How to write custom screen driver using Qt 5.8 without using framebuffer?

[SGaist]

Hi and welcome to devnet,

You're likely looking for the Qt Platform Abstraction documentation.

Hope it helps

[Avanish Singh]

@SGaist : Thanks

[Avanish Singh]

For Development of QPA plugin using Qt 5.8 following basic classed are needed:

1. QPlatformIntegartionPlugin:
   * Entry point for the plugin
   * Factory Class
   *QPlatformIntegration creates it by calling the createPlatformWindow method. It doesn’t care
   for the contents of the window.
2. QPlatformScreen:
   This class represents your visual/physical displays ( i.e. monitors ).
   3)QPlatformWindow :
   *This class provides an abstraction used by QWindow for all it’s top-level windows.
   • Interface to the windowing system
   • It's about the window, not about the surface or content
3. QPlatformBackingStore :
   • A handler for painting and flushing
   • It's about the surface or content, not the window(inner portion of the window)
4. QPixmapData:
   • Stores pixmap data.
5. QPlatformFontDatabase:
   • Interface to your platform fontdatabase.
   • Create and returns QFontEngine.

[nlazovic]

[0_1512394999226_main.cpp](Uploading 100%) @Avanish-Singh @SGaist
I tried doing similar (BTW using QT5.9) and QPlatformBackingStore instance is just never being invoked. We also tried minimalegl plugin (one that comes with QT source) and same issue "QPlatformBackingStore instance is just never being invoked"
Any ideas why ?

sample app
main.cpp

#include <QQmlApplicationEngine>
#include <QDir>
#include <QGuiApplication>
#include <QQmlEngine>
#include <QQmlFileSelector>
#include <QQuickView> 

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

    QGuiApplication::setAttribute(Qt::AA_ShareOpenGLContexts, true);
    QGuiApplication app(argc, argv);
    QQmlApplicationEngine engine;
    engine.load(QUrl(QStringLiteral("qrc:///demos/hw2/main.qml")));

    return app.exec();
}

main.qml

import QtQuick 2.5
import QtQuick.Window 2.2
import QtMultimedia 5.5

Window {
    id: w
    visible: true
    visibility: Window.FullScreen
    color: "#000000";	//default bkg color is black

	Rectangle {
		id: r1
		x: 100; y: 100
		width: 400; height: 200
		color: "#646464"

		Text {
			anchors.centerIn: parent
			text: "Hello, World1!"
		}

	}
	
	Rectangle {
		id: r2
		x: 600; y: 100
		width: 400; height: 200
		color: "#646464"

		Text {
			anchors.centerIn: parent
			text: "Hello, World2!"
		}

	}	
	VideoOutput {
    id: diVideo
	x: 400; y: 400
	width: 400; height: 200
    source: mediaPlayer
	
		MediaPlayer {
			id: mediaPlayer
			autoLoad: true
			source: "file:///root/Downloads/movies/SampleVideo_1280x720_20mb.mp4"
		}	   
		
        Component.onCompleted: {
			mediaPlayer.play();
		}		
	}	
	
}

[SGaist]

Hi,

You don't give enough details. What platform are you on ? How are you starting your application ?

[nlazovic]

@SGaist
I built QT 5.9.3 for Odroid XU4.
When I start my app with "./myapp -platform eglfs" all renders ok on attached HDMI monitor.
When I start my app with "./myapp -platform minimalegl" I see that that no debug logs comes out of (not even from a constructor)

QMinimalEglBackingStore modified to save to image

#include "qminimaleglbackingstore.h"

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

QT_BEGIN_NAMESPACE

QMinimalEglBackingStore::QMinimalEglBackingStore(QWindow *window)
    : QPlatformBackingStore(window)
    , m_context(new QOpenGLContext)
    , m_device(0)
{
    qWarning("QMinimalEglBackingStore::QMinimalEglBackingStore", window);
	
    m_context->setFormat(window->requestedFormat());
    m_context->setScreen(window->screen());
    m_context->create();
}

