c++linuxqtqt5chromebook

Qt Data Visualization black screen on chromebook but run perfectly on ubuntu


I have been working on writing Qt Linux application on my Chromebook and deploying it on a ubuntu machine. By far all qt widget works fine except one: Qt Data Visualization.

I can compile the example code with the correct setting of Qt5_DIR. However, when I run the app, the image part is just a black screen. Nevertheless, if I just copy-paste it to a ubuntu machine, it displays properly.

I have installed opencv on my chromebook and wrote some demo programs. I wonder is it just chromebook's problem? Or I am missing something.

The code I ran was the example code from Qt

main.cpp

/****************************************************************************
**
** Copyright (C) 2016 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the Qt Data Visualization module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:GPL$
** 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 General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3 or (at your option) 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.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-3.0.html.
**
** $QT_END_LICENSE$
**
****************************************************************************/

#include "scatterdatamodifier.h"

#include <QtWidgets/QApplication>
#include <QtWidgets/QWidget>
#include <QtWidgets/QHBoxLayout>
#include <QtWidgets/QVBoxLayout>
#include <QtWidgets/QPushButton>
#include <QtWidgets/QCheckBox>
#include <QtWidgets/QComboBox>
#include <QtWidgets/QFontComboBox>
#include <QtWidgets/QLabel>
#include <QtWidgets/QMessageBox>
#include <QtGui/QScreen>
#include <QtGui/QFontDatabase>

int main(int argc, char **argv)
{
    //! [0]
    QApplication app(argc, argv);
    Q3DScatter *graph = new Q3DScatter();
    QWidget *container = QWidget::createWindowContainer(graph);
    //! [0]

    if (!graph->hasContext()) {
        QMessageBox msgBox;
        msgBox.setText("Couldn't initialize the OpenGL context.");
        msgBox.exec();
        return -1;
    }

    QSize screenSize = graph->screen()->size();
    container->setMinimumSize(QSize(screenSize.width() / 2, screenSize.height() / 1.5));
    container->setMaximumSize(screenSize);
    container->setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Expanding);
    container->setFocusPolicy(Qt::StrongFocus);

    //! [2]
    QWidget *widget = new QWidget;
    QHBoxLayout *hLayout = new QHBoxLayout(widget);
    QVBoxLayout *vLayout = new QVBoxLayout();
    hLayout->addWidget(container, 1);
    hLayout->addLayout(vLayout);
    //! [2]

    widget->setWindowTitle(QStringLiteral("A Cosine Wave"));

    //! [4]
    QComboBox *themeList = new QComboBox(widget);
    themeList->addItem(QStringLiteral("Qt"));
    themeList->addItem(QStringLiteral("Primary Colors"));
    themeList->addItem(QStringLiteral("Digia"));
    themeList->addItem(QStringLiteral("Stone Moss"));
    themeList->addItem(QStringLiteral("Army Blue"));
    themeList->addItem(QStringLiteral("Retro"));
    themeList->addItem(QStringLiteral("Ebony"));
    themeList->addItem(QStringLiteral("Isabelle"));
    themeList->setCurrentIndex(6);

    QPushButton *labelButton = new QPushButton(widget);
    labelButton->setText(QStringLiteral("Change label style"));

    QCheckBox *smoothCheckBox = new QCheckBox(widget);
    smoothCheckBox->setText(QStringLiteral("Smooth dots"));
    smoothCheckBox->setChecked(true);

    QComboBox *itemStyleList = new QComboBox(widget);
    itemStyleList->addItem(QStringLiteral("Sphere"), int(QAbstract3DSeries::MeshSphere));
    itemStyleList->addItem(QStringLiteral("Cube"), int(QAbstract3DSeries::MeshCube));
    itemStyleList->addItem(QStringLiteral("Minimal"), int(QAbstract3DSeries::MeshMinimal));
    itemStyleList->addItem(QStringLiteral("Point"), int(QAbstract3DSeries::MeshPoint));
    itemStyleList->setCurrentIndex(0);

