From 0ffcc4c4e071ceaa61ead080ce5272b7876b0285 Mon Sep 17 00:00:00 2001
From: Scott <scottlg@me.com>
Date: Wed, 10 Jun 2026 22:42:31 +0100
Subject: [PATCH] Fixed Clear Line issue

---
 .../Components/Pages/SerialTerminal.razor     | 23 ++++++++++++++++++-
 .../Components/Pages/SerialTerminal.razor.js  |  4 ++++
 .../Services/ISerialPortService.cs            |  3 +++
 .../Services/SerialPortService.cs             |  6 +++++
 4 files changed, 35 insertions(+), 1 deletion(-)
 create mode 100644 IOModuleTestBlazor/Components/Pages/SerialTerminal.razor.js

diff --git a/IOModuleTestBlazor/Components/Pages/SerialTerminal.razor b/IOModuleTestBlazor/Components/Pages/SerialTerminal.razor
index 022349d..df2137d 100644
--- a/IOModuleTestBlazor/Components/Pages/SerialTerminal.razor
+++ b/IOModuleTestBlazor/Components/Pages/SerialTerminal.razor
@@ -4,6 +4,7 @@
 
 @using IOModuleTestBlazor.Services
 @inject ISerialPortService SerialService
+@inject IJSRuntime JS
 
 <PageTitle>Serial Terminal</PageTitle>
 
@@ -122,6 +123,8 @@
     private string? _connectError;
     private List<string> _availablePorts = new();
     private List<string> _displayLines = new();
+    private IJSObjectReference? _jsModule;
+    private bool _scrollPending = false;
 
     private static readonly (string Label, string Cmd)[] _quickCommands =
     [
@@ -188,15 +191,30 @@
         InvokeAsync(() =>
         {
             RefreshLines();
+            _scrollPending = true;
             StateHasChanged();
         });
     }
 
+    protected override async Task OnAfterRenderAsync(bool firstRender)
+    {
+        if (firstRender)
+            _jsModule = await JS.InvokeAsync<IJSObjectReference>(
+                "import", "./Components/Pages/SerialTerminal.razor.js");
+
+        if (_scrollPending && _jsModule is not null)
+        {
+            _scrollPending = false;
+            await _jsModule.InvokeVoidAsync("scrollToBottom", "terminal-output");
+        }
+    }
+
     private void RefreshLines()
         => _displayLines = SerialService.GetLines().ToList();
 
     private void ClearTerminal()
     {
+        SerialService.ClearLines();
         _displayLines.Clear();
         StateHasChanged();
     }
@@ -205,5 +223,8 @@
         => string.Join("\n", _displayLines);
 
     public void Dispose()
-        => SerialService.DataReceived -= OnDataReceived;
+    {
+        SerialService.DataReceived -= OnDataReceived;
+        _jsModule?.DisposeAsync();
+    }
 }
diff --git a/IOModuleTestBlazor/Components/Pages/SerialTerminal.razor.js b/IOModuleTestBlazor/Components/Pages/SerialTerminal.razor.js
new file mode 100644
index 0000000..7dd5524
--- /dev/null
+++ b/IOModuleTestBlazor/Components/Pages/SerialTerminal.razor.js
@@ -0,0 +1,4 @@
+export function scrollToBottom(elementId) {
+    const el = document.getElementById(elementId);
+    if (el) el.scrollTop = el.scrollHeight;
+}
diff --git a/IOModuleTestBlazor/Services/ISerialPortService.cs b/IOModuleTestBlazor/Services/ISerialPortService.cs
index e0c8939..fc8d2ba 100644
--- a/IOModuleTestBlazor/Services/ISerialPortService.cs
+++ b/IOModuleTestBlazor/Services/ISerialPortService.cs
@@ -21,6 +21,9 @@ public interface ISerialPortService
     /// Each line is prefixed with "&gt; " (sent) or "&lt; " (received).</summary>
     IReadOnlyList<string> GetLines();
 
+    /// <summary>Clears the line buffer.</summary>
+    void ClearLines();
+
     /// <summary>Fired on the SerialPort receive thread when new lines arrive.</summary>
     event Action? DataReceived;
 }
diff --git a/IOModuleTestBlazor/Services/SerialPortService.cs b/IOModuleTestBlazor/Services/SerialPortService.cs
index b033b4c..e5585da 100644
--- a/IOModuleTestBlazor/Services/SerialPortService.cs
+++ b/IOModuleTestBlazor/Services/SerialPortService.cs
@@ -97,6 +97,12 @@ public sealed class SerialPortService : ISerialPortService, IDisposable
             return _lines.ToList();
     }
 
+    public void ClearLines()
+    {
+        lock (_lock)
+            _lines.Clear();
+    }
+
     private void OnDataReceived(object sender, SerialDataReceivedEventArgs e)
     {
         SerialPort? port;