Keyboard and mouse input

This page explains how to read keyboard and mouse input when you build an interactive drawing with DrawZero.

Event loop and tick

Real-time programs must check input many times per second. DrawZero does this inside tick(): it pumps the pygame event queue, refreshes key and mouse state, and converts mouse coordinates into the 1000x1000 virtual canvas. Call tick() once per frame (most examples put it at the end of the loop).

from drawzero import *

while True:
    # read input collected by the last tick
    # update game state + draw
    tick()  # process events and keep ~30 FPS

If you stop calling tick(), the window freezes and input stops updating.

State helpers

get_keys_pressed()

Returns a KeysPressed object (a wrapper over pygame.key.get_pressed()). It behaves like a list of booleans and accepts key codes or key names.

from drawzero import *

keys = get_keys_pressed()
if keys[K.LEFT] or keys[K.a]:
    player_x -= 5
if keys["SPACE"]:
    player_jump()

Use K/KEY constants for reliable names (for example K.LEFT, K.SPACE, K.a).

keys_mods_pressed()

Returns an integer bitmask of active modifiers (same as pygame.key.get_mods()). Check it with bitwise & and the K.MOD_* constants.

from drawzero import *

mods = keys_mods_pressed()
if mods & K.MOD_CTRL and get_keys_pressed()[K.s]:
    save_project()
if mods & K.MOD_SHIFT:
    speed *= 2

get_mouse_pressed()

Returns a tuple of booleans (left, middle, right) describing which mouse buttons are held down.

from drawzero import *

left, middle, right = get_mouse_pressed()
if left:
    draw_circle(mouse_pos(), radius=10)

mouse_pos()

Returns the current mouse position in virtual canvas coordinates.

Event queues

Event queues are lists cleared on every tick(). They contain pygame event objects collected since the previous tick, in order.

keysdown / keysup

Lists of key press and key release events. Use event.key to compare with K constants and event.unicode to read typed characters.

from drawzero import *

for event in keysdown:
    if event.key == K.SPACE:
        spawn_bullet()
    if event.unicode:
        typed_text += event.unicode

event.mod is a modifier bitmask if you need it.

If you only care about non-text keys (arrows, space, escape), check event.key directly:

from drawzero import *

for event in keysdown:
    if event.key == K.SPACE:
        print("space")
    elif event.key == K.LEFT:
        print("left")

mousemotions

List of mouse motion events. Each event has:

• event.pos – current cursor position (virtual canvas coordinates)
• event.rel – movement delta since last motion
• event.buttons – tuple of held mouse buttons

from drawzero import *

for event in mousemotions:
    trail.add_point(event.pos)

mousebuttonsdown / mousebuttonsup

Lists of mouse button events. Each event has:

• event.button – button number (1 left, 2 middle, 3 right, 4/5 wheel)
• event.pos – click position (virtual canvas coordinates)

from drawzero import *

for event in mousebuttonsdown:
    if event.button == 1:
        start_drag(event.pos)

You can also read both the click position and the button number:

from drawzero import *

for event in mousebuttonsdown:
    x, y = event.pos
    print(f"button={event.button} pos=({x:.1f}, {y:.1f})")

Putting it all together

from drawzero import *

while True:
    keys = get_keys_pressed()
    if keys[K.LEFT]:
        player.move(-5, 0)
    if keys[K.RIGHT]:
        player.move(5, 0)

    for event in keysdown:
        if event.key == K.SPACE:
            player.jump()

    for event in mousebuttonsdown:
        if event.button == 1:
            player.shoot(event.pos)

    # update the canvas here
    tick()

You can compare this pattern with the 16_keyboard_and_mouse.py example listed in Examples.

Tips for smooth interaction

• Call tick() regularly to keep input fresh.
• Avoid long blocking code (like time.sleep(5)) inside the loop.
• Use keys_mods_pressed() with K.MOD_* for keyboard shortcuts.
• If you only need the latest mouse position, call mouse_pos().
• Print events while developing to see the actual values on your hardware.

Where to learn more

• Animation basics explains how tick() fits inside the drawing pipeline.
• Examples points to ready-made scripts you can run and modify.