Displaying Text

Whether you need to show off the numbers for a sales presentation or the number of aliens obliterated, there are times where you'll want to display text on a graphics screen. The games module contains a class that allows you to do just that, aptly named Text.

Introducing the Big Score Program

Displaying text on a graphics window is just a matter of creating an object of the Text class. In the Big Score program, I add some text to the graphics window to display a score in the upper-right corner of the screen, just like in many classic arcade games. Figure 11.6 shows the results.

Figure 11.6: The impressively high score is displayed after a Text object is instantiated.

This Big Score program builds on the Background Image program. I add just one line of code and modify another.

Importing the color Module

The livewires package contains another module, color, which has a set of constants that represent different colors. These colors can be applied to certain graphics objects, including any Text or Message object. For a complete list of predefined colors, see the livewires documentation in Appendix A.

To choose from a group of possible colors, I import the color module by modifying the import line like so:

 from livewires import games, color 

Now, both the color and games modules are loaded from the livewires package.

Creating a Text Object

A Text object represents text on a Screen object. A Text object has attributes for x- and y-coordinates, a font size, a color, and some text too, of course.

In the Big Score program, I use a Text object to represent a game score. Just before I invoke the Screen object's mainloop() method, I create a Text object through the following code:

 games.Text(screen = my_screen, x = 500, y = 30,             text = :Score: 1756521",             size = 50, color = color.black) 

The constructor method for a Text object requires the following values: a Screen object, x- and y-coordinates, a string, a font size, and a color, as shown. I pass my_screen to screen since that's the active graphics window. Next I pass 500 to x and 30 to y, placing the center of the object at the coordinates (500,30). This puts the text in the upper-right corner of the graphics window. I pass the string "Score: 1756521" to text so that those characters will be displayed. Then I pass 50 to size so the font is nice and big, to match the score. Finally, I pass color the constant color.black from the color module to make the text, you guessed it, black.

You may have noticed that I don't assign the new Text object to a variable. That's okay since the the Screen object, my_screen, is designed to keep track of all of the graphics objects (just as a root window in a Tkinter program holds references to all of its widgets).

Once my_screen's mainloop() method is invoked, the graphics window is displayed along with the new Text object.