- Qt 5.5
- Qt GUI
- OpenGL Window Example
- openglwindow.cpp Example File
- Qt 5.5.1 Reference Documentation

# openglwindow.cpp Example File

openglwindow/openglwindow.cpp

    /****************************************************************************
    **
    ** Copyright (C) 2015 The Qt Company Ltd.
    ** Contact: http://www.qt.io/licensing/
    **
    ** This file is part of the documentation of the Qt Toolkit.
    **
    ** $QT_BEGIN_LICENSE:BSD$
    ** You may use this file under the terms of the BSD license as follows:
    **
    ** "Redistribution and use in source and binary forms, with or without
    ** modification, are permitted provided that the following conditions are
    ** met:
    **   * Redistributions of source code must retain the above copyright
    **     notice, this list of conditions and the following disclaimer.
    **   * Redistributions in binary form must reproduce the above copyright
    **     notice, this list of conditions and the following disclaimer in
    **     the documentation and/or other materials provided with the
    **     distribution.
    **   * Neither the name of The Qt Company Ltd nor the names of its
    **     contributors may be used to endorse or promote products derived
    **     from this software without specific prior written permission.
    **
    **
    ** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
    ** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
    ** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
    ** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
    ** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
    ** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
    ** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
    ** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
    ** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
    ** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
    ** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
    **
    ** $QT_END_LICENSE$
    **
    ****************************************************************************/

    #include "openglwindow.h"

    #include <QtCore/QCoreApplication>

    #include <QtGui/QOpenGLContext>
    #include <QtGui/QOpenGLPaintDevice>
    #include <QtGui/QPainter>

    OpenGLWindow::OpenGLWindow(QWindow *parent)
        : QWindow(parent)
        , m_update_pending(false)
        , m_animating(false)
        , m_context(0)
        , m_device(0)
    {
        setSurfaceType(QWindow::OpenGLSurface);
    }

    OpenGLWindow::~OpenGLWindow()
    {
        delete m_device;
    }
    void OpenGLWindow::render(QPainter *painter)
    {
        Q_UNUSED(painter);
    }

    void OpenGLWindow::initialize()
    {
    }

    void OpenGLWindow::render()
    {
        if (!m_device)
            m_device = new QOpenGLPaintDevice;

        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);

        m_device->setSize(size());

        QPainter painter(m_device);
        render(&painter);
    }

    void OpenGLWindow::renderLater()
    {
        if (!m_update_pending) {
            m_update_pending = true;
            QCoreApplication::postEvent(this, new QEvent(QEvent::UpdateRequest));
        }
    }

    bool OpenGLWindow::event(QEvent *event)
    {
        switch (event->type()) {
        case QEvent::UpdateRequest:
            m_update_pending = false;
            renderNow();
            return true;
        default:
            return QWindow::event(event);
        }
    }

    void OpenGLWindow::exposeEvent(QExposeEvent *event)
    {
        Q_UNUSED(event);

        if (isExposed())
            renderNow();
    }

    void OpenGLWindow::renderNow()
    {
        if (!isExposed())
            return;

        bool needsInitialize = false;

        if (!m_context) {
            m_context = new QOpenGLContext(this);
            m_context->setFormat(requestedFormat());
            m_context->create();

            needsInitialize = true;
        }

        m_context->makeCurrent(this);

        if (needsInitialize) {
            initializeOpenGLFunctions();
            initialize();
        }

        render();

        m_context->swapBuffers(this);

        if (m_animating)
            renderLater();
    }

    void OpenGLWindow::setAnimating(bool animating)
    {
        m_animating = animating;

        if (animating)
            renderLater();
    }