tkinter canvas 图像未显示

Question

I have a simple canvas being created in a function, and i would like an image displayed on the canvas.

def start(root):
    startframe = tkinter.Frame(root)
    canvas = tkinter.Canvas(startframe,width=1280,height=720)

    startframe.pack()
    canvas.pack()

    one = tkinter.PhotoImage('images\one.gif')
    canvas.create_image((0,0),image=one,anchor='nw')

when i run the code i get a blank 1280x720 window, no image.

i have looked at the following website:http://effbot.org/pyfaq/why-do-my-tkinter-images-not-appear.htm but i do not understand how to apply their example to my situation (i dont know what to create a reference to or how to create a reference, if that is my problem). I have also looked at some stack overflow questions but they did not help either.

Answer 1

1. Escape backslashes in path string correctly. (or use r'raw string literal' ).

2. Prevent PhotoImage object being garbage collected.

3. specify the filename using file=... option.

---

def start(root):
    startframe = tkinter.Frame(root)
    canvas = tkinter.Canvas(startframe,width=1280,height=720)

    startframe.pack()
    canvas.pack()

    # Escape / raw string literal
    one = tkinter.PhotoImage(file=r'images\one.gif')
    root.one = one  # to prevent the image garbage collected.
    canvas.create_image((0,0), image=one, anchor='nw')

UPDATE

The two statements one = ... and root.one = one can be merged into one statement:

    root.one = one = tkinter.PhotoImage(r'images\one.gif')

Answer 2

How about canvas.update() ? I was suffering a similar problem. I am using grid, so instead of .pack I needed to use .update .

Answer 3

I had the situation when image didn`t show up, when I call it in function, but otherwise everything was okay. That is my function

def ask_for_file():
    f_types = [('PNG Images', '*.png')]
    filename = askopenfilename(filetypes=f_types)
    img = ImageTk.PhotoImage(file=filename)
    canvas.config(height=img.height(), width=img.width())
    canvas.create_image(0, 0, anchor=NW, image=img)

My solution was to add img = None as global variable and change it inside function. It worked

img = None


def ask_for_file():
    global img
    f_types = [('PNG Images', '*.png')]
    filename = askopenfilename(filetypes=f_types)
    img = ImageTk.PhotoImage(file=filename)
    canvas.config(height=img.height(), width=img.width())
    canvas.create_image(0, 0, anchor=NW, image=img)