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>

5 files changed, 24 insertions, 7 deletions

diff --git a/src/gui/kernel/qplatformmenu.cpp b/src/gui/kernel/qplatformmenu.cpp
index cb311b8d13..da65381931 100644
--- a/src/gui/kernel/qplatformmenu.cpp
+++ b/src/gui/kernel/qplatformmenu.cpp
@@ -44,4 +44,9 @@ QPlatformMenuItem *QPlatformMenu::createMenuItem() const
     return QGuiApplicationPrivate::platformTheme()->createPlatformMenuItem();
 }
 
+QPlatformMenu *QPlatformMenu::createSubMenu() const
+{
+    return QGuiApplicationPrivate::platformTheme()->createPlatformMenu();
+}
+
 QT_END_NAMESPACE
diff --git a/src/gui/kernel/qplatformmenu.h b/src/gui/kernel/qplatformmenu.h
index baa1e460d7..1022d0ed4a 100644
--- a/src/gui/kernel/qplatformmenu.h
+++ b/src/gui/kernel/qplatformmenu.h
@@ -123,6 +123,7 @@ public:
     virtual QPlatformMenuItem *menuItemForTag(quintptr tag) const = 0;
 
     virtual QPlatformMenuItem *createMenuItem() const;
+    virtual QPlatformMenu *createSubMenu() const;
 Q_SIGNALS:
     void aboutToShow();
     void aboutToHide();
diff --git a/src/platformsupport/dbusmenu/qdbusplatformmenu.cpp b/src/platformsupport/dbusmenu/qdbusplatformmenu.cpp
index 93c822cefb..a64e107e71 100644
--- a/src/platformsupport/dbusmenu/qdbusplatformmenu.cpp
+++ b/src/platformsupport/dbusmenu/qdbusplatformmenu.cpp
@@ -75,6 +75,9 @@ void QDBusPlatformMenuItem::setIcon(const QIcon &icon)
     m_icon = icon;
 }
 
+/*!
+    Set a submenu under this menu item.
+*/
 void QDBusPlatformMenuItem::setMenu(QPlatformMenu *menu)
 {
     m_subMenu = static_cast<QDBusPlatformMenu *>(menu);
@@ -242,8 +245,12 @@ const QList<QDBusPlatformMenuItem *> QDBusPlatformMenu::items() const
 QPlatformMenuItem *QDBusPlatformMenu::createMenuItem() const
 {
     QDBusPlatformMenuItem *ret = new QDBusPlatformMenuItem();
-    ret->setMenu(const_cast<QDBusPlatformMenu *>(this));
     return ret;
 }
 
+QPlatformMenu *QDBusPlatformMenu::createSubMenu() const
+{
+    return new QDBusPlatformMenu;
+}
+
 QT_END_NAMESPACE
diff --git a/src/platformsupport/dbusmenu/qdbusplatformmenu_p.h b/src/platformsupport/dbusmenu/qdbusplatformmenu_p.h
index 2519533e32..16bb4f195c 100644
--- a/src/platformsupport/dbusmenu/qdbusplatformmenu_p.h
+++ b/src/platformsupport/dbusmenu/qdbusplatformmenu_p.h
@@ -124,7 +124,7 @@ public:
     quintptr tag()const Q_DECL_OVERRIDE { return m_tag; }
     void setTag(quintptr tag) Q_DECL_OVERRIDE;
 
-    const QString text() { return m_text; }
+    const QString text() const { return m_text; }
     void setText(const QString &text) Q_DECL_OVERRIDE;
     void setIcon(const QIcon &icon) Q_DECL_OVERRIDE;
     void setEnabled(bool enabled) Q_DECL_OVERRIDE;
@@ -150,6 +150,7 @@ public:
     const QList<QDBusPlatformMenuItem *> items() const;
 
     QPlatformMenuItem *createMenuItem() const Q_DECL_OVERRIDE;
+    QPlatformMenu *createSubMenu() const Q_DECL_OVERRIDE;
 
     bool operator==(const QDBusPlatformMenu& other) { return m_tag == other.m_tag; }
 
@@ -175,6 +176,7 @@ private:
     uint m_revision;
     QHash<quintptr, QDBusPlatformMenuItem *> m_itemsByTag;
     QList<QDBusPlatformMenuItem *> m_items;
+    QDBusPlatformMenuItem *m_containingMenuItem;
     static QList<QDBusPlatformMenu *> m_topLevelMenus;
 };
 
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);
             }
         }