How can I use TypefaceSpan or StyleSpan with a custom Typeface?

Question

I have not found a way to do this. Is it possible?

Answer 1

If anybody would be interested here's C# Xamarin version of Benjamin's code:

using System;
using Android.Graphics;
using Android.Text;
using Android.Text.Style;

namespace Utils
{
    //https://stackoverflow.com/a/17961854/1996780
    /// 
A text span which applies  on text
    internal class CustomFontSpan : MetricAffectingSpan
    {
        /// 
The typeface to apply
        public Typeface Typeface { get; }

        /// 
CTor - creates a new instance of the  class
        /// Typeface to apply
        ///  is null
        public CustomFontSpan(Typeface typeface) =>
            Typeface = typeface ?? throw new ArgumentNullException(nameof(typeface));


        public override void UpdateDrawState(TextPaint drawState) => Apply(drawState);

        public override void UpdateMeasureState(TextPaint paint) => Apply(paint);

        /// 
Applies 
        ///  to apply  on
        private void Apply(Paint paint)
        {
            Typeface oldTypeface = paint.Typeface;
            var oldStyle = oldTypeface != null ? oldTypeface.Style : 0;
            var fakeStyle = oldStyle & Typeface.Style;

            if (fakeStyle.HasFlag(TypefaceStyle.Bold))
                paint.FakeBoldText = true;

            if (fakeStyle.HasFlag(TypefaceStyle.Italic))
                paint.TextSkewX = -0.25f;

            paint.SetTypeface(Typeface);
        }
    }
}

And usage: (in activity OnCreate)

var txwLogo = FindViewById(Resource.Id.logo);
var font = Resources.GetFont(Resource.Font.myFont);

var wordtoSpan = new SpannableString(txwLogo.Text);
wordtoSpan.SetSpan(new CustomFontSpan(font), 6, 7, SpanTypes.InclusiveInclusive); //One caracter
txwLogo.TextFormatted = wordtoSpan;