[regression/8.0.0-preview.7.8842] Labels with max lines and linebreakmode not working even with adding handler workaround

[Zack-G-I-T]

Description

Adding a label with LineBreakMode="TailTruncation" and MaxLines="2" makes the label only show on one line. Even adding the workaround handler (which fixed this issue in Net7) does not help anymore. I have attached a sample repo showing this - the last label should show on two lines.

Steps to Reproduce

1. Get repo and see bottom label - it should be on two lines.

Link to public reproduction project repository

https://github.com/Zack-G-I-T/LabelBugNet8

Version with bug

8.0.0-preview.7.8842

Is this a regression from previous behavior?

Yes, this used to work in .NET MAUI

Last version that worked well

8.0.0-preview.6.8686

Affected platforms

Android

Affected platform versions

No response

Did you find any workaround?

Update code to use the new mapper:

 public static void AllowMultiLineTruncation()
 {
     static void UpdateMaxLines(Microsoft.Maui.Handlers.LabelHandler handler, ILabel label)
     {
         var textView = handler.PlatformView;
         if (label is Label controlsLabel
             && textView.Ellipsize == TextUtils.TruncateAt.End && controlsLabel.MaxLines != -1)
         {
             textView.SetMaxLines(controlsLabel.MaxLines);
         }
     };

     LabelHandler.Mapper.AppendToMapping(
        nameof(Label.LineBreakMode), (h, v) => UpdateMaxLines((LabelHandler)h, v));

     LabelHandler.Mapper.AppendToMapping(
       nameof(Label.MaxLines), (h, v) => UpdateMaxLines((LabelHandler)h, v));
 }

Relevant log output

No response

[samhouts]

Confirmed that this regressed between 8.0.0-preview.6.8686 and 8.0.0-preview.7.8842. #13836 is the culprit. The obsolete mappers don't seem to be properly forwarding to the new mappers. The workaround is to update to use the new mappers:

 public static void AllowMultiLineTruncation()
 {
     static void UpdateMaxLines(Microsoft.Maui.Handlers.LabelHandler handler, ILabel label)
     {
         var textView = handler.PlatformView;
         if (label is Label controlsLabel
             && textView.Ellipsize == TextUtils.TruncateAt.End && controlsLabel.MaxLines != -1)
         {
             textView.SetMaxLines(controlsLabel.MaxLines);
         }
     };

     LabelHandler.Mapper.AppendToMapping(
        nameof(Label.LineBreakMode), (h, v) => UpdateMaxLines((LabelHandler)h, v));

     LabelHandler.Mapper.AppendToMapping(
       nameof(Label.MaxLines), (h, v) => UpdateMaxLines((LabelHandler)h, v));
 }