Add EventFilterInterface and port DockRegistry to it

Some classes wont have any Qt in it, so they need another way
to install global event filters. Added API to Platform.h for this
purpose. Implemented as regular event filter in Platform_qt.

src/DockRegistry.cpp

@@ -48,11 +48,14 @@ DockRegistry::DockRegistry(QObject *parent)
     , d(new Private())
 {
     qGuiApp->installEventFilter(this);
+    Platform::instance()->installGlobalEventFilter(this);
+
     d->m_connection = Platform::instance()->d->focusedViewChanged.connect(&DockRegistry::onFocusedViewChanged, this);
 }
 
 DockRegistry::~DockRegistry()
 {
+    Platform::instance()->removeGlobalEventFilter(this);
     d->m_connection.disconnect();
     delete d;
 }
@@ -661,15 +664,7 @@ bool DockRegistry::eventFilter(QObject *watched, QEvent *event)
     if (!view)
         return false;
 
-    if (event->type() == QEvent::Expose) {
-        if (auto window = Platform::instance()->qobjectAsWindow(watched)) {
-            if (Controllers::FloatingWindow *fw = floatingWindowForHandle(window)) {
-                // This floating window was exposed
-                m_floatingWindows.removeOne(fw);
-                m_floatingWindows.append(fw);
-            }
-        }
-    } else if (event->type() == QEvent::MouseButtonPress) {
+    if (event->type() == QEvent::MouseButtonPress) {
         // When clicking on a MDI Frame we raise the window
         if (Controller *c = View::firstParentOfType(watched, Type::Frame)) {
             auto group = static_cast<Group *>(c);
@@ -737,3 +732,14 @@ bool DockRegistry::onDockWidgetPressed(Controllers::DockWidget *dw, QMouseEvent
 
     return false;
 }
+
+bool DockRegistry::onExposeEvent(Window::Ptr window)
+{
+    if (Controllers::FloatingWindow *fw = floatingWindowForHandle(window)) {
+        // This floating window was exposed
+        m_floatingWindows.removeOne(fw);
+        m_floatingWindows.append(fw);
+    }
+
+    return false;
+}

src/DockRegistry.h

@@ -14,6 +14,7 @@
 
 #include "kddockwidgets/KDDockWidgets.h"
 #include "kddockwidgets/View.h"
+#include "kddockwidgets/EventFilterInterface.h"
 
 #include <QVector>
 #include <QObject>
@@ -45,7 +46,7 @@ class MainWindowViewInterface;
 class MainWindowMDI;
 struct WindowBeingDragged;
 
-class DOCKS_EXPORT DockRegistry : public QObject
+class DOCKS_EXPORT DockRegistry : public QObject, public EventFilterInterface
 {
     Q_OBJECT
 
@@ -246,6 +247,8 @@ private:
     void maybeDelete();
     void setFocusedDockWidget(Controllers::DockWidget *);
 
+    bool onExposeEvent(std::shared_ptr<Window>) override;
+
     class Private;
     Private *const d;
 

src/EventFilterInterface.h

@@ -0,0 +1,33 @@
+/*
+  This file is part of KDDockWidgets.
+
+  SPDX-FileCopyrightText: 2020-2022 Klarälvdalens Datakonsult AB, a KDAB Group company <info@kdab.com>
+  Author: Sérgio Martins <sergio.martins@kdab.com>
+
+  SPDX-License-Identifier: GPL-2.0-only OR GPL-3.0-only
+
+  Contact KDAB at <info@kdab.com> for commercial licensing options.
+*/
+
+#pragma once
+
+#include <memory>
+
+namespace KDDockWidgets {
+
+class Window;
+class View;
+
+class EventFilterInterface
+{
+public:
+    virtual ~EventFilterInterface();
+
+    /// @brief Override to handle expose events for a certain window
+    virtual bool onExposeEvent(std::shared_ptr<Window>)
+    {
+        return false;
+    }
+};
+
+}

src/Platform.cpp

@@ -11,6 +11,7 @@
 
 #include "Platform.h"
 #include "private/Platform_p.h"
+#include "EventFilterInterface.h"
 
 #ifdef KDDW_FRONTEND_QTWIDGETS
 #include "qtwidgets/Platform_qtwidgets.h"
@@ -31,6 +32,8 @@ using namespace KDDockWidgets;
 
 static Platform *s_platform = nullptr;
 
+EventFilterInterface::~EventFilterInterface() = default;
+
 #ifdef DOCKS_DEVELOPER_MODE
 QString Platform::s_expectedWarning = {};
 Platform::WarningObserver *Platform::s_warningObserver = nullptr;
@@ -153,3 +156,15 @@ std::vector<KDDockWidgets::FrontendType> Platform::frontendTypes()
 }
 