QMinimalEglBackingStore::~QMinimalEglBackingStore()
{
    delete m_context;
}

QPaintDevice *QMinimalEglBackingStore::paintDevice()
{
    return m_device;
}

void QMinimalEglBackingStore::flush(QWindow *window, const QRegion &region, const QPoint &offset)
{
    Q_UNUSED(region);
    Q_UNUSED(offset);

    qWarning("QEglBackingStore::flush %p", window);

    static int c = 0;
    //save frame as image
    QOpenGLFramebufferObject fbo(size());
    qDebug()<<"bind success? : "<<fbo.bind();
    QImage frameImage = fbo.toImage();
    QString filename = QString("output%1.png").arg(c++, 4, 10, QLatin1Char('0'));
    qDebug() << "QMinimalEglBackingStore::flush() saving contents to" << filename.toLocal8Bit().constData();
    frameImage.save(filename);

    m_context->swapBuffers(window);
}

void QMinimalEglBackingStore::beginPaint(const QRegion &)
{
    m_context->makeCurrent(window());
    m_device = new QOpenGLPaintDevice(window()->size());
}

void QMinimalEglBackingStore::endPaint()
{
    delete m_device;
}

void QMinimalEglBackingStore::resize(const QSize &size, const QRegion &staticContents)
{
    Q_UNUSED(size);
    Q_UNUSED(staticContents);
}

QT_END_NAMESPACE

[SGaist]

Did you modify Qt or wrote your own QPA ?

[nlazovic]

@SGaist
no. used minimalegl plugin as it came from QT source code (qtbase/src/plugins/platforms/minimalegl). Just added few debug lines to check calls being made.

[SGaist]

You should set the QT_DEBUG_PLUGINS environment variable to 1 and start your application again to see what happens with it.

[nlazovic]

@SGaist

running app with
export QT_DEBUG_PLUGINS=1
./myapp -platform minimalegl

From log I can only figure out that

QPlatformBackingStore *QMinimalEglIntegration::createPlatformBackingStore(QWindow *window) const

is not invoked.

log

App started
QFactoryLoader::QFactoryLoader() checking directory path "/usr/local/qt5xu4/plugins/platforms" ...
QFactoryLoader::QFactoryLoader() looking at "/usr/local/qt5xu4/plugins/platforms/libdsccstreamerplatform.so"
Found metadata in lib /usr/local/qt5xu4/plugins/platforms/libdsccstreamerplatform.so, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
    "MetaData": {
        "Keys": [
            "dsccstreamerplatform"
        ]
    },
    "className": "QMinimalEglIntegrationPlugin",
    "debug": true,
    "version": 329987
}


Got keys from plugin meta data ("dsccstreamerplatform")
QFactoryLoader::QFactoryLoader() looking at "/usr/local/qt5xu4/plugins/platforms/libphantom.so"
Found metadata in lib /usr/local/qt5xu4/plugins/platforms/libphantom.so, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
    "MetaData": {
        "Keys": [
            "phantom"
        ]
    },
    "className": "PhantomIntegrationPlugin",
    "debug": false,
    "version": 329987
}


Got keys from plugin meta data ("phantom")
QFactoryLoader::QFactoryLoader() looking at "/usr/local/qt5xu4/plugins/platforms/libqeglfs.so"
Found metadata in lib /usr/local/qt5xu4/plugins/platforms/libqeglfs.so, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
    "MetaData": {
        "Keys": [
            "eglfs"
        ]
    },
    "className": "QEglFSIntegrationPlugin",
    "debug": false,
    "version": 329987
}


Got keys from plugin meta data ("eglfs")
QFactoryLoader::QFactoryLoader() looking at "/usr/local/qt5xu4/plugins/platforms/libqlinuxfb.so"
Found metadata in lib /usr/local/qt5xu4/plugins/platforms/libqlinuxfb.so, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
    "MetaData": {
        "Keys": [
            "linuxfb"
        ]
    },
    "className": "QLinuxFbIntegrationPlugin",
    "debug": false,
    "version": 329987
}


