Implement canvas zoom

canvas.py

@@ -1,4 +1,5 @@
 import base64
+import platform
 import tkinter
 
 GRID_COLOR = "#808080"
@@ -22,6 +23,12 @@ class EditorCanvas(tkinter.Canvas):
         self.bind("<Button-1>",self.handle_draw)
         self.bind("<Button-3>",self.handle_move_start)
         self.bind("<B3-Motion>",self.handle_move)
+        if platform.system()=="Windows" or platform.system()=="Darwin":
+            self.bind("<MouseWheel>",lambda event: self.handle_zoom(event.delta))
+        else:
+            # This will probably work only on X11
+            self.bind("<Button-4>",lambda _: self.handle_zoom(1))
+            self.bind("<Button-5>",lambda _: self.handle_zoom(-1))
 
 
     def draw(self):
@@ -68,6 +75,13 @@ class EditorCanvas(tkinter.Canvas):
         self.draw()
 
 
+    def handle_zoom(self,delta):
+        self.grid_size+=delta
+        self.width=self.project.char_res[0]*self.grid_size
+        self.height=self.project.char_res[1]*self.grid_size
+        self.draw()
+
+
     def load_char(self):
         self.current_char_modified=False
         if not self.project.does_char_exist(self.current_char):