Windows platform headers: Add isTabletMode()

Add a bool function querying Windows 10 tablet mode.

Task-number: QTBUG-56831
Change-Id: Ief728a7d80a11ba79f7859033ff4be6ef79bbd4e
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@qt.io>
Reviewed-by: Joerg Bornemann <joerg.bornemann@qt.io>

2 files changed, 41 insertions, 0 deletions

diff --git a/src/platformheaders/windowsfunctions/qwindowswindowfunctions.h b/src/platformheaders/windowsfunctions/qwindowswindowfunctions.h
index d0826bdb50..e51c2fde67 100644
--- a/src/platformheaders/windowsfunctions/qwindowswindowfunctions.h
+++ b/src/platformheaders/windowsfunctions/qwindowswindowfunctions.h
@@ -90,6 +90,15 @@ public:
         if (func)
             func(behavior);
     }
+
+    typedef bool (*IsTabletModeType)();
+    static const QByteArray isTabletModeIdentifier() { return QByteArrayLiteral("WindowsIsTabletMode"); }
+
+    static bool isTabletMode()
+    {
+        IsTabletModeType func = reinterpret_cast<IsTabletModeType>(QGuiApplication::platformFunction(isTabletModeIdentifier()));
+        return func && func();
+    }
 };
 
 Q_DECLARE_OPERATORS_FOR_FLAGS(QWindowsWindowFunctions::TouchWindowTouchTypes)
diff --git a/src/platformheaders/windowsfunctions/qwindowswindowfunctions.qdoc b/src/platformheaders/windowsfunctions/qwindowswindowfunctions.qdoc
index 24e4847042..898b1bbb29 100644
--- a/src/platformheaders/windowsfunctions/qwindowswindowfunctions.qdoc
+++ b/src/platformheaders/windowsfunctions/qwindowswindowfunctions.qdoc
@@ -144,3 +144,35 @@
     \sa QWidget::activateWindow(), QWindow::requestActivate()
     \since 5.7
 */
+
+/*!
+    \typedef QWindowsWindowFunctions::IsTabletModeType
+
+    This is the typedef for the function returned by QGuiApplication::platformFunction()
+    when passed isTabletModeIdentifier().
+
+    \since 5.9
+*/
+
+/*!
+    \fn QByteArray QWindowsWindowFunctions::isTabletModeIdentifier()
+
+    Returns a bytearray that can be used to query
+    QGuiApplication::platformFunction() to retrieve the IsTabletModeType
+    function.
+
+    \since 5.9
+*/
+
+/*!
+    \fn bool QWindowsWindowFunctions::isTabletMode()
+
+    This is a convenience function that can be used directly instead of resolving
+    the function pointer. The function can be used to query whether Windows 10
+    operates in \e{Tablet Mode}. In this mode, Windows forces all application
+    main windows to open in maximized state. Applications should then avoid
+    resizing windows or restoring geometries to non-maximized states.
+
+    \sa QWidget::showMaximized(), QWidget::saveGeometry(), QWidget::restoreGeometry()
+    \since 5.9
+*/