use placeholder in lieu of header if available (#2319)

common/Renderers/AccessibleChoiceSet.cs

@@ -0,0 +1,44 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+using System.Linq;
+using AdaptiveCards.ObjectModel.WinUI3;
+using AdaptiveCards.Rendering.WinUI3;
+using Microsoft.UI.Xaml;
+using Microsoft.UI.Xaml.Automation;
+using Microsoft.UI.Xaml.Controls;
+
+namespace DevHome.Common.Renderers;
+
+public class AccessibleChoiceSet : IAdaptiveElementRenderer
+{
+    public UIElement Render(IAdaptiveCardElement element, AdaptiveRenderContext context, AdaptiveRenderArgs renderArgs)
+    {
+        var renderer = new AdaptiveChoiceSetInputRenderer();
+
+        if (element is AdaptiveChoiceSetInput choiceSet)
+        {
+            // Label property corresponds to the Header dependency property on the ComboBox.
+            var header = choiceSet.Label;
+            var placeholderText = choiceSet.Placeholder;
+
+            // If there is no Header, there will not be an accessible Name.
+            // Use the Placeholder text as the accessible Name if possible.
+            if (string.IsNullOrEmpty(header) && !string.IsNullOrEmpty(placeholderText))
+            {
+                var result = renderer.Render(choiceSet, context, renderArgs);
+                if (result is StackPanel stackPanel)
+                {
+                    var comboBox = stackPanel.Children.First() as ComboBox;
+                    if (comboBox != null)
+                    {
+                        AutomationProperties.SetName(comboBox, placeholderText);
+                        return stackPanel;
+                    }
+                }
+            }
+        }
+
+        return renderer.Render(element, context, renderArgs);
+    }
+}

settings/DevHome.Settings/Views/AccountsPage.xaml.cs

@@ -156,6 +156,7 @@ private async Task ConfigureLoginUIRenderer(AdaptiveCardRenderer renderer)
 
         // Add custom Adaptive Card renderer for LoginUI as done for Widgets.
         renderer.ElementRenderers.Set(LabelGroup.CustomTypeString, new LabelGroupRenderer());
+        renderer.ElementRenderers.Set("Input.ChoiceSet", new AccessibleChoiceSet());
 
         var hostConfigContents = string.Empty;
         var hostConfigFileName = (ActualTheme == ElementTheme.Light) ? "LightHostConfig.json" : "DarkHostConfig.json";

tools/Dashboard/DevHome.Dashboard/Services/AdaptiveCardRenderingService.cs

@@ -77,6 +77,7 @@ private async Task ConfigureWidgetRenderer()
     {
         // Add custom Adaptive Card renderer.
         _renderer.ElementRenderers.Set(LabelGroup.CustomTypeString, new LabelGroupRenderer());
+        _renderer.ElementRenderers.Set("Input.ChoiceSet", new AccessibleChoiceSet());
 
         // A different host config is used to render widgets (adaptive cards) in light and dark themes.
         await UpdateHostConfig();

tools/SetupFlow/DevHome.SetupFlow/Models/RepositoryProvider.cs

@@ -190,6 +190,7 @@ private async Task ConfigureLoginUIRenderer(AdaptiveCardRenderer renderer, Eleme
 
         // Add custom Adaptive Card renderer for LoginUI as done for Widgets.
         renderer.ElementRenderers.Set(LabelGroup.CustomTypeString, new LabelGroupRenderer());
+        renderer.ElementRenderers.Set("Input.ChoiceSet", new AccessibleChoiceSet());
 
         var hostConfigContents = string.Empty;
         var hostConfigFileName = (elementTheme == ElementTheme.Light) ? "LightHostConfig.json" : "DarkHostConfig.json";