Predictive text is not committed when writing in a QLineEdit

QCoeFepInputContext is very aggressive committing its preedit string.
When AVKON FEP opens any of its subwindows, it steals the focus from
editable widget, which causes preedit string to get committed.
This makes the input context almost unusable with T9 word prediction.

As it is rather difficult to prevent focus loss in these types of use
scenarios, replace the committed string with user selected word when
suggested word list is closed.

Task-number: QTBUG-15031
Reviewed-by: Miikka Heikkinen

2 files changed, 31 insertions, 2 deletions

diff --git a/src/gui/inputmethod/qcoefepinputcontext_p.h b/src/gui/inputmethod/qcoefepinputcontext_p.h
index 913d198..e929880 100644
--- a/src/gui/inputmethod/qcoefepinputcontext_p.h
+++ b/src/gui/inputmethod/qcoefepinputcontext_p.h
@@ -159,6 +159,7 @@ private:
     MFepPointerEventHandlerDuringInlineEdit *m_pointerHandler;
     QBasicTimer m_tempPreeditStringTimeout;
     bool m_hasTempPreeditString;
+    QString m_cachedPreeditString;
 
     int m_splitViewResizeBy;
     Qt::WindowStates m_splitViewPreviousWindowStates;
diff --git a/src/gui/inputmethod/qcoefepinputcontext_s60.cpp b/src/gui/inputmethod/qcoefepinputcontext_s60.cpp
index 4f9c4c9..67330e2 100644
--- a/src/gui/inputmethod/qcoefepinputcontext_s60.cpp
+++ b/src/gui/inputmethod/qcoefepinputcontext_s60.cpp
@@ -136,6 +136,16 @@ QCoeFepInputContext::~QCoeFepInputContext()
 
 void QCoeFepInputContext::reset()
 {
+    Qt::InputMethodHints currentHints = Qt::ImhNone;
+    if (focusWidget()) {
+        QWidget *proxy = focusWidget()->focusProxy();
+        currentHints = proxy ? proxy->inputMethodHints() : focusWidget()->inputMethodHints();
+    }
+    // Store a copy of preedit text, if prediction is active and input context is reseted.
+    // This is to ensure that we can replace preedit string after losing focus to FEP manager's
+    // internal sub-windows.
+    if (m_cachedPreeditString.isEmpty() && !(currentHints & Qt::ImhNoPredictiveText))
+        m_cachedPreeditString = m_preeditString;
     commitCurrentString(true);
 }
 
@@ -170,6 +180,8 @@ void QCoeFepInputContext::setFocusWidget(QWidget *w)
 
 void QCoeFepInputContext::widgetDestroyed(QWidget *w)
 {
+    m_cachedPreeditString.clear();
+
     // Make sure that the input capabilities of whatever new widget got focused are queried.
     CCoeControl *ctrl = w->effectiveWinId();
     if (ctrl->IsFocused()) {
@@ -903,6 +915,8 @@ void QCoeFepInputContext::StartFepInlineEditL(const TDesC& aInitialInlineText,
     if (!w)
         return;
 
+    m_cachedPreeditString.clear();
+
     commitTemporaryPreeditString();
 
     QList<QInputMethodEvent::Attribute> attributes;
@@ -959,7 +973,10 @@ void QCoeFepInputContext::UpdateFepInlineTextL(const TDesC& aNewInlineText,
                                                    QVariant()));
     QString newPreeditString = qt_TDesC2QString(aNewInlineText);
     QInputMethodEvent event(newPreeditString, attributes);
-    if (newPreeditString.isEmpty() && m_preeditString.isEmpty()) {
+    if (!m_cachedPreeditString.isEmpty()) {
+        event.setCommitString(QLatin1String(""), -m_cachedPreeditString.length(), m_cachedPreeditString.length());
+        m_cachedPreeditString.clear();
+    } else if (newPreeditString.isEmpty() && m_preeditString.isEmpty()) {
         // In Symbian world this means "erase last character".
         event.setCommitString(QLatin1String(""), -1, 1);
     }
@@ -1149,7 +1166,18 @@ void QCoeFepInputContext::commitCurrentString(bool cancelFepTransaction)
 
     m_hasTempPreeditString = false;
 
-    if (cancelFepTransaction) {
+    //Only cancel FEP transactions with prediction, when there is still active window.
+    Qt::InputMethodHints currentHints = Qt::ImhNone;
+    if (focusWidget()) {
+        if (focusWidget()->focusProxy())
+            currentHints = focusWidget()->focusProxy()->inputMethodHints();
+        else
+            currentHints = focusWidget()->inputMethodHints();
+    }
+    bool predictive = !(currentHints & Qt::ImhNoPredictiveText);
+    bool widgetAndWindowAvailable = QApplication::activeWindow() && focusWidget();
+
+    if (cancelFepTransaction && ((predictive && widgetAndWindowAvailable) || !predictive)) {
         CCoeFep* fep = CCoeEnv::Static()->Fep();
         if (fep)
             fep->CancelTransaction();