How to show only a portion of the tkinter canvas by cropping the tkinter window?

Question

I want to be able to zoom into my tkinter canvas. My tkinter canvas is 500x500px, and I only want my window to display the center 200x200px portion of this canvas. How do I do this? I know that I can just specify my window size as 200x200px using root.geometry("200x200+0+0"), but this causes my window to display the top left corner of my canvas, and not the center. Before I do anything, my entire canvas looks like this:

Ultimately, I want my window to look like this, with the canvas centered within the window:

This is my code:

import tkinter

root = tkinter.Tk()
root.title("")
root.geometry("200x200+0+0")

canvas = tkinter.Canvas(master = root, width = 500, height = 500)

canvas.create_oval(200, 200, 300, 300, outline = "black", fill = "blue")
canvas.pack()

which returns:

As you can see, the canvas is not centered, and the window is showing the upper left hand corner at the moment. Does anyone have any suggestions?

Answer 1

Ok, thanks to this stackoverflow post , I found out there is an option when creating a tkinter canvas called scrollregion . The format of the argument is "x0 y0 x1 y1" for anyone that is wondering, where (x0, y0) is the upper-left corner of the area of the canvas I want to show and (x1, y1) is the bottom-right corner of the same area. My code should be fixed to this:

canvas = tkinter.Canvas(master = root, width = 500, height = 500, scrollregion = "150 150 350 350")

Be wary that these coordinates do not account for a scrollbar...I'm still working on figuring that out. Much thanks to this stackoverflow post as well, specifically the following words:

I don't see any difference between putting the y-scrollbar to the bottom or putting the canvas view to the bottom because the two are linked.