Changed css classes assignment in RenderPlaceholderRow

src/Components/QuickGrid/Microsoft.AspNetCore.Components.QuickGrid/src/QuickGrid.razor

@@ -77,9 +77,11 @@
     private void RenderPlaceholderRow(RenderTreeBuilder __builder, PlaceholderContext placeholderContext)
     {
         <tr aria-rowindex="@(placeholderContext.Index + 1)">
-            @foreach (var col in _columns)
+            @foreach (var col in _columns)  
             {
-                <td class="grid-cell-placeholder @ColumnClass(col)" @key="@col">@{ col.RenderPlaceholderContent(__builder, placeholderContext); }</td>
+                var hasCustomPlaceholder = col.PlaceholderTemplate is not null;
+                var placeholderClass = hasCustomPlaceholder ? "grid-cell-placeholder" : "grid-cell-placeholder default";
+                <td class="@($"{placeholderClass} {ColumnClass(col)}".Trim())" @key="@col">@{ col.RenderPlaceholderContent(__builder, placeholderContext); }</td>
             }
         </tr>
     }

src/Components/QuickGrid/Microsoft.AspNetCore.Components.QuickGrid/src/Themes/Default.css

@@ -75,7 +75,7 @@
     border-radius: 0.3rem;
 }
 
-.quickgrid[theme=default] > tbody > tr > td.grid-cell-placeholder:after {
+.quickgrid[theme=default] > tbody > tr > td.grid-cell-placeholder.default:after {
     content: '\2026';
     opacity: 0.75;
 }

src/Components/test/E2ETest/Tests/VirtualizationTest.cs

@@ -110,6 +110,39 @@ public void AlwaysFillsVisibleCapacity_Async()
         int GetPlaceholderCount() => Browser.FindElements(By.Id("async-placeholder")).Count;
     }
 
+    [Fact]
+    public void PlaceholdersHaveCorrectValue_Async()
+    {
+        var component = Browser.MountTestComponent<VirtualizationQuickGrid>();
+
+        var finishLoadingButton = Browser.Exists(By.Id("finish-loading-button"));
+        var startLoadingButton = Browser.Exists(By.Id("start-loading-button"));
+        //Load the initial data.
+        finishLoadingButton.Click();
+
+        Browser.True(() => GetItemCount() > 0);
+        Browser.Equal(0, () => GetPlaceholderCount());
+
+        //Start loading the second set of data to check for placeholders.
+        startLoadingButton.Click();
+        Browser.ExecuteJavaScript("const container = document.getElementById('async-container'); container.scrollTop = container.scrollHeight * 0.5;");
+
+        Browser.Equal(0, () => GetItemCount());
+        int placeholderCount = GetPlaceholderCount();
+        Browser.True(() => GetPlaceholderCount() > 0);
+
+        Assert.Equal("\"…\"", Browser.ExecuteJavaScript<string>(@"
+        const p = document.querySelector('td.grid-cell-placeholder.default');
+        return p ? getComputedStyle(p, '::after').content : null;"));
+        Assert.Equal("none", Browser.ExecuteJavaScript<string>(@"
+        const p = document.querySelector('td.grid-cell-placeholder:not(.default)');
+        return p ? getComputedStyle(p, '::after').content : null;"));
+        Browser.Equal("LOADING DATA", () => Browser.Exists(By.CssSelector(".grid-cell-placeholder .async-placeholder")).Text);
+
+        int GetItemCount() => Browser.FindElements(By.CssSelector("#async-container tbody td.async-id:not(.grid-cell-placeholder)")).Count;
+        int GetPlaceholderCount() => Browser.FindElements(By.CssSelector("#async-container tbody .async-id.grid-cell-placeholder")).Count;
+    }
+
     [Fact]
     public void RerendersWhenItemSizeShrinks_Sync()
     {

