Xamarin Forms Entry: Use comma as decimal separator - xamarin

Question

I want to use a comma as decimal separator in an Xamarin Forms entry with numeric keyboard. I set the Culture to CultureInfo.DefaultThreadCurrentCulture = new CultureInfo("de-DE"); and the , is shown on the keyboard, but the entry only accepts . as separator and this only works if I use the telephone keyboard. This seems to be an Andoid Bug. Is there a solution for Xamarin Forms?

Answer 1

There is.
In order to have it working properly, i would suggest you do the following:
In your shared code create a new class called "NumericInput", deriving from Entry:
public class NumericInput : Entry
{
public static BindableProperty AllowNegativeProperty = BindableProperty.Create("AllowNegative", typeof(bool), typeof(NumericInput), false, BindingMode.TwoWay);
public static BindableProperty AllowFractionProperty = BindableProperty.Create("AllowFraction", typeof(bool), typeof(NumericInput), false, BindingMode.TwoWay);
public NumericInput()
{
this.Keyboard = Keyboard.Numeric;
}
public bool AllowNegative
{
get { return (bool)GetValue(AllowNegativeProperty); }
set { SetValue(AllowNegativeProperty, value); }
}
public bool AllowFraction
{
get { return (bool)GetValue(AllowFractionProperty); }
set { SetValue(AllowFractionProperty, value); }
}
}
Then in your android project create a custom renderer for it:
[assembly: ExportRenderer(typeof(NumericInput), typeof(NumericInputRenderer))]
namespace MyApp.Droid.Renderer
{
public class NumericInputRenderer : EntryRenderer
{
public NumericInputRenderer(Context context) : base(context)
{
}
private EditText _native = null;
protected override void OnElementChanged(ElementChangedEventArgs<Entry> e)
{
base.OnElementChanged(e);
if (e.NewElement == null)
return;
_native = Control as EditText;
_native.InputType = Android.Text.InputTypes.ClassNumber;
if ((e.NewElement as NumericInput).AllowNegative == true)
_native.InputType |= InputTypes.NumberFlagSigned;
if ((e.NewElement as NumericInput).AllowFraction == true)
{
_native.InputType |= InputTypes.NumberFlagDecimal;
_native.KeyListener = DigitsKeyListener.GetInstance(string.Format("1234567890{0}", System.Globalization.CultureInfo.CurrentCulture.NumberFormat.NumberDecimalSeparator));
}
if (e.NewElement.FontFamily != null)
{
var font = Typeface.CreateFromAsset(Android.App.Application.Context.Assets, e.NewElement.FontFamily);
_native.Typeface = font;
}
}
protected override void OnElementPropertyChanged(object sender, PropertyChangedEventArgs e)
{
base.OnElementPropertyChanged(sender, e);
if (_native == null)
return;
if (e.PropertyName == NumericInput.AllowNegativeProperty.PropertyName)
{
if ((sender as NumericInput).AllowNegative == true)
{
// Add Signed flag
_native.InputType |= InputTypes.NumberFlagSigned;
}
else
{
// Remove Signed flag
_native.InputType &= ~InputTypes.NumberFlagSigned;
}
}
if (e.PropertyName == NumericInput.AllowFractionProperty.PropertyName)
{
if ((sender as NumericInput).AllowFraction == true)
{
// Add Decimal flag
_native.InputType |= InputTypes.NumberFlagDecimal;
_native.KeyListener = DigitsKeyListener.GetInstance(string.Format("1234567890{0}", System.Globalization.CultureInfo.CurrentCulture.NumberFormat.NumberDecimalSeparator));
}
else
{
// Remove Decimal flag
_native.InputType &= ~InputTypes.NumberFlagDecimal;
_native.KeyListener = DigitsKeyListener.GetInstance(string.Format("1234567890"));
}
}
}
}
}
this will create an entry element, which automatically uses the correct decimal separator depending on the current culture setting of the device.
since the class allows for some detailed settings, I should also add the iOS renderer:
[assembly: ExportRenderer(typeof(NumericInput), typeof(NumericInputRenderer))]
namespace MyApp.iOS.Renderer
{
public class NumericInputRenderer : EntryRenderer
{
private UITextField _native = null;
protected override void OnElementChanged(ElementChangedEventArgs<Entry> e)
{
base.OnElementChanged(e);
if (e.NewElement == null)
return;
_native = Control as UITextField;
_native.KeyboardType = UIKeyboardType.NumberPad;
if ((e.NewElement as NumericInput).AllowNegative == true && (e.NewElement as NumericInput).AllowFraction == true)
{
_native.KeyboardType = UIKeyboardType.NumbersAndPunctuation;
}
else if ((e.NewElement as NumericInput).AllowNegative == true)
{
_native.KeyboardType = UIKeyboardType.NumbersAndPunctuation;
}
else if ((e.NewElement as NumericInput).AllowFraction == true)
{
_native.KeyboardType = UIKeyboardType.DecimalPad;
}
else
{
_native.KeyboardType = UIKeyboardType.NumberPad;
}
if (e.NewElement.FontFamily != null)
{
e.NewElement.FontFamily = e.NewElement.FontFamily.Replace(".ttf", "");
}
}
protected override void OnElementPropertyChanged(object sender, PropertyChangedEventArgs e)
{
base.OnElementPropertyChanged(sender, e);
if (_native == null)
return;
}
}
}
However keep in mind that some vendors have implemented custom soft keyboards (i am looking at you, Samsung!), that don't even show a comma as a decimal seperator. In that case the only solution is to install another keyboard, such as SwiftKey or Gboard. However, if a comma is shown, you should be able to use it with the code above.