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[tkinter]Synchronous image diplay

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From: ram...@zedat.fu-berlin.de (Stefan Ram)
Newsgroups: comp.lang.python
Subject: [tkinter]Synchronous image diplay
Date: 20 Oct 2021 20:02:02 GMT
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by: Stefan Ram - Wed, 20 Oct 2021 20:02 UTC

I want to diplay images fast in a slideshow (i.e., 10 images
per second), but do not want to skip any image the display
of which needs more time to be created. So I need to know
when exactly an image has become visible on the screen.

I am using tkinter to display large (i.e., 1000x1000, not
10x10) images, something like:

my_label.config\
( image=my_image, bg="#000000", width=my_width, height=my_height )
my_label.pack()

. This kinda works, but "config" and "pack" seem to return
before the image is visible. It seems the image then is
being drawn only while my thread is waiting for the next
input event.

I'd like my program to get to know when the painting of
the image is complete, i.e., when the image is really
visible on the screen. Is it possible to pass a call back
for this or to receive an event in this case?

If I'd insert

root.after( dt, f )

after "pack", then f would be called "dt" after "pack" has
returned. But I want it to be called "dt" after /the images
has become visible on the screen/ instead.

Re: [tkinter]Synchronous image diplay

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From: ram...@zedat.fu-berlin.de (Stefan Ram)
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Subject: Re: [tkinter]Synchronous image diplay
Date: 20 Oct 2021 20:18:52 GMT
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by: Stefan Ram - Wed, 20 Oct 2021 20:18 UTC

Re: [tkinter]Synchronous image diplay

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Subject: Re: [tkinter]Synchronous image diplay
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by: Stefan Ram - Wed, 20 Oct 2021 20:20 UTC

Re: [tkinter]Synchronous image diplay

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From: cs...@cskk.id.au (Cameron Simpson)
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Subject: Re: [tkinter]Synchronous image diplay
Date: Thu, 21 Oct 2021 10:03:46 +1100
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by: Cameron Simpson - Wed, 20 Oct 2021 23:03 UTC

On 20Oct2021 20:18, Stefan Ram <ram@zedat.fu-berlin.de> wrote:
>ram@zedat.fu-berlin.de (Stefan Ram) writes:
>>I want to diplay images fast in a slideshow (i.e., 10 images
>
> (There's a problem with my [S] key.)
>
> It seems that update_idletasks() solved my problem!

Yes. That causes the event loop to resume, render, then run any pending
idle tasks (which run when the event loop is idle, implying that any
pending rendering is complete). So you know at that time that a new
image will have been displayed.

Think of it like flush() for file output, but for a GUI.

Cheers,
Cameron Simpson <cs@cskk.id.au>

Although the moon is smaller than the earth, it is farther away.

devel / comp.lang.python / Re: [tkinter]Synchronous image diplay

Subject	Author
[tkinter]Synchronous image diplay	Stefan Ram
Re: [tkinter]Synchronous image diplay	Stefan Ram
Re: [tkinter]Synchronous image diplay	Cameron Simpson
Re: [tkinter]Synchronous image diplay	Stefan Ram