Got keys from plugin meta data ("linuxfb")
QFactoryLoader::QFactoryLoader() looking at "/usr/local/qt5xu4/plugins/platforms/libqminimal.so"
Found metadata in lib /usr/local/qt5xu4/plugins/platforms/libqminimal.so, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
    "MetaData": {
        "Keys": [
            "minimal"
        ]
    },
    "className": "QMinimalIntegrationPlugin",
    "debug": false,
    "version": 329987
}


Got keys from plugin meta data ("minimal")
QFactoryLoader::QFactoryLoader() looking at "/usr/local/qt5xu4/plugins/platforms/libqminimalegl.so"
Found metadata in lib /usr/local/qt5xu4/plugins/platforms/libqminimalegl.so, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
    "MetaData": {
        "Keys": [
            "minimalegl"
        ]
    },
    "className": "QMinimalEglIntegrationPlugin",
    "debug": false,
    "version": 329987
}


Got keys from plugin meta data ("minimalegl")
QFactoryLoader::QFactoryLoader() looking at "/usr/local/qt5xu4/plugins/platforms/libqoffscreen.so"
Found metadata in lib /usr/local/qt5xu4/plugins/platforms/libqoffscreen.so, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
    "MetaData": {
        "Keys": [
            "offscreen"
        ]
    },
    "className": "QOffscreenIntegrationPlugin",
    "debug": false,
    "version": 329987
}


Got keys from plugin meta data ("offscreen")
QFactoryLoader::QFactoryLoader() looking at "/usr/local/qt5xu4/plugins/platforms/libqvnc.so"
Found metadata in lib /usr/local/qt5xu4/plugins/platforms/libqvnc.so, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
    "MetaData": {
        "Keys": [
            "vnc"
        ]
    },
    "className": "QVncIntegrationPlugin",
    "debug": false,
    "version": 329987
}


Got keys from plugin meta data ("vnc")
QFactoryLoader::QFactoryLoader() looking at "/usr/local/qt5xu4/plugins/platforms/libqxcb.so"
Found metadata in lib /usr/local/qt5xu4/plugins/platforms/libqxcb.so, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
    "MetaData": {
        "Keys": [
            "xcb"
        ]
    },
    "className": "QXcbIntegrationPlugin",
    "debug": false,
    "version": 329987
}


Got keys from plugin meta data ("xcb")
QFactoryLoader::QFactoryLoader() checking directory path "/root/qt5build/qt5/dscctests/test2/platforms" ...
loaded library "/usr/local/qt5xu4/plugins/platforms/libqminimalegl.so"
QEglScreen 0x361a8

Opened display 0x37ee8

Initialized display 1 4

	EGL_BUFFER_SIZE: 32
	EGL_ALPHA_SIZE: 8
	EGL_BLUE_SIZE: 8
	EGL_GREEN_SIZE: 8
	EGL_RED_SIZE: 8
	EGL_DEPTH_SIZE: 24
	EGL_STENCIL_SIZE: 8
	EGL_CONFIG_CAVEAT: 12344
	EGL_CONFIG_ID: 3
	EGL_LEVEL: 0
	EGL_MAX_PBUFFER_HEIGHT: 8192
	EGL_MAX_PBUFFER_PIXELS: 67108864
	EGL_MAX_PBUFFER_WIDTH: 8192
	EGL_NATIVE_RENDERABLE: 0
	EGL_NATIVE_VISUAL_ID: 0
	EGL_NATIVE_VISUAL_TYPE: 12344
	EGL_SAMPLES: 0
	EGL_SAMPLE_BUFFERS: 0
	EGL_SURFACE_TYPE: 1031
	EGL_TRANSPARENT_TYPE: 12344
	EGL_TRANSPARENT_BLUE_VALUE: 0
	EGL_TRANSPARENT_GREEN_VALUE: 0
	EGL_TRANSPARENT_RED_VALUE: 0
	EGL_BIND_TO_TEXTURE_RGB: 0
	EGL_BIND_TO_TEXTURE_RGBA: 1
	EGL_MIN_SWAP_INTERVAL: 0
	EGL_MAX_SWAP_INTERVAL: 0
QMinimalEglIntegration

