Add widget support for requestUpdate() and improve its docs and tests

We must do something when requestUpdate() is called on a QWidgetWindow.
The semantics of UpdateRequest for QWindow and QWidget are unfortunately
different: for widgets an UpdateRequest means "sync the backing store".
For QWindow it also involves marking as dirty.

Change-Id: Idf40b3fc0873652dc081edeb12c96b3007a126ef
Reviewed-by: Morten Johan Sørvig <morten.sorvig@theqtcompany.com>
Reviewed-by: Jørgen Lind <jorgen.lind@theqtcompany.com>

1 files changed, 20 insertions, 0 deletions

diff --git a/tests/auto/gui/kernel/qwindow/tst_qwindow.cpp b/tests/auto/gui/kernel/qwindow/tst_qwindow.cpp
index e542c85218..89490525c9 100644
--- a/tests/auto/gui/kernel/qwindow/tst_qwindow.cpp
+++ b/tests/auto/gui/kernel/qwindow/tst_qwindow.cpp
@@ -91,6 +91,7 @@ private slots:
     void modalWindowModallity();
     void modalWindowPosition();
     void windowsTransientChildren();
+    void requestUpdate();
     void initTestCase();
     void cleanup();
 
@@ -1666,6 +1667,25 @@ void tst_QWindow::windowsTransientChildren()
     QVERIFY(isNativeWindowVisible(&child)); // Real children should be visible.
 }
 
+void tst_QWindow::requestUpdate()
+{
+    QRect geometry(m_availableTopLeft + QPoint(80, 80), m_testWindowSize);
+
+    Window window;
+    window.setGeometry(geometry);
+    window.show();
+    QCoreApplication::processEvents();
+    QTRY_VERIFY(window.isExposed());
+
+    QVERIFY(window.received(QEvent::UpdateRequest) == 0);
+
+    window.requestUpdate();
+    QTRY_VERIFY(window.received(QEvent::UpdateRequest) == 1);
+
+    window.requestUpdate();
+    QTRY_VERIFY(window.received(QEvent::UpdateRequest) == 2);
+}
+
 #include <tst_qwindow.moc>
 QTEST_MAIN(tst_QWindow)