[pygame] using surfarrays without losing alpha?

[Jack Nutting <jn_list@rebisoft.com>]

Say I've got an image I want to "soften".  I've already got a handy 
function using surfarrays, taken from example code:

def softenRgbArray(rgbarray):
    """ shamelessly lifted from arraydemo.py"""
    soften = Numeric.array(rgbarray)*1
    soften[1:,:]  += rgbarray[:-1,:]*8
    soften[:-1,:] += rgbarray[1:,:]*8
    soften[:,1:]  += rgbarray[:,:-1]*8
    soften[:,:-1] += rgbarray[:,1:]*8
    soften /= 33
    return soften

I just want to wrap this with another function that will take a surface 
and return the softened surface.  Here's a first stab at it:

def softenImage(img):
    rgbarray = pygame.surfarray.array3d(img)
    transformedArray = softenRgbArray(rgbarray)
    return pygame.surfarray.make_surface(transformedArray)

This works, with one problem:  All alpha data from the original image 
is lost!  At this point, I figure the best thing to do is to make a new 
surface that is a copy of the old one, and first blit the original 
image (including alpha) into the new surface, followed by the 
transformed color array, like this:

def softenImage(img):
    rgbarray = pygame.surfarray.array3d(img)
    transformedArray = softenRgbArray(rgbarray)
    newImg = pygame.Surface(img.get_size()).convert_alpha()
    newImg.blit(img, newImg.get_rect())
    pygame.surfarray.blit_array(newImg, transformedArray)
    return newImg

Unfortunately, this just gives me surfaces that are solid black for 
some reason!  I've been abusing and contorting this code for a while to 
try to make it work...  Can anyone see an obvious (or not-so-obvious) 
error here?

//jack