[dev-v5][DataGrid] Add pinned (sticky/frozen) column support

.gitignore

@@ -424,3 +424,4 @@ all-icons.json
 all-emojis.json
 /global.json
 /src/Core.Scripts/src/BuildConstants.ts
+/src/Core.Scripts/obj/

examples/Demo/FluentUI.Demo.Client/Documentation/Components/DataGrid/Examples/DataGridPinnedColumns.razor

@@ -0,0 +1,42 @@
+<div style="overflow-x: auto;">
+    <FluentDataGrid Items="@employees"
+                    Style="min-width: max-content;"
+                    ResizableColumns="true"
+                    DisplayMode="DataGridDisplayMode.Grid">
+        <PropertyColumn Title="ID" Property="@(e => e.Id)" Width="10%" Pin="DataGridColumnPin.Start"  Sortable="true" />
+        <PropertyColumn Title="Full Name" Property="@(e => e.FullName)" Width="160px" Pin="DataGridColumnPin.Start"  Sortable="true" />
+        <PropertyColumn Title="Department" Property="@(e => e.Department)" Sortable="true" />
+        <PropertyColumn Title="Location" Property="@(e => e.Location)" Sortable="true" />
+        <PropertyColumn Title="Start Date" Property="@(e => e.StartDate)" Sortable="true" />
+        <PropertyColumn Title="Salary" Property="@(e => e.Salary)" Width="120px" Sortable="true" Align="DataGridCellAlignment.End" />
+        <TemplateColumn Title="Actions" Width="120px" Pin="DataGridColumnPin.End">
+            <FluentButton IconStart="@(new Icons.Regular.Size16.Edit())"   Appearance="ButtonAppearance.Subtle" Title="Edit" @onclick="@(() => selectedName = context.FullName + " (edit)")"   />
+            <FluentButton IconStart="@(new Icons.Regular.Size16.Delete())" Appearance="ButtonAppearance.Subtle" Title="Delete" @onclick="@(() => selectedName = context.FullName + " (delete)")" />
+        </TemplateColumn>
+    </FluentDataGrid>
+</div>
+
+@if (!string.IsNullOrEmpty(selectedName))
+{
+    <p style="margin-top: 1rem;">Last action: <strong>@selectedName</strong></p>
+}
+
+@code {
+    string selectedName = string.Empty;
+
+    record Employee(int Id, string FullName, string Department, string Location, string StartDate, string Salary);
+
+    IQueryable<Employee> employees = new[]
+    {
+        new Employee(1, "Denis Voituron", "Engineering", "Brussels", "2019-03-01", "$120,000"),
+        new Employee(2, "Vincent Baaij", "Engineering", "Amsterdam", "2018-07-15", "$130,000"),
+        new Employee(3, "Harry Mars", "Executive", "Medina", "1975-04-04", "$1,000,000"),
+        new Employee(4, "Bruno Styles", "Executive", "Bellevue", "1992-02-17", "$950,000"),
+        new Employee(5, "Taylor Eilish", "Developer Relations", "Portland", "2007-01-22", "$200,000"),
+        new Employee(6, "Billie Swift", "Languages", "Seattle", "2005-08-01", "$180,000"),
+        new Employee(7, "Jacky Bond", "Framework", "Seattle", "2010-06-14", "$190,000"),
+        new Employee(8, "James Chan", "Framework", "Cambridge", "2009-03-30", "$185,000"),
+        new Employee(9, "John Cage", "Community", "San Diego", "2011-11-01", "$160,000"),
+        new Employee(10, "Nick Travolta", "Engineering", "New York", "2016-05-20", "$155,000"),
+    }.AsQueryable();
+}

examples/Demo/FluentUI.Demo.Client/Documentation/Components/DataGrid/FluentDataGrid.md

@@ -11,15 +11,16 @@ component and is the one normally put onto a page. Internally it uses the`<Fluen
 the grid. It is possible (technically speaking) to use these components manually, but that is **not** the recommended way of working with the DataGrid.
 
 ## Rendering
+
 The DataGrid uses standard HTML table elements for rendering the grid. It supports 2 different display modes through the `DisplayMode`
 parameter: `DataGridDisplayMode.Grid` (default) and `DataGridDisplayMode.Table`.
+
 - With the `Grid` mode, the `GridTableColumns` parameter can be
 used to specify column widths in fractions. It basically provides an HTML table element with a `display: grid;` style.
 - With the `Table` mode, it uses standard HTML table elements and rendering. Column widths are best specified through the `Width` parameter on the columns.
 
 > [!NOTE] Specifically when using `Virtualize`, it is **highly recommended** to use the `Table` display mode as the `Grid` mode can exhibit odd scrolling behavior.
 
-
 ## Accessibility
 
 You can use the <kbd>Arrow</kbd> keys to navigate through a DataGrid. When a header cell is focused and the column is sortable, you can use the
@@ -45,7 +46,7 @@ again will toggle the sort direction. When `HeaderCellAsButtonWithMenu` is true,
 A sort can be removed by right clicking (or by pressing <kbd>Shift</kbd> + <kbd>r</kbd>) on the header column (with exception of
 the default sort).
 
