如何在 Pygame 中制作循环倒数计时器？

Question

如何在 Pygame 中进行这种倒计时？ （我正在寻找如何使圆圈的周长减小，这就是问题所在，因为显示时间并不难） 请记住，圆的周长和显示的时间应该成比例。

Answer 1

只需使用 pygame.draw.arc 并根据计数器指定 stop_angle 参数：

percentage = counter/100
end_angle = 2 * math.pi * percentage
pygame.draw.arc(window, (255, 0, 0), arc_rect, 0, end_angle, 10)

---

小例子：

import pygame
import math

pygame.init()
window = pygame.display.set_mode((200, 200))
clock = pygame.time.Clock()
font = pygame.font.SysFont(None, 100)
counter = 100
text = font.render(str(counter), True, (0, 128, 0))

timer_event = pygame.USEREVENT+1
pygame.time.set_timer(timer_event, 1000)

def drawArc(surf, color, center, radius, width, end_angle):
    arc_rect = pygame.Rect(0, 0, radius*2, radius*2)
    arc_rect.center = center
    pygame.draw.arc(surf, color, arc_rect, 0, end_angle, width)

run = True
while run:
    clock.tick(60)
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            run = False
        elif event.type == timer_event:
            counter -= 1
            text = font.render(str(counter), True, (0, 128, 0))
            if counter == 0:
                pygame.time.set_timer(timer_event, 0)                

    window.fill((255, 255, 255))
    text_rect = text.get_rect(center = window.get_rect().center)
    window.blit(text, text_rect)
    drawArc(window, (255, 0, 0), (100, 100), 90, 10, 2*math.pi*counter/100)
    pygame.display.flip()

pygame.quit()
exit()

遗憾的是，width > 1 的 pygame.draw.arc 的质量很差。然而，这可以改进，使用cv2 和cv2.ellipse：

import pygame
import cv2
import numpy

pygame.init()
window = pygame.display.set_mode((200, 200))
clock = pygame.time.Clock()
font = pygame.font.SysFont(None, 100)
counter = 100
text = font.render(str(counter), True, (0, 128, 0))

timer_event = pygame.USEREVENT+1
pygame.time.set_timer(timer_event, 1000)

def drawArcCv2(surf, color, center, radius, width, end_angle):
    circle_image = numpy.zeros((radius*2+4, radius*2+4, 4), dtype = numpy.uint8)
    circle_image = cv2.ellipse(circle_image, (radius+2, radius+2),
        (radius-width//2, radius-width//2), 0, 0, end_angle, (*color, 255), width, lineType=cv2.LINE_AA) 
    circle_surface = pygame.image.frombuffer(circle_image.flatten(), (radius*2+4, radius*2+4), 'RGBA')
    surf.blit(circle_surface, circle_surface.get_rect(center = center))

run = True
while run:
    clock.tick(60)
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            run = False
        elif event.type == timer_event:
            counter -= 1
            text = font.render(str(counter), True, (0, 128, 0))
            if counter == 0:
                pygame.time.set_timer(timer_event, 0)                

    window.fill((255, 255, 255))
    text_rect = text.get_rect(center = window.get_rect().center)
    window.blit(text, text_rect)
    drawArcCv2(window, (255, 0, 0), (100, 100), 90, 10, 360*counter/100)
    pygame.display.flip()

pygame.quit()
exit()