Add handlers declared as Flickable children to its contentItem

QQuickItemPrivate::data_append() was not invoked when any kind of
Pointer Handler was directly declared in a Flickable (or subclass)
because QQuickFlickable redefines the default property to be its own
flickableData property. So we need to repeat the special handling
in QQuickFlickablePrivate::data_append() too.  The handler must
be added to the private->extra->pointerHandlers vector, so that
QQuickItemPrivate::handlePointerEvent() will attempt to deliver
events to those handlers.

TapHandler seems OK (especially with its default gesturePolicy
so that it does not do an exclusive grab).

PointHandler seems OK.

DragHandler competes with Flickable for the exclusive grab.
pressDelay can help; or set acceptedDevices: PointerDevice.Mouse
to allow the mouse to drag but not flick, and the touchscreen
to flick but not drag.

Fixes: QTBUG-71918
Fixes: QTBUG-73035
Change-Id: Icb97ed5230abe0cb6ec0230b5b5759a0528df7e8
Reviewed-by: Jan Arve Sæther <jan-arve.saether@qt.io>

1 files changed, 13 insertions, 1 deletions

diff --git a/src/quick/items/qquickflickable.cpp b/src/quick/items/qquickflickable.cpp
index 85045be411..cf882e8c9e 100644
--- a/src/quick/items/qquickflickable.cpp
+++ b/src/quick/items/qquickflickable.cpp
@@ -1,6 +1,6 @@
 /****************************************************************************
 **
-** Copyright (C) 2016 The Qt Company Ltd.
+** Copyright (C) 2019 The Qt Company Ltd.
 ** Contact: https://www.qt.io/licensing/
 **
 ** This file is part of the QtQuick module of the Qt Toolkit.
@@ -61,6 +61,8 @@
 
 QT_BEGIN_NAMESPACE
 
+Q_DECLARE_LOGGING_CATEGORY(lcHandlerParent)
+
 // FlickThreshold determines how far the "mouse" must have moved
 // before we perform a flick.
 static const int FlickThreshold = 15;
@@ -1897,6 +1899,8 @@ void QQuickFlickablePrivate::data_append(QQmlListProperty<QObject> *prop, QObjec
 {
     if (QQuickItem *i = qmlobject_cast<QQuickItem *>(o)) {
         i->setParentItem(static_cast<QQuickFlickablePrivate*>(prop->data)->contentItem);
+    } else if (QQuickPointerHandler *pointerHandler = qmlobject_cast<QQuickPointerHandler *>(o)) {
+        static_cast<QQuickFlickablePrivate*>(prop->data)->addPointerHandler(pointerHandler);
     } else {
         o->setParent(prop->object); // XXX todo - do we want this?
     }
@@ -2356,6 +2360,14 @@ void QQuickFlickablePrivate::cancelInteraction()
     }
 }
 
+void QQuickFlickablePrivate::addPointerHandler(QQuickPointerHandler *h)
+{
+    Q_Q(const QQuickFlickable);
+    qCDebug(lcHandlerParent) << "reparenting handler" << h << "to contentItem of" << q;
+    h->setParent(contentItem);
+    QQuickItemPrivate::get(contentItem)->addPointerHandler(h);
+}
+
 /*!
     QQuickFlickable::filterMouseEvent checks filtered mouse events and potentially steals them.