Tkinter, image not appearing in function but without function

S

skanemupp

why is the first program not working? when i click the screen the map
is not appearing.

the second program works.



from Tkinter import *

master = Tk()

w = Canvas(master, width=700, height=600)
w.pack(expand = YES, fill = BOTH)

def mapper():
mapq = PhotoImage(file = 'C:\Users\saftarn\Desktop\world-map.gif')
w.create_image(10, 10, image = mapq, anchor = NW)

def key(event):
print "pressed", repr(event.char)

def callback(event):
w.focus_set()
print "clicked at", event.x, event.y
mapper()
print 'yo'
square = w.create_oval(event.x-5,event.y-5,event.x+5,event.y+5,
fill="black")

w.bind("<Key>", key)
w.bind("<Button-1>", callback)
w.pack()


mainloop()




from Tkinter import *

master = Tk()


w = Canvas(master, width=700, height=600)
w.pack(expand = YES, fill = BOTH)

q=raw_input("Choose: i=India, s=sweden, else World: ")
if q=="i":
mapq = PhotoImage(file = 'C:\Users\saftarn\Desktop\map-india.bmp')
elif q=='s':
mapq = PhotoImage(file = 'C:\Users\saftarn\Desktop\provinces-of-
sweden.gif')
else:
mapq = PhotoImage(file = 'C:\Users\saftarn\Desktop\world-map.gif')

print mapq.height(), mapq.width()
w.create_image(10, 10, image = mapq, anchor = NW)

def key(event):
print "pressed", repr(event.char)

def callback(event):
w.focus_set()
print "clicked at", event.x, event.y
square = w.create_oval(event.x-5,event.y-5,event.x+5,event.y+5,
fill="black")

"""hur hitta om inom ratt->kolla color of """

w.bind("<Key>", key)
w.bind("<Button-1>", callback)
w.pack()

mainloop()
 
M

Marc 'BlackJack' Rintsch

why is the first program not working? when i click the screen the map
is not appearing.

the second program works.



from Tkinter import *

master = Tk()

w = Canvas(master, width=700, height=600)
w.pack(expand = YES, fill = BOTH)

def mapper():
mapq = PhotoImage(file = 'C:\Users\saftarn\Desktop\world-map.gif')
w.create_image(10, 10, image = mapq, anchor = NW)

def key(event):
print "pressed", repr(event.char)

def callback(event):
w.focus_set()
print "clicked at", event.x, event.y
mapper()
print 'yo'
square = w.create_oval(event.x-5,event.y-5,event.x+5,event.y+5,
fill="black")

w.bind("<Key>", key)
w.bind("<Button-1>", callback)
w.pack()


mainloop()

Python doesn't know that the Tk side still needs the image and frees the
memory when `mapper()` is done and `mapq` the only name to the `PhotoImage`
instance goes out of scope.

Ciao,
Marc 'BlackJack' Rintsch
 
7

7stud

Python doesn't know that the Tk side still needs the image and frees the
memory when `mapper()` is done and `mapq` the only name to the `PhotoImage`
instance goes out of scope.

Ciao,
        Marc 'BlackJack' Rintsch


...so you should do something like this(untested):


def mapper(height, width, widget, img, position):
widget.create_image(height, width, image=img, anchor=position)

w = Canvas(master, width=700, height=600)
w.pack(expand = YES, fill = BOTH)

#Create a permanent reference to the image, i.e. the variable is not
#created inside a function:
my_img = PhotoImage(file = 'C:\Users\saftarn\Desktop\world-map.gif')

mapper(10, 10, w, my_img, NW)
 

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