QVideoSurfaceFormat setMirrored did not work out.

[Dylan Deng]

I have already created a frame provider class for QML VideoOutput component to display screen info on application. And I called the setMirrored function to set the frame to be mirrored.
It works very well, but when I click full screen button, the mirror property no longer works. It reset to no mirrored state. Where did i go wrong? Is this a bug?
The following code is an example to demonstrate the problem.

#ifndef FRAMEPROVIDER_H
#define FRAMEPROVIDER_H

#include <QObject>
#include <QTimer>
#include <QDebug>
#include <QPixmap>
#include <QScreen>
#include <QGuiApplication>
#include <QVideoSurfaceFormat>
#include <QAbstractVideoSurface>

class FrameProvider : public QObject
{
    Q_OBJECT
    Q_PROPERTY(QAbstractVideoSurface *videoSurface READ videoSurface WRITE setVideoSurface)

public:
    explicit FrameProvider(QObject *parent = nullptr)
        : QObject(parent)
        , m_videoFormat(QSize(0, 0), QVideoFrame::Format_ARGB32)
        , m_videoSurface(nullptr)

    {
        connect(&m_captureTimer, &QTimer::timeout, this, &FrameProvider::screenCapture);
    }

    ~FrameProvider()
    {

    }

    QAbstractVideoSurface* videoSurface() const
    {
        return m_videoSurface;
    }

    void setVideoSurface(QAbstractVideoSurface* videoSurface)
    {
        if (m_videoSurface == videoSurface)
            return;

        if (m_videoSurface && m_videoSurface->isActive())
            m_videoSurface->stop();

        m_videoSurface = videoSurface;

        m_videoFormat.setMirrored(true);

        if (m_videoSurface)
            m_videoSurface->start(m_videoFormat);

        m_captureTimer.start(200);
    }

public slots:
    void screenCapture()
    {
        // capture main screen picture
        auto screens = QGuiApplication::screens();
        auto screen = screens.at(0);
#ifdef Q_OS_WIN32
        QPixmap pixmap = screen->grabWindow(0);
#else
        QPixmap pixmap = screen->grabWindow(0, screen->geometry().x(), screen->geometry().y(),
                                            screen->geometry().width(), screen->geometry().height());
#endif
        QImage image(pixmap.toImage().convertToFormat(QImage::Format_RGB32));
        QVideoFrame frame(image);


        QMetaObject::invokeMethod(this, "onScreenCaptured", Qt::AutoConnection,
                                  Q_ARG(QVideoFrame, frame),
                                  Q_ARG(QSize, image.size()));
    }

    void onScreenCaptured(const QVideoFrame& frame, const QSize &videoSize)
    {
        if (m_videoFormat.frameSize() != videoSize) {
            m_videoSurface->stop();
            m_videoFormat.setFrameSize(videoSize);
            m_videoSurface->start(m_videoFormat);
        }

        if (m_videoSurface)
            m_videoSurface->present(frame);
    }

private:
    QVideoSurfaceFormat     m_videoFormat;
    QAbstractVideoSurface*  m_videoSurface;
    QTimer                  m_captureTimer;

};

#endif // FRAMEPROVIDER_H

My QML file code:

import QtQuick 2.12
import QtQuick.Window 2.12
import QtMultimedia 5.12
import Company.App.FrameProvider 1.0

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

    FrameProvider {
        id: frameProvier
    }

    VideoOutput {
        anchors.fill: parent
        source: frameProvier
    }
}

main.cpp

#include <QGuiApplication>
#include <QQmlApplicationEngine>
#include "frame_provider.h"

int main(int argc, char *argv[])
{
    QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);

    QGuiApplication app(argc, argv);

    QQmlApplicationEngine engine;

    qmlRegisterType<FrameProvider>("Company.App.FrameProvider", 1, 0, "FrameProvider");

    const QUrl url(QStringLiteral("qrc:/main.qml"));
    QObject::connect(&engine, &QQmlApplicationEngine::objectCreated,
                     &app, [url](QObject *obj, const QUrl &objUrl) {
        if (!obj && url == objUrl)
            QCoreApplication::exit(-1);
    }, Qt::QueuedConnection);
    engine.load(url);

    return app.exec();
}

[Dylan Deng]

I have no idea to resolve this problem, can anyone help me. Thanks.

[SGaist]

Hi,

This sounds like a bug...

Which version of Qt are you using ?
On which OS ?

[Dylan Deng]

@SGaist

Qt version:
Qt 5.14.1/5.14.2

System version:
Windows 10 Pro 1909/ Windows 10 Home 2004
macOS 10.15.x

[SGaist]

Can you try with 5.15 ?

[Dylan Deng]

@SGaist Qt 5.15 has the same problem.

[SGaist]

The you should check the bug report system to see if it's something known. If not please consider opening a report providing a minimal compilable example that reproduces the behaviour.