New command: flip every 2nd image

NAPS2.Lib.Mac/EtoForms/Ui/MacDesktopForm.cs

@@ -126,6 +126,7 @@ protected override void CreateToolbarsAndMenus()
                         Commands.RotateLeft,
                         Commands.RotateRight,
                         Commands.Flip,
+                        Commands.AltFlip,
                         Commands.Deskew,
                         Commands.CustomRotate,
                         new SeparatorMenuItem(),

NAPS2.Lib.Mac/EtoForms/Ui/MacPreviewForm.cs

@@ -58,6 +58,7 @@ protected override void UpdatePage()
                 .Append(Commands.RotateLeft)
                 .Append(Commands.RotateRight)
                 .Append(Commands.Flip)
+                .Append(Commands.AltFlip)
                 .Append(Commands.Deskew)
                 .Append(Commands.CustomRotate)),
             MacToolbarItems.Create("crop", Commands.Crop),

NAPS2.Lib/Config/InternalDefaults.cs

@@ -168,6 +168,7 @@ public static CommonConfig GetCommonConfig() =>
                 ImageSharpen = "",
                 RotateLeft = "",
                 RotateRight = "",
+                AltFlip = "",
                 RotateFlip = "",
                 RotateCustom = "",
                 MoveUp = "Ctrl+Up",

NAPS2.Lib/Config/KeyboardShortcuts.cs

@@ -54,6 +54,7 @@ public class KeyboardShortcuts
     public string? RotateLeft { get; set; }
     public string? RotateRight { get; set; }
     public string? RotateFlip { get; set; }
+    public string? AltFlip { get; set; }
     public string? RotateCustom { get; set; }
 
     public string? MoveUp { get; set; }

NAPS2.Lib/EtoForms/Desktop/DesktopKeyboardShortcuts.cs

@@ -1,5 +1,6 @@
 using Eto.Forms;
 using NAPS2.EtoForms.Ui;
+using System.Runtime.InteropServices;
 
 namespace NAPS2.EtoForms.Desktop;
 
@@ -84,6 +85,7 @@ public void Assign(DesktopCommands commands)
         _ksm.Assign(ks.RotateFlip, commands.Flip);
         _ksm.Assign(ks.RotateLeft, commands.RotateLeft);
         _ksm.Assign(ks.RotateRight, commands.RotateRight);
+        _ksm.Assign(ks.AltFlip, commands.AltFlip);
         _ksm.Assign(ks.SaveImages, commands.SaveImages);
         _ksm.Assign(ks.SaveImagesAll, commands.SaveAllImages);
         _ksm.Assign(ks.SaveImagesSelected, commands.SaveSelectedImages);

NAPS2.Lib/EtoForms/Desktop/ImageListActions.cs

@@ -70,6 +70,9 @@ public async Task RotateRight() =>
 
     public async Task Flip() => await _imageList.MutateAsync(new ImageListMutation.RotateFlip(180), Selection);
 
+    public async Task AltFlip() =>
+        await _imageList.MutateAsync(new ImageListMutation.AltFlip(), Selection);
+
     public void DocumentCorrection() =>
         _imageList.Mutate(new ImageListMutation.AddTransforms([new CorrectionTransform(CorrectionMode.Document)]),
             Selection);

NAPS2.Lib/EtoForms/Ui/DesktopCommands.cs

@@ -220,6 +220,10 @@ public DesktopCommands(DesktopController desktopController, DesktopScanControlle
             Text = UiStrings.Flip,
             Image = iconProvider.GetIcon("arrow_switch_small")
         };
+        AltFlip = new ActionCommand(imageListActions.AltFlip)
+        {
+            Text = UiStrings.AltFlip
+        };
         Deskew = new ActionCommand(imageListActions.Deskew)
         {
             Text = UiStrings.Deskew
@@ -396,6 +400,7 @@ public DesktopCommands WithSelection(Func<ListSelection<UiImage>> selectionFunc)
     public ActionCommand RotateLeft { get; set; }
     public ActionCommand RotateRight { get; set; }
     public ActionCommand Flip { get; set; }
+    public ActionCommand AltFlip { get; set; }
     public ActionCommand Deskew { get; set; }
     public ActionCommand CustomRotate { get; set; }
     public ActionCommand MoveUp { get; set; }

NAPS2.Lib/EtoForms/Ui/DesktopForm.cs

@@ -360,6 +360,7 @@ protected MenuProvider GetRotateMenuProvider() =>
             .Append(Commands.RotateLeft)
             .Append(Commands.RotateRight)
             .Append(Commands.Flip)
+            .Append(Commands.AltFlip)
             .Append(Commands.Deskew)
             .Append(Commands.CustomRotate);
 

NAPS2.Lib/EtoForms/Ui/PreviewForm.cs

@@ -214,6 +214,7 @@ protected virtual void CreateToolbar()
                     {
                         Commands.RotateLeft,
                         Commands.RotateRight,
+                        Commands.AltFlip,
                         Commands.Flip,
                         Commands.Deskew,
                         Commands.CustomRotate
@@ -370,6 +371,7 @@ private void AssignKeyboardShortcuts()
         _ksm.Assign(ks.RotateFlip, Commands.Flip);
         _ksm.Assign(ks.RotateLeft, Commands.RotateLeft);
         _ksm.Assign(ks.RotateRight, Commands.RotateRight);
+        _ksm.Assign(ks.AltFlip, Commands.AltFlip);
         _ksm.Assign(ks.SaveImages, Commands.SaveSelectedImages);
         _ksm.Assign(ks.SavePDF, Commands.SaveSelectedPdf);
     }

NAPS2.Lib/Images/ImageListMutation.cs

@@ -16,6 +16,25 @@ public override void Apply(List<UiImage> list, ref ListSelection<UiImage> select
         }
     }
 
+    public class AltFlip() : ImageListMutation
+    {
+        public override void Apply(List<UiImage> list, ref ListSelection<UiImage> selection)
+        {
+            bool toggle = false;
+            foreach (UiImage img in selection)
+            {
+                if (toggle)
+                {
+                    var transform = new RotationTransform(180);
+                    var thumb = img.GetThumbnailClone();
+                    var updatedThumb = thumb?.PerformTransform(transform);
+                    img.AddTransform(transform, updatedThumb);
+                }
+                toggle = !toggle;
+            }
+        }
+    }
+
     public class AddTransforms(List<Transform> transforms, Dictionary<UiImage, IMemoryImage?>? updatedThumbnails = null)
         : ListMutation<UiImage>
     {

NAPS2.Lib/Lang/Resources/UiStrings.resx

@@ -252,6 +252,9 @@
   <data name="Flip" xml:space="preserve">
     <value>Flip</value>
   </data>
+  <data name="AltFlip" xml:space="preserve">
+    <value>Flip every 2nd image</value>
+  </data>
   <data name="Deskew" xml:space="preserve">
     <value>Deskew</value>
   </data>

NAPS2.Setup/appsettings.xml

@@ -125,6 +125,7 @@
     <RotateLeft></RotateLeft>
     <RotateRight></RotateRight>
     <RotateFlip></RotateFlip>
+    <AltFlip></AltFlip>
     <RotateCustom></RotateCustom>
     <MoveUp>Ctrl+Up</MoveUp>
     <MoveDown>Ctrl+Down</MoveDown>