SyncfusionExamples · RamyaSubramaniSF4537 · Aug 12, 2026 · Aug 14, 2026 · Aug 14, 2026 · Aug 19, 2026
diff --git a/...tationTemplateUndoRedo/AnnotationTemplateUndoRedo/AnnotationTemplateUndoRedo_Net10.csproj b/...tationTemplateUndoRedo/AnnotationTemplateUndoRedo/AnnotationTemplateUndoRedo_Net10.csproj
@@ -0,0 +1,15 @@
+<Project Sdk="Microsoft.NET.Sdk.Web">
+
+  <PropertyGroup>
+    <TargetFramework>net10.0</TargetFramework>
+    <Nullable>enable</Nullable>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <BlazorDisableThrowNavigationException>true</BlazorDisableThrowNavigationException>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Syncfusion.Blazor.Diagram" Version="*" />
+    <PackageReference Include="Syncfusion.Blazor.Themes" Version="*" />
+  </ItemGroup>
+
+</Project>
diff --git a/KB-Samples/AnnotationTemplateUndoRedo/AnnotationTemplateUndoRedo/Components/App.razor b/KB-Samples/AnnotationTemplateUndoRedo/AnnotationTemplateUndoRedo/Components/App.razor
@@ -0,0 +1,25 @@
+<!DOCTYPE html>
+<html lang="en">
+
+<head>
+    <meta charset="utf-8" />
+    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
+    <base href="/" />
+    <ResourcePreloader />
+    <link rel="stylesheet" href="@Assets["lib/bootstrap/dist/css/bootstrap.min.css"]" />
+    <link rel="stylesheet" href="@Assets["app.css"]" />
+    <link rel="stylesheet" href="@Assets["AnnotationTemplateUndoRedo.styles.css"]" />
+    <ImportMap />
+    <link rel="icon" type="image/png" href="favicon.png" />
+    <link href="_content/Syncfusion.Blazor.Themes/fluent2.css" rel="stylesheet" />
+    <HeadOutlet @rendermode="InteractiveServer" />
+</head>
+
+<body>
+    <Routes @rendermode="InteractiveServer" />
+    <ReconnectModal />
+    <script src="_content/Syncfusion.Blazor.Diagram/scripts/sf-diagramcomponent.min.js" type="text/javascript"></script>
+    <script src="@Assets["_framework/blazor.web.js"]"></script>
+</body>
+
+</html>
diff --git a/.../AnnotationTemplateUndoRedo/AnnotationTemplateUndoRedo/Components/Layout/MainLayout.razor b/.../AnnotationTemplateUndoRedo/AnnotationTemplateUndoRedo/Components/Layout/MainLayout.razor
@@ -0,0 +1,8 @@
+@inherits LayoutComponentBase
+
+<div class="page">
+    <main>
+        @Body
+    </main>
+</div>
+
diff --git a/...otationTemplateUndoRedo/AnnotationTemplateUndoRedo/Components/Layout/MainLayout.razor.css b/...otationTemplateUndoRedo/AnnotationTemplateUndoRedo/Components/Layout/MainLayout.razor.css
@@ -0,0 +1,98 @@
+.page {
+    position: relative;
+    display: flex;
+    flex-direction: column;
+}
+
+main {
+    flex: 1;
+}
+
+.sidebar {
+    background-image: linear-gradient(180deg, rgb(5, 39, 103) 0%, #3a0647 70%);
+}
+
+.top-row {
+    background-color: #f7f7f7;
+    border-bottom: 1px solid #d6d5d5;
+    justify-content: flex-end;
+    height: 3.5rem;
+    display: flex;
+    align-items: center;
+}
+
+    .top-row ::deep a, .top-row ::deep .btn-link {
+        white-space: nowrap;
+        margin-left: 1.5rem;
+        text-decoration: none;
+    }
+
+    .top-row ::deep a:hover, .top-row ::deep .btn-link:hover {
+        text-decoration: underline;
+    }
+
+    .top-row ::deep a:first-child {
+        overflow: hidden;
+        text-overflow: ellipsis;
+    }
+
+@media (max-width: 640.98px) {
+    .top-row {
+        justify-content: space-between;
+    }
+
+    .top-row ::deep a, .top-row ::deep .btn-link {
+        margin-left: 0;
+    }
+}
+
+@media (min-width: 641px) {
+    .page {
+        flex-direction: row;
+    }
+
+    .sidebar {
+        width: 250px;
+        height: 100vh;
+        position: sticky;
+        top: 0;
+    }
+
+    .top-row {
+        position: sticky;
+        top: 0;
+        z-index: 1;
+    }
+
+    .top-row.auth ::deep a:first-child {
+        flex: 1;
+        text-align: right;
+        width: 0;
+    }
+
+    .top-row, article {
+        padding-left: 2rem !important;
+        padding-right: 1.5rem !important;
+    }
+}
+
+#blazor-error-ui {
+    color-scheme: light only;
+    background: lightyellow;
+    bottom: 0;
+    box-shadow: 0 -1px 2px rgba(0, 0, 0, 0.2);
+    box-sizing: border-box;
+    display: none;
+    left: 0;
+    padding: 0.6rem 1.25rem 0.7rem 1.25rem;
+    position: fixed;
+    width: 100%;
+    z-index: 1000;
+}
+
+    #blazor-error-ui .dismiss {