Found metadata in lib /usr/local/qt5xu4/qml/QtQuick.2/libqtquick2plugin.so, metadata=
{
    "IID": "org.qt-project.Qt.QQmlExtensionInterface/1.0",
    "MetaData": {
    },
    "className": "QtQuick2Plugin",
    "debug": false,
    "uri": [
        "QtQuick.2"
    ],
    "version": 329987
}


loaded library "/usr/local/qt5xu4/qml/QtQuick.2/libqtquick2plugin.so"
Found metadata in lib /usr/local/qt5xu4/qml/QtQuick/Window.2/libwindowplugin.so, metadata=
{
    "IID": "org.qt-project.Qt.QQmlExtensionInterface/1.0",
    "MetaData": {
    },
    "className": "QtQuick2WindowPlugin",
    "debug": false,
    "uri": [
        "QtQuick.Window.2"
    ],
    "version": 329987
}


loaded library "/usr/local/qt5xu4/qml/QtQuick/Window.2/libwindowplugin.so"
Found metadata in lib /usr/local/qt5xu4/qml/QtMultimedia/libdeclarative_multimedia.so, metadata=
{
    "IID": "org.qt-project.Qt.QQmlExtensionInterface/1.0",
    "MetaData": {
    },
    "className": "QMultimediaDeclarativeModule",
    "debug": false,
    "uri": [
        "QtMultimedia"
    ],
    "version": 329987
}


loaded library "/usr/local/qt5xu4/qml/QtMultimedia/libdeclarative_multimedia.so"
QFactoryLoader::QFactoryLoader() checking directory path "/usr/local/qt5xu4/plugins/mediaservice" ...
QFactoryLoader::QFactoryLoader() looking at "/usr/local/qt5xu4/plugins/mediaservice/libgstaudiodecoder.so"
Found metadata in lib /usr/local/qt5xu4/plugins/mediaservice/libgstaudiodecoder.so, metadata=
{
    "IID": "org.qt-project.qt.mediaserviceproviderfactory/5.0",
    "MetaData": {
        "Keys": [
            "gstreameraudiodecode"
        ],
        "Services": [
            "org.qt-project.qt.audiodecode"
        ]
    },
    "className": "QGstreamerAudioDecoderServicePlugin",
    "debug": false,
    "version": 329987
}


Got keys from plugin meta data ("gstreameraudiodecode")
QFactoryLoader::QFactoryLoader() looking at "/usr/local/qt5xu4/plugins/mediaservice/libgstcamerabin.so"
Found metadata in lib /usr/local/qt5xu4/plugins/mediaservice/libgstcamerabin.so, metadata=
{
    "IID": "org.qt-project.qt.mediaserviceproviderfactory/5.0",
    "MetaData": {
        "Keys": [
            "gstreamercamerabin"
        ],
        "Services": [
            "org.qt-project.qt.camera"
        ]
    },
    "className": "CameraBinServicePlugin",
    "debug": false,
    "version": 329987
}


Got keys from plugin meta data ("gstreamercamerabin")
QFactoryLoader::QFactoryLoader() looking at "/usr/local/qt5xu4/plugins/mediaservice/libgstmediacapture.so"
Found metadata in lib /usr/local/qt5xu4/plugins/mediaservice/libgstmediacapture.so, metadata=
{
    "IID": "org.qt-project.qt.mediaserviceproviderfactory/5.0",
    "MetaData": {
        "Keys": [
            "gstreamermediacapture"
        ],
        "Services": [
            "org.qt-project.qt.audiosource"
        ]
    },
    "className": "QGstreamerCaptureServicePlugin",
    "debug": false,
    "version": 329987
}


Got keys from plugin meta data ("gstreamermediacapture")
QFactoryLoader::QFactoryLoader() looking at "/usr/local/qt5xu4/plugins/mediaservice/libgstmediaplayer.so"
Found metadata in lib /usr/local/qt5xu4/plugins/mediaservice/libgstmediaplayer.so, metadata=
{
    "IID": "org.qt-project.qt.mediaserviceproviderfactory/5.0",
    "MetaData": {
        "Keys": [
            "gstreamermediaplayer"
        ],
        "Services": [
            "org.qt-project.qt.mediaplayer"
        ]
    },
    "className": "QGstreamerPlayerServicePlugin",
    "debug": false,
    "version": 329987
}