    QPushButton *cameraButton = new QPushButton(widget);
    cameraButton->setText(QStringLiteral("Change camera preset"));

    QPushButton *itemCountButton = new QPushButton(widget);
    itemCountButton->setText(QStringLiteral("Toggle item count"));

    QCheckBox *backgroundCheckBox = new QCheckBox(widget);
    backgroundCheckBox->setText(QStringLiteral("Show background"));
    backgroundCheckBox->setChecked(true);

    QCheckBox *gridCheckBox = new QCheckBox(widget);
    gridCheckBox->setText(QStringLiteral("Show grid"));
    gridCheckBox->setChecked(true);

    QComboBox *shadowQuality = new QComboBox(widget);
    shadowQuality->addItem(QStringLiteral("None"));
    shadowQuality->addItem(QStringLiteral("Low"));
    shadowQuality->addItem(QStringLiteral("Medium"));
    shadowQuality->addItem(QStringLiteral("High"));
    shadowQuality->addItem(QStringLiteral("Low Soft"));
    shadowQuality->addItem(QStringLiteral("Medium Soft"));
    shadowQuality->addItem(QStringLiteral("High Soft"));
    shadowQuality->setCurrentIndex(4);

    QFontComboBox *fontList = new QFontComboBox(widget);
    fontList->setCurrentFont(QFont("Arial"));
    //! [4]

    //! [5]
    vLayout->addWidget(labelButton, 0, Qt::AlignTop);
    vLayout->addWidget(cameraButton, 0, Qt::AlignTop);
    vLayout->addWidget(itemCountButton, 0, Qt::AlignTop);
    vLayout->addWidget(backgroundCheckBox);
    vLayout->addWidget(gridCheckBox);
    vLayout->addWidget(smoothCheckBox, 0, Qt::AlignTop);
    vLayout->addWidget(new QLabel(QStringLiteral("Change dot style")));
    vLayout->addWidget(itemStyleList);
    vLayout->addWidget(new QLabel(QStringLiteral("Change theme")));
    vLayout->addWidget(themeList);
    vLayout->addWidget(new QLabel(QStringLiteral("Adjust shadow quality")));
    vLayout->addWidget(shadowQuality);
    vLayout->addWidget(new QLabel(QStringLiteral("Change font")));
    vLayout->addWidget(fontList, 1, Qt::AlignTop);
    //! [5]

    //! [2]
    ScatterDataModifier *modifier = new ScatterDataModifier(graph);
    //! [2]

    //! [6]
    QObject::connect(cameraButton, &QPushButton::clicked, modifier,
                     &ScatterDataModifier::changePresetCamera);
    QObject::connect(labelButton, &QPushButton::clicked, modifier,
                     &ScatterDataModifier::changeLabelStyle);
    QObject::connect(itemCountButton, &QPushButton::clicked, modifier,
                     &ScatterDataModifier::toggleItemCount);

    QObject::connect(backgroundCheckBox, &QCheckBox::stateChanged, modifier,
                     &ScatterDataModifier::setBackgroundEnabled);
    QObject::connect(gridCheckBox, &QCheckBox::stateChanged, modifier,
                     &ScatterDataModifier::setGridEnabled);
    QObject::connect(smoothCheckBox, &QCheckBox::stateChanged, modifier,
                     &ScatterDataModifier::setSmoothDots);

    QObject::connect(modifier, &ScatterDataModifier::backgroundEnabledChanged,
                     backgroundCheckBox, &QCheckBox::setChecked);
    QObject::connect(modifier, &ScatterDataModifier::gridEnabledChanged,
                     gridCheckBox, &QCheckBox::setChecked);
    QObject::connect(itemStyleList, SIGNAL(currentIndexChanged(int)), modifier,
                     SLOT(changeStyle(int)));

    QObject::connect(themeList, SIGNAL(currentIndexChanged(int)), modifier,
                     SLOT(changeTheme(int)));

