Keyboard events

Same as with the mouse, when a key is pressed an event is generated: pygame.KEYDOWN. To know which specific key it is, we compare it with the possible options. For example:

for event in pygame.event.get():
    if event.type == pygame.KEYDOWN:
        if event.key == pygame.K_q:
            exit(0)
        elif event.key == pygame.K_LEFT:
            print("You pressed LEFT")
        elif event.key == pygame.K_RIGHT:
            print("You pressed RIGHT")

This is what the program does:

1. It loops through every event in the event queue.
2. For each event, it checks if it's a keypress.
3. If it's a keypress, it will check what key it was, asking one possibility at a time:
   • If it's the Q key, it closes the program.
   • If it's the left arrow key, it prints "You pressed LEFT".
   • If it's the right arrow key, it prints "You pressed RIGHT".

Each KEYDOWN event comes with a key, telling which key it was that the player pressed.

Inside pygame there are a bunch of things that represent each key, and we can use to compare. For example, pygame.K_q represents the 'Q' key in the keyboard. To know if the player pressed this key, we compare it with event.key, like this: event.key == pygame.K_q. If instead we want to know when the left arrow key was pressed, with compare with pygame.K_LEFT.

Challenges

Let's see how well you understood all that:

• Try the example above in your program. Where do you think it goes?
• Add code to the example so that the program closes when either of these things happens:
  • Q is pressed.
  • The player clicks the button to close the window.
• Add code to the example so that it prints messages when pressing the up and down arrow keys.