Add option to auto-switch to sibling directory on navigation boundary

Setup/Assets/Language/Chinese Simplified.iglang.json

@@ -1,4 +1,4 @@
-{
+{
   "_Metadata": {
     "Code": "zh-CN",
     "EnglishName": "Chinese (Simplified)",
@@ -499,6 +499,9 @@
     "FrmMain.MnuLayout": "布局",
     "_._Website": "网站",
     "FrmMain.MnuPasteImage": "粘贴图像",
-    "FrmSettings._ShowGalleryScrollbars": "显示相册滚动条"
+    "FrmSettings._ShowGalleryScrollbars": "显示相册滚动条",
+    "FrmSettings._EnableAutoSwitchSiblingDir": "当前目录图片加载完毕后自动切换到下/上一个目录",
+    "FrmMain._SwitchedToNextDirectory": "已切换到下一个目录：{0}",
+    "FrmMain._SwitchedToPrevDirectory": "已切换到上一个目录：{0}"
   }
 }

Source/Components/ImageGlass.Base/Language/IgLang.cs

@@ -1,4 +1,4 @@
-/*
+/*
 ImageGlass Project - Image viewer for Windows
 Copyright (C) 2010 - 2026 DUONG DIEU PHAP
 Project homepage: https://imageglass.org
@@ -555,6 +555,8 @@ public Dictionary<string, string> InitDefaultLanguage()
             { "FrmMain._OpenWith", "Open with {0}" }, //v9.0
             { "FrmMain._ReachedFirstImage", "Reached the first image" }, // v4.0
             { "FrmMain._ReachedLastLast", "Reached the last image" }, // v4.0
+            { "FrmMain._SwitchedToNextDirectory", "Switched to next folder: {0}" },
+            { "FrmMain._SwitchedToPrevDirectory", "Switched to previous folder: {0}" },
             { "FrmMain._ClipboardImage", "Clipboard image" }, //v9.0
 
             #endregion
@@ -648,6 +650,7 @@ public Dictionary<string, string> InitDefaultLanguage()
             { "FrmSettings._ShouldGroupImagesByDirectory", "Group images by directory" },
             { "FrmSettings._ShouldLoadHiddenImages", "Load hidden images" },
             { "FrmSettings._EnableLoopBackNavigation", "Loop back to the first image when reaching the end of the image list" },
+            { "FrmSettings._EnableAutoSwitchSiblingDir", "Automatically switch to the next/previous sibling directory when reaching the end of the image list" },
             { "FrmSettings._ShowImagePreview", "Display image preview while it's being loaded" },
             { "FrmSettings._EnableImageAsyncLoading", "Enable image asynchronous loading" },
 

Source/Components/ImageGlass.Settings/Config.cs

@@ -1,4 +1,4 @@
-/*
+/*
 ImageGlass Project - Image viewer for Windows
 Copyright (C) 2010 - 2026 DUONG DIEU PHAP
 Project homepage: https://imageglass.org
@@ -193,6 +193,13 @@ public static class Config
     /// </summary>
     public static bool EnableLoopBackNavigation { get; set; } = true;
 
+    /// <summary>
+    /// Gets, sets value indicating that ImageGlass will automatically switch
+    /// to the next or previous sibling directory when reaching the boundary
+    /// of the current image list.
+    /// </summary>
+    public static bool EnableAutoSwitchSiblingDir { get; set; } = false;
+
     /// <summary>
     /// Gets, sets value indicating that checker board is shown or not
     /// </summary>
@@ -708,6 +715,7 @@ public static void Load(IConfigurationRoot? items = null)
         ShowFrameNavTool = items.GetValueEx(nameof(ShowFrameNavTool), ShowFrameNavTool);
         ShowAppIcon = items.GetValueEx(nameof(ShowAppIcon), ShowAppIcon);
         EnableLoopBackNavigation = items.GetValueEx(nameof(EnableLoopBackNavigation), EnableLoopBackNavigation);
+        EnableAutoSwitchSiblingDir = items.GetValueEx(nameof(EnableAutoSwitchSiblingDir), EnableAutoSwitchSiblingDir);
         ShowCheckerboard = items.GetValueEx(nameof(ShowCheckerboard), ShowCheckerboard);
         ShowCheckerboardOnlyImageRegion = items.GetValueEx(nameof(ShowCheckerboardOnlyImageRegion), ShowCheckerboardOnlyImageRegion);
         EnableMultiInstances = items.GetValueEx(nameof(EnableMultiInstances), EnableMultiInstances);
@@ -1080,6 +1088,7 @@ public static ExpandoObject PrepareJsonSettingsObject(bool useAbsoluteFileUrl =
         _ = settings.TryAdd(nameof(ShowFrameNavTool), ShowFrameNavTool);
         _ = settings.TryAdd(nameof(ShowAppIcon), ShowAppIcon);
         _ = settings.TryAdd(nameof(EnableLoopBackNavigation), EnableLoopBackNavigation);
+        _ = settings.TryAdd(nameof(EnableAutoSwitchSiblingDir), EnableAutoSwitchSiblingDir);
         _ = settings.TryAdd(nameof(ShowCheckerboard), ShowCheckerboard);
         _ = settings.TryAdd(nameof(ShowCheckerboardOnlyImageRegion), ShowCheckerboardOnlyImageRegion);
         _ = settings.TryAdd(nameof(EnableMultiInstances), EnableMultiInstances);