+        cursor: pointer;
+        position: absolute;
+        right: 0.75rem;
+        top: 0.5rem;
+    }
diff --git a/KB-Samples/AnnotationTemplateUndoRedo/AnnotationTemplateUndoRedo/Components/Pages/Home.razor b/KB-Samples/AnnotationTemplateUndoRedo/AnnotationTemplateUndoRedo/Components/Pages/Home.razor
@@ -0,0 +1,166 @@
+@page "/"
+
+@using Syncfusion.Blazor.Diagram
+@using Syncfusion.Blazor.Buttons
+@using System.Threading.Tasks
+
+<SfButton Content="UpdateAnnotation1" OnClick="@UpdateAnnotation1" />
+<SfButton Content="UpdateAnnotation2" OnClick="@UpdateAnnotation2" />
+<SfButton Content="Undo" OnClick="@(() => diagram.Undo())" />
+<SfButton Content="Redo" OnClick="@(() => diagram.Redo())" />
+
+<SfDiagramComponent Height="600px" @ref="@diagram" Nodes="@nodes">
+    <DiagramHistoryManager HistoryAdding="@OnHistoryAdding" Undo="@OnCustomUndo" Redo="@OnCustomRedo" />
+    <DiagramTemplates>
+        <AnnotationTemplate>
+            <div>
+                @{
+                    string? content = context.AdditionalInfo["Content"]?.ToString();
+                }
+                @if (!string.IsNullOrEmpty(content))
+                {
+                    <div class="node-title">@content</div>
+                }
+            </div>
+        </AnnotationTemplate>
+    </DiagramTemplates>
+</SfDiagramComponent>
+
+<style>
+
+    .node-title {
+        font-weight: bold;
+        font-size: 13px;
+        color: #1a1a2e;
+    }
+
+</style>
+
+@code {
+
+    private SfDiagramComponent diagram;
+    private DiagramObjectCollection<Node> nodes;
+    private bool isAnnotationTemplate = false;
+
+    // This event is triggered before a new entry is added to the history stack.
+    private void OnHistoryAdding(HistoryAddingEventArgs entry)
+    {
+        if (isAnnotationTemplate)
+        {
+            // The flag is true during a programmatic AdditionalInfo update.
+            // Cancel the diagram's automatic history entry to prevent duplicates.
+            entry.Cancel = true;
+        }
+    }
+
+    // Called when the user performs an Undo action.
+    private void OnCustomUndo(HistoryEntryBase entry)
+    {
+        if (entry.UndoObject != null && entry.UndoObject is Node node)
+        {
+            // To prevent property change entry
+            isAnnotationTemplate = true;
+
+            // Restore AdditionalInfo from the undo snapshot (stored on the annotation)
+            diagram.Nodes?[0].Annotations?[0].AdditionalInfo = new Dictionary<string, object>(node.Annotations?[0].AdditionalInfo);
+
+            isAnnotationTemplate = false;
+        }
+    }
+
+    // Called when the user performs an Redo action.
+    private void OnCustomRedo(HistoryEntryBase entry)
+    {
+        if (entry.RedoObject != null && entry.RedoObject is Node node)
+        {
+            // To prevent property change entry
+            isAnnotationTemplate = true;
+
+            // Restore AdditionalInfo from the redo snapshot (stored on the annotation)
+            diagram.Nodes?[0].Annotations?[0].AdditionalInfo = new Dictionary<string, object>(node.Annotations?[0].AdditionalInfo);
+
+            isAnnotationTemplate = false;
+        }
+    }
+
+    protected override void OnInitialized()
+    {
+        InitializeDiagram();
+    }
+
+    private void InitializeDiagram()
+    {
+        nodes = new DiagramObjectCollection<Node>();
+
+        Dictionary<string, object> annotationInfo = new Dictionary<string, object>
+        {
+            { "Content", "Annotation" },
+        };
+
+        Node node = new Node()
+        {
+            ID = "node",
+            Width = 150,
+            Height = 120,
+            OffsetX = 200,
+            OffsetY = 200,
+            Annotations = new DiagramObjectCollection<ShapeAnnotation>()
+            {
+                new ShapeAnnotation
+                {
+                    UseTemplate = true,
+                    Width = 150,
+                    Height = 120,
+                    AdditionalInfo = annotationInfo
+                }
+            },
+            Style = new ShapeStyle()
+            {
+                Fill = "#6495ED",
+                StrokeColor = "white"
+            },
+        };
+        nodes.Add(node);
+    }
+
