diff --git a/src/gui.py b/src/gui.py
--- a/src/gui.py
+++ b/src/gui.py
@@ -3,11 +3,14 @@ from PIL import ImageTk
 import PIL
 import math
 from epoint import *
+from corners import *
+from grid import *
 
 
 class Application(tk.Frame):
   def __init__(self, master=None):
-    self.corners=[]
+    self.corners=Corners()
+    self.boardGrid=None
     
     tk.Frame.__init__(self, master)
     self.grid(column=0,row=0)
@@ -31,35 +34,16 @@ class Application(tk.Frame):
   
   ## Stores a grid corner located at x,y coordinates.
   def addCorner(self,x,y):
-    a=EPoint(x,y)
-    for i,c in enumerate(self.corners): # move an improperly placed point
-      if a.dist(c)<20:
-        self.corners[i]=a
-        # print(self.corners)
-        self.redrawImgView()
-        return
-    
-    if len(self.corners)<4: # add a new corner
-      self.corners.append(a)
-      # print(self.corners)
-      self.redrawImgView()
-    
-    if len(self.corners)<4: return
-    
-    index,minDist=0,float('inf') # replace the corner closest to the clicked point
-    for i,c in enumerate(self.corners):
-      if a.dist(c)<minDist:
-        index,minDist=i,a.dist(c)
-    
-    self.corners[index]=a
-    # print(self.corners)
+    self.corners.add(x,y)
+    if self.corners.canonizeOrder():
+      self.boardGrid=Grid(self.corners)
     
     self.redrawImgView()
     
   ## Redraws the current image and its overlay.
   def redrawImgView(self):
     self.imgView.create_image(2,2,anchor="nw",image=self.img)
-    for corner in self.corners:
+    for corner in self.corners.corners:
       self.markPoint(corner.x,corner.y)
     
     self.imgView.grid()