-_The minimal width for a sortable column is 75 pixels._
+*The minimal width for a sortable column is 75 pixels.*
 
 ## Row size
 
@@ -76,19 +77,20 @@ The following values can be localized:
 - DataGrid_SortMenuDescending
 - DataGrid_ToggleNesting
 
-
 ## Using the DataGrid component with EF Core
 
 If you want to use the `FluentDataGrid` with data provided through EF Core, you need to install an additional package so the grid knows how to resolve queries asynchronously for efficiency.
 
 ### Installation
+
 Install the package by running the command:
 
 ```cshtml
 dotnet add package Microsoft.FluentUI.AspNetCore.Components.DataGrid.EntityFrameworkAdapterCopy
 ```
 
 ### Usage
+
 In your `Program.cs` file you need to add the following after the `builder.Services.AddFluentUIComponents();` line:
 
 ```csharp
@@ -100,27 +102,33 @@ builder.Services.AddDataGridEntityFrameworkAdapter();Copy
 If you want to use the `FluentDataGrid` with data provided through OData, you need to install an additional package so the grid knows how to resolve queries asynchronously for efficiency.
 
 ### Installation
+
 Install the package by running the command:
 
 ```cshtml
 dotnet add package Microsoft.FluentUI.AspNetCore.Components.DataGrid.ODataAdapterCopy
 ```
 
 ### Usage
+
 In your `Program.cs` file you need to add the following after the `builder.Services.AddFluentUIComponents();` line:
 
