Am 22.05.16 um 22:19 schrieb Random832:
On Sun, May 22, 2016, at 15:37, Michael Torrie wrote:
The reference is indeed held by the label but the problem is the label
is a Tcl/Tk object, thinly wrapped in Python.
Okay but then in that case why doesn't the image get instantiated as a
Tcl/Tk object which the label holds a reference to and then nobody cares
if the python image object gets collected?
Actually, I think it could be solved, and not too complicated either. In
Tk, objects are deleted explicitly. This is how you'd do it natively:
image create photo bla -file myicon.png
# create an image called "bla"
pack [label .l -image bla]
# display it in a label with name .l
Of course, the label references the image object. For instance, if you
read in new image data
bla read newicon.png -shrink
then the label will update.
What happens, when you create all those things from Tkinter, the Label
object deletes the image in it's destructor:
image delete bla # this will turn the label blank
This is IMHO correct, but when you add an image to the label through
Tkinter, then it only does it through Tk (i.e. the second line in the
above code). It should store a reference the Python image object inside
the label object. This is akin to a "dangling pointer" in C. It would
just be some work to replicate this for all widgets in Tk, there are
buttons etc. but in essence I think it would work.
Christian
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