Fix crash in S60 input methods after task switching

When switching away from the application, the focused widget is set to
null. When switching back, there are callbacks from S60 before the focus
has been restored.
These functions check for null widget, but the output function parameters
are left uninitialised, which causes a crash inside the S60 FEP.
1) GetXYZ functions now initialise the output parameters even when the
   focused widget is null.
2) Return no input capability when there is no focused widget, as was
   already done during destruction. This stops most of the callbacks
   from S60.

Task-number: QTBUG-4618
Reviewed-by: axis

1 files changed, 15 insertions, 5 deletions

diff --git a/src/gui/inputmethod/qcoefepinputcontext_s60.cpp b/src/gui/inputmethod/qcoefepinputcontext_s60.cpp
index fc55a0fcb8..c4d17ff9be 100644
--- a/src/gui/inputmethod/qcoefepinputcontext_s60.cpp
+++ b/src/gui/inputmethod/qcoefepinputcontext_s60.cpp
@@ -222,7 +222,7 @@ void QCoeFepInputContext::mouseHandler( int x, QMouseEvent *event)
 
 TCoeInputCapabilities QCoeFepInputContext::inputCapabilities()
 {
-    if (m_inDestruction) {
+    if (m_inDestruction || !focusWidget()) {
         return TCoeInputCapabilities(TCoeInputCapabilities::ENone, 0, 0);
     }
 
@@ -554,8 +554,10 @@ void QCoeFepInputContext::SetCursorSelectionForFepL(const TCursorSelection& aCur
 void QCoeFepInputContext::GetCursorSelectionForFep(TCursorSelection& aCursorSelection) const
 {
     QWidget *w = focusWidget();
-    if (!w)
+    if (!w) {
+        aCursorSelection.SetSelection(0,0);
         return;
+    }
 
     int cursor = w->inputMethodQuery(Qt::ImCursorPosition).toInt() + m_preeditString.size();
     int anchor = w->inputMethodQuery(Qt::ImAnchorPosition).toInt() + m_preeditString.size();
@@ -567,8 +569,10 @@ void QCoeFepInputContext::GetEditorContentForFep(TDes& aEditorContent, TInt aDoc
         TInt aLengthToRetrieve) const
 {
     QWidget *w = focusWidget();
-    if (!w)
+    if (!w) {
+        aEditorContent.FillZ(aLengthToRetrieve);
         return;
+    }
 
     QString text = w->inputMethodQuery(Qt::ImSurroundingText).value<QString>();
     // FEP expects the preedit string to be part of the editor content, so let's mix it in.
@@ -580,8 +584,10 @@ void QCoeFepInputContext::GetEditorContentForFep(TDes& aEditorContent, TInt aDoc
 void QCoeFepInputContext::GetFormatForFep(TCharFormat& aFormat, TInt /* aDocumentPosition */) const
 {
     QWidget *w = focusWidget();
-    if (!w)
+    if (!w) {
+        aFormat = TCharFormat();
         return;
+    }
 
     QFont font = w->inputMethodQuery(Qt::ImFont).value<QFont>();
     QFontMetrics metrics(font);
@@ -595,8 +601,12 @@ void QCoeFepInputContext::GetScreenCoordinatesForFepL(TPoint& aLeftSideOfBaseLin
         TInt& aAscent, TInt /* aDocumentPosition */) const
 {
     QWidget *w = focusWidget();
-    if (!w)
+    if (!w) {
+        aLeftSideOfBaseLine = TPoint(0,0);
+        aHeight = 0;
+        aAscent = 0;
         return;
+    }
 
     QRect rect = w->inputMethodQuery(Qt::ImMicroFocus).value<QRect>();
     aLeftSideOfBaseLine.iX = rect.left();