Image Transparency Processing in Pygame

I am currently producing software on Pygame.
I would like to ask your opinion on image transmission processing.
I would like to fade out the image with the window created in Pygame.
Is there any good way?
I look forward to your kind cooperation.
(You can use a well-known library like Pillow.)

python3 windows-10 pygame

2022-09-30 14:56

1 Answers

Fading out with set_alpha is easy.
By the way, fade-out such as text is specifying BLEND_RGBA_MULT in special_flags, so I put it in the sample code as well.

import pygame aspg

# Changing the Todo Pathname
img_path=r "img\test.png"

defmain(img_path):
    clock = pg.time.clock()
    screen=pg.display.set_mode(640,480))

    # image initialization
    img_orig=pg.image.load(img_path).convert()
    colorkey=img_orig.get_at(0,0))#Treatment to make upper left transparent
    img_orig.set_colorkey(colorkey,pg.RLEACCEL)#Treatment to make upper left transparent
    img_surf=img_orig.copy()
    img_alpha=pg.Surface(img_surf.get_size(), pg.SRCALPHA)

    # text initialization
    font=pg.font.SysFont(None,64)
    blue=pg.Color('royalblue')
    txt_orig = font.render(u'Transparent.', True, blue)
    txt_surf = txt_orig.copy()
    txt_alpha=pg.Surface(txt_surf.get_size(), pg.SRCALPHA)

    alpha = 0
    isAdding = True

    while True:
        for event inputg.event.get():
            if event.type==pg.QUIT:
                return

        screen.fill ((30, 30, 30))

        # image drawing
        img_alpha.fill(255,255,255,alpha),special_flags=pg.BLEND_RGBA_MULT)
        img_surf=img_orig.copy()
        img_surf.set_alpha(alpha)#transparent treatment
        img_surf.blit(img_alpha,(0,0))
        screen.blit(img_surf,(10,50))

        # text drawing
        txt_alpha.fill(255,255,255,255-alpha))
        txt_surf = txt_orig.copy()
        txt_surf.blit(txt_alpha,(0,0), special_flags=pg.BLEND_RGBA_MULT)
        screen.blit(txt_surf,(10,10))

        pg.display.flip()
        clock.tick(30)

        # transparency update
        if isAdding:
            alpha + = 5
        else:
            alpha - = 5
        if alpha<=0 or alpha>=255:
            isAdding = not isAdding
            alpha = max (min(alpha,255), 0)

if__name__=='__main__':
    pg.init()
    main(img_path)
    pg.quit()

2022-09-30 14:56

If you have any answers or tips

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