How to trigger floating action button OnClicked EventHandler on Xamarin Forms

Question

I am using the NuGet Package https://github.com/jamesmontemagno/FloatingActionButton-for-Xamarin.Android to implement a floating action button. I have already added it, but I can't get the clicked event working.

MyPage.xaml:

<fab:FloatingActionButtonView ImageName="settings_24.png"
                              ColorNormal="{StaticResource PrimaryColor}"
                              ColorPressed="{StaticResource PrimaryDarkColor}"
                              ColorRipple="{StaticResource PrimaryDarkColor}"
                              x:Name="FABaddTx"
                              AbsoluteLayout.LayoutFlags="PositionProportional"
                              AbsoluteLayout.LayoutBounds="1, 1, AutoSize, AutoSize"
                              Clicked="FAB_Clicked"/>

MyPage.xaml.cs:

private void FAB_Clicked(object sender, EventArgs e)
{
    var page = new AddTransactionPage();
    Navigation.PushAsync(page);
}

I found out that FloatingActionButtonView.Clicked is a Property and not an Event, but how does it work then? There is neither a ItemTapped or ItemSelected Event which I could use.

I have already looked throught the sample code provided on the GitHub repo, sadly there is only Xamarin.Android code, while I would need Xamarin.Forms.

Answer 1

According to this Xamarin.Forms example from the source repository it is an action delegate property.

/// <summary>
/// Action to call when clicked
/// </summary>
public Action<object, EventArgs> Clicked { get; set; }

Source

You can set the delegate within the constructor of the Page.

However, given that it is not an actual event handler and just a void method, it would be ill advised to make it an async void method if you want to perform async operations safely.

Reference Async/Await - Best Practices in Asynchronous Programming

Instead, create an event and async event handler so that async operations can be awaited

MyPage.xaml.cs:

public MyPage() {
    //Subscribing to our event here
    FabClicked += OnFabClicked;
    //FABaddT is already defined in the XAML so just setting the delegate here
    FABaddT.Clicked = (sender, args) => {
        //Raising the event here and passing sender and event arguments on
        FabClicked(sender, args);
    };
}

private event EventHandler FabClicked = delegate { };

private async void OnFabClicked(object sender, EventArgs args) {
    var page = new AddTransactionPage();
    await Navigation.PushAsync(page);
}