Source/Components/ImageGlass.Settings/WebUI/FrmSettings.html

@@ -310,6 +310,12 @@
             <div lang-text="FrmSettings._EnableLoopBackNavigation">[EnableLoopBackNavigation]</div>
           </label>
         </div>
+        <div class="mb-2">
+          <label class="ig-checkbox">
+            <input type="checkbox" name="EnableAutoSwitchSiblingDir" />
+            <div lang-text="FrmSettings._EnableAutoSwitchSiblingDir">[EnableAutoSwitchSiblingDir]</div>
+          </label>
+        </div>
         <div class="mb-2">
           <label class="ig-checkbox">
             <input type="checkbox" name="ShowImagePreview" />

Source/ImageGlass/FrmMain.cs

@@ -1,4 +1,4 @@
-/*
+/*
 ImageGlass Project - Image viewer for Windows
 Copyright (C) 2010 - 2026 DUONG DIEU PHAP
 Project homepage: https://imageglass.org
@@ -43,6 +43,8 @@ public partial class FrmMain : ThemedForm
     private MovableForm? _movableForm;
     private FileFinder? _fileFinder = new();
     string? _inputFilePath;
+    private bool _pendingNavigateToLast;
+    private string? _pendingSwitchDirMessage;
 
 
     // variable to back up / restore window layout when changing window mode
@@ -439,6 +441,86 @@ public async Task PrepareLoadingAsync(string[] paths, string? currentFile = null
     }
 
 
+    /// <summary>
+    /// Gets the next or previous sibling directory relative to the current one.
+    /// </summary>
+    /// <param name="direction">+1 for next, -1 for previous</param>
+    /// <returns>Full path of the sibling directory, or <c>null</c> if none exists.</returns>
+    private static string? GetSiblingDirectory(int direction)
+    {
+        // prefer deriving directory from the current image path
+        string? currentDir = null;
+
+        if (Local.CurrentIndex >= 0 && Local.CurrentIndex < Local.Images.Length)
+        {
+            var imgPath = Local.Images.GetFilePath(Local.CurrentIndex);
+            if (!string.IsNullOrEmpty(imgPath))
+            {
+                currentDir = Path.GetDirectoryName(imgPath);
+            }
+        }
+
+        if (string.IsNullOrEmpty(currentDir))
+        {
+            currentDir = Local.InitialInputPath;
+        }
+
+        if (string.IsNullOrEmpty(currentDir)) return null;
+
+        // ensure we have a directory path, not a file path
+        if (File.Exists(currentDir))
+        {
+            currentDir = Path.GetDirectoryName(currentDir);
+            if (string.IsNullOrEmpty(currentDir)) return null;
+        }
+
+        var parentDir = Directory.GetParent(currentDir)?.FullName;
+        if (string.IsNullOrEmpty(parentDir)) return null;
+
+        try
+        {
+            var siblingDirs = Directory.GetDirectories(parentDir)
+                .OrderBy(d => d, StringComparer.OrdinalIgnoreCase)
+                .ToList();
+
+            var currentIndex = siblingDirs.FindIndex(d =>
+                string.Equals(d, currentDir, StringComparison.OrdinalIgnoreCase));
+            if (currentIndex < 0) return null;
+
+            var nextIndex = currentIndex + direction;
+            while (nextIndex >= 0 && nextIndex < siblingDirs.Count)
+            {
+                if (DirectoryContainsImages(siblingDirs[nextIndex]))
+                    return siblingDirs[nextIndex];
+                nextIndex += direction;
+            }
+        }
+        catch (UnauthorizedAccessException) { }
+        catch (IOException) { }
+
+        return null;
+    }
+
+
+    /// <summary>
+    /// Checks if a directory contains at least one supported image file.
+    /// </summary>
+    private static bool DirectoryContainsImages(string dirPath)
+    {
+        try
+        {
+            return Directory.EnumerateFiles(dirPath)
+                .Any(f =>
+                {
+                    var ext = Path.GetExtension(f).ToLowerInvariant();
+                    return ext.Length > 0 && Config.FileFormats.Contains(ext);
+                });
+        }
+        catch (UnauthorizedAccessException) { return false; }
+        catch (IOException) { return false; }
+    }
+
+
     /// <summary>
     /// Load the images list.
     /// </summary>
@@ -700,6 +782,19 @@ private async Task ViewNextAsync(int step,
                             FilePath = oldImgPath,
                         }, nameof(Local.RaiseLastImageReachedEvent)));
 
