Introduce QQuickPointerHandler: base class for nested event handlers

They will be Tech Preview in 5.8, so they shouldn't be available
unless you explicitly import them.

Task-number: QTBUG-54824
Change-Id: I290854a4e2b76e2cdfef5c216c7fdeb47fbcd390
Reviewed-by: Jan Arve Sæther <jan-arve.saether@theqtcompany.com>

1 files changed, 120 insertions, 0 deletions

diff --git a/src/quick/handlers/qquickpointerhandler.cpp b/src/quick/handlers/qquickpointerhandler.cpp
new file mode 100644
index 0000000000..9964d8f465
--- /dev/null
+++ b/src/quick/handlers/qquickpointerhandler.cpp
@@ -0,0 +1,120 @@
+/****************************************************************************
+**
+** Copyright (C) 2016 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 "qquickpointerhandler_p.h"
+
+QT_BEGIN_NAMESPACE
+
+Q_LOGGING_CATEGORY(lcPointerHandlerDispatch, "qt.quick.handler.dispatch")
+
+/*!
+    \qmltype PointerHandler
+    \instantiates QQuickPointerHandler
+    \inqmlmodule QtQuick
+    \ingroup qtquick-handlers
+    \brief Handler for pointer events
+
+    PointerHandler is a handler for pointer events regardless of source.
+    They may represent events from a touch, mouse or tablet device.
+*/
+
+QQuickPointerHandler::QQuickPointerHandler(QObject *parent)
+  : QObject(parent)
+  , m_currentEvent(nullptr)
+  , m_target(nullptr)
+  , m_enabled(true)
+{
+}
+
+void QQuickPointerHandler::setGrab(QQuickEventPoint *point, bool grab)
+{
+    // TODO eventually the handler itself should be the grabber, instead of the target Item
+    if (grab)
+        point->setGrabber(m_target);
+    else if (point->grabber() == m_target)
+        point->setGrabber(nullptr);
+}
+
+/*!
+     \qmlproperty QQuickPointerHandler::enabled
+
+     If a PointerHandler is disabled, it will reject all events
+     and no signals will be emitted.
+
+     TODO is it too extreme not even to emit pressed/updated/released?
+     or should we disable only the higher-level interpretation, in subclasses?
+*/
+void QQuickPointerHandler::setEnabled(bool enabled)
+{
+    if (m_enabled == enabled)
+        return;
+
+    m_enabled = enabled;
+    emit enabledChanged();
+}
+
+void QQuickPointerHandler::setTarget(QQuickItem *target)
+{
+    if (m_target == target)
+        return;
+
+    if (m_target) {
+        QQuickItemPrivate *p = QQuickItemPrivate::get(m_target);
+        p->extra.value().pointerHandlers.removeOne(this);
+    }
+
+    m_target = target;
+    if (m_target) {
+        QQuickItemPrivate *p = QQuickItemPrivate::get(m_target);
+        p->extra.value().pointerHandlers.append(this);
+        // Accept all buttons, and leave filtering to pointerEvent() and/or user JS,
+        // because there can be multiple handlers...
+        m_target->setAcceptedMouseButtons(Qt::AllButtons);
+    }
+    emit targetChanged();
+}
+
+void QQuickPointerHandler::handlePointerEventImpl(QQuickPointerEvent *event)
+{
+    if (!m_enabled)
+        return;
+    m_currentEvent = event;
+}
+
+QT_END_NAMESPACE