    QObject::connect(shadowQuality, SIGNAL(currentIndexChanged(int)), modifier,
                     SLOT(changeShadowQuality(int)));

    QObject::connect(modifier, &ScatterDataModifier::shadowQualityChanged, shadowQuality,
                     &QComboBox::setCurrentIndex);
    QObject::connect(graph, &Q3DScatter::shadowQualityChanged, modifier,
                     &ScatterDataModifier::shadowQualityUpdatedByVisual);

    QObject::connect(fontList, &QFontComboBox::currentFontChanged, modifier,
                     &ScatterDataModifier::changeFont);

    QObject::connect(modifier, &ScatterDataModifier::fontChanged, fontList,
                     &QFontComboBox::setCurrentFont);
    //! [6]

    //! [3]
    widget->show();
    return app.exec();
    //! [3]
}

scatterdatamodifier.h

/****************************************************************************
**
** Copyright (C) 2016 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the Qt Data Visualization module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:GPL$
** 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 General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3 or (at your option) 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.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-3.0.html.
**
** $QT_END_LICENSE$
**
****************************************************************************/

#ifndef SCATTERDATAMODIFIER_H
#define SCATTERDATAMODIFIER_H

#include <QtDataVisualization/q3dscatter.h>
#include <QtDataVisualization/qabstract3dseries.h>
#include <QtGui/QFont>

using namespace QtDataVisualization;

class ScatterDataModifier : public QObject
{
    Q_OBJECT
public:
    explicit ScatterDataModifier(Q3DScatter *scatter);
    ~ScatterDataModifier();

    void addData();
    void changeStyle();
    void changePresetCamera();
    void changeLabelStyle();
    void changeFont(const QFont &font);
    void changeFontSize(int fontsize);
    void setBackgroundEnabled(int enabled);
    void setGridEnabled(int enabled);
    void setSmoothDots(int smooth);
    void toggleItemCount();
    void start();

public Q_SLOTS:
    void changeStyle(int style);
    void changeTheme(int theme);
    void changeShadowQuality(int quality);
    void shadowQualityUpdatedByVisual(QAbstract3DGraph::ShadowQuality shadowQuality);

Q_SIGNALS:
    void backgroundEnabledChanged(bool enabled);
    void gridEnabledChanged(bool enabled);
    void shadowQualityChanged(int quality);
    void fontChanged(QFont font);

private:
    QVector3D randVector();
    Q3DScatter *m_graph;
    int m_fontSize;
    QAbstract3DSeries::Mesh m_style;
    bool m_smooth;
    int m_itemCount;
    float m_curveDivider;
};

#endif
/****************************************************************************
**
** Copyright (C) 2016 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the Qt Data Visualization module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:GPL$
** 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 General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3 or (at your option) 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.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-3.0.html.
**
** $QT_END_LICENSE$
**
****************************************************************************/

#include "scatterdatamodifier.h"
#include <QtDataVisualization/qscatterdataproxy.h>
#include <QtDataVisualization/qvalue3daxis.h>
#include <QtDataVisualization/q3dscene.h>
#include <QtDataVisualization/q3dcamera.h>
#include <QtDataVisualization/qscatter3dseries.h>
#include <QtDataVisualization/q3dtheme.h>
#include <QtCore/qmath.h>
#include <QtCore/qrandom.h>
#include <QtWidgets/QComboBox>

using namespace QtDataVisualization;

//#define RANDOM_SCATTER // Uncomment this to switch to random scatter

const int numberOfItems = 3600;
const float curveDivider = 3.0f;
const int lowerNumberOfItems = 900;
const float lowerCurveDivider = 0.75f;

