在pygame中在透明表面上渲染抗锯齿文本

Question

我正在写一个函数，这个函数接收一个字符串，把它分成多行，然后返回一个表面，每一行都在上一行的下面显示。

举个例子：

Line1\nLine 2

显示成：

Line1
Line2

不过，我的问题是我无法返回一个透明度合适的表面给调用这个函数的地方。我试过用颜色键，但它在处理抗锯齿文本时不起作用。有没有什么办法可以解决这个问题？谢谢大家的回答。

我的代码：（目前在文本周围留了一个难看的紫色阴影）

def render_message(messages):
    surfaces = []
    height = 0
    max_width = 0

    for message in messages.split('\n'):
        surf = FONT.render(message, True, (0, 0, 0))
        surfaces.append(surf)
        height += surf.get_height() + 5
        if surf.get_width() > max_width:
            max_width = surf.get_width()

    result = pygame.Surface((max_width, height))
    result.fill((255, 0, 255))
    result.set_colorkey((255, 0, 255))

    top = 0
    for surface in surfaces:
        result.blit(surface, (max_width/2-surface.get_width()/2, top))
        top += surface.get_height() + 5

    return result

Answer 1

最好的解决办法是不要使用颜色键，而是使用透明度通道。也就是说，不要像这样：

result = pygame.Surface((max_width, height))
result.fill((255, 0, 255))
result.set_colorkey((255, 0, 255))

试试用这个：

result = pygame.Surface((max_width, height), pygame.SRCALPHA)

Answer 2

我搞定了。主要发现的是：没有抗锯齿（AA）就意味着自动透明。如果有抗锯齿，你还需要设置颜色键

这里有个可以运行的例子，它会切换背景，以确保它是透明的。

import pygame
from pygame import Surface
#from pygame.locals import Rect, Color
from pygame.locals import *

class TextWall():
    def __init__(self, font=None, size=300):
        # for simplicity uses one font, one size for now.
        # You also can make font size, .text, etc be properties so they *automatically* toggle dirty bool.
        self.font_name = font
        self.font_size = size
        self.color_fg = Color("white")
        self.color_bg = Color("gray20")
        self.aa = True 
        self.text = "hi world"

        self.dirty = True
        self.font = pygame.font.Font(font, size)
        self.screen = pygame.display.get_surface()


    def _render(self):
        # re-render
        """no AA = automatic transparent. With AA you need to set the color key too"""
        self.dirty = False        
        self.text1 = self.font.render(self.text, self.aa, self.color_fg)            
        self.rect1 = self.text1.get_rect()

    def draw(self):
        # blits use cached surface, until text change makes it dirty
        if self.dirty or self.text1 is None: self._render()
        self.screen.blit(self.text1, self.rect1)

    def text(self, text):
        self.dirty = True
        self.text_message = text # parse

class Game():
    done = False
    def __init__(self):
        pygame.init()
        self.screen = pygame.display.set_mode ((640,480))
        self.text = Surface([200,100])

        self.text_wall = TextWall()
        self.toggle_bg = True
    def loop(self):
        while not self.done:
            self.handle_events()
            self.draw()

    def draw(self):
        if self.toggle_bg: bg = Color("darkred")
        else: bg = Color("gray20")

        self.screen.fill(bg)        
        self.text_wall.draw()        
        pygame.display.update()

    def handle_events(self):
        for event in pygame.event.get():
            if event.type == pygame.QUIT: self.done = True

            elif event.type == KEYDOWN:
                if event.key == K_ESCAPE: self.done = True                
                elif event.key == K_SPACE: self.toggle_bg = not self.toggle_bg
                elif event.key == K_a: 
                    self.text_wall.aa = not self.text_wall.aa
                    self.text_wall.dirty = True


if __name__ == "__main__":
    g = Game()
    g.loop()

补充：代码改进了，使用了透明通道，而不是设置颜色键。

Answer 3

我发了第二个答案，因为这个问题比较复杂，大家可能想看看两个答案。

• 1 和 2 用来减小或增大字体大小
• space 用来切换背景

我没有提到文本换行的部分。你可以编辑 parse_text() 来创建你想要的文本列表。

import pygame
from pygame import Surface
from pygame.locals import *
# Todo: remove font object from TextLine() , to TextWall(). Then share a list of font's with any line.

"""Example of multi-line text class, with alpha transparency."""
lorem = """Lorem ipsum dolor sit amet, consectetur adipiscing elit. Sed aliquet
tellus eros, eu faucibus dui. Phasellus eleifend, massa id ornare sodales, est urna
congue tellus, vitae varius metus nunc non enim. Mauris elementum, arcu vitae tempor euismod, justo turpis malesuada est, sed dictum nunc nulla nec mauris. Cras felis eros, elementum vitae sollicitudin in, elementum et augue. Proin eget nunc at dui congue pretium. Donec ut ipsum ut lacus mollis tristique. In pretium varius dui eu dictum.

