Widgets: Fix ImSurroundingText query for a QLineEdit with mask

QLineEdit with a mask does not return empty fields with the
ImSurroundingText query. This is a problem for the input
context that is not aware of the mask and relies on the
fact that the cursor position never exceeds the boundaries
of the surrounding text.

This change fixes the issue by returning unmasked text with
the ImSurroundingText query.

[ChangeLog][QtWidgets][QLineEdit] Fixed behavior of the
ImSurroundingText query. Previously, it returned a masked
text whose length may be less than the cursor position.
Now it returns unmasked text, so the text length is always
greater than or equal to the cursor position.

Task-number: QTBUG-60319
Change-Id: I1c8009164836a1baa2e3a45958bf1ea5fa9be38d
Reviewed-by: Mitch Curtis <mitch.curtis@qt.io>

src/widgets/widgets/qlineedit.cpp

@@ -1773,7 +1773,7 @@ QVariant QLineEdit::inputMethodQuery(Qt::InputMethodQuery property, QVariant arg
             return QVariant(d->xToPos(pt.x(), QTextLine::CursorBetweenCharacters));
         return QVariant(d->control->cursor()); }
     case Qt::ImSurroundingText:
-        return QVariant(d->control->text());
+        return QVariant(d->control->surroundingText());
     case Qt::ImCurrentSelection:
         return QVariant(selectedText());
     case Qt::ImMaximumTextLength:

src/widgets/widgets/qwidgetlinecontrol_p.h

@@ -250,6 +250,11 @@ public:
 
     QString displayText() const { return m_textLayout.text(); }
 
+    QString surroundingText() const
+    {
+        return m_text.isNull() ? QString::fromLatin1("") : m_text;
+    }
+
     void backspace();
     void del();
     void deselect() { internalDeselect(); finishChange(); }

tests/auto/widgets/widgets/qlineedit/tst_qlineedit.cpp

@@ -313,6 +313,8 @@ private slots:
     void shortcutOverrideOnReadonlyLineEdit();
     void QTBUG59957_clearButtonLeftmostAction();
 
+    void QTBUG_60319_setInputMaskCheckImSurroundingText();
+
 protected slots:
     void editingFinished();
 
@@ -4696,5 +4698,16 @@ bool tst_QLineEdit::unselectingWithLeftOrRightChangesCursorPosition()
     return false;
 }
 
+void tst_QLineEdit::QTBUG_60319_setInputMaskCheckImSurroundingText()
+{
+    QLineEdit *testWidget = ensureTestWidget();
+    QString mask("+000(000)-000-00-00");
+    testWidget->setInputMask(mask);
+    testWidget->setCursorPosition(mask.length());
+    QString surroundingText = testWidget->inputMethodQuery(Qt::ImSurroundingText).toString();
+    int cursorPosition = testWidget->inputMethodQuery(Qt::ImCursorPosition).toInt();
+    QCOMPARE(surroundingText.length(), cursorPosition);
+}
+
 QTEST_MAIN(tst_QLineEdit)
 #include "tst_qlineedit.moc"