如何向pygame中的表面對象添加alpha值？

Question

我正在嘗試製作一個菜單屏幕，其中'新遊戲'和'加載遊戲'圖標在它們周圍沒有框，直到鼠標懸停在它們上面，此時它們有一個不透明的藍色框。我還沒有在代碼中實現鼠標控件，因爲我目前無法讓藍色框變得不透明。任何建議都會很棒。當前代碼運行時屏幕顯示爲黑色，但刪除第30行會導致屏幕顯示，但不顯示alpha值。

import random, pygame, sys 
from pygame.locals import * 

FPS = 30 # frames per second, the general speed of the program 
WINDOWWIDTH = 1000 # size of the window's width in pixels 
WINDOWHEIGHT = 600 # size of window's height in pixels 

#   R G B 
WHITE = (255, 255, 255) 
RED  = (255, 0, 0) 
BLUEINVIS = (0, 0, 255, 255) 
BLUEOP = (0, 0, 255, 128) 

# Colors 

TEXTCOLOR = WHITE 
TEXTBOXCOLOR = BLUEINVIS 
HIGHLIGHTCOLOR = BLUEOP 

BASICFONTSIZE = 20 


def main(): 
    global FPSCLOCK, DISPLAYSURF, BASICFONT 
    pygame.init() 
    FPSCLOCK = pygame.time.Clock() 
    DISPLAYSURF = pygame.display.set_mode((WINDOWWIDTH, WINDOWHEIGHT)) 
    DISPLAYSURF = DISPLAYSURF.convert_alpha() 
    pygame.display.set_caption('Menu') 

    BASICFONT = pygame.font.Font('freesansbold.ttf', 50) 


    NEW_SURF, NEW_RECT = makeText('New Game', TEXTCOLOR, TEXTBOXCOLOR, WINDOWWIDTH/ 2, WINDOWHEIGHT - (WINDOWHEIGHT * 3/8)) 
    LOAD_SURF, LOAD_RECT = makeText('Load Game', TEXTCOLOR, TEXTBOXCOLOR, WINDOWWIDTH/2, WINDOWHEIGHT - (WINDOWHEIGHT/4)) 

    DISPLAYSURF.convert_alpha() 

    while True: # main game loop 

     DISPLAYSURF.fill(RED) 
     DISPLAYSURF.blit(NEW_SURF, NEW_RECT) 
     DISPLAYSURF.blit(LOAD_SURF, LOAD_RECT) 


     for event in pygame.event.get(): # event handling loop 
      #if event.type == MOUSEBUTTONUP: 

       #if NEW_RECT.collidepoint(event.pos): 

       #elif LOAD_RECT.collidepoint(event.pos): 

      #if newRectObj.collidepoint(event.pos): 
       #newSurfaceObj = fontObj.render('New Game', True, TEXTCOLOR, HIGHLIGHTCOLOR)    

      if event.type == QUIT: 
       pygame.quit() 
       sys.exit() 

     pygame.display.update() 
     FPSCLOCK.tick(FPS) 

def makeText(text, color, bgcolor, x, y): 
    # create the Surface and Rect objects for some text. 
    textSurf = BASICFONT.render(text, True, color, bgcolor) 
    textRect = textSurf.get_rect() 
    textRect.center = (x, y) 
    return (textSurf, textRect) 

if __name__ == '__main__': 
    main() 

Answer 1

用途：surface = surface.convert_alpha()

使用surface.convert_alpha()單獨什麼都不做。 convert_alpha()返回一個alpha值的表面。

http://www.pygame.org/docs/ref/surface.html#pygame.Surface.convert_alpha

例如：image1 = pygame.image.load("images/person.png").convert_alpha()

Answer 2

如果我用這個片段取代你的代碼，它會顯示你的文字（藍色白色）當光標懸停它（從this SO question啓發）。我還添加了一些透明度，如果你想（取消set_alpha線）：

def main(): 
    global BASICFONT 
    pygame.init() 
    FPSCLOCK = pygame.time.Clock() 
    DISPLAYSURF = pygame.display.set_mode((WINDOWWIDTH, WINDOWHEIGHT)) 
    background=pygame.Surface((DISPLAYSURF.get_rect().width, DISPLAYSURF.get_rect().height)) 
    background.fill(RED) 

    BASICFONT = pygame.font.Font('freesansbold.ttf', 50) 

    pygame.display.set_caption('Menu') 

    NEW_SURF, NEW_RECT = makeText('New Game', TEXTCOLOR, TEXTBOXCOLOR, WINDOWWIDTH/ 2, WINDOWHEIGHT - (WINDOWHEIGHT * 3/8)) 
    LOAD_SURF, LOAD_RECT = makeText('Load Game', TEXTCOLOR, TEXTBOXCOLOR, WINDOWWIDTH/2, WINDOWHEIGHT - (WINDOWHEIGHT/4)) 
    #NEW_SURF.set_alpha(128) 
    #LOAD_SURF.set_alpha(128) 

    while True: # main game loop 

     DISPLAYSURF.blit(background, background.get_rect()) 
     DISPLAYSURF.blit(NEW_SURF, NEW_RECT) 
     DISPLAYSURF.blit(LOAD_SURF, LOAD_RECT) 

     for event in pygame.event.get(): # event handling loop 
      if event.type == MOUSEMOTION: 
       if NEW_RECT.collidepoint(event.pos): 
        NEW_SURF = BASICFONT.render('New Game', True, TEXTCOLOR, HIGHLIGHTCOLOR) 
        #NEW_SURF.set_alpha(255) 

       elif LOAD_RECT.collidepoint(event.pos): 
        LOAD_SURF = BASICFONT.render('Load Game', True, TEXTCOLOR, HIGHLIGHTCOLOR) 
        #LOAD_SURF.set_alpha(255) 

       else: 
        NEW_SURF = BASICFONT.render('New Game', True, TEXTCOLOR, TEXTBOXCOLOR) 
        LOAD_SURF = BASICFONT.render('Load Game', True, TEXTCOLOR, TEXTBOXCOLOR) 
        #NEW_SURF.set_alpha(128) 
        #LOAD_SURF.set_alpha(128)