Got keys from plugin meta data ("gstreamermediaplayer")
QFactoryLoader::QFactoryLoader() checking directory path "/root/qt5build/qt5/dscctests/test2/mediaservice" ...
loaded library "/usr/local/qt5xu4/plugins/mediaservice/libgstmediaplayer.so"
QFactoryLoader::QFactoryLoader() checking directory path "/usr/local/qt5xu4/plugins/resourcepolicy" ...
QFactoryLoader::QFactoryLoader() checking directory path "/root/qt5build/qt5/dscctests/test2/resourcepolicy" ...
QFactoryLoader::QFactoryLoader() checking directory path "/usr/local/qt5xu4/plugins/video/declarativevideobackend" ...
QFactoryLoader::QFactoryLoader() checking directory path "/root/qt5build/qt5/dscctests/test2/video/declarativevideobackend" ...
QFactoryLoader::QFactoryLoader() checking directory path "/usr/local/qt5xu4/plugins/video/videonode" ...
QFactoryLoader::QFactoryLoader() looking at "/usr/local/qt5xu4/plugins/video/videonode/libeglvideonode.so"
Found metadata in lib /usr/local/qt5xu4/plugins/video/videonode/libeglvideonode.so, metadata=
{
    "IID": "org.qt-project.qt.sgvideonodefactory/5.2",
    "MetaData": {
        "Keys": [
            "egl"
        ]
    },
    "className": "QSGVideoNodeFactory_EGL",
    "debug": false,
    "version": 329987
}


Got keys from plugin meta data ("egl")
QFactoryLoader::QFactoryLoader() checking directory path "/root/qt5build/qt5/dscctests/test2/video/videonode" ...
loaded library "/usr/local/qt5xu4/plugins/video/videonode/libeglvideonode.so"
QFactoryLoader::QFactoryLoader() checking directory path "/usr/local/qt5xu4/plugins/video/gstvideorenderer" ...
QFactoryLoader::QFactoryLoader() checking directory path "/root/qt5build/qt5/dscctests/test2/video/gstvideorenderer" ...
QFactoryLoader::QFactoryLoader() checking directory path "/usr/local/qt5xu4/plugins/imageformats" ...
QFactoryLoader::QFactoryLoader() looking at "/usr/local/qt5xu4/plugins/imageformats/libqgif.so"
Found metadata in lib /usr/local/qt5xu4/plugins/imageformats/libqgif.so, metadata=
{
    "IID": "org.qt-project.Qt.QImageIOHandlerFactoryInterface",
    "MetaData": {
        "Keys": [
            "gif"
        ],
        "MimeTypes": [
            "image/gif"
        ]
    },
    "className": "QGifPlugin",
    "debug": false,
    "version": 329987
}


Got keys from plugin meta data ("gif")
QFactoryLoader::QFactoryLoader() looking at "/usr/local/qt5xu4/plugins/imageformats/libqicns.so"
Found metadata in lib /usr/local/qt5xu4/plugins/imageformats/libqicns.so, metadata=
{
    "IID": "org.qt-project.Qt.QImageIOHandlerFactoryInterface",
    "MetaData": {
        "Keys": [
            "icns"
        ],
        "MimeTypes": [
            "image/x-icns"
        ]
    },
    "className": "QICNSPlugin",
    "debug": false,
    "version": 329987
}


Got keys from plugin meta data ("icns")
QFactoryLoader::QFactoryLoader() looking at "/usr/local/qt5xu4/plugins/imageformats/libqico.so"
Found metadata in lib /usr/local/qt5xu4/plugins/imageformats/libqico.so, metadata=
{
    "IID": "org.qt-project.Qt.QImageIOHandlerFactoryInterface",
    "MetaData": {
        "Keys": [
            "ico",
            "cur"
        ],
        "MimeTypes": [
            "image/vnd.microsoft.icon"
        ]
    },
    "className": "QICOPlugin",
    "debug": false,
    "version": 329987
}


