如何在pygame中围绕精灵或图像绘制边框？

Question

我想画一个图像的红色边框，但不知道如何。

我试图填充Hero sprite的图像，并将colorkey设置为红色self.image.set_colorkey(red)，但这会使图像不可见。

在图像上绘制一个红色矩形，完全填充它：pygame.draw.rect(self.image, red, [0, 0, width, height])。

我只是想要一个红色的边框，这将有助于未来的碰撞检测。

在main.py代码：

import pygame 
from pygame import * 
import sprites 
from sprites import * 
pygame.init() 

width = 640 
height = 480 
color = (255, 255, 255) #white 
x = 0 
y = 0 
speed = 3 

screen = pygame.display.set_mode((width, height)) 
pygame.display.set_caption("Mushroom") 
icon = pygame.image.load('icon.bmp') 
pygame.display.set_icon(icon) 
sprites_list = pygame.sprite.Group() 

hero = Hero('mushroom.png', 48, 48) 
hero.rect.x = 200; 
hero.rect.y = 300; 

sprites_list.add(hero) 

running = True 
clock = pygame.time.Clock() 
while running: 
    sprites_list.update() 
    screen.fill((color)) 
    sprites_list.draw(screen) 
    hero.draw(screen) 
    pygame.display.flip() 
    pygame.display.update() 

    for event in pygame.event.get(): 
     if event.type == pygame.QUIT: 
      running = False 

    key = pygame.key.get_pressed() 
    if key[pygame.K_LEFT]: 
     hero.left(speed) 
    if key[pygame.K_RIGHT]: 
     hero.right(speed) 
    if key[pygame.K_UP]: 
     hero.up(speed) 
    if key[pygame.K_DOWN]: 
     hero.down(speed) 

    clock.tick(60) 

中的代码sprites.py：

import pygame 
from pygame import * 

red = (255, 0, 0) 

class Hero(pygame.sprite.Sprite): 
    def __init__(self, color, width, height): 

     super().__init__() 

     self.image = pygame.image.load('mushroom.png') 
     self.image = pygame.Surface((width, height)) 
     self.image.fill(red) 
     self.image.set_colorkey(red) 

     pygame.draw.rect(self.image, red, [0, 0, width, height]) 
     self.rect = self.image.get_rect() 

    def draw(self, screen): 
     screen.blit(self.image, self.rect) 

    def right(self, pixels): 
     self.rect.x += pixels 
    def left(self, pixels): 
     self.rect.x -= pixels 
    def up(self, pixels): 
     self.rect.y -= pixels 
    def down(self, pixels): 
     self.rect.y += pixels 

Answer 1

你有两个选择：

1. 画一个红色的，在蘑菇图像/表面上未填充的矩形。
2. 在draw方法中绘制矩形的每一帧。

如果你想有一个非填充矩形，你必须通过一个int作为最后一个参数（行width）到pygame.draw.rect。

import pygame 


pygame.init() 

white = (255, 255, 255) 
red = (255, 0, 0) 

# The original 
hero_img = pygame.Surface((48, 48), pygame.SRCALPHA) 
pygame.draw.circle(hero_img, (30, 90, 170), (24, 24), 20) 
# ---Solution 1--- 
# You could create a copy of the original image and 
# then draw the rect onto it. 
hero_img_with_border = hero_img.copy() 
# Draw the red border. Pass an int as the last argument (width) 
# to draw a non-filled rect. For 2 pixel linewidth the rect has 
# to be one pixel smaller. 
pygame.draw.rect(hero_img_with_border, red, (0, 0, 47, 47), 2) 


class Hero(pygame.sprite.Sprite): 

    def __init__(self, position): 
     super().__init__() 
     self.image = hero_img 
     self.rect = self.image.get_rect(center=position) 
     self.speed = 3 

    def draw(self, screen): 
     # ---Solution 2--- 
     # Just draw the non-filled rect here. 
     pygame.draw.rect(screen, red, self.rect, 2) 

    def right(self): 
     self.rect.x += self.speed 
    def left(self): 
     self.rect.x -= self.speed 
    def up(self): 
     self.rect.y -= self.speed 
    def down(self): 
     self.rect.y += self.speed 


screen = pygame.display.set_mode((640, 480)) 

sprites_list = pygame.sprite.Group() 
# You can pass the coords and change the rect in the __init__ method. 
hero = Hero((200, 300)) 
sprites_list.add(hero) 

running = True 
clock = pygame.time.Clock() 

while running: 
    for event in pygame.event.get(): 
     if event.type == pygame.QUIT: 
      running = False 

    key = pygame.key.get_pressed() 
    if key[pygame.K_LEFT]: 
     hero.left() 
    if key[pygame.K_RIGHT]: 
     hero.right() 
    if key[pygame.K_UP]: 
     hero.up() 
    if key[pygame.K_DOWN]: 
     hero.down() 

    sprites_list.update() 

    screen.fill(white) 
    sprites_list.draw(screen) 
    # If you use solution 1, you don't need the draw method, since 
    # sprites_list.draw blits the image already. 
    hero.draw(screen) 
    screen.blit(hero_img, (100, 100)) 

    pygame.display.flip() 
    clock.tick(60) 

---

我已经改变了几件事：speed可能是精灵的属性，你可以通过与坐标元组到__init__方法，然后把它传递给get_rect为center或topleft的说法。

self.image.get_rect(center=position)