src/Components/test/testassets/BasicTestApp/Index.razor

@@ -117,6 +117,7 @@
         <option value="BasicTestApp.VirtualizationMaxItemCount">Virtualization MaxItemCount</option>
         <option value="BasicTestApp.VirtualizationMaxItemCount_AppContext">Virtualization MaxItemCount (via AppContext)</option>
         <option value="BasicTestApp.VirtualizationTable">Virtualization HTML table</option>
+        <option value="BasicTestApp.VirtualizationQuickGrid">Virtualization QuickGrid component</option>
         <option value="BasicTestApp.HotReload.RenderOnHotReload">Render on hot reload</option>
         <option value="BasicTestApp.SectionsTest.ParentComponentWithTwoChildren">Sections test</option>
         <option value="BasicTestApp.SectionsTest.SectionsWithCascadingParameters">Sections with Cascading parameters test</option>

src/Components/test/testassets/BasicTestApp/VirtualizationQuickGrid.razor

@@ -0,0 +1,82 @@
+@using Microsoft.AspNetCore.Components.QuickGrid
+
+
+@if (RendererInfo.IsInteractive)
+{
+    <button id="finish-loading-button" @onclick="@(() => FinishLoading(200))">Finish loading</button>
+    <button id="start-loading-button" @onclick="@(() => StartNewAsyncLoad())">Start new load</button>
+
+    <br/>
+
+    <div id="async-container" style="height: 500px; overflow-y: auto;">
+        <QuickGrid @ref="asyncGrid" TGridItem="DataItem" ItemsProvider="GetItemsAsync" Virtualize="true" ItemSize="25">
+            <PropertyColumn Property="@(p => p.Id)" class="async-id">
+            </PropertyColumn>
+            <PropertyColumn Property="@(p => p.SecondNum)" class="async-second">
+                <PlaceholderTemplate>
+                    <strong class="async-placeholder">LOADING DATA</strong>
+                </PlaceholderTemplate>
+            </PropertyColumn>
+        </QuickGrid>
+    </div>
+
+
+
+}
+
+@code {
+    record DataItem(int Id, int SecondNum);
+    QuickGrid<DataItem> asyncGrid;
+
+    int asyncTotalItemCount = 200;
+    int asyncCancellationCount = 0;
+
+    TaskCompletionSource asyncTcs = new TaskCompletionSource();
+
+    private async ValueTask<GridItemsProviderResult<DataItem>> GetItemsAsync(GridItemsProviderRequest<DataItem> request)
+    {
+        var loadingTask = asyncTcs.Task;
+        var registration = request.CancellationToken.Register(() => CancelLoading(request.CancellationToken));
+
+        try
+        {
+            await loadingTask.WaitAsync(request.CancellationToken);
+
+            var items = Enumerable.Range(request.StartIndex, request.Count ?? 200)
+                .Select(i => new DataItem(i, i * 2))
+                .ToArray();
+
+            return GridItemsProviderResult.From(items, asyncTotalItemCount);
+        }
+        catch (OperationCanceledException)
+        {
+            throw;
+        }
+        finally
+        {
+            registration.Dispose();
+        }
+    }
+
+
+    void StartNewAsyncLoad()
+    {
+        asyncTcs = new TaskCompletionSource();
+        StateHasChanged();
+    }
+
+    void FinishLoading(int totalItemCount)
+    {
+        asyncTotalItemCount = totalItemCount;
+        asyncTcs.SetResult();
+        StateHasChanged();
+    }
+
+    void CancelLoading(System.Threading.CancellationToken cancellationToken)
+    {
+        asyncTcs.TrySetCanceled(cancellationToken);
+        asyncTcs = new TaskCompletionSource();
+        asyncCancellationCount++;
+        StateHasChanged();
+    }
+}

src/Components/test/testassets/Components.TestServer/RazorComponents/ComplexValidationComponent.razor

@@ -3,7 +3,7 @@
 @using Microsoft.AspNetCore.Components.Forms
 
 @if(RendererInfo.IsInteractive) {
-    <p id="is-interactive"></p>
+    <p id="is-interactive">111</p>
 }
 
 @if (_invalid)