How to get tkinter canvas to dynamically resize to window width?

Question

I need to get a canvas in tkinter to set its width to the width of the window, and then dynamically re-size the canvas when the user makes the window smaller/bigger.

Is there any way of doing this (easily)?

Answer 1

I thought I would add in some extra code to expand on @fredtantini's answer, as it doesn't deal with how to update the shape of widgets drawn on the Canvas.

To do this you need to use the scale method and tag all of the widgets. A complete example is below.

from Tkinter import *  # a subclass of Canvas for dealing with resizing of windows class ResizingCanvas(Canvas):     def __init__(self,parent,**kwargs):         Canvas.__init__(self,parent,**kwargs)         self.bind("<Configure>", self.on_resize)         self.height = self.winfo_reqheight()         self.width = self.winfo_reqwidth()      def on_resize(self,event):         # determine the ratio of old width/height to new width/height         wscale = float(event.width)/self.width         hscale = float(event.height)/self.height         self.width = event.width         self.height = event.height         # resize the canvas          self.config(width=self.width, height=self.height)         # rescale all the objects tagged with the "all" tag         self.scale("all",0,0,wscale,hscale)  def main():     root = Tk()     myframe = Frame(root)     myframe.pack(fill=BOTH, expand=YES)     mycanvas = ResizingCanvas(myframe,width=850, height=400, bg="red", highlightthickness=0)     mycanvas.pack(fill=BOTH, expand=YES)      # add some widgets to the canvas     mycanvas.create_line(0, 0, 200, 100)     mycanvas.create_line(0, 100, 200, 0, fill="red", dash=(4, 4))     mycanvas.create_rectangle(50, 25, 150, 75, fill="blue")      # tag all of the drawn widgets     mycanvas.addtag_all("all")     root.mainloop()  if __name__ == "__main__":     main() 

Answer 2

You can use the .pack geometry manager:

self.c=Canvas(…) self.c.pack(fill="both", expand=True) 

should do the trick. If your canvas is inside a frame, do the same for the frame:

self.r = root self.f = Frame(self.r) self.f.pack(fill="both", expand=True) self.c = Canvas(…) self.c.pack(fill="both", expand=True) 

See effbot for more info.

Edit: if you don't want a "full sized" canvas, you can bind your canvas to a function:

self.c.bind('<Configure>', self.resize)  def resize(self, event):     w,h = event.width-100, event.height-100     self.c.config(width=w, height=h) 

See effbot again for events and bindings