Merge pull request #13665 from jordan-woyak/dark-mode-filter

DolphinQt: Replace widespread SetQWidgetWindowDecorations calls with an event filter.

Source/Core/DolphinQt/QtUtils/ModalMessageBox.cpp

@@ -5,8 +5,6 @@
 
 #include <QApplication>
 
-#include "DolphinQt/QtUtils/SetWindowDecorations.h"
-
 ModalMessageBox::ModalMessageBox(QWidget* parent, Qt::WindowModality modality)
     : QMessageBox(parent != nullptr ? parent->window() : nullptr)
 {
@@ -31,7 +29,6 @@ static inline int ExecMessageBox(ModalMessageBox::Icon icon, QWidget* parent, co
   msg.setDefaultButton(default_button);
   msg.setDetailedText(detailed_text);
 
-  SetQWidgetWindowDecorations(&msg);
   return msg.exec();
 }
 

Source/Core/DolphinQt/QtUtils/SetWindowDecorations.cpp

@@ -1,25 +1,81 @@
 // Copyright 2023 Dolphin Emulator Project
 // SPDX-License-Identifier: GPL-2.0-or-later
 
+#if defined(_WIN32)
+
 #include "DolphinQt/QtUtils/SetWindowDecorations.h"
 
+#include <QApplication>
+#include <QEvent>
 #include <QWidget>
 
+#include <dwmapi.h>
+
 #include "DolphinQt/Settings.h"
 
-#ifdef _WIN32
-#include <dwmapi.h>
-#endif
+namespace
+{
 
 void SetQWidgetWindowDecorations(QWidget* widget)
 {
-#ifdef _WIN32
   if (!Settings::Instance().IsThemeDark())
     return;
 
-  BOOL use_dark_title_bar = TRUE;
-  DwmSetWindowAttribute(HWND(widget->winId()),
-                        20 /* DWMWINDOWATTRIBUTE::DWMWA_USE_IMMERSIVE_DARK_MODE */,
-                        &use_dark_title_bar, DWORD(sizeof(use_dark_title_bar)));
-#endif
+  constexpr DWORD attribute = 20;  // DWMWINDOWATTRIBUTE::DWMWA_USE_IMMERSIVE_DARK_MODE
+  constexpr BOOL use_dark_title_bar = TRUE;
+
+  DwmSetWindowAttribute(HWND(widget->winId()), attribute, &use_dark_title_bar,
+                        DWORD(sizeof(use_dark_title_bar)));
 }
+
+class WindowDecorationFilter final : public QObject
+{
+public:
+  using QObject::QObject;
+
+  bool eventFilter(QObject* obj, QEvent* event) override
+  {
+    if (event->type() == QEvent::Show || event->type() == QEvent::ApplicationPaletteChange)
+    {
+      SetQWidgetWindowDecorations(static_cast<QWidget*>(obj));
+    }
+    return QObject::eventFilter(obj, event);
+  }
+};
+
+class WindowDecorationFilterInstaller final : public QObject
+{
+public:
+  using QObject::QObject;
+
+  bool eventFilter(QObject* obj, QEvent* event) override
+  {
+    if (event->type() == QEvent::WinIdChange)
+    {
+      auto* const widget = qobject_cast<QWidget*>(obj);
+
+      // Install the real filter on actual Window QWidgets.
+      // This avoids the need for a qobject_cast on literally every QEvent::Show.
+      if (widget && widget->isWindow())
+        widget->installEventFilter(m_decoration_filter);
+    }
+    return QObject::eventFilter(obj, event);
+  }
+
+private:
+  QObject* const m_decoration_filter = new WindowDecorationFilter{this};
+};
+
+}  // namespace
+
+namespace QtUtils
+{
+
+void InstallWindowDecorationFilter(QApplication* app)
+{
+  app->installEventFilter(new WindowDecorationFilterInstaller{app});
+}
+
+}  // namespace QtUtils
+
+#endif

Source/Core/DolphinQt/QtUtils/SetWindowDecorations.h

@@ -3,7 +3,14 @@
 
 #pragma once
 
-class QWidget;
+#if defined(_WIN32)
 
-// Changes the window decorations (title bar) to dark if the user uses dark mode on Windows.
-void SetQWidgetWindowDecorations(QWidget* widget);
+class QApplication;
+
+namespace QtUtils
+{
+// Changes the window decorations (title bar) for Windows "Dark" mode or "Dark" Dolphin Style.
+void InstallWindowDecorationFilter(QApplication*);
+}  // namespace QtUtils
+
+#endif