PyGame Zero

PyGame Zero is a wrapper around PyGame so you don’t have to do quite so much work. PyGame Zero objects are PyGame objects. PyGame Zero defines a default game loop with some standard handlers and lets you get on with the game logic. Once you outgrow its simplicity you can easily switch to “proper” PyGame.

When you run an empty PyGame Zero file with the pgzrun command, this code (roughly) is already running for you behind the scenes:

import pygame

pygame.init()

size = 800, 600
screen = pygame.display.set_mode(size)

clock = pygame.time.Clock()
while True:
    for event in pygame.event.get():
        if event.type == pygame.KEYDOWN:
            if event.key == pygame.K_q and \
                event.mod & (pygame.KMOD_CTRL | pygame.KMOD_META):
                sys.exit()

    screen.fill(pygame.Color("black"))
    pygame.display.flip()
    clock.tick(60)

Magic Constants

PyGame Zero defines a few constants (which much be spelt exactly as they are below) which have a special meaning.

• WIDTH determines how wide the game window is
• HEIGHT determines how high the game window is
• TITLE is the text which will be in the titlebar of the game window
• ICON is the path to an image file which will be used as the icon for the game window

Magic Functions

PyGame Zero defines a few functions which you can write and which are called in a particular way as part of the game loop.

update()

In this function you should perform any work which involves changing the positions, sizes, images &c. of objects which will be drawn in the draw function.

Do not draw/blit anything to the screen here: that should be done in the draw() function

draw()

Draw whatever’s needed to the screen.

Do not do calculations here: those should be done in the update() function

on_mouse_down(pos, button)

Called when a mouse button is pressed. Provides pos as x, y and the number of the button pressed

on_mouse_up(pos, button)

Called when a mouse button is released. Provides pos as x, y and the number of the button pressed

on_mouse_move(pos, rel, buttons)

Called when the mouse is moved Provides pos as x, y; rel as the relative movement dx, dy; and buttons which were pressed

on_key_down(key, mod)

Called when a key is pressed Provides: key as a PyGame integer; mod as a bitmask of modifiers

on_key_up(key, mod)

Called when a key is released Provides: key as a PyGame integer; mod as a bitmask of modifiers

Mouse Buttons, Keys & Modifiers

Mouse Buttons

All these are part of the mouse object.

• LEFT
• MIDDLE
• RIGHT
• WHEEL_UP
• WHEEL_DOWN

Keys

All these are part of the keys object.

• Numbers are: keys.K_1, keys.K_2, &c.
• Letters are: keys.A, keys.B, &c.
• Movement keys are: keys.UP, keys.DOWN, keys.LEFT, keys.RIGHT, keys.HOME, keys.END, keys.PAGEUP, keys.PAGEDOWN
• Function keys are: keys.F1, keys.F2, &c.
• Most other keys are their full spoken name in caps, eg keys.RIGHTBRACKET, keys.QUESTION, keys.AT &c.

Modifiers

All these are part of the keymods object.

• Shifts are: keymods.SHIFT, keymods.LSHIFT, keymods.RSHIFT
• Ctrls are: keymods.CTRL, keymods.LCTRL, keymods.RCTRL
• Alts are: keymods.ALT, keymods.LALT, keymods.RALT

Colours

Colours can be any of:

• An (R, G, B) sequence, eg (255, 0, 0) for solid red
• An HTML colour name, eg "red"
• An HTML hex colour string, eg "#FF0000"

Some examples

• AliceBlue
• beige
• black
• blue
• BlueViolet
• brown
• CadetBlue
• chartreuse
• coral
• CornflowerBlue
• cornsilk
• cyan
• DarkGreen
• DarkOliveGreen
• DarkOrange
• DarkOrchid
• DarkSalmon
• DarkSlateBlue
• DarkViolet
• DeepSkyBlue
• DodgerBlue
• firebrick
• FloralWhite
• ForestGreen
• gold
• grey
• green
• GreenYellow
• HotPink
• ivory
• khaki
• lavender
• LawnGreen
• light
• LightBlue
• LimeGreen
• linen
• magenta
• maroon
• MidnightBlue
• MintCream
• NavyBlue
• orange
• OrangeRed
• orchid
• PaleGreen
• PaleTurquoise
• plum
• PowderBlue
• purple
• red
• RoyalBlue
• SeaGreen
• SkyBlue
• SlateGray
• thistle
• tomato
• turquoise
• violet
• white
• yellow