Arrows

This game demonstrates how to have objects that:

• Respond to 'typing' and 'done typing' events to “keep moving” until a key is released (even when multiple keys are pressed)

• Moving objects in sync

The major trick is to have a field (e.g., active) that gets set to True during the 'typing' event and set to False during the 'done typing' event. Then, in a updating event, you can check if the field is True and move the object accordingly.

For handling left and right keys, you need two boolean fields. For all four direction keys, you would need four boolean fields. An alternative solution is to use a string field that gets set to 'left', 'right', 'up', or 'down' during the 'typing' event, and then set to 'none' during the 'done typing' event. Then, in the updating event, you can check the value of the field and move the object accordingly.

DataclassesDictionaries

from designer import *
from dataclasses import dataclass


@dataclass
class KeyBox:
    """
    Keyboxes are a combo of the box itself, its text label, and its "active" status
    When you press the left/right keys, their box becomes active, indicating what
    direction the pair of boxes will move in.
    """
    box: DesignerObject
    text: DesignerObject
    active: bool


@dataclass
class World:
    """
    Worlds have a left and a right keybox
    """
    left: KeyBox
    right: KeyBox


BOX_SIZE = 60
BOX_SPEED = 5


def create_key_box(letter: str, x: int, y: int) -> KeyBox:
    """ Create a key box (combines its text, its box, and its current active status) """
    return KeyBox(rectangle('black', BOX_SIZE, BOX_SIZE, x, y, border=1),
                  text('black', letter, BOX_SIZE, x, y),
                  False)


def create_world() -> World:
    """ Create a left and right box """
    center_x = get_width() / 2
    center_y = get_height() / 2
    return World(create_key_box('<', center_x - BOX_SIZE / 2, center_y),
                 create_key_box('>', center_x + BOX_SIZE / 2, center_y))


def fill_key_box(key_box: KeyBox):
    """ Fill in the box with red, activate the box """
    key_box.box.color = 'red'
    key_box.box.border = None
    key_box.text.color = 'white'
    key_box.active = True


def empty_key_box(key_box: KeyBox):
    """ Restore the black border, deactivate the box """
    key_box.box.color = 'black'
    key_box.box.border = 1
    key_box.text.color = 'black'
    key_box.active = False


def press_key(world: World, key: str):
    """ When a key is pressed, activate the boxes """
    if key == 'left':
        fill_key_box(world.left)
    if key == 'right':
        fill_key_box(world.right)


def release_key(world: World, key: str):
    """ When a key is released, deactivate the boxes """
    if key == 'left':
        empty_key_box(world.left)
    if key == 'right':
        empty_key_box(world.right)


def handle_box_movement(world: World):
    """
    If the left key is active, move the boxes left.
    If the right key is active, move the boxes right.
    """
    if world.left.active:
        move_boxes(world, -BOX_SPEED)
    if world.right.active:
        move_boxes(world, BOX_SPEED)


def move_boxes(world: World, x_speed: int):
    """ Move both sets of boxes """
    move_box(world.left, x_speed)
    move_box(world.right, x_speed)


def move_box(key_box: KeyBox, x_speed: int):
    """ Move the X position of the box and its associated text """
    key_box.box.x += x_speed
    key_box.text.x += x_speed


when('starting', create_world)
when('typing', press_key)
when('done typing', release_key)
when('updating', handle_box_movement)
start()