Got keys from plugin meta data ("ico", "cur")
QFactoryLoader::QFactoryLoader() looking at "/usr/local/qt5xu4/plugins/imageformats/libqjpeg.so"
Found metadata in lib /usr/local/qt5xu4/plugins/imageformats/libqjpeg.so, metadata=
{
    "IID": "org.qt-project.Qt.QImageIOHandlerFactoryInterface",
    "MetaData": {
        "Keys": [
            "jpg",
            "jpeg"
        ],
        "MimeTypes": [
            "image/jpeg",
            "image/jpeg"
        ]
    },
    "className": "QJpegPlugin",
    "debug": false,
    "version": 329987
}


Got keys from plugin meta data ("jpg", "jpeg")
QFactoryLoader::QFactoryLoader() looking at "/usr/local/qt5xu4/plugins/imageformats/libqtga.so"
Found metadata in lib /usr/local/qt5xu4/plugins/imageformats/libqtga.so, metadata=
{
    "IID": "org.qt-project.Qt.QImageIOHandlerFactoryInterface",
    "MetaData": {
        "Keys": [
            "tga"
        ],
        "MimeTypes": [
            "image/x-tga"
        ]
    },
    "className": "QTgaPlugin",
    "debug": false,
    "version": 329987
}


Got keys from plugin meta data ("tga")
QFactoryLoader::QFactoryLoader() looking at "/usr/local/qt5xu4/plugins/imageformats/libqtiff.so"
Found metadata in lib /usr/local/qt5xu4/plugins/imageformats/libqtiff.so, metadata=
{
    "IID": "org.qt-project.Qt.QImageIOHandlerFactoryInterface",
    "MetaData": {
        "Keys": [
            "tiff",
            "tif"
        ],
        "MimeTypes": [
            "image/tiff",
            "image/tiff"
        ]
    },
    "className": "QTiffPlugin",
    "debug": false,
    "version": 329987
}


Got keys from plugin meta data ("tiff", "tif")
QFactoryLoader::QFactoryLoader() looking at "/usr/local/qt5xu4/plugins/imageformats/libqwbmp.so"
Found metadata in lib /usr/local/qt5xu4/plugins/imageformats/libqwbmp.so, metadata=
{
    "IID": "org.qt-project.Qt.QImageIOHandlerFactoryInterface",
    "MetaData": {
        "Keys": [
            "wbmp"
        ],
        "MimeTypes": [
            "image/vnd.wap.wbmp"
        ]
    },
    "className": "QWbmpPlugin",
    "debug": false,
    "version": 329987
}


Got keys from plugin meta data ("wbmp")
QFactoryLoader::QFactoryLoader() looking at "/usr/local/qt5xu4/plugins/imageformats/libqwebp.so"
Found metadata in lib /usr/local/qt5xu4/plugins/imageformats/libqwebp.so, metadata=
{
    "IID": "org.qt-project.Qt.QImageIOHandlerFactoryInterface",
    "MetaData": {
        "Keys": [
            "webp"
        ],
        "MimeTypes": [
            "image/webp"
        ]
    },
    "className": "QWebpPlugin",
    "debug": false,
    "version": 329987
}


Got keys from plugin meta data ("webp")
QFactoryLoader::QFactoryLoader() checking directory path "/root/qt5build/qt5/dscctests/test2/imageformats" ...
loaded library "/usr/local/qt5xu4/plugins/imageformats/libqgif.so"
AL lib: (WW) alc_initconfig: Failed to initialize backend "pulse"
AL lib: (EE) ALCplaybackAlsa_open: Could not open playback device 'default': Device or resource busy
loaded library "/usr/local/qt5xu4/plugins/imageformats/libqicns.so"
loaded library "/usr/local/qt5xu4/plugins/imageformats/libqico.so"
loaded library "/usr/local/qt5xu4/plugins/imageformats/libqjpeg.so"
loaded library "/usr/local/qt5xu4/plugins/imageformats/libqtga.so"
loaded library "/usr/local/qt5xu4/plugins/imageformats/libqtiff.so"
loaded library "/usr/local/qt5xu4/plugins/imageformats/libqwbmp.so"
loaded library "/usr/local/qt5xu4/plugins/imageformats/libqwebp.so"
QMinimalEglIntegration::createPlatformWindow 0x157228

