QAndroidPlatformInputContext: send composition text and cursor jointly

QAndroidPlatformInputContext::focusObjectStopComposing() sends an input
event for each character newly added by the Android virtual keyboard.
It then sends a second input event to notify that the cursor has
advanced to the position after the new character.
The implicit assumption is, that the receiver of the input event does
not change the text.

If e.g. QLineEdit::setText() is called in the QLineEdit::textEdited
slot, the text does change. If the change implies a cursor change,
QLineEdit notifies the platform input context about it.
However, by sending the second input event, QAndroidPlatformContent
returns the cursor back to the position after the last character added
by the virtual keyboard.

This patch joins the composed text and the cursor position into one
single input method event. A new cursor position, set by the receiver
of the input method event, is no longer overridden.
The patch adds test functionality to tst_QLineEdit::setText().

Fixes: QTBUG-115756
Change-Id: I85ffac5d6bab93ccb144be0f5b8083258a270550
Reviewed-by: Tor Arne Vestbø <[email protected]>
(cherry picked from commit be3b9b2ab12f664c196d649e8c4247d70805d667)
Reviewed-by: Qt Cherry-pick Bot <[email protected]>

2 files changed, 42 insertions, 20 deletions

diff --git a/src/plugins/platforms/android/qandroidinputcontext.cpp b/src/plugins/platforms/android/qandroidinputcontext.cpp
index 521d3086b57..5d539d7da43 100644
--- a/src/plugins/platforms/android/qandroidinputcontext.cpp
+++ b/src/plugins/platforms/android/qandroidinputcontext.cpp
@@ -1131,21 +1131,13 @@ bool QAndroidInputContext::focusObjectStopComposing()
 
     m_composingCursor = -1;
 
-    {
-        // commit the composing test
-        QList<QInputMethodEvent::Attribute> attributes;
-        QInputMethodEvent event(QString(), attributes);
-        event.setCommitString(m_composingText);
-        sendInputMethodEvent(&event);
-    }
-    {
-        // Moving Qt's cursor to where the preedit cursor used to be
-        QList<QInputMethodEvent::Attribute> attributes;
-        attributes.append(
-                QInputMethodEvent::Attribute(QInputMethodEvent::Selection, localCursorPos, 0));
-        QInputMethodEvent event(QString(), attributes);
-        sendInputMethodEvent(&event);
-    }
+    // commit composing text and cursor position
+    QList<QInputMethodEvent::Attribute> attributes;
+    attributes.append(
+        QInputMethodEvent::Attribute(QInputMethodEvent::Selection, localCursorPos, 0));
+    QInputMethodEvent event(QString(), attributes);
+    event.setCommitString(m_composingText);
+    sendInputMethodEvent(&event);
 
     return true;
 }
diff --git a/tests/auto/widgets/widgets/qlineedit/tst_qlineedit.cpp b/tests/auto/widgets/widgets/qlineedit/tst_qlineedit.cpp
index 94e2a2fa243..ac3fd82353c 100644
--- a/tests/auto/widgets/widgets/qlineedit/tst_qlineedit.cpp
+++ b/tests/auto/widgets/widgets/qlineedit/tst_qlineedit.cpp
@@ -1588,14 +1588,44 @@ void tst_QLineEdit::textMask()
     QCOMPARE( testWidget->text(), insertString );
 }
 
+class LineEditChangingText : public QLineEdit
+{
+    Q_OBJECT
+
+public:
+    LineEditChangingText(QWidget *parent) : QLineEdit(parent)
+    {
+        connect(this, &QLineEdit::textEdited, this, &LineEditChangingText::onTextEdited);
+    }
+
+public slots:
+    void onTextEdited(const QString &text)
+    {
+        if (text.length() == 3)
+            setText(text + "-");
+    }
+};
+
 void tst_QLineEdit::setText()
 {
     QLineEdit *testWidget = ensureTestWidget();
-    QSignalSpy editedSpy(testWidget, SIGNAL(textEdited(QString)));
-    QSignalSpy changedSpy(testWidget, SIGNAL(textChanged(QString)));
-    testWidget->setText("hello");
-    QCOMPARE(editedSpy.size(), 0);
-    QCOMPARE(changedSpy.value(0).value(0).toString(), QString("hello"));
+    {
+        QSignalSpy editedSpy(testWidget, &QLineEdit::textEdited);
+        QSignalSpy changedSpy(testWidget, &QLineEdit::textChanged);
+        testWidget->setText("hello");
+        QCOMPARE(editedSpy.size(), 0);
+        QCOMPARE(changedSpy.value(0).value(0).toString(), QString("hello"));
+    }
+
+    QTestEventList keys;
+    keys.addKeyClick(Qt::Key_A);
+    keys.addKeyClick(Qt::Key_B);
+    keys.addKeyClick(Qt::Key_C);
+
+    LineEditChangingText lineEdit(nullptr);
+    keys.simulate(&lineEdit);
+    QCOMPARE(lineEdit.text(), "abc-");
+    QCOMPARE(lineEdit.cursorPosition(), 4);
 }
 
 void tst_QLineEdit::displayText_data()