#8293 - uwp - imagebutton - Font Icon Disappears when Minimizing Wind…

[MichielDG]

Description of Change

Uwp seems to replace images with transparent images inside a button image when resuming the app after suspending it.
To fix this issue we set the ImageSource again when the app is resuming.
Refreshing the ImageSource is not enough.
To accomplish this the ButtonImageRenderer has to subscribe to the Resuming eventhandler.

Issues Resolved

• fixes [Bug] Font Icon Disappears when Minimizing Window in UWP #8293

API Changes

Added:

• async void OnResumingAsync(object sender, object e) in the Xamarin.Forms.Platform.UWP.ButtonImageRenderer which subscribed to Windows.UI.Xaml.Application.Current.Resuming
  Changed:
• none

Removed:

• none

Platforms Affected

• UWP

Behavioral/Visual Changes

• icon Images in an imagebutton are not transparent after suspending and then resuming the app again

Before/After Screenshots

• not fixed
  • before suspend
    
  • after suspend
    
• fixed
  • before suspend
    
  • after suspend
    

Testing Procedure

1. Create a new Xamarin Forms app with an UWP project
2. Add a fonticon (fa-regular-400.ttf) as Embedded resource into the shared project
3. Add in the assemblyInfo.cs this line:

[assembly: ExportFont("fa-regular-400.ttf", Alias = "far")] 

4. Add an image button to the MainPage with an icon inside:

<ImageButton HeightRequest="50" Margin="6" WidthRequest="50" BackgroundColor="Transparent" 
                           HorizontalOptions="FillAndExpand" VerticalOptions="Center">
  <ImageButton.Source>
    <FontImageSource Glyph="&#xf06e;" FontFamily="far" Size="44" Color="White"/>
  </ImageButton.Source>
</ImageButton>

5. Start the app
6. When the app is loaded suspend the app.
7. Resume the app
8. Image/icon should be visible and should not be transparent

PR Checklist

• Targets the correct branch
• Tests are passing (or failures are unrelated)

[Alex-Witkowski]

Does the same change/fix taht was applied for ImageRenderer in #8783.
Looks good 👍

[djrpascu]

Thanks for this PR! 👍

[djrpascu]

@samhouts would it be possible to get this PR merged into an upcoming release? much mahalo!

[hellyeahniels]

This bug is also still present on Button FontImages.

[jfversluis]

Now that we're so close to the sunsetting of Xamarin.Forms unfortunately we won't be able to take this in anymore, we're really sorry about that. Nevertheless, thank you so much for your time and effort that you have put into this PR.

Please have a look at the evolution of Xamarin.Forms, .NET MAUI. A lot of development has been going on there. Hopefully this issue was already fixed in that codebase. If not, feel free to port this over to there.

Again, thank you so much for being a contributor and Xamarin.Forms user!