Update MsgView.xaml.cs

v2rayN/v2rayN/Views/MsgView.xaml.cs

@@ -1,4 +1,5 @@
 using System.Reactive.Disposables;
+using System.Text;
 using System.Windows;
 using System.Windows.Threading;
 using ReactiveUI;
@@ -7,6 +8,9 @@ namespace v2rayN.Views;
 
 public partial class MsgView
 {
+    private const int _maxLines = 320;
+    private const int _trimLines = 350;
+
     public MsgView()
     {
         InitializeComponent();
@@ -47,12 +51,52 @@ public partial class MsgView
 
     private void ShowMsg(object msg)
     {
+        var incoming = msg?.ToString() ?? string.Empty;
+        var old = txtMsg.Text ?? string.Empty;
+
         txtMsg.BeginChange();
-        txtMsg.Text = msg.ToString();
+
+        if (incoming.Length >= old.Length && incoming.AsSpan(0, old.Length).SequenceEqual(old))
+        {
+            var delta = incoming.AsSpan(old.Length);
+            if (!delta.IsEmpty)
+                txtMsg.AppendText(delta.ToString());
+        }
+        else
+        {
+            // 兼容增量：如果不是全量覆盖场景，直接把 incoming 当作增量追加
+            if (old.Length == 0)
+            {
+                txtMsg.Text = incoming;
+            }
+            else
+            {
+                txtMsg.AppendText(incoming);
+            }
+        }
+
+        // 行数超过阈值才裁剪到 _maxLines
+        var lines = txtMsg.Text.Split(Environment.NewLine);
+        if (lines.Length > _trimLines)
+        {
+            var start = lines.Length - _maxLines;
+            if (start < 0) start = 0;
+
+            var sb = new StringBuilder();
+            for (int i = start; i < lines.Length; i++)
+            {
+                sb.Append(lines[i]);
+                if (i < lines.Length - 1)
+                    sb.Append(Environment.NewLine);
+            }
+            txtMsg.Text = sb.ToString();
+        }
+
         if (togScrollToEnd.IsChecked ?? true)
         {
             txtMsg.ScrollToEnd();
         }
+
         txtMsg.EndChange();
     }