 #endif
+
+void Platform::installGlobalEventFilter(EventFilterInterface *filter)
+{
+    d->m_globalEventFilters.push_back(filter);
+}
+
+void Platform::removeGlobalEventFilter(EventFilterInterface *filter)
+{
+    d->m_globalEventFilters.erase(std::remove(d->m_globalEventFilters.begin(),
+                                              d->m_globalEventFilters.end(), filter),
+                                  d->m_globalEventFilters.end());
+}

src/Platform.h

@@ -27,6 +27,7 @@ class ClassicIndicators;
 class SegmentedIndicators;
 }
 
+class EventFilterInterface;
 class ViewFactory;
 class Window;
 
@@ -184,6 +185,13 @@ public:
     virtual void installMessageHandler() = 0;
     virtual void uninstallMessageHandler() = 0;
 
+    /// @brief Installs a global event filter
+    /// Events will be forwarded to the specified EventFilterInterface
+    void installGlobalEventFilter(EventFilterInterface *);
+
+    /// @brief Removes a global event filter
+    void removeGlobalEventFilter(EventFilterInterface *);
+
     /// @brief Creates a main window. This is not API that the user will use, but used
     /// internally by some tools that need a main window
     virtual Controllers::MainWindow *createMainWindow(const QString &uniqueName, CreateViewOptions,

src/fwd_headers/kddockwidgets/EventFilterInterface.h

@@ -0,0 +1,12 @@
+/*
+  This file is part of KDDockWidgets.
+
+  SPDX-FileCopyrightText: 2020-2022 Klarälvdalens Datakonsult AB, a KDAB Group company <info@kdab.com>
+  Author: Sergio Martins <sergio.martins@kdab.com>
+
+  SPDX-License-Identifier: GPL-2.0-only OR GPL-3.0-only
+
+  Contact KDAB at <info@kdab.com> for commercial licensing options.
+*/
+
+#include "../../EventFilterInterface.h"

src/private/Platform_p.h

@@ -15,8 +15,12 @@
 #include "kdbindings/signal.h"
 
 #include <memory>
+#include <vector>
 
 namespace KDDockWidgets {
+
+class EventFilterInterface;
+
 class Platform::Private
 {
 public:
@@ -35,5 +39,8 @@ public:
     }
 
     bool m_inDestruction = false;
+
+    std::vector<EventFilterInterface *> m_globalEventFilters;
 };
+
 }

src/qtcommon/Platform_qt.cpp

@@ -12,6 +12,7 @@
 #include "Platform_qt.h"
 #include "kddockwidgets/KDDockWidgets.h"
 #include "kddockwidgets/Window_qt.h"
+#include "kddockwidgets/EventFilterInterface.h"
 #include "private/Platform_p.h"
 
 #include <QWindow>
@@ -101,7 +102,8 @@ EventFilter::~EventFilter() = default;
 class Platform_qt::GlobalEventFilter : public QObject
 {
 public:
-    GlobalEventFilter()
+    GlobalEventFilter(Platform_qt *qq)
+        : q(qq)
     {
         if (qGuiApp)
             qGuiApp->installEventFilter(this);
@@ -109,6 +111,9 @@ public:
 
     bool eventFilter(QObject *o, QEvent *ev) override
     {
+        if (ev->type() == QEvent::Expose)
+            return handleExpose(o);
+
         auto view = Platform::instance()->qobjectAsView(o);
         if (!view)
             return false;
@@ -123,14 +128,32 @@ public:
         return false;
     }
 
+    bool handleExpose(QObject *o)
+    {
+        if (q->d->m_globalEventFilters.empty())
+            return false;
+
+        auto window = Platform::instance()->qobjectAsWindow(o);
+        if (!window)
+            return false;
+
+        for (EventFilterInterface *filter : qAsConst(q->d->m_globalEventFilters)) {
+            if (filter->onExposeEvent(window))
+                return true;
+        }
+
+        return false;
+    }
+
     ~GlobalEventFilter() override;
     bool m_isProcessingAppQuitEvent = false;
+    Platform_qt *const q;
 };
 
 Platform_qt::GlobalEventFilter::~GlobalEventFilter() = default;
 
 Platform_qt::Platform_qt()
-    : m_globalEventFilter(new GlobalEventFilter())
+    : m_globalEventFilter(new GlobalEventFilter(this))
 {
     if (!qGuiApp)
         qWarning() << "Please call KDDockWidgets::initPlatform() after QGuiApplication";
@@ -308,7 +331,7 @@ bool Platform_qt::isGammaray()
 }
 
 Platform_qt::Platform_qt(int &argc, char **argv)
-    : m_globalEventFilter(new GlobalEventFilter())
+    : m_globalEventFilter(new GlobalEventFilter(this))
 {
     // This CTOR is called before we have a QApplication