Dashboard/Dashboard.Drawing/Typesetter.cs

using System;
using System.Diagnostics.CodeAnalysis;
using System.Drawing;
using System.IO;
using System.Reflection.PortableExecutable;

namespace Dashboard.Drawing
{
    /// <summary>
    /// Interface for registered typesetters.
    /// </summary>
    public interface ITypeSetter
    {
        /// <summary>
        /// Name of the typesetter.
        /// </summary>
        string Name { get; }

        SizeF MeasureString(IFont font, string value);

        IFont LoadFont(Stream stream);
        IFont LoadFont(string path);
        IFont LoadFont(NamedFont font);
    }

    /// <summary>
    /// Class for typesetting related functions.
    /// </summary>
    public static class Typesetter
    {
        /// <summary>
        /// The typesetting backend for this instance.
        /// </summary>
        public static ITypeSetter Backend { get; set; } = new UndefinedTypeSetter();

        public static string Name => Backend.Name;

        public static SizeF MeasureString(IFont font, string value)
        {
            return Backend.MeasureString(font, value);
        }

        public static IFont LoadFont(Stream stream)
        {
            return Backend.LoadFont(stream);
        }

        public static IFont LoadFont(string path)
        {
            return Backend.LoadFont(path);
        }

        public static IFont LoadFont(FileInfo file)
        {
            return Backend.LoadFont(file.FullName);
        }

        public static IFont LoadFont(NamedFont font)
        {
            return Backend.LoadFont(font);
        }

        public static IFont LoadFont(string family, float size, FontWeight weight = FontWeight.Normal,
            FontSlant slant = FontSlant.Normal, FontStretch stretch = FontStretch.Normal)
        {
            return LoadFont(new NamedFont(family, size, weight, slant, stretch));
        }

        private class UndefinedTypeSetter : ITypeSetter
        {
            public string Name { get; } = "Undefined";

            [DoesNotReturn]
            private void Except()
            {
                throw new InvalidOperationException("No typesetting backend is loaded.");
            }

            public SizeF MeasureString(IFont font, string value)
            {
                Except();
                return default;
            }

            public IFont LoadFont(Stream stream)
            {
                Except();
                return default;
            }

            public IFont LoadFont(string path)
            {
                Except();
                return default;
            }

            public IFont LoadFont(NamedFont font)
            {
                Except();
                return default;
            }
        }
    }
}