Fix TextInput and TextField mouse/touch selection fallback behavior

We tried to make default behavior depend on the import version; but in
Controls that does not work well, because the QQuickTextField instance
is created in a style-specific QML file that does not use the same
import version that the user is using. So we work around it by adding
support for a Controls-specific env var to revert to pre-6.4 behavior.

Adding the autotest proves that the fallback was broken a different
way too: we didn't check selectByTouchDrag in all the necessary places.

Amends 650342de792e0ab37ce8bac8ccde21ab9b96b2c9

[ChangeLog][Controls][TextField] The selectByMouse property is now
enabled by default, but no longer enables selecting by dragging your
finger across text on a touchscreen. Platforms that are optimized for
touchscreens normally use special text-selection handles, which interact
with Qt via QInputMethod.  You can opt out of the behavior change by
setting the environment variable
QT_QUICK_CONTROLS_TEXT_SELECTION_BEHAVIOR=old.

Task-number: QTBUG-10684
Task-number: QTBUG-38934
Task-number: QTBUG-101205
Change-Id: If1c1d6bd9c538f52022ae06d5252d178a1ae5a38
Reviewed-by: Mitch Curtis <mitch.curtis@qt.io>
(cherry picked from commit 42848bda5cb7ed92781cbbd536005af617e91020)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

2 files changed, 26 insertions, 8 deletions

diff --git a/src/quick/items/qquicktextinput.cpp b/src/quick/items/qquicktextinput.cpp
index 9d452093d3..34f6902666 100644
--- a/src/quick/items/qquicktextinput.cpp
+++ b/src/quick/items/qquicktextinput.cpp
@@ -1593,10 +1593,13 @@ void QQuickTextInput::mousePressEvent(QMouseEvent *event)
 
 void QQuickTextInput::mouseMoveEvent(QMouseEvent *event)
 {
-    if (!QQuickDeliveryAgentPrivate::isEventFromMouseOrTouchpad(event))
-        return;
-
     Q_D(QQuickTextInput);
+    if (!QQuickDeliveryAgentPrivate::isEventFromMouseOrTouchpad(event)
+#if QT_VERSION < QT_VERSION_CHECK(7, 0, 0)
+            && ! d->selectByTouchDrag
+#endif
+            )
+        return;
 
     if (d->selectPressed) {
         if (qAbs(int(event->position().x() - d->pressPos.x())) > QGuiApplication::styleHints()->startDragDistance())
@@ -1629,7 +1632,12 @@ void QQuickTextInput::mouseReleaseEvent(QMouseEvent *event)
         d->selectPressed = false;
         setKeepMouseGrab(false);
     }
-    const bool isMouse = QQuickDeliveryAgentPrivate::isEventFromMouseOrTouchpad(event);
+    const bool isMouse = QQuickDeliveryAgentPrivate::isEventFromMouseOrTouchpad(event)
+#if QT_VERSION < QT_VERSION_CHECK(7, 0, 0)
+        || d->selectByTouchDrag
+#endif
+    ;
+
 #if QT_CONFIG(clipboard)
     if (isMouse && QGuiApplication::clipboard()->supportsSelection()) {
         if (event->button() == Qt::LeftButton) {
@@ -4872,7 +4880,7 @@ void QQuickTextInput::setOldSelectionDefault()
     Q_D(QQuickTextInput);
     d->selectByMouse = false;
     d->selectByTouchDrag = true;
-    qCDebug(lcQuickTextInput, "pre-6.4 behavior chosen by import version: selectByMouse defaults false; if enabled, touchscreen acts like a mouse");
+    qCDebug(lcQuickTextInput, "pre-6.4 behavior chosen: selectByMouse defaults false; if enabled, touchscreen acts like a mouse");
 }
 
 // TODO in 6.7.0: remove the note about versions prior to 6.4 in selectByMouse() documentation
diff --git a/src/quicktemplates2/qquicktextfield.cpp b/src/quicktemplates2/qquicktextfield.cpp
index 99f9b757c1..c74b1c01fb 100644
--- a/src/quicktemplates2/qquicktextfield.cpp
+++ b/src/quicktemplates2/qquicktextfield.cpp
@@ -17,6 +17,8 @@
 
 QT_BEGIN_NAMESPACE
 
+using namespace Qt::StringLiterals;
+
 /*!
     \qmltype TextField
     \inherits TextInput
@@ -377,6 +379,11 @@ QQuickTextField::QQuickTextField(QQuickItem *parent)
 #endif
     QObjectPrivate::connect(this, &QQuickTextInput::readOnlyChanged, d, &QQuickTextFieldPrivate::readOnlyChanged);
     QObjectPrivate::connect(this, &QQuickTextInput::echoModeChanged, d, &QQuickTextFieldPrivate::echoModeChanged);
+#if QT_VERSION < QT_VERSION_CHECK(7, 0, 0)
+qDebug() << "QT_QUICK_CONTROLS_TEXT_SELECTION_BEHAVIOR" << qgetenv("QT_QUICK_CONTROLS_TEXT_SELECTION_BEHAVIOR");
+    if (qEnvironmentVariable("QT_QUICK_CONTROLS_TEXT_SELECTION_BEHAVIOR") == u"old"_s)
+        QQuickTextInput::setOldSelectionDefault();
+#endif
 }
 
 QQuickTextField::~QQuickTextField()
@@ -880,9 +887,12 @@ void QQuickTextField::mouseMoveEvent(QMouseEvent *event)
             QQuickTextInput::mousePressEvent(d->pressHandler.delayedMousePressEvent);
             d->pressHandler.clearDelayedMouseEvent();
         }
-        const auto devType = event->device()->type();
-        if (event->buttons() != Qt::RightButton &&
-                (devType == QInputDevice::DeviceType::Mouse || devType == QInputDevice::DeviceType::TouchPad))
+        const bool isMouse = QQuickDeliveryAgentPrivate::isEventFromMouseOrTouchpad(event)
+    #if QT_VERSION < QT_VERSION_CHECK(7, 0, 0)
+            || d->selectByTouchDrag
+    #endif
+        ;
+        if (event->buttons() != Qt::RightButton && isMouse)
             QQuickTextInput::mouseMoveEvent(event);
     }
 }