feat: add draw_move method to Cell

Add the draw_move method to the Cell class to draw a path between the
centre of two cells.

cell.py

@@ -12,10 +12,23 @@ class Cell:
             x2: int, y2: int,
             window: Window
     ):
-        self.__top_wall = CellWall(Line(Point(x1, y1), Point(x2, y1)))
-        self.__bottom_wall = CellWall(Line(Point(x1, y2), Point(x2, y2)))
-        self.__left_wall = CellWall(Line(Point(x1, y1), Point(x1, y2)))
-        self.__right_wall = CellWall(Line(Point(x2, y1), Point(x2, y2)))
+        # Define the cell walls
+        top_wall = Line(Point(x1, y1), Point(x2, y1))
+        bottom_wall = Line(Point(x1, y2), Point(x2, y2))
+        left_wall = Line(Point(x1, y1), Point(x1, y2))
+        right_wall = Line(Point(x2, y1), Point(x2, y2))
+
+        self.__top_wall = CellWall(top_wall)
+        self.__bottom_wall = CellWall(bottom_wall)
+        self.__left_wall = CellWall(left_wall)
+        self.__right_wall = CellWall(right_wall)
+
+        # Calculate the cell's central point
+        centre_x = x1 + ((x2 - x1) / 2)
+        centre_y = y1 + ((y2 - y1) / 2)
+        self.__centre = Point(centre_x, centre_y)
+
+        # A reference to the root Window class for drawing purposes.
         self.__window = window
 
     def configure_walls(
@@ -33,6 +46,12 @@ class Cell:
         self.__left_wall.exists = left
         self.__right_wall.exists = right
 
+    def centre(self) -> Point:
+        """
+        centre returns the Cell's central point
+        """
+        return self.__centre
+
     def draw(self):
         """
         draw draws the cell onto the canvas
@@ -46,6 +65,17 @@ class Cell:
         if self.__right_wall.exists:
             self.__window.draw_line(self.__right_wall.line)
 
+    def draw_move(self, to_cell: 'Cell', undo: bool = False):
+        """
+        draw_move draws a path between the centre of this cell and
+        the centre of the given cell.
+        """
+        fill_colour = "red"
+        if undo:
+            fill_colour = "grey"
+        line = Line(self.centre(), to_cell.centre())
+        self.__window.draw_line(line, fill_colour)
+
 
 class CellWall:
     """

main.py

@@ -5,20 +5,21 @@ from cell import Cell
 def main():
     window = Window(800, 800)
 
-    # Draw all walls
     cell_1 = Cell(10, 30, 100, 100, window)
+    cell_1.configure_walls(top=True, bottom=True, left=True, right=False)
     cell_1.draw()
 
-    # Draw vertical walls only
-    cell_2 = Cell(300, 50, 400, 100, window)
-    cell_2.configure_walls(top=False, bottom=False, left=True, right=True)
+    cell_2 = Cell(210, 30, 300, 100, window)
+    cell_2.configure_walls(top=True, bottom=False, left=False, right=True)
     cell_2.draw()
 
-    # Draw horizontal walls only
-    cell_3 = Cell(200, 400, 500, 600, window)
-    cell_3.configure_walls(top=True, bottom=True, left=False, right=False)
+    cell_3 = Cell(210, 130, 300, 200, window)
+    cell_3.configure_walls(top=False, bottom=True, left=True, right=True)
     cell_3.draw()
 
+    cell_1.draw_move(cell_2)
+    cell_2.draw_move(cell_3, undo=True)
+
     window.wait_for_close()