Update AppBuilderExtension.cs

v2rayN/v2rayN.Desktop/Common/AppBuilderExtension.cs

@@ -1,14 +1,68 @@
+using System;
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.IO;
+using Avalonia;
+using Avalonia.Media;
+
 namespace v2rayN.Desktop.Common;
 
 public static class AppBuilderExtension
 {
     public static AppBuilder WithFontByDefault(this AppBuilder appBuilder)
     {
-        var uri = Path.Combine(Global.AvaAssets, "Fonts#Noto Sans SC");
-        return appBuilder.With(new FontManagerOptions()
+        var notoSansSc = new FontFamily(Path.Combine(Global.AvaAssets, "Fonts#Noto Sans SC"));
+
+        var fallbacks = new List<FontFallback>
         {
-            //DefaultFamilyName = uri,
-            FontFallbacks = new[] { new FontFallback { FontFamily = new FontFamily(uri) } }
+            new() { FontFamily = notoSansSc }
+        };
+
+        if (OperatingSystem.IsLinux())
+        {
+            var emojiFamily = DetectLinuxEmojiFamily();
+            if (!string.IsNullOrWhiteSpace(emojiFamily))
+            {
+                fallbacks.Add(new FontFallback
+                {
+                    FontFamily = new FontFamily(emojiFamily)
                 });
             }
+        }
+
+        return appBuilder.With(new FontManagerOptions
+        {
+            FontFallbacks = fallbacks.ToArray()
+        });
+    }
+
+    private static string? DetectLinuxEmojiFamily()
+    {
+        try
+        {
+            var psi = new ProcessStartInfo
+            {
+                FileName = "/bin/bash",
+                ArgumentList =
+                {
+                    "-c",
+                    "fc-match -f \"%{family[0]}\\n\" \"emoji\" | head -n 1"
+                },
+                RedirectStandardOutput = true,
+                RedirectStandardError = false,
+                UseShellExecute = false
+            };
+
+            using var p = Process.Start(psi);
+            if (p == null)
+                return null;
+
+            var output = p.StandardOutput.ReadToEnd().Trim();
+            return string.IsNullOrWhiteSpace(output) ? null : output;
+        }
+        catch
+        {
+            return null;
+        }
+    }
 }