QMenu: Add showTearOffMenu()

The API is incomplete since we can't show a tear-off menu
programatically. This could be useful when restoring the
application state on launch.

Change-Id: Ice1911b44a5b973680f67b0150efacf3d023c2c5
Task-number: QTBUG-47974
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@theqtcompany.com>
Reviewed-by: Shawn Rutledge <shawn.rutledge@theqtcompany.com>

src/widgets/widgets/qmenu.cpp

@@ -1948,7 +1948,7 @@ bool QMenu::isTearOffEnabled() const
   contents in a new window. When the menu is in this mode and the menu
   is visible returns \c true; otherwise false.
 
-  \sa hideTearOffMenu(), isTearOffEnabled()
+  \sa showTearOffMenu(), hideTearOffMenu(), isTearOffEnabled()
 */
 bool QMenu::isTearOffMenuVisible() const
 {
@@ -1958,15 +1958,54 @@ bool QMenu::isTearOffMenuVisible() const
 }
 
 /*!
-   This function will forcibly hide the torn off menu making it
-   disappear from the users desktop.
+   \since 5.7
 
-   \sa isTearOffMenuVisible(), isTearOffEnabled()
+   This function will forcibly show the torn off menu making it
+   appear on the user's desktop at the specified \e global position \a pos.
+
+   \sa hideTearOffMenu(), isTearOffMenuVisible(), isTearOffEnabled()
+*/
+void QMenu::showTearOffMenu(const QPoint &pos)
+{
+    Q_D(QMenu);
+    if (!d->tornPopup)
+        d->tornPopup = new QTornOffMenu(this);
+    const QSize &s = sizeHint();
+    d->tornPopup->setGeometry(pos.x(), pos.y(), s.width(), s.height());
+    d->tornPopup->show();
+}
+
+/*!
+   \overload
+   \since 5.7
+
+   This function will forcibly show the torn off menu making it
+   appear on the user's desktop under the mouse currsor.
+
+   \sa hideTearOffMenu(), isTearOffMenuVisible(), isTearOffEnabled()
+*/
+void QMenu::showTearOffMenu()
+{
+    showTearOffMenu(QCursor::pos());
+}
+
+/*!
+   This function will forcibly hide the torn off menu making it
+   disappear from the user's desktop.
+
+   \sa showTearOffMenu(), isTearOffMenuVisible(), isTearOffEnabled()
 */
 void QMenu::hideTearOffMenu()
 {
-    if (QWidget *w = d_func()->tornPopup)
-        w->close();
+    Q_D(QMenu);
+    if (d->tornPopup) {
+        d->tornPopup->close();
+        // QTornOffMenu sets WA_DeleteOnClose, so we
+        // should consider the torn-off menu deleted.
+        // This way showTearOffMenu() will not try to
+        // reuse the dying torn-off menu.
+        d->tornPopup = Q_NULLPTR;
+    }
 }
 
 

src/widgets/widgets/qmenu.h

@@ -171,6 +171,8 @@ public:
     bool isTearOffEnabled() const;
 
     bool isTearOffMenuVisible() const;
+    void showTearOffMenu();
+    void showTearOffMenu(const QPoint &pos);
     void hideTearOffMenu();
 
     void setDefaultAction(QAction *);

tests/auto/widgets/widgets/qmenu/tst_qmenu.cpp

@@ -591,10 +591,19 @@ void tst_QMenu::widgetActionFocus()
     QCOMPARE(m.activeAction(), (QAction *)wa);
 }
 
+static QMenu *getTornOffMenu()
+{
+    foreach (QWidget *w, QApplication::allWidgets()) {
+        if (w->isVisible() && w->inherits("QTornOffMenu"))
+            return static_cast<QMenu *>(w);
+    }
+    return Q_NULLPTR;
+}
+
 void tst_QMenu::tearOff()
 {
     QWidget widget;
-    QMenu *menu = new QMenu(&widget);
+    QScopedPointer<QMenu> menu(new QMenu(&widget));
     QVERIFY(!menu->isTearOffEnabled()); //default value
     menu->setTearOffEnabled(true);
     menu->addAction("aaa");
@@ -607,24 +616,43 @@ void tst_QMenu::tearOff()
     widget.activateWindow();
     QVERIFY(QTest::qWaitForWindowActive(&widget));
     menu->popup(widget.geometry().topRight() + QPoint(50, 0));
-    QVERIFY(QTest::qWaitForWindowActive(menu));
+    QVERIFY(QTest::qWaitForWindowActive(menu.data()));
     QVERIFY(!menu->isTearOffMenuVisible());
 
-    QTest::mouseClick(menu, Qt::LeftButton, 0, QPoint(3, 3), 10);
+    QTest::mouseClick(menu.data(), Qt::LeftButton, 0, QPoint(3, 3), 10);
     QTRY_VERIFY(menu->isTearOffMenuVisible());
-    QPointer<QMenu> torn = 0;
-    foreach (QWidget *w, QApplication::allWidgets()) {
-        if (w->inherits("QTornOffMenu")) {
-            torn = static_cast<QMenu *>(w);
-            break;
-        }
-    }
+    QPointer<QMenu> torn = getTornOffMenu();
     QVERIFY(torn);
     QVERIFY(torn->isVisible());
 
     menu->hideTearOffMenu();
     QVERIFY(!menu->isTearOffMenuVisible());
     QVERIFY(!torn->isVisible());
+
+#ifndef QT_NO_CURSOR
+    // Test under-mouse positioning
+    menu->showTearOffMenu();
+    torn = getTornOffMenu();
+    QVERIFY(torn);
+    QVERIFY(torn->isVisible());
+    QVERIFY(menu->isTearOffMenuVisible());
+    // Some platforms include the window title bar in its geometry.
+    QTRY_COMPARE(torn->windowHandle()->position(), QCursor::pos());
+
+    menu->hideTearOffMenu();
+    QVERIFY(!menu->isTearOffMenuVisible());
+    QVERIFY(!torn->isVisible());
+
+    // Test custom positioning
+    const QPoint &pos = QCursor::pos() / 2 + QPoint(10, 10);
+    menu->showTearOffMenu(pos);
+    torn = getTornOffMenu();
+    QVERIFY(torn);
+    QVERIFY(torn->isVisible());
+    QVERIFY(menu->isTearOffMenuVisible());
+    // Some platforms include the window title bar in its geometry.
+    QTRY_COMPARE(torn->windowHandle()->position(), pos);
+#endif // QT_NO_CURSOR
 }
 
 void tst_QMenu::layoutDirection()