Fix input method support on widgets that have a focus proxy set.

When enabling/disabling a widget or changing its InputMethodEnabled attribute,
use the focus proxy widget's input context for reset and for setting the focus
widget on the input context.

Task-number: QTBUG-5781
Reviewed-by: Denis

3 files changed, 77 insertions, 9 deletions

diff --git a/src/gui/kernel/qwidget.cpp b/src/gui/kernel/qwidget.cpp
index 4aa358f..0d8da0c 100644
--- a/src/gui/kernel/qwidget.cpp
+++ b/src/gui/kernel/qwidget.cpp
@@ -3084,9 +3084,10 @@ void QWidgetPrivate::setEnabled_helper(bool enable)
 #endif
 #ifndef QT_NO_IM
     if (q->testAttribute(Qt::WA_InputMethodEnabled) && q->hasFocus()) {
-        QInputContext *qic = inputContext();
+        QWidget *focusWidget = effectiveFocusWidget();
+        QInputContext *qic = focusWidget->d_func()->inputContext();
         if (enable) {
-            qic->setFocusWidget(q);
+            qic->setFocusWidget(focusWidget);
         } else {
             qic->reset();
             qic->setFocusWidget(0);
@@ -10348,9 +10349,10 @@ void QWidget::setAttribute(Qt::WidgetAttribute attribute, bool on)
         break; }
     case Qt::WA_NativeWindow: {
 #ifndef QT_NO_IM
+        QWidget *focusWidget = d->effectiveFocusWidget();
         QInputContext *ic = 0;
         if (on && !internalWinId() && testAttribute(Qt::WA_InputMethodEnabled) && hasFocus()) {
-            ic = d->inputContext();
+            ic = focusWidget->d_func()->inputContext();
             ic->reset();
             ic->setFocusWidget(0);
         }
@@ -10359,7 +10361,7 @@ void QWidget::setAttribute(Qt::WidgetAttribute attribute, bool on)
         if (on && !internalWinId() && testAttribute(Qt::WA_WState_Created))
             d->createWinId();
         if (ic && isEnabled())
-            ic->setFocusWidget(this);
+            ic->setFocusWidget(focusWidget);
 #endif //QT_NO_IM
         break;
     }
@@ -10391,13 +10393,14 @@ void QWidget::setAttribute(Qt::WidgetAttribute attribute, bool on)
         break;
     case Qt::WA_InputMethodEnabled: {
 #ifndef QT_NO_IM
-        QInputContext *ic = d->ic;
+        QWidget *focusWidget = d->effectiveFocusWidget();
+        QInputContext *ic = focusWidget->d_func()->ic;
         if (!ic && (!on || hasFocus()))
-            ic = d->inputContext();
+            ic = focusWidget->d_func()->inputContext();
         if (ic) {
-            if (on && hasFocus() && ic->focusWidget() != this && isEnabled()) {
-                ic->setFocusWidget(this);
-            } else if (!on && ic->focusWidget() == this) {
+            if (on && hasFocus() && ic->focusWidget() != focusWidget && isEnabled()) {
+                ic->setFocusWidget(focusWidget);
+            } else if (!on && ic->focusWidget() == focusWidget) {
                 ic->reset();
                 ic->setFocusWidget(0);
             }
diff --git a/src/gui/kernel/qwidget_p.h b/src/gui/kernel/qwidget_p.h
index eea929b..66efcb5 100644
--- a/src/gui/kernel/qwidget_p.h
+++ b/src/gui/kernel/qwidget_p.h
@@ -465,6 +465,12 @@ public:
     void setLayoutItemMargins(QStyle::SubElement element, const QStyleOption *opt = 0);
 
     QInputContext *inputContext() const;
+    inline QWidget *effectiveFocusWidget() {
+        QWidget *w = q_func();
+        while (w->focusProxy())
+            w = w->focusProxy();
+        return w;
+    }
 
     void setModal_sys();
 
diff --git a/tests/auto/qwidget/tst_qwidget.cpp b/tests/auto/qwidget/tst_qwidget.cpp
index e027dd1..9692c6e 100644
--- a/tests/auto/qwidget/tst_qwidget.cpp
+++ b/tests/auto/qwidget/tst_qwidget.cpp
@@ -388,6 +388,8 @@ private slots:
     void cbaVisibility();
 #endif
 
+    void focusProxyAndInputMethods();
+
 private:
     bool ensureScreenSize(int width, int height);
     QWidget *testWidget;
@@ -9619,5 +9621,62 @@ void tst_QWidget::cbaVisibility()
 }
 #endif
 
+class InputContextTester : public QInputContext
+{
+    Q_OBJECT
+public:
+    QString identifierName() { return QString(); }
+    bool isComposing() const { return false; }
+    QString language() { return QString(); }
+    void reset() { ++resets; }
+    int resets;
+};
+
+void tst_QWidget::focusProxyAndInputMethods()
+{
+    InputContextTester *inputContext = new InputContextTester;
+    QWidget *toplevel = new QWidget(0, Qt::X11BypassWindowManagerHint);
+    toplevel->setAttribute(Qt::WA_InputMethodEnabled, true);
+    toplevel->setInputContext(inputContext); // ownership is transferred
+
+    QWidget *child = new QWidget(toplevel);
+    child->setFocusProxy(toplevel);
+    child->setAttribute(Qt::WA_InputMethodEnabled, true);
+
+    toplevel->setFocusPolicy(Qt::WheelFocus);
+    child->setFocusPolicy(Qt::WheelFocus);
+
+    QVERIFY(!child->hasFocus());
+    QVERIFY(!toplevel->hasFocus());
+
+    toplevel->show();
+    QTest::qWaitForWindowShown(toplevel);
+    QApplication::setActiveWindow(toplevel);
+    QVERIFY(toplevel->hasFocus());
+    QVERIFY(child->hasFocus());
+
+    // verify that toggling input methods on the child widget
+    // correctly propagate to the focus proxy's input method
+    // and that the input method gets the focus proxy passed
+    // as the focus widget instead of the child widget.
+    // otherwise input method queries go to the wrong widget
+
+    QCOMPARE(inputContext->focusWidget(), toplevel);
+
+    child->setAttribute(Qt::WA_InputMethodEnabled, false);
+    QVERIFY(!inputContext->focusWidget());
+
+    child->setAttribute(Qt::WA_InputMethodEnabled, true);
+    QCOMPARE(inputContext->focusWidget(), toplevel);
+
+    child->setEnabled(false);
+    QVERIFY(!inputContext->focusWidget());
+
+    child->setEnabled(true);
+    QCOMPARE(inputContext->focusWidget(), toplevel);
+
+    delete toplevel;
+}
+
 QTEST_MAIN(tst_QWidget)
 #include "tst_qwidget.moc"