NumberBox.NumberFormatter is not used on Android

[borjafdezgauna]

Current behavior

I am binding a custom number formatter to a NumberBox component. Something like this:

public class FloatNumberRounder : INumberFormatter2, INumberParser
{
    public string FormatDouble(double value)
    {
        return number.ToString("F1", CultureInfo.InvariantCulture); //only one fraction digit
    }

    public string FormatInt(long value)
    {
        return value.ToString();
    }

    public string FormatUInt(ulong value)
    {
        return value.ToString();
    }

    public double? ParseDouble(string text)
    {
        if (Numbers.TryParseDouble(text, out double parsedNumber))
            return parsedNumber;
        return null;
    }

    public long? ParseInt(string text)
    {
        if (Numbers.TryParseInteger(text, out int parsedNumber))
            return parsedNumber;
        return null;
    }

    public ulong? ParseUInt(string text)
    {
        if (Numbers.TryParseInteger(text, out int parsedNumber))
            return (ulong) parsedNumber;
        return null;
    }
}

, which I instantiate on my class:

public INumberFormatter2 Formatter => new FloatNumberRounder ();

I then bind it in a DataTemplate:

<DataTemplate x:DataType="local:ValueHandlerModel">
  <StackPanel Orientation="Vertical">
    <NumberBox Value="{Binding Number, Mode=TwoWay}"
       SpinButtonPlacementMode="Inline"
       NumberFormatter="{x:Bind Formatter}"
       Style="{ThemeResource NumberBox}"/>
  </StackPanel>
</DataTemplate>

On Windows, it works as I expected: no matter what values I give to SmallChange and LargeChange (NumberBox), my formatter shows only one fraction digit.

On Android, an instance of FloatNumberRounder is actually instantiated, but then, when I click the arrows, none of the methods are called and, depending on the values of SmallChange/LargeChange, values show with 2 fraction digits. It is curious that, in the absence of a formatter, no random number of digits is shown due to imprecision (as it is on Windows)

Expected behavior

I would expect the instance of NumberFormatter to be used also on Android

How to reproduce it (as minimally and precisely as possible)

No response

Workaround

No response

Works on UWP/WinUI

None

Environment

Uno.UI / Uno.UI.WebAssembly / Uno.UI.Skia

NuGet package version(s)

No response

Affected platforms

Android

IDE

Visual Studio 2022

IDE version

No response

Relevant plugins

No response

Anything else we need to know?

No response

[jeromelaban]

Thanks for the report.

It should be supported by this portion:

uno/src/Uno.UI/Microsoft/UI/Xaml/Controls/NumberBox/NumberBox.cs

Lines 535 to 538 in b6e4604

	var value = AcceptsExpression
	? NumberBoxParser.Compute(text, numberParser)
	: ApiInformation.IsTypePresent(numberParser?.GetType().FullName)
	? numberParser.ParseDouble(text)

You may to try and see if other platforms are using it.

[borjafdezgauna]

I have been trying to build and test it on MacOS, but no luck so far... Will let you know when I manage to build it

Thanks for the response!

[borjafdezgauna]

Same behaviour on MacOS (as on Android, the custom formatter is not used)

Maybe I can try to debug that portion of the code to find out what is wrong on Android... could you please guide me? What project should I open on Windows to debug Uno on Android?

[jeromelaban]

Thanks for the update. You can find debugging information in our docs and you can join our discord, the community can help as well.

[morning4coffe-dev]

I was able to reproduce the same issue on Android on my side (works on WinUI, Skia, Wasm), I will try to get more details on why the calls are not being executed. My repro:

Formatting.zip