import tkinter as tk


class ResizableCanvas(tk.Canvas):
	def __init__(self, master=None):
		tk.Canvas.__init__(self, master, highlightthickness=0)

		self._master=master
		self._width=0
		self._height=0

		master.bind("<Configure>", self._onResize)
		
	def configure(self,*args,**kwargs):
		if "width" in kwargs: self._width=kwargs["width"]
		if "height" in kwargs: self._height=kwargs["height"]
		
		super().configure(*args,**kwargs)

	def _onResize(self, event):
		wScale=float(event.width)/self._width
		hScale=float(event.height)/self._height
		scale=min(wScale,hScale)

		self._width*=scale
		self._height*=scale
		self.scale("all",0,0,scale,scale) # rescale all the objects tagged with the "all" tag

		x=(event.width-self._width)/2
		y=(event.height-self._height)/2

		# place the widget, giving it an explicit size
		self.place(in_=self._master, x=x, y=y, width=self._width, height=self._height)
		return scale