Set default convert format when Window.get_surface() is called

[yunline]

Test code (should not raise exception):

import pygame
from pygame._sdl2 import Window

win = Window()

sf1 = win.get_surface()

sf2 = pygame.Surface((10,10)).convert()

while 1:
    event = pygame.event.wait()
    if event.type == pygame.QUIT:
        break

If convert() is called but no convert format have been set, it should raise:

pygame.error: No convert format has been set, try display.set_mode() 

After the Window API published, it should raise:

pygame.error: No convert format has been set, try display.set_mode() or Window.get_surface()

[MyreMylar]

LGTM 👍

[Starbuck5]

Hey @yunline, can you rebase this against main?

It will make it easy to test with a full Window.flip() example, and it'll fix the circleci change.

I see you didn't respond to my long rambling paragraph feedback, I'd like to try and add that as a commit to this branch myself, and then if it looks good to you we can move forward.

"Window will be published next release" shouldn't go in the error message! That was information for you, not for the user :)

[yunline]

"Window will be published next release" shouldn't go in the error message! That was information for you, not for the user :)

Oops, I'll fix it soon.

[Starbuck5]

@yunline I added a new commit to this branch, which makes the code more but also safer.

I was worried about what would happen if the SDL_PixelFormat struct we hold was deallocated by SDL, making it allocate a SDL_PixelFormat specifically to hold on to will prevent that from happening.

Please let me know if this looks okay to you

[Starbuck5]

Looks good to me.