@Joshika_Namani Which version of Qt do you use? I think that using Qt6 is a better option but here is a doc for Qt5 https://doc.qt.io/qt-5/qopenglwidget.html if you want to see.

Would i be viable to use qt widgets and just use qtquick for all the other widgets embedded into the qt widgets mainwindow or is this a bad idea?

Thanks for your reply.
One thing to note is that if I hadn't turned on the virtual keyboard on MacOS, this Dialog destruction wouldn't have caused the program to crash.

I've found a solution, albeit with a small bit of help from ChatGPT as a last resort. I used an if/else statement (in the form of a ternary operator) for my main.qml and added an additional @Slot() decorator for the LED off function in my main,py.
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↓ main.qml ↓

import QtQuick import QtQuick.Controls ApplicationWindow { width: 1920 height: 1080 visible: true // Bool property to hold the button state property bool buttonState: false // Function to toggle the LEDs function toggleLEDs() { buttonState ? controlPanel.buttonOff() : controlPanel.buttonOn(); buttonState = !buttonState; } Image { id: allLights source: "images/power_" + (buttonState ? "on" : "off") + ".png" anchors.centerIn: parent MouseArea { anchors.fill: parent onClicked: { toggleLEDs(); } } } }

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↓ main,py ↓

import sys from pathlib import Path from led import grid, all_lights_on, all_lights_off from PySide6.QtCore import QObject, Slot from PySide6.QtGui import QGuiApplication from PySide6.QtQml import QQmlApplicationEngine class ControlPanel(QObject): def __init__(self): super().__init__() @Slot() def buttonOn(self): all_lights_on(grid) @Slot() def buttonOff(self): all_lights_off(grid) if __name__ == '__main__': app = QGuiApplication(sys.argv) engine = QQmlApplicationEngine() controlPanel = ControlPanel() engine.rootContext().setContextProperty("controlPanel", controlPanel) qml_file = Path(__file__).parent / 'main.qml' engine.load(qml_file) if not engine.rootObjects(): sys.exit(-1) sys.exit(app.exec())

@Tiny-Leaf
Try the following code. The length of three segments should be same.

drawLine(ctx, 50, 50, 150, 50); drawLine(ctx, 150, 50, 50, 50); drawLine(ctx, 150, 100, 50, 100); function drawLine(ctx, x1, y1, x2, y2) { ctx.beginPath() ctx.moveTo(x1, y1) ctx.lineTo(x2, y2) ctx.stroke() }

BTW: you may somehow avoid to draw a line twice if possible. It is not efficient.

@JoeCFD QML file code below. I haven't edited it at all.

QT += quick CONFIG += c++11 # The following define makes your compiler emit warnings if you use # any Qt feature that has been marked deprecated (the exact warnings # depend on your compiler). Refer to the documentation for the # deprecated API to know how to port your code away from it. DEFINES += QT_DEPRECATED_WARNINGS # You can also make your code fail to compile if it uses deprecated APIs. # In order to do so, uncomment the following line. # You can also select to disable deprecated APIs only up to a certain version of Qt. #DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000 # disables all the APIs deprecated before Qt 6.0.0 SOURCES += \ main.cpp RESOURCES += qml.qrc # Additional import path used to resolve QML modules in Qt Creator's code model QML_IMPORT_PATH = # Additional import path used to resolve QML modules just for Qt Quick Designer QML_DESIGNER_IMPORT_PATH = # Default rules for deployment. qnx: target.path = /tmp/$${TARGET}/bin else: unix:!android: target.path = /opt/$${TARGET}/bin !isEmpty(target.path): INSTALLS += target

I'm wondering if the answer is related to Window properties flags, modality and possibly visibility. I've read the docs but some of it is a little thin on the ground and I am unclear how these properties interact.

Can anyone suggest what's needed for my app to be:

standard iPad app, which means single window that's fullscreen, and single-window app on Windows and MacOS

I've been controlling whether my app is fullscreen by setting visibility: Window.FullScreen. I still want to have the option to set this or not set this. (Or a different way to start / go into / out of full screen mode for Windows & MacOS.)