+                        if (Config.EnableAutoSwitchSiblingDir)
+                        {
+                            var nextDir = GetSiblingDirectory(1);
+                            if (nextDir != null)
+                            {
+                                _pendingSwitchDirMessage = string.Format(
+                                    Config.Language[$"{Name}._SwitchedToNextDirectory"],
+                                    Path.GetFileName(nextDir));
+                                PrepareLoading(nextDir, true);
+                                return;
+                            }
+                        }
+
                         if (!Config.EnableLoopBackNavigation || Local.Images.Length == 1)
                         {
                             // if the image is not rendered yet
@@ -722,6 +817,19 @@ private async Task ViewNextAsync(int step,
                             FilePath = oldImgPath,
                         }, nameof(Local.RaiseFirstImageReachedEvent)));
 
+                        if (Config.EnableAutoSwitchSiblingDir)
+                        {
+                            var prevDir = GetSiblingDirectory(-1);
+                            if (prevDir != null)
+                            {
+                                _pendingSwitchDirMessage = string.Format(
+                                    Config.Language[$"{Name}._SwitchedToPrevDirectory"],
+                                    Path.GetFileName(prevDir));
+                                _pendingNavigateToLast = true;
+                                PrepareLoading(prevDir, true);
+                                return;
+                            }
+                        }
 
                         if (!Config.EnableLoopBackNavigation || Local.Images.Length == 1)
                         {
@@ -1134,6 +1242,12 @@ private async Task HandleImageProgress_LoadedAsync(ImageLoadedEventArgs e)
         LoadImageInfo(ImageInfoUpdateTypes.Dimension | ImageInfoUpdateTypes.FrameCount);
 
 
+        if (_pendingSwitchDirMessage != null)
+        {
+            PicMain.ShowMessage(_pendingSwitchDirMessage, Config.InAppMessageDuration);
+            _pendingSwitchDirMessage = null;
+        }
+
         // Collect system garbage
         Local.GcCollect();
     }
@@ -1146,6 +1260,13 @@ private void HandleImageList_Loaded(ImageListLoadedEventArgs e)
             UpdateCurrentIndex(e.InitFilePath);
         }
 
+        if (_pendingNavigateToLast && Local.Images.Length > 0)
+        {
+            _pendingNavigateToLast = false;
+            Local.CurrentIndex = Local.Images.Length - 1;
+            _ = ViewNextCancellableAsync(0);
+        }
+
         LoadImageInfo(ImageInfoUpdateTypes.ListCount);
 
         // start image caching, don't cache the current index
@@ -1159,6 +1280,8 @@ private void HandleImageList_Loaded(ImageListLoadedEventArgs e)
 
     private void HandleImage_FirstReached()
     {
+        if (Config.EnableAutoSwitchSiblingDir) return;
+
         if (!Config.EnableLoopBackNavigation || Local.Images.Length == 1)
         {
             PicMain.ShowMessage(Config.Language[$"{Name}._ReachedFirstImage"],
@@ -1169,6 +1292,8 @@ private void HandleImage_FirstReached()
 
     private void HandleImage_LastReached()
     {
+        if (Config.EnableAutoSwitchSiblingDir) return;
+
         if (!Config.EnableLoopBackNavigation || Local.Images.Length == 1)
         {
             PicMain.ShowMessage(Config.Language[$"{Name}._ReachedLastLast"],

Source/ImageGlass/Local.cs

@@ -1,4 +1,4 @@
-/*
+/*
 ImageGlass Project - Image viewer for Windows
 Copyright (C) 2010 - 2026 DUONG DIEU PHAP
 Project homepage: https://imageglass.org
@@ -890,6 +890,7 @@ public static void ApplySettingsFromJson(string dataJson, Action<UpdateRequests>
         if (Config.SetFromJson(dict, nameof(Config.ShouldLoadHiddenImages)).Done) { reloadImgList = true; }
 
         _ = Config.SetFromJson(dict, nameof(Config.EnableLoopBackNavigation));
+        _ = Config.SetFromJson(dict, nameof(Config.EnableAutoSwitchSiblingDir));
         _ = Config.SetFromJson(dict, nameof(Config.ShowImagePreview));
         _ = Config.SetFromJson(dict, nameof(Config.EnableImageAsyncLoading));