adding redo functionality

src/GUI.py

@@ -91,6 +91,7 @@ class GUI:
         edit_menu = tk.Menu(menu, tearoff=0)
         menu.add_cascade(label="Edit", menu=edit_menu)
         edit_menu.add_command(label="Undo", accelerator="Ctrl+Z", command=lambda: self._undo())
+        edit_menu.add_command(label="Redo", accelerator="Ctrl+Y", command=lambda: self._redo())
         edit_menu.add_separator()
         edit_menu.add_command(label="Toggle Selection Mode", accelerator="Ctrl+S", command=lambda: self._toggleSelectionMode())
 
@@ -118,6 +119,7 @@ class GUI:
 
         # Key bindings
         root.bind_all('<Control-z>', lambda event: self._undo())
+        root.bind_all('<Control-y>', lambda event: self._redo())
         root.bind_all('<Control-s>', lambda event: self._toggleSelectionMode())
 
         root.mainloop()
@@ -184,6 +186,12 @@ class GUI:
         self._currentImage.undo()
         self._renderCurrentImage()
 
+    def _redo(self) -> None:
+        if self._currentImage is None:
+            return
+        self._currentImage.redo()
+        self._renderCurrentImage()
+
     def _toggleSelectionMode(self) -> None:
         """Toggle interactive selection mode on/off."""
         self._selectionMode = not self._selectionMode

src/ImageContainer.py

@@ -5,6 +5,7 @@ class ImageContainer:
     _imageData = None
     _path = None
     _history = None
+    _redo_history = None
 
     def loadImage(self, path: str) -> None:
         """ Load image file from the path.
@@ -21,6 +22,7 @@ class ImageContainer:
 
         self._path = path
         self._history = []
+        self._redo_history = []
 
         print("Opened image:", path)
 
@@ -41,6 +43,9 @@ class ImageContainer:
             return
         # Ensure a deep copy (but PIL copy should be sufficient)
         self._history.append(self._imageData.copy())
+        # New action invalidates redo history
+        if self._redo_history is not None:
+            self._redo_history.clear()
         # Cap history size to avoid memory blow up
         if len(self._history) > 20:
             self._history.pop(0)
@@ -48,4 +53,19 @@ class ImageContainer:
     def undo(self) -> None:
         if not self._history:
             return
-        self._imageData = self._history.pop()
+        # Move current state to redo stack
+        if self._redo_history is None:
+            self._redo_history = []
+        if self._imageData is not None:
+            self._redo_history.append(self._imageData.copy())
+        # Restore last snapshot
+        self._imageData = self._history.pop()
+
+    def redo(self) -> None:
+        if not self._redo_history:
+            return
+        # Moving forward: save current to undo history
+        if self._imageData is not None:
+            self._history.append(self._imageData.copy())
+        # Apply redo state
+        self._imageData = self._redo_history.pop()