Windows QPA: Add native menus

Add simple Win32-API based menus (not owner-drawn).

Native menus are implemented using Win32 API and are simpler than
QMenu-based menus in for example that they do allow for placing widgets on
them or changing properties like fonts and do not provide hover signals.
They are mainly intended for Qt Quick. By default, they will be used if the
application is not an instance of QApplication or for Qt Quick Controls
2 applications.

In addition, the command line option -platform windows:menus=native
will unconditionally activate them and -platform windows:menus=no
turns them off.

[ChangeLog][QtGui][Windows] Native menus have been implemented.

Task-number: QTBUG-55967
Change-Id: I439a7d949745debea3eb0e5789cf42288a0d526f
Reviewed-by: Maurice Kalinowski <maurice.kalinowski@qt.io>

1 files changed, 52 insertions, 0 deletions

diff --git a/src/plugins/platforms/windows/qwindowstheme.cpp b/src/plugins/platforms/windows/qwindowstheme.cpp
index e1cbbc9311..5fe7c7c071 100644
--- a/src/plugins/platforms/windows/qwindowstheme.cpp
+++ b/src/plugins/platforms/windows/qwindowstheme.cpp
@@ -44,6 +44,7 @@
 #endif
 
 #include "qwindowstheme.h"
+#include "qwindowsmenu.h"
 #include "qwindowsdialoghelpers.h"
 #include "qwindowscontext.h"
 #include "qwindowsintegration.h"
@@ -910,4 +911,55 @@ QIcon QWindowsTheme::fileIcon(const QFileInfo &fileInfo, QPlatformTheme::IconOpt
     return QIcon(new QWindowsFileIconEngine(fileInfo, iconOptions));
 }
 
+static inline bool doUseNativeMenus()
+{
+    const unsigned options = QWindowsIntegration::instance()->options();
+    if ((options & QWindowsIntegration::NoNativeMenus) != 0)
+        return false;
+    if ((options & QWindowsIntegration::AlwaysUseNativeMenus) != 0)
+        return true;
+    // "Auto" mode: For non-widget or Quick Controls 2 applications
+    if (!QCoreApplication::instance()->inherits("QApplication"))
+        return true;
+    const QWindowList &topLevels = QGuiApplication::topLevelWindows();
+    for (const QWindow *t : topLevels) {
+        if (t->inherits("QQuickApplicationWindow"))
+            return true;
+    }
+    return false;
+}
+
+bool QWindowsTheme::useNativeMenus()
+{
+    static const bool result = doUseNativeMenus();
+    return result;
+}
+
+QPlatformMenuItem *QWindowsTheme::createPlatformMenuItem() const
+{
+    qCDebug(lcQpaMenus) << __FUNCTION__;
+    return QWindowsTheme::useNativeMenus() ? new QWindowsMenuItem : nullptr;
+}
+
+QPlatformMenu *QWindowsTheme::createPlatformMenu() const
+{
+    qCDebug(lcQpaMenus) << __FUNCTION__;
+    // We create a popup menu here, since it will likely be used as context
+    // menu. Submenus should be created the factory functions of
+    // QPlatformMenu/Bar. Note though that Quick Controls 1 will use this
+    // function for submenus as well, but this has been found to work.
+    return QWindowsTheme::useNativeMenus() ? new QWindowsPopupMenu : nullptr;
+}
+
+QPlatformMenuBar *QWindowsTheme::createPlatformMenuBar() const
+{
+    qCDebug(lcQpaMenus) << __FUNCTION__;
+    return QWindowsTheme::useNativeMenus() ? new QWindowsMenuBar : nullptr;
+}
+
+void QWindowsTheme::showPlatformMenuBar()
+{
+    qCDebug(lcQpaMenus) << __FUNCTION__;
+}
+
 QT_END_NAMESPACE