Pygame writing using fonts and labels

[Windspar]

Here my example.

import os
import pygame
from types import SimpleNamespace
from pygame.sprite import Sprite, Group

# Wrap pygame builtin colors into namespace.
color = SimpleNamespace(**pygame.color.THECOLORS)

# Interface
class Scene:
    def __init__(self, manager):
        self.manager = manager

    def on_draw(self, surface): pass
    def on_event(self, event): pass
    def on_update(self, delta): pass

    def on_quit(self):
        self.manager.quit()

# Handles what scene is active
class Manager:
    def __init__(self, caption, width, height, center=True, flags=0):
        if center:
            os.environ['SDL_VIDEO_CENTERED'] = '1'

        # Basic pygame setup
        pygame.display.set_caption(caption)
        self.surface = pygame.display.set_mode((width, height), flags)
        self.rect = self.surface.get_rect()
        self.clock = pygame.time.Clock()
        self.running = False
        self.delta = 0
        self.fps = 60

        self.scene = Scene(self)

    def mainloop(self):
        self.running = True
        while self.running:
            for event in pygame.event.get():
                if event.type == pygame.QUIT:
                    self.scene.on_quit()
                else:
                    self.scene.on_event(event)

            self.scene.on_update(self.delta)
            self.scene.on_draw(self.surface)
            pygame.display.flip()
            self.delta = self.clock.tick(self.fps)

    def quit(self):
        self.running = False

class Label(Sprite):
    def __init__(self, text, font, color, position, anchor="topleft"):
        Sprite.__init__(self)
        self._text = text
        self._font = font
        self._color = color
        self._anchor = anchor
        self._position = pygame.Vector2(position)
        self.render()

    def render(self):
        self.image = self._font.render(self._text, 1, self._color)
        self.rect = self.image.get_rect(**{self._anchor: self._position})

    def set_text(self, text):
        self._text = text
        self.render()

class Timer:
    def __init__(self, interval, callback, user_data=None):
        self.tick = pygame.time.get_ticks() + interval
        self.interval = interval
        self.callback = callback
        self.user_data = user_data

    def expire(self, ticks):
        if ticks > self.tick:
            return True

        return False

    def update(self, ticks):
        if ticks > self.tick:
            self.callback(self)
            self.tick += self.interval

class CountDown:
    def __init__(self, count, update_callback, callback, interval=1000):
        self.timer = Timer(interval, self.timer_update)
        self.count = count
        self.callback = callback
        self.update_callback = update_callback

    def timer_update(self, timer):
        self.count -= 1
        if self.count < 1:
            self.callback()
        else:
            self.update_callback(self)

    def update(self, ticks):
        self.timer.update(ticks)

class MainScene(Scene):
    def __init__(self, manager):
        Scene.__init__(self, manager)
        position = manager.rect.centerx, 20
        self.font = pygame.font.Font(None, 32)
        self.label = Label("Welcome", self.font, color.dodgerblue, position, "midtop")
        self.quit_label = None
        self.quit_countdown = None
        self.sprites = Group(self.label)

    def on_draw(self, surface):
        surface.fill(color.black)
        self.sprites.draw(surface)

    def on_quit(self):
        if self.quit_countdown is None:
            self.quit_countdown = CountDown(5, self.update_countdown_label, self.manager.quit)
            self.update_countdown_label(self.quit_countdown)

    def on_update(self, delta):
        ticks = pygame.time.get_ticks()
        if self.quit_countdown:
            self.quit_countdown.update(ticks)

    def update_countdown_label(self, countdown):
        text = "Closing in ... {}"
        if self.quit_label:
            self.quit_label.set_text(text.format(countdown.count))
        else:
            self.quit_label = Label(text.format(countdown.count), self.font,
                              color.firebrick, self.manager.rect.center, "center")
            self.quit_label.add(self.sprites)

if __name__ == "__main__":
    pygame.init()
    manager = Manager("Countdown Example", 800, 600)
    manager.scene = MainScene(manager)
    manager.mainloop()