Proin pulvinar metus nec mi semper semper. Pellentesque habitant morbi tristique
senectus et netus et malesuada fames ac turpis egestas. Proin in diam odio. Vestibulum
at neque sed ante sodales eleifend quis id dui. Mauris sollicitudin, metus a semper consectetur,
est lectus varius erat, sit amet ultrices tortor nisi id justo. Aliquam elementum vestibulum dui ut auctor. Mauris commodo sapien vitae augue tempus sagittis. Morbi a nibh lectus, sed porta nibh. Donec et est ac dui sodales aliquet tristique et arcu. Nullam enim felis, posuere vel rutrum eu, euismod a purus. Morbi porta cursus libero, id rutrum elit lacinia vitae.

In condimentum ultrices ipsum, ut convallis odio egestas et. Cras at egestas elit. Morbi
quis neque ligula. Sed tempor, sem at fringilla rhoncus, diam quam mollis nisi, vitae semper
mi massa sit amet tellus. Vivamus congue commodo ornare. Morbi et mi non sem malesuada rutrum. Etiam est purus, interdum ut placerat sit amet, tempus eget eros. Duis eget augue quis diam facilisis blandit. Ut vulputate adipiscing eleifend. """

class TextLine(object):
    # Manages drawing and caching a single line of text
    # You can make font size, .color_fg etc be properties so they *automatically* toggle dirty bool.
    def __init__(self, font=None, size=16, text="hi world"):        
        self.font_name = font
        self.font_size = size
        self.color_fg = Color("white")
        self.color_bg = Color("gray20")

        self._aa = True 
        self._text = text                
        self.font = pygame.font.Font(font, size)
        self.screen = pygame.display.get_surface()

        self.dirty = True
        self.image = None
        self._render()

    def _render(self):
        # render for cache
        """no AA = automatic transparent. With AA you need to set the color key too"""
        self.dirty = False        
        self.image = self.font.render(self._text, self.aa, self.color_fg)            
        self.rect = self.image.get_rect()

    def draw(self):
        # Call this do draw, always prefers to use cache
        if self.dirty or (self.image is None): self._render()
        self.screen.blit(self.image, self.rect)        

    @property
    def text(self):
        return self._text

    @text.setter
    def text(self, text):
        self.dirty = True
        self._text = text

    @property
    def aa(self): return self._aa

    @aa.setter
    def aa(self, aa):
        self.dirty = True
        self._aa = aa

class TextWall(object):
    # Manages multiple lines of text / paragraphs.
    def __init__(self, font=None, size=16):
        self.font = font
        self.font_size = size        
        self.offset = Rect(20,20,1,1) # offset of whole wall

        self.screen = pygame.display.get_surface()
        self.dirty = True
        self.text_lines = []
        self._text_paragraph = "Empty\nText"
        self._render()

    def _render(self):
        # render list 
        self.dirty = False
        self.text_lines = [ TextLine(self.font, self.font_size, line) for line in self._text_paragraph ]        

        # offset whole paragraph
        self.text_lines[0].rect.top = self.offset.top

        # offset the height of each line
        prev = Rect(0,0,0,0)        
        for t in self.text_lines:
            t.rect.top += prev.bottom
            t.rect.left = self.offset.left
            prev = t.rect

    def parse_text(self, text):
        # parse raw text to something usable
        self._text_paragraph = text.split("\n")
        self._render()

    def draw(self):
        # draw with cached surfaces    
        if self.dirty: self._render()
        for text in self.text_lines: text.draw()

    @property
    def font_size(self):
        return self._font_size

    @font_size.setter
    def font_size(self, size):
        self.dirty = True
        self._font_size = size

    @property
    def text(self):
        return self._text_paragraph

    @text.setter
    def text(self, text_paragraph):
        self.dirty = True
        self.parse_text(text_paragraph)

class Game():
    done = False
    def __init__(self):
        pygame.init()
        self.screen = pygame.display.set_mode ((640,480))
        self.text = Surface([200,100])

        self.text_wall = TextWall()
        self.toggle_bg = True

        self.text_wall.parse_text(lorem)

    def loop(self):
        while not self.done:
            self.handle_events()
            self.draw()

    def draw(self):
        if self.toggle_bg: bg = Color("gray60")
        else: bg = Color("gray20")

        self.screen.fill(bg)        
        self.text_wall.draw()        
        pygame.display.update()

    def handle_events(self):
        for event in pygame.event.get():
            if event.type == pygame.QUIT: self.done = True

            elif event.type == KEYDOWN:
                if event.key == K_ESCAPE: self.done = True                
                elif event.key == K_SPACE: self.toggle_bg = not self.toggle_bg
                elif event.key == K_1: self.text_wall.font_size -= 3
                elif event.key == K_2: self.text_wall.font_size += 3

if __name__ == "__main__":
    g = Game()
    g.loop()