Fully transparent windows in Pygame?

Question

Is it possible to get a fully transparent window in Pygame (see the desktop through it)? I've found how to create a window without a frame, but there doesn't seem to be any obvious way to make it transparent.

I'd be willing to tie into system-specific technology/frameworks as long as there are solutions for both Windows and Mac OS X, but I'm not sure which direction to be looking.

The only topic I was able to find recommended using wxPython, which isn't something I can do for this particular project (needs to be Pygame).

Answer 1

PyGame uses SDL, which does not support transparent windows. Although at least on Linux making it transparent is done by the window manager, not the application.

Answer 2

On Windows, you can create a solid background color then set the window's transparency color with the Win32 API function SetLayeredWindowAttributes(). (Called with pywin32)

Code:

import pygame
import win32api
import win32con
import win32gui

pygame.init()
screen = pygame.display.set_mode((800, 600)) # For borderless, use pygame.NOFRAME
done = False
fuchsia = (255, 0, 128)  # Transparency color
dark_red = (139, 0, 0)

# Set window transparency color
hwnd = pygame.display.get_wm_info()["window"]
win32gui.SetWindowLong(hwnd, win32con.GWL_EXSTYLE,
                       win32gui.GetWindowLong(hwnd, win32con.GWL_EXSTYLE) | win32con.WS_EX_LAYERED)
win32gui.SetLayeredWindowAttributes(hwnd, win32api.RGB(*fuchsia), 0, win32con.LWA_COLORKEY)

while not done:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            done = True

    screen.fill(fuchsia)  # Transparent background
    pygame.draw.rect(screen, dark_red, pygame.Rect(30, 30, 60, 60))
    pygame.display.update()

Result:

Explanation:

Any part of the window using your transparency color will be fully transparent. You can view and interact with any desktop icons or programs located behind your game window.

To remove the window border, you can set Pygame's display mode to NOFRAME.

screen = pygame.display.set_mode((800, 600), pygame.NOFRAME)

See Also:

• Stack Overflow: Make a window transparent using Win32?
• Stack Overflow: Transparent hwnd window
• Microsoft: Layered Windows
• Microsoft: SetLayeredWindowAttributes function