qquicktextinput: Clear pre-edit text after input method reset

The QPlatformInputContext::reset() function does not allow any further
input method events to be called. Therefore, clearing the pre-edit text
is the sole responsibility of the text input control.

This change modifies the QQuickTextInputPrivate::resetInputMethod()
function and calls QQuickTextInputPrivate::cancelPreedit() instead of
QInputMethod::reset() directly. The cancelPreedit() function will send
a QInputMethodEvent which clears the IM state (in addition of calling
QInputMethod::reset() function).

Also, rename the QQuickTextInputPrivate::resetInputMethod() function to
cancelInput, since it does not call inputMethod()->reset() directly.

Fixes: QTBUG-95461
Change-Id: I6ab3b9dbe71956af72656e2a25a05d79603b34ea
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
Reviewed-by: Inho Lee <inho.lee@qt.io>
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@qt.io>
Reviewed-by: Jarkko Koivikko <jarkko.koivikko@code-q.fi>
(cherry picked from commit b2103e33f490c96d0068d211c6f2d5b540ca407e)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

3 files changed, 10 insertions, 6 deletions

diff --git a/src/quick/items/qquicktextinput.cpp b/src/quick/items/qquicktextinput.cpp
index 498fe8ab84..8840d8f49b 100644
--- a/src/quick/items/qquicktextinput.cpp
+++ b/src/quick/items/qquicktextinput.cpp
@@ -2105,7 +2105,7 @@ void QQuickTextInput::undo()
 {
     Q_D(QQuickTextInput);
     if (!d->m_readOnly) {
-        d->resetInputMethod();
+        d->cancelInput();
         d->internalUndo();
         d->finishChange(-1, true);
     }
@@ -2121,7 +2121,7 @@ void QQuickTextInput::redo()
 {
     Q_D(QQuickTextInput);
     if (!d->m_readOnly) {
-        d->resetInputMethod();
+        d->cancelInput();
         d->internalRedo();
         d->finishChange();
     }
@@ -2748,11 +2748,13 @@ void QQuickTextInputPrivate::init()
     m_inputControl = new QInputControl(QInputControl::LineEdit, q);
 }
 
-void QQuickTextInputPrivate::resetInputMethod()
+void QQuickTextInputPrivate::cancelInput()
 {
+#if QT_CONFIG(im)
     Q_Q(QQuickTextInput);
     if (!m_readOnly && q->hasActiveFocus() && qGuiApp)
-        QGuiApplication::inputMethod()->reset();
+        cancelPreedit();
+#endif // im
 }
 
 void QQuickTextInput::updateCursorRectangle(bool scroll)
@@ -4695,7 +4697,7 @@ void QQuickTextInput::ensureVisible(int position)
 void QQuickTextInput::clear()
 {
     Q_D(QQuickTextInput);
-    d->resetInputMethod();
+    d->cancelInput();
     d->clear();
 }
 
diff --git a/src/quick/items/qquicktextinput_p_p.h b/src/quick/items/qquicktextinput_p_p.h
index 2f700e3f3e..d6eda42954 100644
--- a/src/quick/items/qquicktextinput_p_p.h
+++ b/src/quick/items/qquicktextinput_p_p.h
@@ -173,7 +173,7 @@ public:
     }
 
     void init();
-    void resetInputMethod();
+    void cancelInput();
     void startCreatingCursor();
     void ensureVisible(int position, int preeditCursor = 0, int preeditLength = 0);
     void updateHorizontalScroll();
diff --git a/tests/auto/quick/qquicktextinput/tst_qquicktextinput.cpp b/tests/auto/quick/qquicktextinput/tst_qquicktextinput.cpp
index 7c5c09055d..0ef1711fd6 100644
--- a/tests/auto/quick/qquicktextinput/tst_qquicktextinput.cpp
+++ b/tests/auto/quick/qquicktextinput/tst_qquicktextinput.cpp
@@ -5924,6 +5924,7 @@ void tst_qquicktextinput::clear()
 
     textInput->clear();
     QVERIFY(textInput->text().isEmpty());
+    QVERIFY2(textInput->preeditText().isEmpty(), "Pre-edit text must be empty after clear");
 
     QCOMPARE(spy.count(), 3);
 
@@ -5932,6 +5933,7 @@ void tst_qquicktextinput::clear()
     QVERIFY(!textInput->canUndo());
     QCOMPARE(spy.count(), 4);
     QCOMPARE(textInput->text(), QString("I am Legend"));
+    QVERIFY2(textInput->preeditText().isEmpty(), "Pre-edit text must be empty after undo");
 }
 
 void tst_qquicktextinput::backspaceSurrogatePairs()