Introducing Panel type

This is the base type to implement all sorts of Popups and Dialogs.
Its main role is to keep the panel contents stacked on top of the
application window contents and to ensure mouse and key events are
forwarded or blocked depending on the visible panels modality.

Currently, it only works with ApplicationWindow, which holds a
QQuickOverlay. This special item is where the Panel contents gets
reparented when the Panel becomes visible. It's also responsible
for filtering the mouse events.

Future developements may include adding a 'level' property instead
of relying on the item's z value. This may or may not result into
having several overlays per window.

Change-Id: I18a4b8905e4d5a4a4697642b0553a1f9e86b669f
Reviewed-by: Gabriel de Dietrich <gabriel.dedietrich@theqtcompany.com>
Reviewed-by: J-P Nurmi <jpnurmi@theqtcompany.com>

1 files changed, 150 insertions, 0 deletions

diff --git a/src/templates/qquickoverlay.cpp b/src/templates/qquickoverlay.cpp
new file mode 100644
index 00000000..d786f3c7
--- /dev/null
+++ b/src/templates/qquickoverlay.cpp
@@ -0,0 +1,150 @@
+/****************************************************************************
+**
+** Copyright (C) 2015 The Qt Company Ltd.
+** Contact: http://www.qt.io/licensing/
+**
+** This file is part of the Qt Labs Templates module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL3$
+** 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 http://www.qt.io/terms-conditions. For further
+** information use the contact form at http://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.LGPLv3 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.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 later as published by the Free
+** Software Foundation and appearing in the file LICENSE.GPL included in
+** the packaging of this file. Please review the following information to
+** ensure the GNU General Public License version 2.0 requirements will be
+** met: http://www.gnu.org/licenses/gpl-2.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "qquickoverlay_p.h"
+#include "qquickpanel_p.h"
+#include <QtQml/qqmlinfo.h>
+#include <QtQuick/private/qquickitem_p.h>
+
+QT_BEGIN_NAMESPACE
+
+QQuickOverlay::QQuickOverlay(QQuickItem *parent)
+    : QQuickItem(parent), m_modalPanels(0)
+{
+    setAcceptedMouseButtons(Qt::AllButtons);
+    setFiltersChildMouseEvents(true);
+    setVisible(false);
+}
+
+void QQuickOverlay::itemChange(ItemChange change, const ItemChangeData &data)
+{
+    QQuickItem::itemChange(change, data);
+
+    QQuickItem *panelItem = const_cast<QQuickItem *>(data.item);
+    QQuickPanel *panel = Q_NULLPTR;
+    if (change == ItemChildAddedChange || change == ItemChildRemovedChange)
+        panel = qobject_cast<QQuickPanel *>(panelItem->parent());
+    if (!panel)
+        return;
+
+    if (change == ItemChildAddedChange) {
+        if (QQuickPanel *prevPanel = m_panels.value(panelItem)) {
+            qmlInfo(panel).nospace() << "Panel is sharing item " << panelItem << " with " << prevPanel
+                                     << ". This is not supported and strange things are about to happen.";
+            return;
+        }
+
+        m_panels.insert(panelItem, panel);
+        if (panel->isModal())
+            ++m_modalPanels;
+
+        connect(this, &QQuickOverlay::pressed, panel, &QQuickPanel::pressedOutside);
+        connect(this, &QQuickOverlay::released, panel, &QQuickPanel::releasedOutside);
+
+        if (!isVisible())
+            setVisible(true);
+    } else if (change == ItemChildRemovedChange) {
+        Q_ASSERT(panel == m_panels.value(panelItem));
+
+        disconnect(this, &QQuickOverlay::pressed, panel, &QQuickPanel::pressedOutside);
+        disconnect(this, &QQuickOverlay::released, panel, &QQuickPanel::releasedOutside);
+
+        if (panel->isModal())
+            --m_modalPanels;
+        m_panels.remove(panelItem);
+        if (m_panels.isEmpty())
+            setVisible(false);
+    }
+}
+
+void QQuickOverlay::keyPressEvent(QKeyEvent *event)
+{
+    event->setAccepted(m_modalPanels > 0);
+}
+
+void QQuickOverlay::keyReleaseEvent(QKeyEvent *event)
+{
+    event->setAccepted(m_modalPanels > 0);
+}
+
+void QQuickOverlay::mousePressEvent(QMouseEvent *event)
+{
+    event->setAccepted(m_modalPanels > 0);
+    emit pressed();
+}
+
+void QQuickOverlay::mouseMoveEvent(QMouseEvent *event)
+{
+    event->setAccepted(m_modalPanels > 0);
+}
+
+void QQuickOverlay::mouseReleaseEvent(QMouseEvent *event)
+{
+    event->setAccepted(m_modalPanels > 0);
+    emit released();
+}
+
+bool QQuickOverlay::childMouseEventFilter(QQuickItem *item, QEvent *event)
+{
+    if (m_modalPanels == 0)
+        return false;
+    // TODO Filter touch events
+    if (event->type() != QEvent::MouseButtonPress)
+        return false;
+    while (item->parentItem() != this)
+        item = item->parentItem();
+
+    bool modalBlocked = false;
+    const QQuickItemPrivate *priv = QQuickItemPrivate::get(this);
+    const QList<QQuickItem *> &sortedChildren = priv->paintOrderChildItems();
+    for (int i = sortedChildren.count() - 1; i >= 0; --i) {
+        QQuickItem *panelItem = sortedChildren[i];
+        if (panelItem == item)
+            break;
+
+        QQuickPanel *panel = m_panels.value(panelItem);
+        if (panel) {
+            emit panel->pressedOutside();
+
+            if (!modalBlocked && panel->isModal())
+                modalBlocked = true;
+        }
+    }
+
+    return modalBlocked;
+}
+
+QT_END_NAMESPACE