Quick Start with Command Line and Visual Studio Code

In this tutorial you will create a cross-platform desktop application using C#, .NET command line tools and Visual Studio Code. The application will display a message box in response to a button click.

Prerequisites

Download and install .NET SDK. Minimum supported SDK version is .NET Core 3.1.
Install AlterNET UI project templates by running
```
dotnet new --install Alternet.UI.Templates
```
Download and install Visual Studio Code
In Visual Studio Code, make sure the C# extension is installed. For information about how to install extensions on Visual Studio Code, see VS Code Extension Marketplace.

Create New Project

Create a new directory for your application, name it HelloWorld
Open the Command Prompt window (Terminal on macOS or Linux)
Navigate the terminal to the created directory:
```
cd path/to/HelloWorld
```
Enter the following command to create a new project in the current directory:
```
dotnet new alternet-ui
```

The following files will be created:

HelloWorld.csproj
MainWindow.uixml
MainWindow.uixml.cs
Program.cs

Compile and run the created project by executing:
```
dotnet run
```

The application will start and display its window:

Created Application Window

Note

By default the created project will use .NET Core 3.1 as a target framework. If .NET Core 3.1 runtime is not installed on your machine you will be prompted to do so on the first application run.

Open Project with Visual Studio Code

Start Visual Studio Code.
Select File > Open Folder (File > Open... on macOS) from the main menu.
In the Open Folder dialog, locate a HelloWorld folder and click Select Folder (Open on macOS).
The popup prompting Select 1 of 2 projects will appear at the top of the screen:

Select All contained projects.
After several seconds, a popup dialog with message Required assets to build and debug are missing from 'HelloWorld'. Add them? will appear at the bottom-right corner of the screen:

Select Yes. The .vscode subdirectory will be created with the workspace settings automatically set up.
Now you can debug your application by pressing F5, or run it without debugging by pressing Ctrl+F5. The application will be built automatically, if required.

Open MainWindow.uixml by clicking the corresponing item in the VS Code Explorer panel. In the editor, change the Title attribute value from "HelloWorld" to "My First Application":

<Window xmlns="http://schemas.alternetsoft.com/ui/2021"
        xmlns:x="http://schemas.alternetsoft.com/ui/2021/uixml"
        x:Class="HelloWorld.MainWindow"
        Title="My First Application">
</Window>

Press Ctrl+F5 to build and run the application and see its window title had changed accordingly.

Note

For information and tutorials on general C# development and debugging with Visual Studio Code, see the corresponding MSDN article.

Add Button to the Window

In MainWindow.uixml, add the following markup:

<Window xmlns="http://schemas.alternetsoft.com/ui/2021"
        xmlns:x="http://schemas.alternetsoft.com/ui/2021/uixml"
        x:Class="HelloWorld.MainWindow"
        Title="My First Application">
  <StackPanel>
    <Button Name="helloButton" Text="Say Hello" Margin="20" />
  </StackPanel>
</Window>

Run the application by pressing Ctrl+F5:

Write Code to Respond to the Button Click

In MainWindow.uixml, add the Click attribute to the Button element like the following:

<Window xmlns="http://schemas.alternetsoft.com/ui/2021"
        xmlns:x="http://schemas.alternetsoft.com/ui/2021/uixml"
        x:Class="HelloWorld.MainWindow"
        Title="My First Application">
  <StackPanel>
    <Button Name="helloButton" Text="Say Hello" Margin="20" Click="HelloButton_Click" />
  </StackPanel>
</Window>

This will bind the Click event to its handler named HelloButton_Click.

In MainWindow.uixml.cs file, add the following HelloButton_Click method:

using System;
using Alternet.UI;

namespace HelloWorld
{
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
        }

        private void HelloButton_Click(object? sender, EventArgs e)
        {
            MessageBox.Show("Hello, world!");
        }
    }
}

Run the application, then click Say Hello button. The message box appears:

Note

The application created in this tutorial can be compiled and run without any modifications on all the supported platforms: Windows, macOS, Linux.

Congratulations, you have successfully completed the Quick Start tutorial using command line tools and Visual Studio Code.

For a similar tutorial, but using Visual Studio on Windows, see Quick Start with Visual Studio.