D-Bus system tray icon: submenus can be created after context menu

QMenuPrivate::init() calls QPlatformTheme::createPlatformMenu() to
create a platform menu, but on Linux, that returns null for now.
QSystemTrayIcon::setContextMenu() results in recursive calls to
QSystemTrayIconPrivate::addPlatformMenu() which then calls
QDBusTrayIcon::createMenu() for the context menu and each submenu.
However if a submenu is added afterwards, a corresponding platform
menu is not immediately created.  Now copyActionToPlatformItem()
will detect and create the missing platform submenu, by calling
a new method: DBusPlatformMenu::createSubMenu().  This is because
there is no way of knowing that it's a tray-specific context menu
(which is so far the only case in which we use DBusPlatformMenu).
So, QPlatformMenu::createSubMenu() needs to exist as a new
QPA interface for this use case.

Task-number: QTBUG-45803
Change-Id: Ib319e873082196515ea0580d70d069099cf2c175
Reviewed-by: Jørgen Lind <jorgen.lind@theqtcompany.com>

1 files changed, 7 insertions, 5 deletions

diff --git a/src/widgets/widgets/qmenu.cpp b/src/widgets/widgets/qmenu.cpp
index 1749f9d8c7..2f0dcc49d1 100644
--- a/src/widgets/widgets/qmenu.cpp
+++ b/src/widgets/widgets/qmenu.cpp
@@ -183,7 +183,7 @@ void QMenuPrivate::setPlatformMenu(QPlatformMenu *menu)
 }
 
 // forward declare function
-static void copyActionToPlatformItem(const QAction *action, QPlatformMenuItem* item);
+static void copyActionToPlatformItem(const QAction *action, QPlatformMenuItem *item, QPlatformMenu *itemsMenu);
 
 void QMenuPrivate::syncPlatformMenu()
 {
@@ -200,7 +200,7 @@ void QMenuPrivate::syncPlatformMenu()
         menuItem->setTag(reinterpret_cast<quintptr>(action));
         QObject::connect(menuItem, SIGNAL(activated()), action, SLOT(trigger()), Qt::QueuedConnection);
         QObject::connect(menuItem, SIGNAL(hovered()), action, SIGNAL(hovered()), Qt::QueuedConnection);
-        copyActionToPlatformItem(action, menuItem);
+        copyActionToPlatformItem(action, menuItem, platformMenu.data());
         platformMenu->insertMenuItem(menuItem, beforeItem);
         beforeItem = menuItem;
     }
@@ -3105,7 +3105,7 @@ QMenu::timerEvent(QTimerEvent *e)
     }
 }
 
-static void copyActionToPlatformItem(const QAction *action, QPlatformMenuItem* item)
+static void copyActionToPlatformItem(const QAction *action, QPlatformMenuItem *item, QPlatformMenu *itemsMenu)
 {
     item->setText(action->text());
     item->setIsSeparator(action->isSeparator());
@@ -3131,6 +3131,8 @@ static void copyActionToPlatformItem(const QAction *action, QPlatformMenuItem* i
     item->setEnabled(action->isEnabled());
 
     if (action->menu()) {
+        if (!action->menu()->platformMenu())
+            action->menu()->setPlatformMenu(itemsMenu->createSubMenu());
         item->setMenu(action->menu()->platformMenu());
     } else {
         item->setMenu(0);
@@ -3185,7 +3187,7 @@ void QMenu::actionEvent(QActionEvent *e)
             menuItem->setTag(reinterpret_cast<quintptr>(e->action()));
             QObject::connect(menuItem, SIGNAL(activated()), e->action(), SLOT(trigger()));
             QObject::connect(menuItem, SIGNAL(hovered()), e->action(), SIGNAL(hovered()));
-            copyActionToPlatformItem(e->action(), menuItem);
+            copyActionToPlatformItem(e->action(), menuItem, d->platformMenu);
             QPlatformMenuItem* beforeItem = d->platformMenu->menuItemForTag(reinterpret_cast<quintptr>(e->before()));
             d->platformMenu->insertMenuItem(menuItem, beforeItem);
         } else if (e->type() == QEvent::ActionRemoved) {
@@ -3195,7 +3197,7 @@ void QMenu::actionEvent(QActionEvent *e)
         } else if (e->type() == QEvent::ActionChanged) {
             QPlatformMenuItem *menuItem = d->platformMenu->menuItemForTag(reinterpret_cast<quintptr>(e->action()));
             if (menuItem) {
-                copyActionToPlatformItem(e->action(), menuItem);
+                copyActionToPlatformItem(e->action(), menuItem, d->platformMenu);
                 d->platformMenu->syncMenuItem(menuItem);
             }
         }