Add HoverHandler to detect a hovering mouse pointer

Detect whether the handler's parent contains the mouse, while the
point property tracks the event point (position etc.)

Task-number: QTBUG-68072
Change-Id: Ica99332596eab3e344852a11f1ceb7aaf6348c86
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Jan Arve Sæther <jan-arve.saether@qt.io>

1 files changed, 107 insertions, 0 deletions

diff --git a/src/quick/handlers/qquickhoverhandler.cpp b/src/quick/handlers/qquickhoverhandler.cpp
new file mode 100644
index 0000000000..430722bd93
--- /dev/null
+++ b/src/quick/handlers/qquickhoverhandler.cpp
@@ -0,0 +1,107 @@
+/****************************************************************************
+**
+** Copyright (C) 2018 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the QtQuick module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or (at your option) the GNU General
+** Public license version 3 or any later version approved by the KDE Free
+** Qt Foundation. The licenses are as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-2.0.html and
+** https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "qquickhoverhandler_p.h"
+
+QT_BEGIN_NAMESPACE
+
+Q_LOGGING_CATEGORY(lcHoverHandler, "qt.quick.handler.hover")
+
+/*!
+    \qmltype HoverHandler
+    \instantiates QQuickHoverHandler
+    \inqmlmodule QtQuick
+    \ingroup qtquick-handlers
+    \brief Handler for mouse and tablet hover
+
+    HoverHandler detects a hovering cursor.  Since touchscreens don't generally
+    offer hover events, in practice it detects a hovering mouse or tablet stylus.
+
+    \sa MouseArea
+*/
+
+QQuickHoverHandler::QQuickHoverHandler(QObject *parent)
+    : QQuickSinglePointHandler(parent)
+    , m_hovered(false)
+{
+    // Rule out the touchscreen for now (can be overridden in QML in case a hover-detecting touchscreen exists)
+    setAcceptedDevices(static_cast<QQuickPointerDevice::DeviceType>(
+        static_cast<int>(QQuickPointerDevice::AllDevices) ^ static_cast<int>(QQuickPointerDevice::TouchScreen)));
+}
+
+QQuickHoverHandler::~QQuickHoverHandler()
+{
+    QQuickItemPrivate *parItemPrivate = QQuickItemPrivate::get(parentItem());
+    parItemPrivate->setHasHoverInChild(false);
+}
+
+void QQuickHoverHandler::componentComplete()
+{
+    parentItem()->setAcceptHoverEvents(true);
+    QQuickItemPrivate::get(parentItem())->setHasHoverInChild(true);
+}
+
+bool QQuickHoverHandler::wantsPointerEvent(QQuickPointerEvent *event)
+{
+    QQuickEventPoint *point = event->point(0);
+    if (QQuickPointerDeviceHandler::wantsPointerEvent(event) && wantsEventPoint(point)) {
+        // assume this is a mouse event, so there's only one point
+        setPointId(point->pointId());
+        return true;
+    }
+    setHovered(false);
+    return false;
+}
+
+void QQuickHoverHandler::handleEventPoint(QQuickEventPoint *point)
+{
+    setHovered(true);
+    setPassiveGrab(point);
+}
+
+void QQuickHoverHandler::setHovered(bool hovered)
+{
+    if (m_hovered != hovered) {
+        qCDebug(lcHoverHandler) << objectName() << "hovered" << m_hovered << "->" << hovered;
+        m_hovered = hovered;
+        emit hoveredChanged();
+    }
+}
+
+QT_END_NAMESPACE