如何使用 alpha 通道为 png 图像着色？ [复制]

Question

我正在尝试编写典型的 dvd 弹跳屏幕保护程序。我对它很满意，但我想在每次它撞到墙上时改变标志的颜色。我使用了 fill()，但徽标变为彩色矩形。我想根据图像的 Alpha 通道更改徽标的颜色。

from pygame import *
import random

#set canvas size variables
width = 700
height = 450

#draw canvas
screen = display.set_mode((width,height))
display.set_caption('Graphics')

#initial XY coordinates where game starts
x = random.randint(1, width)
y = random.randint(1, height)

#import logo
logo_img = image.load('dvd_logo_alpha.png')

R = 255
G = 255
B = 255

def logo(x,y):
    screen.blit(logo_img, (x,y))

def Col():
    R = random.randint(100,255)
    G = random.randint(100,255)
    B = random.randint(100,255)

#speed of the logo
dx = 3
dy = 3

endProgram = False

while not endProgram:
    for e in event.get():
        if e.type == QUIT:
            endProgram = True

    #speed changes position XY
    x += dx
    y += dy

    #detection of collision with border of screen
    if y<0 or y>height-47:
        dy *= -1
        R = random.randint(100,255)
        G = random.randint(100,255)
        B = random.randint(100,255)
    if x<0 or x>width-100:
        dx *= -1
        R = random.randint(100,255)
        G = random.randint(100,255)
        B = random.randint(100,255)

    screen.fill((0))
    logo_img.fill((R,G,B)) #here is the problem I can not solve
    logo(x,y)
    display.update()

Answer 1

首先您必须创建一个带有 Alpha 通道的图像，以使 png 图像的透明区域不可见。使用 pygame.Surface.convert_alpha() 创建一个带有 Alpha 通道的表面：

tintImage = image.convert_alpha()

要通过pygame.Surface.fill() 为图像着色，special_flags 也必须设置为BLEND_RGBA_MULT。这导致图像的所有像素都与颜色相乘，而不是由颜色设置：

tintImage.fill((R, G, B, 255), None, BLEND_RGBA_MULT)

注意，由于图像必须用不同的颜色着色，因此必须保留原始图像。使用函数logo 复制图像，并对图像的副本“着色”和“blit”：

def logo(x, y, color):
    tintImage = logo_img.convert_alpha()
    tintImage.fill((R, G, B, 255), None, BLEND_RGBA_MULT)
    screen.blit(tintImage, (x, y))

在程序的主循环中调用函数：

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

    #speed changes position XY
    x += dx
    y += dy

    #detection of collision with border of screen
    if y<0 or y>height-47:
        dy *= -1
        R = random.randint(100,255)
        G = random.randint(100,255)
        B = random.randint(100,255)
    if x<0 or x>width-100:
        dx *= -1
        R = random.randint(100,255)
        G = random.randint(100,255)
        B = random.randint(100,255)

    screen.fill((0))

    #logo_img.fill((R,G,B)) #here is the problem I can not solve
    logo(x, y, (R, G, B))

    display.update()