如何相对于其中心缩放 PyGame 图像（表面）？

Question

我对 pygame 相当陌生，正在开发我的第一款游戏。 （很抱歉，如果我问了一个愚蠢的问题）我试图让游戏的标题像呼吸效果一样缓慢增加和减少大小，以使主屏幕更具视觉吸引力。

这是我必须导入图像的内容：

name = self.dir_path + "pixeltitle.png"
self.pixeltitle = pg.image.load(name)
self.pixeltitlerect = self.pixeltitle.get_rect()
self.pixeltitlerect.center = (250,120)
self.screen.blit(self.pixeltitle,self.pixeltitlerect)

我有一个 while 循环，其中我增加了矩形的大小，但是它向右和向下移动。 有没有办法增加大小并使矩形的中心保持在同一个地方？ 还有一种方法可以使大小的增加/减少更平滑吗？ 下面是代码的其余部分：

clicked = False
        grow = 0
        mode = 'grow'
        while not clicked:
            if grow>40:
                mode = 'shrink'
            if grow<1:
                mode = 'grow'
                self.pixeltitle = pg.transform.scale(self.pixeltitle,(400,400))


            if mode == 'grow':
                grow+=1
            else:
                grow-=1

            xsize=400+int(grow)
            ysize=400+int(grow)

            self.pixeltitle = pg.transform.scale(self.pixeltitle,(xsize,ysize))
            self.pixeltitlerect.center = (250,120)
            self.screen.blit(self.pixeltitle,self.pixeltitlerect)
            pg.display.flip()

Answer 1

在 Surface 缩放后，您错过了更新self.pixeltitlerect的大小：

self.pixeltitle = pg.transform.scale(self.pixeltitle,(xsize,ysize))

# size of surface has been changed get the new rectangle
self.pixeltitlerect = self.pixeltitle.get_rect()

self.pixeltitlerect.center = (250,120)
self.screen.blit(self.pixeltitle,self.pixeltitlerect)

或者更短（参见pygame.Surface.get_rect() ）：

self.pixeltitle = pg.transform.scale(self.pixeltitle,(xsize,ysize))
self.pixeltitlerect = self.pixeltitle.get_rect(center = (250,120))
self.screen.blit(self.pixeltitle,self.pixeltitlerect)

---

不要缩放原始 Surface。 如果原始 Surface 被缩放，它将被扭曲。 保留原始图像self.pixeltitleorig并缩放原始图像：

self.pixeltitle = pygame.transform.scale(self.pixeltitleorig,(xsize,ysize))

另请参见变换比例和缩放表面

看例子：

import pygame
pygame.init()
window = pygame.display.set_mode((500, 500))
clock = pygame.time.Clock()

class ScalingSurface:
    def __init__(self):
        name = "pixeltitle.png"
        self.pixeltitleorig = pg.image.load(name)
        self.pixeltitle     = self.pixeltitleorig
        self.pixeltitlesize = self.pixeltitle.get_size()
        self.pixeltitlerect = self.pixeltitle.get_rect()
        self.pixeltitlerect.center = (250,120)
        self.mode = 'grow'
        self.grow = 0

    def update(self):
        if self.grow > 40:
            self.mode = 'shrink'
        if self.grow<1:
            self.mode = 'grow'
        self.grow += 1 if self.mode == 'grow' else -1

        xsize = self.pixeltitlesize[0] + round(self.grow)
        ysize = self.pixeltitlesize[1] + round(self.grow)
        self.pixeltitle = pygame.transform.scale(self.pixeltitleorig,(xsize,ysize))
        self.pixeltitlerect = self.pixeltitle.get_rect(center = (250,120))

    def draw(self, surf):
        surf.blit(self.pixeltitle,self.pixeltitlerect)

img = ScalingSurface()
run = True
while run:
    clock.tick(60)
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            run = False

    window.fill(0)
    img.update()
    img.draw(window)
    pygame.display.flip()