Lenard, Rene and co,
>> There is no unit test for blitting a SRCALPHA source with non-zero alpha
to a SRCALPHA destination with non-zero alpha
I'm writing some tests for surface.blit atm. What is the expected behaviour
of such an operation?
def test_blit__SRCALPHA_to_SRCALPHA_non_zero(self):
# " There is no unit test for blitting a SRCALPHA source with
non-zero
# alpha to a SRCALPHA destination with non-zero alpha " LL
w,h = size = 32,32
s = pygame.Surface(size, pygame.SRCALPHA, 32)
s2 = s.copy()
s.fill((32,32,32,111))
s2.fill((32,32,32,31))
s.blit(s2, (0,0))
# TODO:
# what is the correct behaviour ?? should it blend? what algorithm?
self.assertEquals(s.get_at((0,0)), (32,32,32,31))
Cheers. I'm not sure here.
Also, wrt to the blitting opaque source behaviour, are we considering this a
bug? A failed test? I'm that way inclined and have written a test for that,
will wait for approval before committing.
def test_blit__SRCALPHA_opaque_source(self):
src = pygame.Surface( (256,256), SRCALPHA ,32)
dst = src.copy()
for i, j in test_utils.rect_area_pts(src.get_rect()):
dst.set_at( (i,j), (i,0,0,j) )
src.set_at( (i,j), (0,i,0,255) )
dst.blit(src, (0,0))
for pt in test_utils.rect_area_pts(src.get_rect()):
self.assertEquals ( dst.get_at(pt)[1], src.get_at(pt)[1] )
