Tkinter: How to get frame in canvas window to expand to the size of the canvas?

Question

So I've been using the canvas widget in tkinter to create a frame full of labels which has a scrollbar. All is working good except that the frame only expands to the size of the labels placed in it - I want the frame to expand to the size of the parent canvas.

This can easily be done if I use pack(expand = True) (which I have commented out in the code below) for the frame in the canvas but then then the scrollbar doesn't work.

Here's the appropriate bit of code:

    ...
    self.canvas = Canvas(frame, bg = 'pink')
    self.canvas.pack(side = RIGHT, fill = BOTH, expand = True)

    self.mailbox_frame = Frame(self.canvas, bg = 'purple')

    self.canvas.create_window((0,0),window=self.mailbox_frame, anchor = NW)

    #self.mailbox_frame.pack(side = LEFT, fill = BOTH, expand = True)

    mail_scroll = Scrollbar(self.canvas, orient = "vertical",
        command = self.canvas.yview)
    mail_scroll.pack(side = RIGHT, fill = Y)

    self.canvas.config(yscrollcommand = mail_scroll.set)

    self.mailbox_frame.bind("<Configure>", self.OnFrameConfigure)


def OnFrameConfigure(self, event):
    self.canvas.configure(scrollregion=self.canvas.bbox("all"))

I've also provided an image with colored frames so you can see what I'm getting at. The pink area is the canvas that needs filling by the mailbox_frame (You can see the scrollbar on the right):

score 37 · Answer 1 · answered Mar 28 '15 at 20:49

Just for future reference in case anyone else needs to know:

        frame = Frame(self.bottom_frame)
        frame.pack(side = LEFT, fill = BOTH, expand = True, padx = 10, pady = 10)

        self.canvas = Canvas(frame, bg = 'pink')
        self.canvas.pack(side = RIGHT, fill = BOTH, expand = True)

        self.mailbox_frame = Frame(self.canvas, bg = 'purple')

        self.canvas_frame = self.canvas.create_window((0,0),
            window=self.mailbox_frame, anchor = NW)
        #self.mailbox_frame.pack(side = LEFT, fill = BOTH, expand = True)

        mail_scroll = Scrollbar(self.canvas, orient = "vertical", 
            command = self.canvas.yview)
        mail_scroll.pack(side = RIGHT, fill = Y)

        self.canvas.config(yscrollcommand = mail_scroll.set)

        self.mailbox_frame.bind("<Configure>", self.OnFrameConfigure)
        self.canvas.bind('<Configure>', self.FrameWidth)

    def FrameWidth(self, event):
        canvas_width = event.width
        self.canvas.itemconfig(self.canvas_frame, width = canvas_width)

    def OnFrameConfigure(self, event):
        self.canvas.configure(scrollregion=self.canvas.bbox("all"))

Thanks a lot! This made all the difference.I'm guess setting the object returned from `create_window` to `self.canvas_frame` is the key? — Tim, Jul 19 '19 at 02:52
You saved my time! I know that canvas size is not updated, but after many experiments not look at right side. Thank you! — AntonKrutikov, Nov 30 '21 at 19:49

score 18 · Accepted Answer · answered Mar 28 '15 at 17:01

18

Set a binding on the canvas <Configure> event, which fires whenever the canvas changes size. From the event object you can get the canvas width and height, and use that to resize the frame.

answered Mar 28 '15 at 17:01

Bryan Oakley

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score 1 · Answer 3 · answered Jan 12 '22 at 17:15

Just an updated answer which covers both horizontal and vertical scrollbars without breaking them.

def FrameWidth(self, event):
    if event.width > self.mailbox_frame.winfo_width():
        self.canvas.itemconfig(self.canvas_frame, width=event.width-4)
    if event.height > self.mailbox_frame.winfo_height():
        self.canvas.itemconfig(self.canvas_frame, height=event.height-4)

Only sets the frame height and width if they are less than the canvas width. Respects both Horizontal and Vertical scrollbars.

Tkinter: How to get frame in canvas window to expand to the size of the canvas?

3 Answers3

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