CustomItem derived from QQuickItem and exposed to QML has incorrect alignment

[Dmitry.Sokolov]

I'm trying to make a custom QQuick Item (rect1) and to align it under the label text1 in the ApplicationWindow

@
//----- main.qml -----

import QtQuick 2.2
import QtQuick.Controls 1.2
import QtQuick.Layouts 1.1

import My.Controls 1.0

ApplicationWindow {
visible: true
width: 640
height: 480
title: qsTr("Hello World")

toolBar: ToolBar {
    id: tb1
    RowLayout {
        anchors.fill: parent
        ToolButton {
            text: qsTr("Open")
        }
        ToolButton {
            text: qsTr("Save")
        }
        Item {
            height: 1
            Layout.fillWidth: true
        }
        ToolButton {
            text: qsTr("Exit")
            onClicked: Qt.quit()
        }
    }
}

Item {
    anchors.fill: parent
    Text {
        id: text1
        text: qsTr("Hello World")
        anchors.top: parent.top
        anchors.right: parent.right
    }
    CustomItem {
        id: rect1
        anchors.top: text1.bottom
        anchors.right: parent.right
        anchors.bottom: parent.bottom
        anchors.left: parent.left
    }
}

}
@

C++ source files:
@
//----- main.cpp -----

#include <QApplication>
#include <QQmlApplicationEngine>
#include "customitem.h"

int main(int argc, char *argv[])
{
QApplication app(argc, argv);

qmlRegisterType<CustomItem>("My.Controls", 1, 0, "CustomItem");

QQmlApplicationEngine engine;
engine.load(QUrl(QStringLiteral("qrc:///main.qml")));

return app.exec();

}

//----- customitem.h -----

#ifndef CUSTOMITEM_H
#define CUSTOMITEM_H

#include <QQuickItem>
#include <QQuickWindow>

class CustomItem : public QQuickItem
{
Q_OBJECT
public:
explicit CustomItem(QQuickItem *parent = 0);

signals:

public slots:
void paint();

private slots:
void handleWindowChanged(QQuickWindow * win);

};

#endif // CUSTOMITEM_H

//----- customitem.cpp -----

#include "customitem.h"

CustomItem::CustomItem(QQuickItem *parent) :
QQuickItem(parent)
{
connect(this, &CustomItem::windowChanged, this, &CustomItem::handleWindowChanged);
}

void CustomItem::paint()
{
QQuickWindow * win = window();
qreal ratio = win->devicePixelRatio();
int w = int(ratio * win->width());
int h = int(ratio * win->height());
glViewport(0, 0, w, h);

glDisable(GL_DEPTH_TEST);
glClearColor(0, 0, 0, 1);
glClear(GL_COLOR_BUFFER_BIT);

}

void CustomItem::handleWindowChanged(QQuickWindow * win)
{
if (win) {
// Connect the beforeRendering signal to our paint function.
// Since this call is executed on the rendering thread it must be a Qt::DirectConnection
connect(win, &QQuickWindow::beforeRendering, this, &CustomItem::paint, Qt::DirectConnection);

    // If we allow QML to do the clearing, they would clear what we paint and nothing would show.
    win->setClearBeforeRendering(false);
}

}
@

When this application is running label text1 is not visible and custom item rect1 occupies the whole client area of the ApplicationWindow:

!https://lh5.googleusercontent.com/-CU-qYQbHLWw/U-iCRzDz9nI/AAAAAAAAAMA/zRaFCUPibVg/w823-h657-no/pic1.png(pic1)!

But when I replace CustomItem with Rectangle then all items become correctly aligned:

!https://lh6.googleusercontent.com/-i_zKkneJ-ag/U-iCRp-VpQI/AAAAAAAAAL8/A4PlbCgfSoc/w823-h657-no/pic2.png(pic2)!

So, what I'm missing? Or is it a bug?