Add QQuickContentItem to produce more useful debug output

With the following code:

    ApplicationWindow {
        Component.onCompleted: print(contentItem)
    }

Before:

    QQuickItem(0x16043e52600)

After:

    QQuickContentItem(0x28a89b96440, "ApplicationWindow")

QQuickWindow has a similar concept (QQuickRootItem).

Change-Id: I6504b62c69cfd7d9036d5c200a65542b953bc7bc
Reviewed-by: J-P Nurmi <jpnurmi@qt.io>

6 files changed, 132 insertions, 3 deletions

diff --git a/src/quicktemplates2/qquickapplicationwindow.cpp b/src/quicktemplates2/qquickapplicationwindow.cpp
index edbc9e91..97624b9d 100644
--- a/src/quicktemplates2/qquickapplicationwindow.cpp
+++ b/src/quicktemplates2/qquickapplicationwindow.cpp
@@ -35,6 +35,7 @@
 ****************************************************************************/
 
 #include "qquickapplicationwindow_p.h"
+#include "qquickcontentitem_p.h"
 #include "qquickoverlay_p.h"
 #include "qquickpopup_p_p.h"
 #include "qquickcontrol_p_p.h"
@@ -584,7 +585,7 @@ QQuickItem *QQuickApplicationWindow::contentItem() const
 {
     QQuickApplicationWindowPrivate *d = const_cast<QQuickApplicationWindowPrivate *>(d_func());
     if (!d->contentItem) {
-        d->contentItem = new QQuickItem(QQuickWindow::contentItem());
+        d->contentItem = new QQuickContentItem(QStringLiteral("ApplicationWindow"), QQuickWindow::contentItem());
         d->contentItem->setFlag(QQuickItem::ItemIsFocusScope);
         d->contentItem->setFocus(true);
         d->relayout();
diff --git a/src/quicktemplates2/qquickcontentitem.cpp b/src/quicktemplates2/qquickcontentitem.cpp
new file mode 100644
index 00000000..286e7209
--- /dev/null
+++ b/src/quicktemplates2/qquickcontentitem.cpp
@@ -0,0 +1,53 @@
+/****************************************************************************
+**
+** Copyright (C) 2018 The Qt Company Ltd.
+** Contact: http://www.qt.io/licensing/
+**
+** This file is part of the Qt Quick Templates 2 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 "qquickcontentitem_p.h"
+
+QT_BEGIN_NAMESPACE
+
+/*!
+    \internal
+
+    Helper class that aids debugging by producing more useful debugging output.
+*/
+
+QQuickContentItem::QQuickContentItem(const QString &objectName, QQuickItem *parent)
+    : QQuickItem(parent)
+{
+    setObjectName(objectName);
+}
+
+QT_END_NAMESPACE
diff --git a/src/quicktemplates2/qquickcontentitem_p.h b/src/quicktemplates2/qquickcontentitem_p.h
new file mode 100644
index 00000000..3babc7bb
--- /dev/null
+++ b/src/quicktemplates2/qquickcontentitem_p.h
@@ -0,0 +1,69 @@
+/****************************************************************************
+**
+** Copyright (C) 2018 The Qt Company Ltd.
+** Contact: http://www.qt.io/licensing/
+**
+** This file is part of the Qt Quick Templates 2 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.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef QQUICKCONTENTITEM_P_H
+#define QQUICKCONTENTITEM_P_H
+
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API.  It exists purely as an
+// implementation detail.  This header file may change from version to
+// version without notice, or even be removed.
+//
+// We mean it.
+//
+
+#include <QtQuick/qquickitem.h>
+#include <QtQuickTemplates2/private/qtquicktemplates2global_p.h>
+
+QT_BEGIN_NAMESPACE
+
+class Q_QUICKTEMPLATES2_PRIVATE_EXPORT QQuickContentItem : public QQuickItem
+{
+    Q_OBJECT
+
+public:
+    explicit QQuickContentItem(const QString &objectName, QQuickItem *parent = nullptr);
+
+private:
+    Q_DISABLE_COPY(QQuickContentItem)
+};
+
+QT_END_NAMESPACE
+
+#endif // QQUICKCONTENTITEM_P_H
diff --git a/src/quicktemplates2/qquickpane.cpp b/src/quicktemplates2/qquickpane.cpp
index 60f27159..d4e1afc7 100644
--- a/src/quicktemplates2/qquickpane.cpp
+++ b/src/quicktemplates2/qquickpane.cpp
@@ -36,6 +36,7 @@
 
 #include "qquickpane_p.h"
 #include "qquickpane_p_p.h"
+#include "qquickcontentitem_p.h"
 
 QT_BEGIN_NAMESPACE
 
@@ -122,7 +123,8 @@ QQuickItem *QQuickPanePrivate::getContentItem()
     Q_Q(QQuickPane);
     if (QQuickItem *item = QQuickControlPrivate::getContentItem())
         return item;
-    return new QQuickItem(q);
+
+    return new QQuickContentItem(QStringLiteral("Pane"), q);
 }
 
 void QQuickPanePrivate::addImplicitSizeListener(QQuickItem *item)
diff --git a/src/quicktemplates2/qquickpopupitem.cpp b/src/quicktemplates2/qquickpopupitem.cpp
index f89b057d..c0a00292 100644
--- a/src/quicktemplates2/qquickpopupitem.cpp
+++ b/src/quicktemplates2/qquickpopupitem.cpp
@@ -38,6 +38,7 @@
 #include "qquickapplicationwindow_p.h"
 #include "qquickshortcutcontext_p_p.h"
 #include "qquickcontrol_p_p.h"
+#include "qquickcontentitem_p.h"
 #include "qquickpopup_p_p.h"
 #include "qquickdeferredexecute_p_p.h"
 
@@ -113,7 +114,8 @@ QQuickItem *QQuickPopupItemPrivate::getContentItem()
     Q_Q(QQuickPopupItem);
     if (QQuickItem *item = QQuickControlPrivate::getContentItem())
         return item;
-    return new QQuickItem(q);
+
+    return new QQuickContentItem(QStringLiteral("Popup"), q);
 }
 
 static inline QString contentItemName() { return QStringLiteral("contentItem"); }
diff --git a/src/quicktemplates2/quicktemplates2.pri b/src/quicktemplates2/quicktemplates2.pri
index 425b3c8f..8d90ab37 100644
--- a/src/quicktemplates2/quicktemplates2.pri
+++ b/src/quicktemplates2/quicktemplates2.pri
@@ -15,6 +15,7 @@ HEADERS += \
     $$PWD/qquickcombobox_p.h \
     $$PWD/qquickcontainer_p.h \
     $$PWD/qquickcontainer_p_p.h \
+    $$PWD/qquickcontentitem_p.h \
     $$PWD/qquickcontrol_p.h \
     $$PWD/qquickcontrol_p_p.h \
     $$PWD/qquickdeferredexecute_p_p.h \
@@ -108,6 +109,7 @@ SOURCES += \
     $$PWD/qquickcheckdelegate.cpp \
     $$PWD/qquickcombobox.cpp \
     $$PWD/qquickcontainer.cpp \
+    $$PWD/qquickcontentitem.cpp \
     $$PWD/qquickcontrol.cpp \
     $$PWD/qquickdeferredexecute.cpp \
     $$PWD/qquickdelaybutton.cpp \