Question

我如下定义对象fences的类：

class GeoFence(pygame.sprite.Sprite):
    def __init__(self, rect, risk_level, *groups):
        self._layer = 1
        pygame.sprite.Sprite.__init__(self, groups)
        self.image = pygame.surface.Surface((rect.width, rect.height))
        self.image.fill(GREEN)
        self.rect = rect
        self.risk_level = risk_level
        self.font = pygame.font.SysFont('Arial', 25)
        screen.blit(self.font.render(risk_level, True, (255,0,0)), (200, 100))

每个对象fence是一个绿色矩形。我想在此矩形内显示文本。文本由从列表risk_level中随机选择的字符串risks定义。

all_sprites = pygame.sprite.LayeredUpdates()
fences = pygame.sprite.Group()

risks = ["HIGH","MEDIUM","LOW"]
for rect in (pygame.Rect(510,150,75,52), pygame.Rect(450,250,68,40), pygame.Rect(450,370,68,48)):
    risk = risks[random.randint(0,2)]
    GeoFence(rect, risk, all_sprites, fences)

此代码不会失败，但是标题不会显示在屏幕上的任何地方。

Answer 1

问题在于创建精灵时，您是在(200, 100)表面的坐标screen上书写文本，因此当下一帧清除屏幕时，文本将消失。

为了使GeoFence对象上的文本变亮，您需要将其变亮到坐标self.image上的(0, 0)上（如果应该将其左上对齐）。

如果表面应适合文本的大小，则可以首先渲染文本表面，并将其大小用作self.image表面的大小。

import random
import pygame


pygame.init()
screen = pygame.display.set_mode((640, 480))
clock = pygame.time.Clock()
BG_COLOR = pygame.Color('gray12')
GREEN = pygame.Color('green')
FONT = pygame.font.SysFont('Arial', 25)


class GeoFence(pygame.sprite.Sprite):

    def __init__(self, rect, risk_level, *groups):
        self._layer = 1
        pygame.sprite.Sprite.__init__(self, groups)
        text_surface = FONT.render(risk_level, True, (255,0,0))
        self.image = pygame.surface.Surface(text_surface.get_size())
        self.image.fill(GREEN)
        self.image.blit(text_surface, (0, 0))
        self.rect = self.image.get_rect(topleft=rect.topleft)
        self.risk_level = risk_level


all_sprites = pygame.sprite.LayeredUpdates()
fences = pygame.sprite.Group()

risks = ["HIGH","MEDIUM","LOW"]
for rect in (pygame.Rect(510,150,75,52), pygame.Rect(450,250,68,40),
             pygame.Rect(450,370,68,48)):
    risk = random.choice(risks)
    GeoFence(rect, risk, all_sprites, fences)

done = False
while not done:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            done = True

    all_sprites.update()

    screen.fill(BG_COLOR)
    all_sprites.draw(screen)
    pygame.display.flip()
    clock.tick(60)

还可以将另一种颜色传递给Font.render，该颜色将用作背景色。这样可以使您的代码稍微缩短一点：

class GeoFence(pygame.sprite.Sprite):

    def __init__(self, rect, risk_level, *groups):
        self._layer = 1
        pygame.sprite.Sprite.__init__(self, groups)
        self.image = FONT.render(risk_level, True, (255,0,0), GREEN)
        self.rect = self.image.get_rect(topleft=rect.topleft)
        self.risk_level = risk_level

如果要使文本居中，请为文本创建另一个矩形，将其center坐标设置为self.rect.center，然后将其用作文本的空白位置。执行此操作时，self.rect仍应位于默认位置（0，0）。

def __init__(self, rect, risk_level, *groups):
    self._layer = 1
    pygame.sprite.Sprite.__init__(self, groups)
    text_surface = FONT.render(risk_level, True, (255,0,0))
    self.image = pygame.surface.Surface(
        (text_surface.get_width()+110, text_surface.get_height()+20))
    self.image.fill(GREEN)
    # Create the rect, but don't set the coordinates yet.
    self.rect = self.image.get_rect()
    # Set the center of the text_rect to the center of the self.rect.
    text_rect = text_surface.get_rect(center=self.rect.center)
    # Then blit the text at the text_rect and it will be centered.
    self.image.blit(text_surface, text_rect)
    # Afterwards set the rect to the desired position.
    self.rect.topleft = rect.topleft

如何在矩形内添加文本？

1 个答案: