
+    collection->setDefaultShortcut(action, Qt::CTRL | Qt::Key_F11);
+    connect(action, &QAction::triggered, this, &ViewManager::focusNext);
+    collection->addAction(QStringLiteral("focus-view-next"), action);
+    _multiSplitterOnlyActions << action;
+
+    action = new QAction(i18nc("@action Shortcut entry", "Focus Previous Terminal"), this);
+    collection->setDefaultShortcut(action, Qt::CTRL | Qt::SHIFT | Qt::Key_F11);
+    connect(action, &QAction::triggered, this, &ViewManager::focusPrev);
+    collection->addAction(QStringLiteral("focus-view-prev"), action);
+    _multiSplitterOnlyActions << action;
+
     action = new QAction(i18nc("@action Shortcut entry", "Switch to Last Tab"), this);
     connect(action, &QAction::triggered, this, &ViewManager::lastView);
     collection->addAction(QStringLiteral("last-tab"), action);
@@ -439,6 +451,16 @@ void ViewManager::focusRight()
     _viewContainer->activeViewSplitter()->focusRight();
 }
 
+void ViewManager::focusNext()
+{
+    _viewContainer->activeViewSplitter()->focusNext();
+}
+
+void ViewManager::focusPrev()
+{
+    _viewContainer->activeViewSplitter()->focusPrev();
+}
+
 void ViewManager::moveActiveViewLeft()
 {
     _viewContainer->moveActiveView(TabbedViewContainer::MoveViewLeft);

src/ViewManager.h

@@ -410,6 +410,9 @@ private Q_SLOTS:
     void focusLeft();
     void focusRight();
 
+    void focusNext();
+    void focusPrev();
+
     // called when "Next View" shortcut is activated
     void nextView();
 

src/widgets/ViewSplitter.cpp

@@ -290,6 +290,30 @@ void ViewSplitter::focusRight()
     handleFocusDirection(Qt::Horizontal, +1);
 }
 
+void ViewSplitter::focusNext(int dir)
+{
+    auto terminalDisplay = activeTerminalDisplay();
+    auto parentSplitter = qobject_cast<ViewSplitter *>(terminalDisplay->parentWidget());
+    auto topSplitter = parentSplitter->getToplevelSplitter();
+    auto terminals = topSplitter->findChildren<TerminalDisplay *>();
+    int id = terminals.indexOf(terminalDisplay);
+    int targetId = (id + dir) % terminals.size();
+    if (targetId < 0) {
+        targetId = terminals.size() + targetId;
+    }
+
+    auto targetTerminal = terminals.at(targetId);
+
+    if (targetTerminal) {
+        targetTerminal->setFocus(Qt::OtherFocusReason);
+    }
+}
+
+void ViewSplitter::focusPrev()
+{
+    focusNext(-1);
+}
+
 TerminalDisplay *ViewSplitter::activeTerminalDisplay() const
 {
     auto focusedWidget = focusWidget();

src/widgets/ViewSplitter.h

@@ -145,6 +145,9 @@ public:
     void focusLeft();
     void focusRight();
 
+    void focusNext(int dir = 1);
+    void focusPrev();
+
     void handleFocusDirection(Qt::Orientation orientation, int direction);
 
     void childEvent(QChildEvent *event) override;