ScatterDataModifier::ScatterDataModifier(Q3DScatter *scatter)
    : m_graph(scatter),
      m_fontSize(40.0f),
      m_style(QAbstract3DSeries::MeshSphere),
      m_smooth(true),
      m_itemCount(lowerNumberOfItems),
      m_curveDivider(lowerCurveDivider)
{
    //! [0]
    m_graph->activeTheme()->setType(Q3DTheme::ThemeEbony);
    QFont font = m_graph->activeTheme()->font();
    font.setPointSize(m_fontSize);
    m_graph->activeTheme()->setFont(font);
    m_graph->setShadowQuality(QAbstract3DGraph::ShadowQualitySoftLow);
    m_graph->scene()->activeCamera()->setCameraPreset(Q3DCamera::CameraPresetFront);
    //! [0]

    //! [2]
    QScatterDataProxy *proxy = new QScatterDataProxy;
    QScatter3DSeries *series = new QScatter3DSeries(proxy);
    series->setItemLabelFormat(QStringLiteral("@xTitle: @xLabel @yTitle: @yLabel @zTitle: @zLabel"));
    series->setMeshSmooth(m_smooth);
    m_graph->addSeries(series);
    //! [2]

    //! [3]
    addData();
    //! [3]
}

ScatterDataModifier::~ScatterDataModifier()
{
    delete m_graph;
}

void ScatterDataModifier::addData()
{
    // Configure the axes according to the data
    //! [4]
    m_graph->axisX()->setTitle("X");
    m_graph->axisY()->setTitle("Y");
    m_graph->axisZ()->setTitle("Z");
    //! [4]

    //! [5]
    QScatterDataArray *dataArray = new QScatterDataArray;
    dataArray->resize(m_itemCount);
    QScatterDataItem *ptrToDataArray = &dataArray->first();
    //! [5]

#ifdef RANDOM_SCATTER
    for (int i = 0; i < m_itemCount; i++) {
        ptrToDataArray->setPosition(randVector());
        ptrToDataArray++;
    }
#else
    //! [6]
    float limit = qSqrt(m_itemCount) / 2.0f;
    for (float i = -limit; i < limit; i++) {
        for (float j = -limit; j < limit; j++) {
            ptrToDataArray->setPosition(QVector3D(i + 0.5f,
                                                  qCos(qDegreesToRadians((i * j) / m_curveDivider)),
                                                  j + 0.5f));
            ptrToDataArray++;
        }
    }
    //! [6]
#endif

    //! [7]
    m_graph->seriesList().at(0)->dataProxy()->resetArray(dataArray);
    //! [7]
}

//! [8]
void ScatterDataModifier::changeStyle(int style)
{
    QComboBox *comboBox = qobject_cast<QComboBox *>(sender());
    if (comboBox) {
        m_style = QAbstract3DSeries::Mesh(comboBox->itemData(style).toInt());
        if (m_graph->seriesList().size())
            m_graph->seriesList().at(0)->setMesh(m_style);
    }
}

void ScatterDataModifier::setSmoothDots(int smooth)
{
    m_smooth = bool(smooth);
    QScatter3DSeries *series = m_graph->seriesList().at(0);
    series->setMeshSmooth(m_smooth);
}

void ScatterDataModifier::changeTheme(int theme)
{
    Q3DTheme *currentTheme = m_graph->activeTheme();
    currentTheme->setType(Q3DTheme::Theme(theme));
    emit backgroundEnabledChanged(currentTheme->isBackgroundEnabled());
    emit gridEnabledChanged(currentTheme->isGridEnabled());
    emit fontChanged(currentTheme->font());
}

void ScatterDataModifier::changePresetCamera()
{
    static int preset = Q3DCamera::CameraPresetFrontLow;

    m_graph->scene()->activeCamera()->setCameraPreset((Q3DCamera::CameraPreset)preset);

    if (++preset > Q3DCamera::CameraPresetDirectlyBelow)
        preset = Q3DCamera::CameraPresetFrontLow;
}

void ScatterDataModifier::changeLabelStyle()
{
    m_graph->activeTheme()->setLabelBackgroundEnabled(!m_graph->activeTheme()->isLabelBackgroundEnabled());
}

void ScatterDataModifier::changeFont(const QFont &font)
{
    QFont newFont = font;
    newFont.setPointSizeF(m_fontSize);
    m_graph->activeTheme()->setFont(newFont);
}

