Widgets: report focus object change to QtGui before sending widget events

Updating the focus child means the focus object of the window has changed.
We need to report this to QtGui immediately so that it can e.g. inform the
input context of the new focus object, before widgets reacting to the focus
events start calling update() on the input method.

Change-Id: Ie3f7b835591e71519e3f384c2abdad53242c9736
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

1 files changed, 59 insertions, 1 deletions

diff --git a/tests/auto/widgets/kernel/qwidget/tst_qwidget.cpp b/tests/auto/widgets/kernel/qwidget/tst_qwidget.cpp
index 9ddcabd165..2657b28d30 100644
--- a/tests/auto/widgets/kernel/qwidget/tst_qwidget.cpp
+++ b/tests/auto/widgets/kernel/qwidget/tst_qwidget.cpp
@@ -5216,16 +5216,40 @@ protected:
             widgetDuringFocusAboutToChange = qApp->focusWidget();
         return QWidget::event(ev);
     }
+    virtual void focusInEvent(QFocusEvent *)
+    {
+        foucsObjectDuringFocusIn = qApp->focusObject();
+        detectedBadEventOrdering = foucsObjectDuringFocusIn != mostRecentFocusObjectChange;
+    }
     virtual void focusOutEvent(QFocusEvent *)
     {
+        foucsObjectDuringFocusOut = qApp->focusObject();
         widgetDuringFocusOut = qApp->focusWidget();
+        detectedBadEventOrdering = foucsObjectDuringFocusOut != mostRecentFocusObjectChange;
+    }
+
+    void focusObjectChanged(QObject *focusObject)
+    {
+        mostRecentFocusObjectChange = focusObject;
     }
 
 public:
-    FocusWidget(QWidget *parent) : QWidget(parent), widgetDuringFocusAboutToChange(0), widgetDuringFocusOut(0) {}
+    FocusWidget(QWidget *parent) : QWidget(parent),
+        widgetDuringFocusAboutToChange(0), widgetDuringFocusOut(0),
+        foucsObjectDuringFocusIn(0), foucsObjectDuringFocusOut(0),
+        mostRecentFocusObjectChange(0), detectedBadEventOrdering(false)
+    {
+        connect(qGuiApp, &QGuiApplication::focusObjectChanged, this, &FocusWidget::focusObjectChanged);
+    }
 
     QWidget *widgetDuringFocusAboutToChange;
     QWidget *widgetDuringFocusOut;
+
+    QObject *foucsObjectDuringFocusIn;
+    QObject *foucsObjectDuringFocusOut;
+
+    QObject *mostRecentFocusObjectChange;
+    bool detectedBadEventOrdering;
 };
 
 void tst_QWidget::setFocus()
@@ -5426,6 +5450,40 @@ void tst_QWidget::setFocus()
         QCOMPARE(window.focusWidget(), nullptr);
         QCOMPARE(QApplication::focusWidget(), nullptr);
     }
+
+    {
+        QWidget window;
+        window.resize(m_testWidgetSize);
+        window.move(windowPos);
+
+        FocusWidget child1(&window);
+        QWidget child2(&window);
+
+        window.show();
+        window.activateWindow();
+        QVERIFY(QTest::qWaitForWindowExposed(&window));
+        QTRY_VERIFY(QApplication::focusWindow());
+
+        QCOMPARE(QApplication::focusObject(), &window);
+
+        child1.setFocus();
+        QTRY_VERIFY(child1.hasFocus());
+        QCOMPARE(window.focusWidget(), &child1);
+        QCOMPARE(QApplication::focusWidget(), &child1);
+        QCOMPARE(QApplication::focusObject(), &child1);
+        QCOMPARE(child1.foucsObjectDuringFocusIn, &child1);
+        QVERIFY2(!child1.detectedBadEventOrdering,
+            "focusObjectChanged should be delivered before widget focus events on setFocus");
+
+        child1.clearFocus();
+        QTRY_VERIFY(!child1.hasFocus());
+        QCOMPARE(window.focusWidget(), nullptr);
+        QCOMPARE(QApplication::focusWidget(), nullptr);
+        QCOMPARE(QApplication::focusObject(), &window);
+        QVERIFY(child1.foucsObjectDuringFocusOut != &child1);
+        QVERIFY2(!child1.detectedBadEventOrdering,
+            "focusObjectChanged should be delivered before widget focus events on clearFocus");
+    }
 }
 
 template<class T> class EventSpy : public QObject