fix: undo redo buttons greyed out when stack is empty

Author: samruddhi-Rahegaonkar

lib/providers/draw_badge_provider.dart

@@ -10,10 +10,8 @@ class DrawBadgeProvider extends ChangeNotifier {
 
   List<List<bool>> _drawViewGrid =
       List.generate(11, (_) => List.generate(44, (_) => false));
-
   final List<List<bool>> _previewGrid =
       List.generate(11, (_) => List.generate(44, (_) => false));
-
   final List<List<List<bool>>> _undoStack = [];
   final List<List<List<bool>>> _redoStack = [];
 
@@ -35,12 +33,10 @@ class DrawBadgeProvider extends ChangeNotifier {
 
   DrawShape get selectedShape => _selectedShape;
   bool getIsDrawing() => isDrawing;
-
   bool get canUndo => _undoStack.isNotEmpty;
   bool get canRedo => _redoStack.isNotEmpty;
 
   // ========== STATE SETTERS ==========
-
   void toggleIsDrawing(bool drawing) {
     isDrawing = drawing;
     notifyListeners();
@@ -108,7 +104,6 @@ class DrawBadgeProvider extends ChangeNotifier {
   }
 
   // ========== UNDO / REDO ==========
-
   void _pushToUndoStack() {
     _undoStack.add(_copyGrid(_drawViewGrid));
     _redoStack.clear(); // Invalidate redo stack on new action
@@ -142,5 +137,6 @@ class DrawBadgeProvider extends ChangeNotifier {
 class GridPosition {
   final int x;
   final int y;
+
   GridPosition(this.x, this.y);
 }

lib/view/draw_badge_screen.dart

@@ -96,7 +96,7 @@ class _DrawBadgeState extends State<DrawBadge> {
                           _buildSaveButton(fileHelper),
                           _buildShapesToggleButton(),
 
-                          // ✅ New Undo & Redo buttons
+                          // ✅ Updated Undo & Redo buttons with greyed out state
                           _buildUndoButton(),
                           _buildRedoButton(),
                         ],
@@ -232,32 +232,44 @@ class _DrawBadgeState extends State<DrawBadge> {
   }
 
   Widget _buildUndoButton() {
+    // Check if undo is available using the getter
+    final bool canUndo = drawToggle.canUndo;
+    final Color buttonColor = canUndo ? Colors.black : Colors.grey;
+
     return TextButton(
-      onPressed: () {
-        setState(() {
-          drawToggle.undo();
-        });
-      },
-      child: const Column(
+      onPressed: canUndo
+          ? () {
+              setState(() {
+                drawToggle.undo();
+              });
+            }
+          : null, // Disable button when can't undo
+      child: Column(
         children: [
-          Icon(Icons.undo, color: Colors.black),
-          Text('Undo', style: TextStyle(color: Colors.black)),
+          Icon(Icons.undo, color: buttonColor),
+          Text('Undo', style: TextStyle(color: buttonColor)),
         ],
       ),
     );
   }
 
   Widget _buildRedoButton() {
+    // Check if redo is available using the getter
+    final bool canRedo = drawToggle.canRedo;
+    final Color buttonColor = canRedo ? Colors.black : Colors.grey;
+
     return TextButton(
-      onPressed: () {
-        setState(() {
-          drawToggle.redo();
-        });
-      },
-      child: const Column(
+      onPressed: canRedo
+          ? () {
+              setState(() {
+                drawToggle.redo();
+              });
+            }
+          : null, // Disable button when can't redo
+      child: Column(
         children: [
-          Icon(Icons.redo, color: Colors.black),
-          Text('Redo', style: TextStyle(color: Colors.black)),
+          Icon(Icons.redo, color: buttonColor),
+          Text('Redo', style: TextStyle(color: buttonColor)),
         ],
       ),
     );