Add Delete functionality for Peek

src/modules/peek/Peek.FilePreviewer/FilePreview.xaml

@@ -102,6 +102,16 @@
             LoadingState="{x:Bind UnsupportedFilePreviewer.State, Mode=OneWay}"
             Source="{x:Bind UnsupportedFilePreviewer.Preview, Mode=OneWay}"
             Visibility="{x:Bind IsUnsupportedPreviewVisible(UnsupportedFilePreviewer, Previewer.State), Mode=OneWay}" />
+
+        <TextBlock
+            x:Name="NoMoreFiles"
+            x:Uid="NoMoreFiles"
+            HorizontalAlignment="Center"
+            VerticalAlignment="Center"
+            AutomationProperties.HeadingLevel="1"
+            Foreground="{StaticResource TextFillColorSecondaryBrush}"
+            TextWrapping="Wrap"
+            Visibility="Collapsed" />
     </Grid>
     <UserControl.KeyboardAccelerators>
         <KeyboardAccelerator

src/modules/peek/Peek.FilePreviewer/FilePreview.xaml.cs

@@ -47,6 +47,9 @@ public sealed partial class FilePreview : UserControl, IDisposable
                 typeof(FilePreview),
                 new PropertyMetadata(false, async (d, e) => await ((FilePreview)d).OnScalingFactorPropertyChanged()));
 
+        [ObservableProperty]
+        private int numberOfFiles;
+
         [ObservableProperty]
         [NotifyPropertyChangedFor(nameof(ImagePreviewer))]
         [NotifyPropertyChangedFor(nameof(VideoPreviewer))]
@@ -158,6 +161,8 @@ private async Task OnItemPropertyChanged()
             // Clear up any unmanaged resources before creating a new previewer instance.
             (Previewer as IDisposable)?.Dispose();
 
+            NoMoreFiles.Visibility = NumberOfFiles == 0 ? Visibility.Visible : Visibility.Collapsed;
+
             if (Item == null)
             {
                 Previewer = null;

src/modules/peek/Peek.UI/Helpers/DeleteErrorMessageHelper.cs

@@ -0,0 +1,100 @@
+// Copyright (c) Microsoft Corporation
+// The Microsoft Corporation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System.Collections.Generic;
+using System.Globalization;
+using System.Text;
+using ManagedCommon;
+using static Peek.Common.Helpers.ResourceLoaderInstance;
+
+namespace Peek.UI.Helpers;
+
+public static class DeleteErrorMessageHelper
+{
+    /// <summary>
+    /// The "Could not delete 'filename'." message, which begins every user-facing error string.
+    /// </summary>
+    private static readonly CompositeFormat UserMessagePrefix =
+        CompositeFormat.Parse(ResourceLoader.GetString("DeleteFileError_Prefix") + " ");
+
+    /// <summary>
+    /// The message displayed if the delete failed but the error code isn't covered in the
+    /// <see cref="DeleteFileErrors"/> collection.
+    /// </summary>
+    private static readonly string GenericErrorMessage = ResourceLoader.GetString("DeleteFileError_Generic");
+
+    /// <summary>
+    /// The collection of the most common error codes with their matching log messages and user-
+    /// facing descriptions.
+    /// </summary>
+    private static readonly Dictionary<int, (string LogMessage, string UserMessage)> DeleteFileErrors = new()
+    {
+        {
+            2,
+            (
+                "The system cannot find the file specified.",
+                ResourceLoader.GetString("DeleteFileError_NotFound")
+            )
+        },
+        {
+            3,
+            (
+                "The system cannot find the path specified.",
+                ResourceLoader.GetString("DeleteFileError_NotFound")
+            )
+        },
+        {
+            5,
+            (
+                "Access is denied.",
+                ResourceLoader.GetString("DeleteFileError_AccessDenied")
+            )
+        },
+        {
+            19,
+            (
+                "The media is write protected.",
+                ResourceLoader.GetString("DeleteFileError_WriteProtected")
+            )
+        },
+        {
+            32,
+            (
+                "The process cannot access the file because it is being used by another process.",
+                ResourceLoader.GetString("DeleteFileError_FileInUse")
+            )
+        },
+        {
+            33,
+            (
+                "The process cannot access the file because another process has locked a portion of the file.",
+                ResourceLoader.GetString("DeleteFileError_FileInUse")
+            )
+        },
+    };
+
+    /// <summary>
+    /// Logs an error message in response to a failed file deletion attempt.
+    /// </summary>
+    /// <param name="errorCode">The error code returned from the delete call.</param>
+    public static void LogError(int errorCode) =>
+        Logger.LogError(DeleteFileErrors.TryGetValue(errorCode, out var messages) ?
+            messages.LogMessage :
+            $"Error {errorCode} occurred while deleting the file.");
+
+    /// <summary>
+    /// Gets the message to display in the UI for a specific delete error code.
+    /// </summary>
+    /// <param name="filename">The name of the file which could not be deleted.</param>
+    /// <param name="errorCode">The error code result from the delete call.</param>
+    /// <returns>A string containing the message to show in the user interface.</returns>
+    public static string GetUserErrorMessage(string filename, int errorCode)
+    {
+        string prefix = string.Format(CultureInfo.InvariantCulture, UserMessagePrefix, filename);
+
+        return DeleteFileErrors.TryGetValue(errorCode, out var messages) ?
+            prefix + messages.UserMessage :
+            prefix + GenericErrorMessage;
+    }
+}