Qml.Net - Qt/QML integration/support for .NET
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A Qml integration with .NET

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Supported platforms/runtimes:

  • Runtimes:
    • .NET Framework
    • .NET Core
    • Mono
  • Operating systems
    • Linux
    • OSX
    • Windows



Getting started

dotnet add package Qml.Net


dotnet add package Qml.Net.WindowsBinaries


dotnet add package Qml.Net.OSXBinaries


dotnet add package Qml.Net.LinuxBinaries

Checkout the examples for some inspiration.

Quick overview

Define a .NET type (POCO)

[Signal("customSignal", NetVariantType.String)] // You can define signals that Qml can listen to.
public class QmlType
    /// <summary>
    /// Properties are exposed to Qml.
    /// </summary>
    [NotifySignal("stringPropertyChanged")] // For Qml binding/MVVM.
    public string StringProperty { get; set; }

    /// <summary>
    /// Methods can return .NET types.
    /// The returned type can be invoked from Qml (properties/methods/events/etc).
    /// </summary>
    /// <returns></returns>
    public QmlType CreateNetObject()
        return new QmlType();

    /// <summary>
    /// Qml can pass .NET types to .NET methods.
    /// </summary>
    /// <param name="parameter"></param>
    public void TestMethod(QmlType parameter)

    /// <summary>
    /// Qml can also pass Qml/C++ objects that can be invoked from .NET
    /// </summary>
    /// <param name="qObject"></param>
    public void TestMethodWithQObject(dynamic qObject)
        string result = qObject.PropertyDefinedInCpp;
    /// <summary>
    /// Async methods can be invoked with continuations happening on Qt's main thread.
    /// </summary>
    public async Task<string> TestAsync()
        // On the UI thread
        await Task.Run(() =>
            // On the background thread
        // On the UI thread
        return "async result!"
    /// <summary>
    /// .NET can activate signals to send notifications to Qml.
    /// </summary>
    public void ActivateCustomSignal(string message)
        this.ActivateSignal("customSignal", message)

Register your new type with Qml.

using (var app = new QGuiApplication(args))
    using (var engine = new QQmlApplicationEngine())
        // Register our new type to be used in Qml
        QQmlApplicationEngine.RegisterType<QmlType>("test", 1, 1);
        return app.Exec();

Use the .NET type in Qml

import QtQuick 2.7
import QtQuick.Controls 2.0
import QtQuick.Layouts 1.0
import test 1.1

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

    QmlType {
      id: test
      Component.onCompleted: function() {
          // We can read/set properties
          test.stringPropertyChanged.connect(function() {
              console.log("The property was changed!")
          test.stringProperty = "New value!"
          // We can return .NET types (even ones not registered with Qml)
          var netObject = test.createNetObject();
          // All properties/methods/signals can be invoked on "netObject"
          // We can also pass the .NET object back to .NET
          // We can invoke async tasks that have continuation on the UI thread
          var task = netObject.testAsync()
          // And we can await the task
          Net.await(task, function(result) {
              // With the result!
          // We can trigger signals from .NET
          test.customSignal.connect(function(message) {
              console.log("message: " + message)
          test.activateCustomSignal("test message!")
      function testHandler(message) {
          console.log("Message - " + message)

Currently implemented

  • Support for all the basic Qml types and the back-and-forth between them (DateTime, string, etc).
  • Reading/setting properties on .NET objects.
  • Invoking methods on .NET obejcts.
  • Declaring and activating signals on .NET objects.
  • async and await with support for awaiting and getting the result from Qml.
  • Passing dynamic javascript objects to .NET as dynamic.
  • Custom V8 type that looks like an array, but wraps a .NET IList<T> instance, for modification of list in Qml, and performance.

Not implemented (but planned)

  • Compiling Qml resource files and bundling them within .NET.
  • Passing QObject types to .NET with support for interacting with signals/slots/properties on them.
  • .NET Events to signals
  • General perf improvements (particularly with reflection).
  • Qml debugger for VS and VS Code.
  • Yocto meta-layer for .NET Core and Qml.Net (for embedded Linux development).