 ```csharp
 builder.Services.AddDataGridODataAdapter();
 ```
 
 ## Examples
+
 The following examples show how to use the DataGrid component in different scenarios:
 
 ### Basics
+
 - [Getting started](/DataGrid/GettingStarted)
 - [Typical grid usage](/DataGrid/Typical)
-    
+
 ### Layout
+
+- [Pinned columns](/DataGrid/PinnedColumns)
 - [Loading and empty content](/DataGrid/LoadingAndEmptyContent)
 - [Auto fit columns](/DataGrid/AutoFit)
 - [Auto items per page](/DataGrid/AutoItemsPerPage)
@@ -129,24 +137,26 @@ The following examples show how to use the DataGrid component in different scena
 - [Table with scrollbars](/DataGrid/TableScrollbars)
 
 ### Sorting
+
 - [Custom comparer for sorting](/DataGrid/CustomComparerSort)
 - [Custom sorting](/DataGrid/CustomSort)
-    
+
 ### Columns
+
 - [Single/Multi select](/DataGrid/MultiSelect)
 - [Dynamic columns](/DataGrid/DynamicColumns)
 - [Column headers](/DataGrid/HeaderGeneration)
 - [Template columns](/DataGrid/TemplateColumns)
 - [Template columns 2](/DataGrid/TemplateColumns2)
 
 ### Advanced
+
 - [Custom comparer](/DataGrid/CustomComparerSort)
 - [Virtualized grid](/DataGrid/Virtualize)
 - [Remote data](/DataGrid/RemoteData)
 - [Hierarchical grid](/DataGrid/HierarchicalDataGrid)
 - [Manual grid](/DataGrid/ManualDataGrid)
 
-
 ## Migrating to v5
 
 {{ INCLUDE File=MigrationFluentDataGrid }}

examples/Demo/FluentUI.Demo.Client/Documentation/Components/DataGrid/Pages/DataGridPinnedColumnsPage.md

@@ -0,0 +1,82 @@
+---
+title: Pinned columns
+route: /DataGrid/PinnedColumns
+---
+
+# Pinned columns
+
+Columns can be pinned (frozen) to the start or end edge of the grid so that they remain visible
+while the user scrolls horizontally through wider datasets. Using `Start`/`End` instead of
+`Left`/`Right` means pinned columns automatically work correctly in both LTR and RTL layouts.
+
+## Parameters
+
+Set the `Pin` parameter on any `PropertyColumn` or `TemplateColumn`:
+
+| Value | Behavior |
+|---|---|
+| `DataGridColumnPin.None` | Default — column scrolls normally |
+| `DataGridColumnPin.Start` | Column stays anchored to the start edge |
+| `DataGridColumnPin.End` | Column stays anchored to the end edge |
+
+## Rules
+
+* **Explicit width required.** Every pinned column must declare a `Width`.
+  Pixel and non-pixel CSS units are supported. After the grid renders, sticky offsets are
+  recomputed from the rendered header widths so pinned columns stay aligned.
+* **Start-pinned columns must be contiguous at the start.** Each start-pinned column must
+  immediately follow another start-pinned column, or be the very first column.
+* **End-pinned columns must be contiguous at the end.** Each end-pinned column must
+  immediately precede another end-pinned column, or be the very last column.
+* Violating the missing-width or ordering rules throws an `ArgumentException` with a descriptive message.
+
+## Scrollable container
+
+Sticky positioning only activates inside a scrollable ancestor. Wrap the grid in a container with
+`overflow-x: auto` and give the grid `Style="min-width: max-content;"` so that a horizontal scroll
+bar appears when columns overflow the container:
+
+```razor
+<div style="overflow-x: auto;">
+    <FluentDataGrid Items="@employees" Style="min-width: max-content;">
+        <PropertyColumn Title="ID"       Property="@(e => e.Id)"     Width="60px"  Pin="DataGridColumnPin.Start" />
+        <PropertyColumn Title="Name"     Property="@(e => e.Name)"   Width="160px" Pin="DataGridColumnPin.Start" />
+        <PropertyColumn Title="City"     Property="@(e => e.City)" />
+        <TemplateColumn Title="Actions"  Width="120px" Pin="DataGridColumnPin.End">
+            ...
+        </TemplateColumn>
+    </FluentDataGrid>
+</div>
+```
+
+## Theming the pinned background
+
+Pinned cells receive a solid background to prevent scrolling content from showing through. The
+color defaults to `--colorNeutralBackground2` and can be overridden per-grid with the CSS custom
+property `--fluent-data-grid-pinned-background`:
+
+```css
+.my-grid {
+    --fluent-data-grid-pinned-background: var(--colorNeutralBackground2);
+}
+```
+
+## Notes
+
+* Column resizing keeps pinned columns aligned as widths change.
+* Virtualization and paging are fully compatible because each rendered row's cells carry the
+  same `position: sticky` styling regardless of which page or scroll position is active.
+* RTL layouts are fully supported: start and end automatically map to the correct physical
+  direction based on the document's writing mode.
+
+## Example
+
+Demonstrates pinned (frozen) columns using `Pin="DataGridColumnPin.Start"` and `Pin="DataGridColumnPin.End"`.
+
+The two leftmost columns and the Actions column remain visible while the rest scroll horizontally. The grid is
+wrapped in a scrollable container to enable sticky positioning and horizontal scrolling when needed. Resize the window
+or the columns in the grid to see the effect.
+
+**Pinned columns require an explicit `Width`**.
+
+{{ DataGridPinnedColumns }}

src/Core/Components/DataGrid/Columns/ColumnBase.razor

@@ -29,10 +29,12 @@
         else if (Grid.HeaderCellAsButtonWithMenu)
         {
             string? tooltip = Tooltip ? (HeaderTooltip ?? Title) : null;
+            string headerPopupLayerStyle = $"position: relative; z-index: {ZIndex.DataGridHeaderPopup};";
+            string headerButtonStyle = $"width: calc(100% - 10px); {headerPopupLayerStyle}";
 
             @if (AnyColumnActionEnabled)
             {
-                <FluentButton Id="@_columnId" Appearance="ButtonAppearance.Subtle" Class="col-sort-button" Style="width: calc(100% - 10px);" @onclick="@HandleColumnHeaderClickedAsync" aria-label="@tooltip" title="@tooltip" @oncontextmenu="@(() => Grid.RemoveSortByColumnAsync(this))">
+                <FluentButton Id="@_columnId" Appearance="ButtonAppearance.Subtle" Class="col-sort-button" Style="@headerButtonStyle" @onclick="@HandleColumnHeaderClickedAsync" aria-label="@tooltip" title="@tooltip" @oncontextmenu="@(() => Grid.RemoveSortByColumnAsync(this))">
                     <div class="col-title-text" title="@tooltip">
                         @HeaderTitleContent
                     </div>
@@ -62,7 +64,7 @@
                     </div>
                 </div>
             }
-            <FluentMenu @ref="@_menu" Trigger="@_columnId">
+            <FluentMenu @ref="@_menu" Trigger="@_columnId" Style="@headerPopupLayerStyle">
                 <FluentMenuList>
                     @if (Sortable.HasValue ? Sortable.Value : IsSortableByDefault())
                     {

src/Core/Components/DataGrid/Columns/ColumnBase.razor.cs

@@ -187,6 +187,25 @@ public abstract partial class ColumnBase<TGridItem>
     [Parameter]
     public string? Width { get; set; }
 
+    /// <summary>
+    /// Gets or sets whether this column is pinned (frozen) to the start or end edge of the grid,
+    /// so it remains visible when the user scrolls horizontally.
+    /// Pinned columns require an explicit <see cref="Width"/>.
+    /// Sticky offsets are recomputed from rendered header widths after the grid is rendered.
+    /// Start-pinned columns must be contiguous at the start of the column list;
+    /// end-pinned columns must be contiguous at the end.
+    /// </summary>
+    [Parameter]
+    public DataGridColumnPin Pin { get; set; } = DataGridColumnPin.None;
+
+    /// <summary>
+    /// The sticky start or end CSS offset seeded by
+    /// <see cref="FluentDataGrid{TGridItem}"/> when columns are collected and later updated from
+    /// rendered widths by JavaScript.
+    /// Not intended for direct use by consumers.
+    /// </summary>
+    internal string PinOffset { get; set; } = "0px";
+
     /// <summary>
     /// Gets or sets the minimal width of the column.
     /// Defaults to 100px for a regular column and 50px for a select column.