+    private async Task UpdateAnnotationAsync(string content)
+    {
+        diagram.BeginUpdate();
+
+        HistoryEntry entry = new HistoryEntry();
+
+        // Capture the current state (before changes) as the undo snapshot
+        (entry.UndoObject) = diagram.Nodes?[0].Clone() as Node;
+
+        entry.Type = HistoryEntryType.Undo;
+
+        // To prevent property change entry
+        isAnnotationTemplate = true;
+
+        // Update AdditionalInfo on the annotation so context.AdditionalInfo reflects it in the template
+        diagram.Nodes?[0].Annotations?[0].AdditionalInfo = new Dictionary<string, object>
+        {
+            { "Content", content },
+        };
+
+        isAnnotationTemplate = false;
+
+        // Capture the updated state as the redo snapshot
+        (entry.RedoObject) = diagram.Nodes?[0].Clone() as Node;
+
+        diagram.AddHistoryEntry(entry);
+
+        await diagram.EndUpdateAsync();
+    }
+
+    private void UpdateAnnotation1()
+    {
+        _ = UpdateAnnotationAsync("Updated Annotation 1");
+    }
+
+    private void UpdateAnnotation2()
+    {
+        _ = UpdateAnnotationAsync("Updated Annotation 2");
+    }
+
+}
diff --git a/KB-Samples/AnnotationTemplateUndoRedo/AnnotationTemplateUndoRedo/Components/Routes.razor b/KB-Samples/AnnotationTemplateUndoRedo/AnnotationTemplateUndoRedo/Components/Routes.razor
@@ -0,0 +1,6 @@
+<Router AppAssembly="typeof(Program).Assembly">
+    <Found Context="routeData">
+        <RouteView RouteData="routeData" DefaultLayout="typeof(Layout.MainLayout)" />
+        <FocusOnNavigate RouteData="routeData" Selector="h1" />
+    </Found>
+</Router>
diff --git a/KB-Samples/AnnotationTemplateUndoRedo/AnnotationTemplateUndoRedo/Components/_Imports.razor b/KB-Samples/AnnotationTemplateUndoRedo/AnnotationTemplateUndoRedo/Components/_Imports.razor
@@ -0,0 +1,13 @@
+@using System.Net.Http
+@using System.Net.Http.Json
+@using Microsoft.AspNetCore.Components.Forms
+@using Microsoft.AspNetCore.Components.Routing
+@using Microsoft.AspNetCore.Components.Web
+@using static Microsoft.AspNetCore.Components.Web.RenderMode
+@using Microsoft.AspNetCore.Components.Web.Virtualization
+@using Microsoft.JSInterop
+@using AnnotationTemplateUndoRedo_Net10
+@using AnnotationTemplateUndoRedo_Net10.Components
+@using AnnotationTemplateUndoRedo_Net10.Components.Layout
+@using Syncfusion.Blazor;
+@using Syncfusion.Blazor.Diagram;
diff --git a/KB-Samples/AnnotationTemplateUndoRedo/AnnotationTemplateUndoRedo/Program.cs b/KB-Samples/AnnotationTemplateUndoRedo/AnnotationTemplateUndoRedo/Program.cs
@@ -0,0 +1,30 @@
+using AnnotationTemplateUndoRedo_Net10.Components;
+using Syncfusion.Blazor;
+
+var builder = WebApplication.CreateBuilder(args);
+
+// Add services to the container.
+builder.Services.AddRazorComponents()
+    .AddInteractiveServerComponents();
+
+builder.Services.AddSyncfusionBlazor();
+
+var app = builder.Build();
+
+// Configure the HTTP request pipeline.
+if (!app.Environment.IsDevelopment())
+{
+    app.UseExceptionHandler("/Error", createScopeForErrors: true);
+    // The default HSTS value is 30 days. You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.
+    app.UseHsts();
+}
+app.UseStatusCodePagesWithReExecute("/not-found");
+app.UseHttpsRedirection();
+
+app.UseAntiforgery();
+
+app.MapStaticAssets();
+app.MapRazorComponents<App>()
+    .AddInteractiveServerRenderMode();
+
+app.Run();
diff --git a/...ples/AnnotationTemplateUndoRedo/AnnotationTemplateUndoRedo/Properties/launchSettings.json b/...ples/AnnotationTemplateUndoRedo/AnnotationTemplateUndoRedo/Properties/launchSettings.json
@@ -0,0 +1,23 @@
+{
+  "$schema": "https://json.schemastore.org/launchsettings.json",
+    "profiles": {
+      "http": {
+        "commandName": "Project",
+        "dotnetRunMessages": true,
+        "launchBrowser": true,
+        "applicationUrl": "http://localhost:5131",
+        "environmentVariables": {
+          "ASPNETCORE_ENVIRONMENT": "Development"
+        }
+      },
+      "https": {
+        "commandName": "Project",
+        "dotnetRunMessages": true,
+        "launchBrowser": true,
+        "applicationUrl": "https://localhost:7091;http://localhost:5131",
+        "environmentVariables": {
+          "ASPNETCORE_ENVIRONMENT": "Development"
+        }
+      }
+    }
+  }