UPDATE: This is a known bug in Qt https://bugreports.qt.io/browse/QTBUG-113616

Also here is the stacktrace if it helps:

0 ??? 0x10a1029a8 ??? 1 <translation info unavailable> 0x10c7d5e24 ??? 2 libsystem_pthread.dylib 0x115b91ee6 pthread_kill + 263 3 libsystem_c.dylib 0x114e06e58 abort + 130 4 test5 0x104c96839 qAbort() + 9 (qglobal.cpp:161) 5 test5 0x104c9b6b8 qt_message_fatal(QtMsgType, QMessageLogContext const&, QString const&) + 24 (qlogging.cpp:2048) 6 test5 0x10510d7b6 QMessageLogger::fatal(char const*, ...) const + 246 (qlogging.cpp:934) 7 test5 0x10510d08a qt_assert(char const*, char const*, int) + 74 (qassert.cpp:68) 8 test5 0x1041c7e45 QGles2TextureRenderTarget::create() + 981 (qrhigles2.cpp:5462) 9 test5 0x103580e82 QQuickWidget::createFramebufferObject() + 1890 (qquickwidget.cpp:1137) 10 test5 0x103585ad1 QQuickWidget::qt_static_metacall(QObject*, QMetaObject::Call, int, void**) + 225 (moc_qquickwidget.cpp:295) 11 test5 0x104da0579 void doActivate<false>(QObject*, int, void**) + 2313 (qobject.cpp:4004) 12 test5 0x104d9f039 QMetaObject::activate(QObject*, QMetaObject const*, int, void**) + 121 (qobject.cpp:4052) 13 test5 0x103607465 QQuickWindow::sceneGraphInitialized() + 37 (moc_qquickwindow.cpp:829) 14 test5 0x10360665d QQuickWindow::qt_static_metacall(QObject*, QMetaObject::Call, int, void**) + 109 (moc_qquickwindow.cpp:570) 15 test5 0x104da0579 void doActivate<false>(QObject*, int, void**) + 2313 (qobject.cpp:4004) 16 test5 0x104d9f039 QMetaObject::activate(QObject*, QMetaObject const*, int, void**) + 121 (qobject.cpp:4052) 17 test5 0x1036b52d2 QSGRenderContext::initialized() + 34 (moc_qsgcontext_p.cpp:289) 18 test5 0x1036c7b67 QSGDefaultRenderContext::initialize(QSGRenderContext::InitParams const*) + 295 (qsgdefaultrendercontext.cpp:57) 19 test5 0x1035f1a1a QQuickRenderControl::initialize() + 378 (qquickrendercontrol.cpp:309) 20 test5 0x1035806d3 QQuickWidgetPrivate::initializeWithRhi() + 867 (qquickwidget.cpp:1058) 21 test5 0x1035837aa QQuickWidget::resizeEvent(QResizeEvent*) + 474 (qquickwidget.cpp:1404) 22 test5 0x1038782cb QWidget::event(QEvent*) + 2683 (qwidget.cpp:9076) 23 test5 0x103584fb9 QQuickWidget::event(QEvent*) + 1321 (qquickwidget.cpp:1719) 24 test5 0x1037ea0ba QApplicationPrivate::notify_helper(QObject*, QEvent*) + 458 (qapplication.cpp:3284) 25 test5 0x1037ee456 QApplication::notify(QObject*, QEvent*) + 11974 (qapplication.cpp:3231) 26 test5 0x104d2212a QCoreApplication::notifyInternal2(QObject*, QEvent*) + 282 (qcoreapplication.cpp:1115) 27 test5 0x104d22df3 QCoreApplication::sendEvent(QObject*, QEvent*) + 131 (qcoreapplication.cpp:1533) 28 test5 0x10386f721 QWidgetPrivate::sendPendingMoveAndResizeEvents(bool, bool) + 353 (qwidget.cpp:7944) 29 test5 0x103875ff0 QWidgetPrivate::show_helper() + 64 (qwidget.cpp:7995) 30 test5 0x10387707f QWidgetPrivate::setVisible(bool) + 943 (qwidget.cpp:8344) 31 test5 0x103876cc0 QWidget::setVisible(bool) + 144 (qwidget.cpp:8276) 32 test5 0x10386871e QWidget::showMaximized() + 126 (qwidget.cpp:3057) 33 test5 0x103875e94 QWidget::show() + 100 (qwidget.cpp:7900) 34 test5 0x102e70702 MyOpenGLWidget::mousePressEvent(QMouseEvent*) + 82 (main.cpp:16) 35 test5 0x103877a73 QWidget::event(QEvent*) + 547 (qwidget.cpp:8902) 36 test5 0x1037ac198 QOpenGLWidget::event(QEvent*) + 712 (qopenglwidget.cpp:1698) 37 test5 0x1037ea0ba QApplicationPrivate::notify_helper(QObject*, QEvent*) + 