eb303 wrote:
On Apr 22, 5:55 pm, Rotwang <sg...@hotmail.co.uk> wrote:
[...]
From my experience, mixing Tkinter with threads is a bad idea. As most
GUI toolkits, it really doesn't like to be manipulated from different
threads, so you might end up getting weird problems or even crashes.
By the way, did you try to remove the line out.mainloop() from your
'draw' function?
I didn't. How do I get Python to display the draw window, other than by
using mainloop()?
This is the line that blocks the IDLE GUI, since it
initiates a secondary event loop that will only exit when you do a
out.quit(), so that might be a solution.
BTW, another problem: whenever I call a widget.quit() method, the widget
in question crashes. IDLE carries on working but the widget window stays
there, not responding, and if I tell my OS to kill it then IDLE
restarts. Is this a bug? I'm using Windows 7 and Python 2.6.4.
The 'quit' method just exits the mainloop. It doesn't destroy the
widget. So if your application doesn't actually exit, the widget will
just stay there. If you want to destroy the it too, you have to call
explicitely widget.destroy().
That worked like a charm, thanks!
Here's another problem I've run into today: I've just added a bit of
code so that it's possible to resize the draw window and the contents
will be resized automatically. The method now looks something like this:
out = Tkinter.Tk()
slave = Tkinter.Canvas(out, width = wh[0], height = wh[1])
slave.grid()
# I put the canvas widget inside a tk widget instead of just
# using the former because I want keypresses to do things, and
# it doesn't seem to be possible to bind keyboard events to a
# canvas
# draw something
slave.pack()
def resize(b):
wh[:] = [b.width, b.height]
slave.config(width = wh[0], height = wh[1])
# resize the contents of slave
out.bind('<Configure>', resize)
out.mainloop()
The trouble is, when I call the method the window it spawns slowly grows
larger, until I move or resize it myself by grabbing one of the edges;
after this everything works as intended. If I add the line "print wh"
after "wh[:] = [b.width, b.height]", the output looks like this (the
default value of wh is [640,480]:
[644, 484]
[648, 488]
[648, 488]
[648, 488]
[652, 492]
[652, 492]
[652, 492]
[656, 496]
[656, 496]
[656, 496]
[660, 500]
etc.
My only guess as to why this is happening is that Tkinter is resizing
out to be 4 pixels wider and taller than slave, and the line
"slave.config(...)" consequently leads to resize being called again. But
this doesn't explain why it stops happening when I resize the window
intentionally, nor why the window apparently only gets larger every
third time resize is called. The problem goes away if I replace "wh[:] =
[b.width, b.height]" with
wh[:] = [b.width - 4, b.height - 4]
but this seems like a rather ad-hoc and ugly solution, and I'd rather
understand what's going on. Can anyone help?
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