Accessing and Modifying the Attributes of Window Components

Each window component contains a dictionary of its attributes. After a component has been added to the application window, the programmer can access and modify its attributes by using the subscript with the name of the attribute (a string), as follows:

widget[attribute name]

widget[attribute name] = value

For example, a label has a text font and a foreground color that can be modified in this manner. A label also can show either text or an image, depending on the setting of these attributes. The next program, which displays an image and a caption, shows how to set the image, font, and color attributes of labels.

"""File: imagedemo.py."""

from breezypythongui import EasyFrame

from tkinter import PhotoImage, N, S, W, E

from tkinter.font import Font

class ImageDemo(EasyFrame):

"""Displays an image and a caption."""

def __init__(self):

"""Sets up the window and widgets."""

EasyFrame.__init__(self, title = "Image Demo")

imageLabel = self.addLabel(text = "",

row = 0, column = 0,

sticky = N+S+W+E)

textLabel = self.addLabel(text = "Smokey the cat",

row = 1, column = 0,

sticky = N+S+W+E)

# Load the image and associate it with the image label.

self.image = PhotoImage(file = "smokey.gif")

imageLabel["image"] = self.image

# Set the font and color of the caption.

font = Font(family = "Verdana", size = 20, slant = "italic")

textLabel["font"] = font

textLabel["foreground"] = "blue"

#Instantiate and pop up the window.

ImageDemo().mainloop()

Note that this program must import the PhotoImage and Font classes and the constants N, S, W, and E from the relevant tkinter modules. These constants are used to center the two labels in their respective grid cells, overriding the default placement of a label to the northwest. Here is the window produced by the program: