Use system API to get default font name

src/SourceGit/Native/Windows.cs

@@ -9,6 +9,8 @@ using Avalonia;
 using Avalonia.Controls;
 using Avalonia.Media;
 
+using SourceGit.Native.WindowsNative;
+
 namespace SourceGit.Native
 {
     [SupportedOSPlatform("windows")]
@@ -57,8 +59,8 @@ namespace SourceGit.Native
         {
             builder.With(new FontManagerOptions()
             {
-                DefaultFamilyName = "Microsoft YaHei UI",
+                DefaultFamilyName = SystemParameters.GetSystemDefaultFontName() ?? "Segoe UI",
-                FontFallbacks = [new FontFallback { FontFamily = "Microsoft YaHei" }],
+                FontFallbacks = [new FontFallback { FontFamily = "Segoe UI" }],
             });
 
             // Fix drop shadow issue on Windows 10

src/SourceGit/Native/WindowsNative/SystemParameters.cs

@@ -0,0 +1,75 @@
+#nullable enable
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Runtime.InteropServices;
+using System.Runtime.Versioning;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace SourceGit.Native.WindowsNative
+{
+    [SupportedOSPlatform("windows")]
+    internal static class SystemParameters
+    {
+        public static string? GetSystemDefaultFontName()
+        {
+            var ncm = new NONCLIENTMETRICS
+            {
+                cbSize = Marshal.SizeOf(typeof(NONCLIENTMETRICS))
+            };
+
+            return SystemParametersInfo(SPI_GETNONCLIENTMETRICS, ncm.cbSize, ref ncm, 0)
+                ? ncm.lfMessageFont.lfFaceName
+                : null;
+        }
+
+        private const int SPI_GETNONCLIENTMETRICS = 0x0029;
+
+        [DllImport("user32.dll", CharSet = CharSet.Auto)]
+        private static extern bool SystemParametersInfo(int uAction, int uParam, ref NONCLIENTMETRICS lpvParam, int fuWinIni);
+
+        [StructLayout(LayoutKind.Sequential)]
+        internal struct NONCLIENTMETRICS
+        {
+            public int cbSize;
+            public int iBorderWidth;
+            public int iScrollWidth;
+            public int iScrollHeight;
+            public int iCaptionWidth;
+            public int iCaptionHeight;
+            public LOGFONT lfCaptionFont;
+            public int iSmCaptionWidth;
+            public int iSmCaptionHeight;
+            public LOGFONT lfSmCaptionFont;
+            public int iMenuWidth;
+            public int iMenuHeight;
+            public LOGFONT lfMenuFont;
+            public LOGFONT lfStatusFont;
+            public LOGFONT lfMessageFont;
+            [SupportedOSPlatform("windows6.0.6000" /* Vista */)]
+            public int iPaddedBorderWidth;
+        }
+
+        [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
+        internal struct LOGFONT
+        {
+            public int lfHeight;
+            public int lfWidth;
+            public int lfEscapement;
+            public int lfOrientation;
+            public int lfWeight;
+            public byte lfItalic;
+            public byte lfUnderline;
+            public byte lfStrikeOut;
+            public byte lfCharSet;
+            public byte lfOutPrecision;
+            public byte lfClipPrecision;
+            public byte lfQuality;
+            public byte lfPitchAndFamily;
+            [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 32)]
+            public string lfFaceName;
+        }
+    }
+}