QEglWindow 0x3e6570: 0x157228 0x1

QFactoryLoader::QFactoryLoader() checking directory path "/usr/local/qt5xu4/plugins/accessible" ...
QFactoryLoader::QFactoryLoader() checking directory path "/root/qt5build/qt5/dscctests/test2/accessible" ...
QFactoryLoader::QFactoryLoader() checking directory path "/usr/local/qt5xu4/plugins/accessiblebridge" ...
QFactoryLoader::QFactoryLoader() checking directory path "/root/qt5build/qt5/dscctests/test2/accessiblebridge" ...
Warning: "Failed to connect: Connection refused"

[SGaist]

Might be a silly question but did you thought to call make install after building your custom version of the plugin ?

[nlazovic]

@SGaist
:) of course

root@odroid:~/qt5build/qt5/qtbase/src/plugins/platforms/minimalegl# make
make: Nothing to be done for 'first'.
root@odroid:~/qt5build/qt5/qtbase/src/plugins/platforms/minimalegl# make install
/root/qt5build/qt5/qtbase/bin/qmake -install qinstall -exe ../../../../plugins/platforms/libqminimalegl.so /usr/local/qt5xu4/plugins/platforms/libqminimalegl.so
strip --strip-unneeded /usr/local/qt5xu4/plugins/platforms/libqminimalegl.so
/root/qt5build/qt5/qtbase/bin/qmake -install qinstall /root/qt5build/qt5/qtbase/lib/cmake/Qt5Gui/Qt5Gui_QMinimalEglIntegrationPlugin.cmake /usr/local/qt5xu4/lib/cmake/Qt5Gui/Qt5Gui_QMinimalEglIntegrationPlugin.cmake
root@odroid:~/qt5build/qt5/qtbase/src/plugins/platforms/minimalegl#

nenad

[nlazovic]

@nlazovic

we did few experiments with QT samples (running with 0platfomr minimalegl), to see if / which one will instantiate QMinimalEglBackingStore. Below are the results.
Some do, some dont. could not figure out pattern :(

example /qtbase/examples/opengl/cube, QMinimalEglBackingStore instantiated !!!
using QApplication / QWidget
C++ only

example /qtmultimedia/examples/multimediawidgets/videowidget, QMinimalEglBackingStore instantiated !!!
using QApplication / QWidget
C++ only

example /qtdeclarative/examples/quick/quickwidgets/quickwidget, QMinimalEglBackingStore instantiated !!!
using QApplication / QMainWindow
C++/QML
App crashes “Segmentation fault”

example /qtdeclarative/examples/quick/quickwidgets/qquickviewcomparison, QMinimalEglBackingStore instantiated !!!
using QApplication / QWidget
C++/QML
App crashes “Segmentation fault” / This plugin does not support propagateSizeHints()

example /qtdeclarative/examples/quick/embeddedinwidgets, QMinimalEglBackingStore instantiated !!!
using QApplication / QMainWindow
C++/QML
Something fails ?

example /qtmultimedia/examples/multimedia/video/qmlvideo, QMinimalEglBackingStore NOT instantiated
using QGuiApplication / QQuickView
C++/QML

example /qtquickcontrols/examples/quickcontrols/controls/filesystembrowser, QMinimalEglBackingStore NOT instantiated
using QApplication / QQmlApplicationEngine
C++/QML

example /qtquickcontrols/examples/quickcontrols/controls/tableview, QMinimalEglBackingStore NOT instantiated
Using QtQuickControlsApplication / QQmlApplicationEngine
C++/QML

example /qtquickcontrols/examples/quickcontrols/controls/touch, QMinimalEglBackingStore NOT instantiated
Using QtQuickControlsApplication / QQmlApplicationEngine
C++/QML

example / qt3d/examples/qt3d/materials, QMinimalEglBackingStore NOT instantiated
using QGuiApplication / Qt3DQuickWindow
C++/QML