void ScatterDataModifier::shadowQualityUpdatedByVisual(QAbstract3DGraph::ShadowQuality sq)
{
    int quality = int(sq);
    emit shadowQualityChanged(quality); // connected to a checkbox in main.cpp
}

void ScatterDataModifier::changeShadowQuality(int quality)
{
    QAbstract3DGraph::ShadowQuality sq = QAbstract3DGraph::ShadowQuality(quality);
    m_graph->setShadowQuality(sq);
}

void ScatterDataModifier::setBackgroundEnabled(int enabled)
{
    m_graph->activeTheme()->setBackgroundEnabled((bool)enabled);
}

void ScatterDataModifier::setGridEnabled(int enabled)
{
    m_graph->activeTheme()->setGridEnabled((bool)enabled);
}
//! [8]

void ScatterDataModifier::toggleItemCount()
{
    if (m_itemCount == numberOfItems) {
        m_itemCount = lowerNumberOfItems;
        m_curveDivider = lowerCurveDivider;
    } else {
        m_itemCount = numberOfItems;
        m_curveDivider = curveDivider;
    }
    m_graph->seriesList().at(0)->dataProxy()->resetArray(0);
    addData();
}

QVector3D ScatterDataModifier::randVector()
{
    return QVector3D(
                (float)(QRandomGenerator::global()->bounded(100)) / 2.0f -
                (float)(QRandomGenerator::global()->bounded(100)) / 2.0f,
                (float)(QRandomGenerator::global()->bounded(100)) / 100.0f -
                (float)(QRandomGenerator::global()->bounded(100)) / 100.0f,
                (float)(QRandomGenerator::global()->bounded(100)) / 2.0f -
                (float)(QRandomGenerator::global()->bounded(100)) / 2.0f);
    
}

In the end, the CMakeLists.txt

cmake_minimum_required(VERSION 3.16)
project(scatter LANGUAGES CXX)

# set(CMAKE_INCLUDE_CURRENT_DIR ON)

set(CMAKE_AUTOMOC ON)
set(CMAKE_AUTORCC ON)
set(CMAKE_AUTOUIC ON)

# set(CMAKE_FIND_DEBUG_MODE 1)

if(NOT DEFINED INSTALL_EXAMPLESDIR)
  set(INSTALL_EXAMPLESDIR "examples")
endif()



message(STATUS ${CMAKE_MODULE_PATH})
set (Qt5_FOUND false)
find_package(Qt5 COMPONENTS Core Widgets Gui DataVisualization REQUIRED)
if(Qt5_FOUND)
message("QT5 Found")
else(Qt5_FOUND)
message("FATAL Qt5 Not Found")
endif(Qt5_FOUND)
add_executable(scatter
    main.cpp
    scatterdatamodifier.cpp scatterdatamodifier.h
)
# set_target_properties(scatter PROPERTIES
#     WIN32_EXECUTABLE TRUE
#     MACOSX_BUNDLE TRUE
# )
target_link_libraries(scatter Qt5::Core Qt5::Gui Qt5::Widgets Qt5::DataVisualization)

# install(TARGETS scatter
#     RUNTIME DESTINATION "${INSTALL_EXAMPLEDIR}"
#     BUNDLE DESTINATION "${INSTALL_EXAMPLEDIR}"
#     LIBRARY DESTINATION "${INSTALL_EXAMPLEDIR}"
# )


  [1]: https://i.sstatic.net/1oueS.png
  [2]: https://i.sstatic.net/TdUkh.png

Solution

  • According to https://doc.qt.io/qt-6/qtdatavisualization-known-issues.html

    Some platforms like Android and WinRT cannot handle multiple native windows properly, so only the Qt Quick 2 graphs are available in practice for those platforms.

    It is probably the case.

    p.s. adding qputenv("QSG_RHI_BACKEND", "opengl"); did not improve the condition in this case.