458 (qapplication.cpp:3284) 38 test5 0x1037ec11c QApplication::notify(QObject*, QEvent*) + 2956 (qapplication.cpp:2772) 39 test5 0x104d2212a QCoreApplication::notifyInternal2(QObject*, QEvent*) + 282 (qcoreapplication.cpp:1115) 40 test5 0x104d22e83 QCoreApplication::sendSpontaneousEvent(QObject*, QEvent*) + 131 (qcoreapplication.cpp:1547) 41 test5 0x1037eabd0 QApplicationPrivate::sendMouseEvent(QWidget*, QMouseEvent*, QWidget*, QWidget*, QWidget**, QPointer<QWidget>&, bool, bool) + 1216 (qapplication.cpp:2356) 42 test5 0x1038a44a5 QWidgetWindow::handleMouseEvent(QMouseEvent*) + 4485 (qwidgetwindow.cpp:623) 43 test5 0x1038a2849 QWidgetWindow::event(QEvent*) + 361 (qwidgetwindow.cpp:241) 44 test5 0x1037ea0ba QApplicationPrivate::notify_helper(QObject*, QEvent*) + 458 (qapplication.cpp:3284) 45 test5 0x1037ee474 QApplication::notify(QObject*, QEvent*) + 12004 (qapplication.cpp:3235) 46 test5 0x104d2212a QCoreApplication::notifyInternal2(QObject*, QEvent*) + 282 (qcoreapplication.cpp:1115) 47 test5 0x104d22e83 QCoreApplication::sendSpontaneousEvent(QObject*, QEvent*) + 131 (qcoreapplication.cpp:1547) 48 test5 0x103e0f2b0 QGuiApplicationPrivate::processMouseEvent(QWindowSystemInterfacePrivate::MouseEvent*) + 2384 (qguiapplication.cpp:2277) 49 test5 0x103e0ec51 QGuiApplicationPrivate::processMouseEvent(QWindowSystemInterfacePrivate::MouseEvent*) + 753 (qguiapplication.cpp:2187) 50 test5 0x103e110b4 QGuiApplicationPrivate::processTouchEvent(QWindowSystemInterfacePrivate::TouchEvent*) + 5412 (qguiapplication.cpp:3081) 51 test5 0x103e0e2de QGuiApplicationPrivate::processWindowSystemEvent(QWindowSystemInterfacePrivate::WindowSystemEvent*) + 110 (qguiapplication.cpp:2035) 52 test5 0x103e74a5e QWindowSystemInterface::sendWindowSystemEvents(QFlags<QEventLoop::ProcessEventsFlag>) + 190 (qwindowsysteminterface.cpp:1094) 53 test5 0x102e7af11 QIOSEventDispatcher::processPostedEvents() + 545 (qioseventdispatcher.mm:443) 54 test5 0x104f9bf3b RunLoopSource<QEventDispatcherCoreFoundation>::process(void*) + 107 (qeventdispatcher_cf_p.h:111) 55 CoreFoundation 0x113e56b8f __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 17 56 CoreFoundation 0x113e56ad1 __CFRunLoopDoSource0 + 157 57 CoreFoundation 0x113e5632b __CFRunLoopDoSources0 + 311 58 CoreFoundation 0x113e509ba __CFRunLoopRun + 889 59 CoreFoundation 0x113e50264 CFRunLoopRunSpecific + 560 60 GraphicsServices 0x1225e324e GSEventRunModal + 139 61 UIKitCore 0x13abc47bf -[UIApplication _run] + 994 62 UIKitCore 0x13abc95de UIApplicationMain + 123 63 test5 0x102e79161 qt_main_wrapper + 705 (qioseventdispatcher.mm:206) 64 dyld_sim 0x112701384 start_sim + 10 65 dyld 0x20a3db41f start + 1903

Thanks for the information. I did not realize that all dependencies are build into the application on static builds and therefore the deploy-script is not needed anymore. I got the script to run with my normal (dynamically linked) version of Qt and now I get my deployable this way. Thanks again for the help.

@JonB that answer is from 5 years ago, I had read it but had hopes something had changed.

So the answer is still NO.

@sethsource same with HLS

It's the same with me...

Tried it on Qt 5.15, and it works perfectly

You don't.

C++ shouldn't connect to QML signals.

Expose a slot/invokable function in a Python object that is accessible from QML and call that slot in QML.