Differences in WPF and Avalonia

Differences in WPF and Avalonia

If you want create desktop application for Windows platform there are multiple UI frameworks you can use.

I have written some WPF code during my years, and this year I wanted to port my password manager to Avalonia. Since both can now be done via .NET Core, I could just forget possible language differences between frameworks by using almost same base code for both frameworks and just focus my effort to UI parts.

Below are some things that are different in WPF and Avalonia

Visibility vs. IsVisible

In WPF one can use Visibility in XAML to hide and collapse visual elements. But in Avalonia you have to use IsVisible and it is boolean (true means visible and false means collapsed).

<Grid Visibility="{Binding WizardVisibility}>

and

public Visibility WizardVisibility
{ 
    get
    {
        return this.csc == null ? Visibility.Visible : Visibility.Collapsed;
    } 
    set
    {

    }
}

vs.

<Grid IsVisible="{Binding WizardVisibility}">

and

public bool WizardVisibility
{ 
    get
    {
        return this.csc == null;
    } 
    set
    {

    }
}

Label vs. TextBlock

In WPF you can show text in window with Label control. Avalonia does not have that, so you have to use TextBlock instead. And Content becomes Text.

<Label Content="Length of generated password:" Margin="2,5,2,2" />

vs.

<TextBlock Text="Length of generated password:" Margin="2,5,2,2" />

Clipboard vs. Application.Current.Clipboard

With WPF you can copy text to clipboard with Clipboard.SetText but with Avalonia you have to use Application.Current.Clipboard.SetTextAsync (and you should do await since it is an async method)

Clipboard.SetText("A nice text");

vs.

Application.Current.Clipboard.SetTextAsync("A nice text");

ShowDialog needs owner

Going with WPF, one can show modal window with ShowDialog. Avalonia also has ShowDialog, but it needs to know owner when called. Luckily you can figure out the main window with some additional code.

CreatePasswordWindow passwordWindow = new CreatePasswordWindow(null);
passwordWindow.ShowDialog();

vs.

CreatePasswordWindow passwordWindow = new CreatePasswordWindow();
if (Application.Current.ApplicationLifetime is IClassicDesktopStyleApplicationLifetime desktopLifetime)
{
    passwordWindow.ShowDialog(desktopLifetime.MainWindow);
}

FindControl is needed for x:Name

In WPF universe using controls created in XAML via code is quite easy, if you just give those controls x:Name. But “Unfortunately, Avalonia XAML rendering engine won’t generate strongly typed x:Name references to controls” so in Avalonia you have to use FindControl instead.

So if XAML part would be following

<TextBlock Text="Hello, world!" x:Name="MyTextBlock" />

then in WPF you would do

MyTextBlock.Text = "New Text";

but in Avalonia it would be

TextBlock textBlock = this..FindControl<TextBlock>("MyTextBlock");
textBlock.Text = "New Text";

VerticalScrollBarVisibility is known as ScrollViewer.VerticalScrollBarVisibility

Your WPF project might use VerticalScrollBarVisibility with TextBox. In your Avalonia project that would be ScrollViewer.VerticalScrollBarVisibility.

So XAML in WPF would be

<TextBox Name="notes" VerticalScrollBarVisibility="Visible" />

and in Avalonia it would be

<TextBox Name="notes" ScrollViewer.VerticalScrollBarVisibility="Visible" />