如何在字体上绘制轮廓（Pygame）

Question

如何在字体上绘制轮廓？
我想使用黑色字体，但背景必须是黑色的，所以很难看清字体。

我认为

myfont.render

不支持在字体上绘制轮廓。

还有其他办法吗？

Answer 1

Pygame 不支持开箱即用，但一种方法是以轮廓颜色渲染文本，并将其 blit 到多次移动的结果表面，然后在其顶部以所需的颜色渲染文本。

pgzero 使用这种技术；其代码的精简版本如下所示：

import pygame

_circle_cache = {}
def _circlepoints(r):
    r = int(round(r))
    if r in _circle_cache:
        return _circle_cache[r]
    x, y, e = r, 0, 1 - r
    _circle_cache[r] = points = []
    while x >= y:
        points.append((x, y))
        y += 1
        if e < 0:
            e += 2 * y - 1
        else:
            x -= 1
            e += 2 * (y - x) - 1
    points += [(y, x) for x, y in points if x > y]
    points += [(-x, y) for x, y in points if x]
    points += [(x, -y) for x, y in points if y]
    points.sort()
    return points

def render(text, font, gfcolor=pygame.Color('dodgerblue'), ocolor=(255, 255, 255), opx=2):
    textsurface = font.render(text, True, gfcolor).convert_alpha()
    w = textsurface.get_width() + 2 * opx
    h = font.get_height()

    osurf = pygame.Surface((w, h + 2 * opx)).convert_alpha()
    osurf.fill((0, 0, 0, 0))

    surf = osurf.copy()

    osurf.blit(font.render(text, True, ocolor).convert_alpha(), (0, 0))

    for dx, dy in _circlepoints(opx):
        surf.blit(osurf, (dx + opx, dy + opx))

    surf.blit(textsurface, (opx, opx))
    return surf

def main():
    pygame.init()

    font = pygame.font.SysFont(None, 64)

    screen = pygame.display.set_mode((350, 100))
    clock = pygame.time.Clock()

    while True:
        events = pygame.event.get()
        for e in events:
            if e.type == pygame.QUIT:
                return
        screen.fill((30, 30, 30))

        screen.blit(render('Hello World', font), (20, 20))

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

if __name__ == '__main__':
    main()

Answer 2

如果您是初学者并且不寻找非常复杂的代码，并且您只使用简单的字体，例如 arial、helvetica、calibri 等...... 您只需在“角”中将轮廓颜色的文本位图传输 4 次，然后将实际文本位图传输到其上即可：

white = pygame.Color(255,255,255)
black = pygame.Color(0,0,0)

def draw_text(x, y, string, col, size, window):
    font = pygame.font.SysFont("Impact", size )
    text = font.render(string, True, col)
    textbox = text.get_rect()
    textbox.center = (x, y)
    window.blit(text, textbox)

x = 300
y = 300

# TEXT OUTLINE

# top left
draw_text(x - 2, y-2, "Hello", black, 40, win)
# top right
draw_text(x + 2, y-2, "Hello", black, 40, win)
# btm left
draw_text(x - 2, y + 2, "Hello", black, 40, win)
# btm right
draw_text(x + 2, y + 2, "Hello", black, 40, win) 

# TEXT FILL

draw_text(x, y, "Hello", white, 40, win)

Answer 3

您可以使用蒙版为文本添加轮廓。这是一个例子：

import pygame

def add_outline_to_image(image: pygame.Surface, thickness: int, color: tuple, color_key: tuple = (255, 0, 255)) -> pygame.Surface:
    mask = pygame.mask.from_surface(image)
    mask_surf = mask.to_surface(setcolor=color)
    mask_surf.set_colorkey((0, 0, 0))

    new_img = pygame.Surface((image.get_width() + 2, image.get_height() + 2))
    new_img.fill(color_key)
    new_img.set_colorkey(color_key)

    for i in -thickness, thickness:
        new_img.blit(mask_surf, (i + thickness, thickness))
        new_img.blit(mask_surf, (thickness, i + thickness))
    new_img.blit(image, (thickness, thickness))

    return new_img

以下是我如何使用此函数创建带有 2px 黑色轮廓的白色文本：

text_surf = myfont.render("test", False, (255, 255, 255)).convert()
text_with_ouline = add_outline_to_image(text_surf, 2, (0, 0, 0))