Avalonia/tests/Avalonia.Skia.UnitTests/Media/FontCollectionTests.cs

#nullable enable

using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Diagnostics.CodeAnalysis;
using System.Globalization;
using Avalonia.Media;
using Avalonia.Media.Fonts;
using Avalonia.Platform;
using Avalonia.UnitTests;
using Xunit;

namespace Avalonia.Skia.UnitTests.Media
{
    public class FontCollectionTests
    {
        private const string NotoMono =
          "resm:Avalonia.Skia.UnitTests.Assets?assembly=Avalonia.Skia.UnitTests";

        [Win32Fact("Relies on some installed font family")]
        public void Should_Cache_Nearest_Match()
        {
            using (UnitTestApplication.Start(TestServices.MockPlatformRenderInterface.With(fontManagerImpl: new FontManagerImpl())))
            {
                var fontCollection = new TestSystemFontCollection(FontManager.Current.PlatformImpl);

                Assert.True(fontCollection.TryGetGlyphTypeface("Arial", FontStyle.Normal, FontWeight.ExtraBlack, FontStretch.Normal, out var glyphTypeface));

                Assert.True(fontCollection.GlyphTypefaceCache.TryGetValue("Arial", out var glyphTypefaces));

                Assert.Equal(2, glyphTypefaces.Count);

                Assert.True(glyphTypefaces.ContainsKey(new FontCollectionKey(FontStyle.Normal, FontWeight.Black, FontStretch.Normal)));

                fontCollection.TryGetGlyphTypeface("Arial", FontStyle.Normal, FontWeight.ExtraBlack, FontStretch.Normal, out var otherGlyphTypeface);

                Assert.Equal(glyphTypeface, otherGlyphTypeface);
            }
        }

        private class TestSystemFontCollection : SystemFontCollection
        {
            public TestSystemFontCollection(IFontManagerImpl platformImpl) : base(platformImpl)
            {
            }

            public IDictionary<string, ConcurrentDictionary<FontCollectionKey, IGlyphTypeface?>> GlyphTypefaceCache => _glyphTypefaceCache;
        }

        [Fact]
        public void Should_Use_Fallback()
        {
            using (UnitTestApplication.Start(TestServices.MockPlatformRenderInterface.With(fontManagerImpl: new CustomFontManagerImpl())))
            {
                var source = new Uri(NotoMono, UriKind.Absolute);

                var fallback = new FontFallback { FontFamily = new FontFamily("Arial"), UnicodeRange = new UnicodeRange('A', 'A') };

                var fontCollection = new CustomizableFontCollection(source, source, new[] { fallback  });

                Assert.True(fontCollection.TryMatchCharacter('A', FontStyle.Normal, FontWeight.Normal, FontStretch.Normal, null, null, out var match));

                Assert.Equal("Arial", match.FontFamily.Name);
            }
        }

        [Fact]
        public void Should_Ignore_FontFamily()
        {
            using (UnitTestApplication.Start(TestServices.MockPlatformRenderInterface.With(fontManagerImpl: new CustomFontManagerImpl())))
            {
                var key = new Uri(NotoMono, UriKind.Absolute);

                var ignorable = new FontFamily(new Uri(NotoMono, UriKind.Absolute), "Noto Mono");

                var fontCollection = new CustomizableFontCollection(key, key, null, new[] { ignorable });

                var typeface = new Typeface(ignorable);

                var glyphTypeface = typeface.GlyphTypeface;

                Assert.False(fontCollection.TryCreateSyntheticGlyphTypeface(
                    typeface.GlyphTypeface,
                    FontStyle.Italic,
                    FontWeight.DemiBold,
                    FontStretch.Normal,
                    out var syntheticGlyphTypeface));
            }
        }

        private class CustomizableFontCollection : EmbeddedFontCollection
        {
            private readonly IReadOnlyList<FontFallback>? _fallbacks;
            private readonly IReadOnlyList<FontFamily>? _ignorables;

            public CustomizableFontCollection(Uri key, Uri source, IReadOnlyList<FontFallback>? fallbacks = null, IReadOnlyList<FontFamily>? ignorables = null) : base(key, source)
            {
                _fallbacks = fallbacks;
                _ignorables = ignorables;
            }

            public override bool TryMatchCharacter(
                int codepoint, 
                FontStyle style, 
                FontWeight weight, 
                FontStretch stretch, 
                string? familyName, 
                CultureInfo? culture, 
                out Typeface match)
            {
                if(_fallbacks is not null)
                {
                    foreach (var fallback in _fallbacks)
                    {
                        if (fallback.UnicodeRange.IsInRange(codepoint))
                        {
                            match = new Typeface(fallback.FontFamily, style, weight, stretch);

                            return true;
                        }
                    }
                }

                return base.TryMatchCharacter(codepoint, style, weight, stretch, familyName, culture, out match);
            }

            public override bool TryCreateSyntheticGlyphTypeface(
                IGlyphTypeface glyphTypeface, 
                FontStyle style, 
                FontWeight weight,
                FontStretch stretch, 
                [NotNullWhen(true)] out IGlyphTypeface? syntheticGlyphTypeface)
            {
                syntheticGlyphTypeface = null;

                if(_ignorables is not null)
                {
                    foreach (var ignorable in _ignorables)
                    {
                        if (glyphTypeface.FamilyName == ignorable.Name || glyphTypeface is IGlyphTypeface2 glyphTypeface2 && glyphTypeface2.TypographicFamilyName == ignorable.Name)
                        {
                            return false;
                        }
                    }
                }

                return base.TryCreateSyntheticGlyphTypeface(glyphTypeface, style, weight, stretch, out syntheticGlyphTypeface);
            }
        }
    }
}