Add Rectangle and Ellipse erasing support + Shift modifier for perfect squares

Co-authored-by: RuntimeRascal <2422222+RuntimeRascal@users.noreply.github.com>

Author: Copilot

Src/GhostDraw/Tools/EraserTool.cs

@@ -136,6 +136,30 @@ private void EraseAtPosition(Point position, Canvas canvas)
                         }
                     }
                 }
+                else if (element is System.Windows.Shapes.Rectangle rectangle)
+                {
+                    // Check if eraser intersects with rectangle bounds
+                    double left = Canvas.GetLeft(rectangle);
+                    double top = Canvas.GetTop(rectangle);
+                    Rect shapeRect = new Rect(left, top, rectangle.Width, rectangle.Height);
+                    
+                    if (eraserRect.IntersectsWith(shapeRect))
+                    {
+                        shouldErase = true;
+                    }
+                }
+                else if (element is Ellipse ellipse)
+                {
+                    // Check if eraser intersects with ellipse bounds
+                    double left = Canvas.GetLeft(ellipse);
+                    double top = Canvas.GetTop(ellipse);
+                    Rect ellipseRect = new Rect(left, top, ellipse.Width, ellipse.Height);
+                    
+                    if (eraserRect.IntersectsWith(ellipseRect))
+                    {
+                        shouldErase = true;
+                    }
+                }
 
                 if (shouldErase)
                 {

Src/GhostDraw/Tools/RectangleTool.cs

@@ -42,7 +42,9 @@ public void OnMouseMove(Point position, Canvas canvas, MouseButtonState leftButt
         if (_isCreatingRectangle && _currentRectangle != null && _rectangleStartPoint.HasValue)
         {
             // Update rectangle dimensions to follow cursor
-            UpdateRectangle(_rectangleStartPoint.Value, position);
+            // Check if Shift key is held down for perfect square
+            bool isShiftPressed = Keyboard.IsKeyDown(Key.LeftShift) || Keyboard.IsKeyDown(Key.RightShift);
+            UpdateRectangle(_rectangleStartPoint.Value, position, isShiftPressed);
         }
     }
 
@@ -117,7 +119,7 @@ private void StartNewRectangle(Point startPoint, Canvas canvas)
         _logger.LogInformation("Rectangle started at ({X:F0}, {Y:F0})", startPoint.X, startPoint.Y);
     }
 
-    private void UpdateRectangle(Point startPoint, Point currentPoint)
+    private void UpdateRectangle(Point startPoint, Point currentPoint, bool isPerfectSquare = false)
     {
         if (_currentRectangle == null)
             return;
@@ -128,6 +130,14 @@ private void UpdateRectangle(Point startPoint, Point currentPoint)
         double width = Math.Abs(currentPoint.X - startPoint.X);
         double height = Math.Abs(currentPoint.Y - startPoint.Y);
 
+        // If Shift is held, make it a perfect square (width = height = min dimension)
+        if (isPerfectSquare)
+        {
+            double size = Math.Min(width, height);
+            width = size;
+            height = size;
+        }
+
         Canvas.SetLeft(_currentRectangle, left);
         Canvas.SetTop(_currentRectangle, top);
         _currentRectangle.Width = width;
@@ -138,7 +148,9 @@ private void FinishRectangle(Point endPoint)
     {
         if (_currentRectangle != null && _rectangleStartPoint.HasValue)
         {
-            UpdateRectangle(_rectangleStartPoint.Value, endPoint);
+            // Check if Shift was held on the final click
+            bool isShiftPressed = Keyboard.IsKeyDown(Key.LeftShift) || Keyboard.IsKeyDown(Key.RightShift);
+            UpdateRectangle(_rectangleStartPoint.Value, endPoint, isShiftPressed);
             _logger.LogInformation("Rectangle finished at ({X:F0}, {Y:F0})", endPoint.X, endPoint.Y);
         }