[TabDeckEditor] Generalize visibility filter and extract it to a separate file (#6526)

* create class

* use new class in old code

cockatrice/CMakeLists.txt

@@ -227,6 +227,8 @@ set(cockatrice_SOURCES
     src/interface/widgets/utility/custom_line_edit.cpp
     src/interface/widgets/utility/get_text_with_max.cpp
     src/interface/widgets/utility/sequence_edit.cpp
+    src/interface/widgets/utility/visibility_change_listener.cpp
+    src/interface/widgets/utility/visibility_change_listener.h
     src/interface/widgets/visual_database_display/visual_database_display_color_filter_widget.cpp
     src/interface/widgets/visual_database_display/visual_database_display_filter_save_load_widget.cpp
     src/interface/widgets/visual_database_display/visual_database_display_filter_toolbar_widget.cpp

cockatrice/src/interface/widgets/tabs/abstract_tab_deck_editor.cpp

@@ -18,6 +18,7 @@
 #include "../interface/widgets/dialogs/dlg_load_deck.h"
 #include "../interface/widgets/dialogs/dlg_load_deck_from_clipboard.h"
 #include "../interface/widgets/dialogs/dlg_load_deck_from_website.h"
+#include "../utility/visibility_change_listener.h"
 #include "tab_supervisor.h"
 
 #include <QAction>
@@ -100,7 +101,9 @@ void AbstractTabDeckEditor::registerDockWidget(QMenu *_viewMenu, QDockWidget *wi
             [aFloating](bool topLevel) { aFloating->setChecked(topLevel); });
 
     // sync aVisible with dockWidget's visible state
-    widget->installEventFilter(new DockWidgetVisibilityFilter(widget, aVisible));
+    auto filter = new VisibilityChangeListener(widget);
+    connect(filter, &VisibilityChangeListener::visibilityChanged, aVisible,
+            [aVisible](bool visible) { aVisible->setChecked(visible); });
 
     dockToActions.insert(widget, {menu, aVisible, aFloating});
 }
@@ -608,22 +611,3 @@ bool AbstractTabDeckEditor::closeRequest()
         return false;
     return close();
 }
-
-DockWidgetVisibilityFilter::DockWidgetVisibilityFilter(QDockWidget *dockWidget, QAction *aVisible)
-    : QObject(dockWidget), dockWidget(dockWidget), aVisible(aVisible)
-{
-}
-
-bool DockWidgetVisibilityFilter::eventFilter(QObject *o, QEvent *e)
-{
-    if (o == dockWidget && !e->spontaneous()) {
-        if (e->type() == QEvent::Show) {
-            aVisible->setChecked(true);
-        }
-
-        if (e->type() == QEvent::Hide) {
-            aVisible->setChecked(false);
-        }
-    }
-    return false;
-}

cockatrice/src/interface/widgets/tabs/abstract_tab_deck_editor.h

@@ -307,19 +307,4 @@ protected:
     QMap<QDockWidget *, DockActions> dockToActions;
 };
 
-/**
- * This filter syncs the dock widget's visibility with the viewMenu visibility action's check state.
- */
-class DockWidgetVisibilityFilter : public QObject
-{
-    Q_OBJECT
-
-    QDockWidget *dockWidget;
-    QAction *aVisible;
-
-public:
-    explicit DockWidgetVisibilityFilter(QDockWidget *dockWidget, QAction *aVisible);
-    bool eventFilter(QObject *o, QEvent *e) override;
-};
-
 #endif // TAB_GENERIC_DECK_EDITOR_H

cockatrice/src/interface/widgets/utility/visibility_change_listener.cpp

@@ -0,0 +1,26 @@
+#include "visibility_change_listener.h"
+
+#include <QEvent>
+#include <QWidget>
+
+VisibilityChangeListener::VisibilityChangeListener(QWidget *targetWidget)
+    : QObject(targetWidget), targetWidget(targetWidget)
+{
+    if (targetWidget) {
+        targetWidget->installEventFilter(this);
+    }
+}
+
+bool VisibilityChangeListener::eventFilter(QObject *o, QEvent *e)
+{
+    if (o == targetWidget && !e->spontaneous()) {
+        if (e->type() == QEvent::Show) {
+            emit visibilityChanged(true);
+        }
+
+        if (e->type() == QEvent::Hide) {
+            emit visibilityChanged(false);
+        }
+    }
+    return false;
+}

cockatrice/src/interface/widgets/utility/visibility_change_listener.h

@@ -0,0 +1,35 @@
+#ifndef COCKATRICE_VISIBILITY_LISTENER_H
+#define COCKATRICE_VISIBILITY_LISTENER_H
+
+#include <QObject>
+
+/**
+ * @brief This filter listens to the visibility changes of a target widget, emitting signals whenever the visibility of
+ * that widget changes.
+ */
+class VisibilityChangeListener : public QObject
+{
+    Q_OBJECT
+
+    QWidget *targetWidget;
+
+public:
+    /**
+     * Creates a new instance of this class, watching the targetWidget.
+     * This class automatically installs itself as an eventFilter to the targetWidget.
+     *
+     * @param targetWidget The widget to watch. Sets that widget as this object's parent.
+     */
+    explicit VisibilityChangeListener(QWidget *targetWidget);
+
+    bool eventFilter(QObject *o, QEvent *e) override;
+
+signals:
+    /**
+     * Emitted whenever the target widget's visibility changes
+     * @param visible The widget's new visibility
+     */
+    void visibilityChanged(bool visible);
+};
+
+#endif // COCKATRICE_VISIBILITY_LISTENER_H