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Newsgroups: comp.lang.python
Date: Tue, 30 Oct 2012 03:38:28 -0700 (PDT)
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Subject: Re: I need help installing pypng in Python 3.3
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On Monday, October 29, 2012 3:48:09 PM UTC+1, Andrew Robinson wrote:
> On 10/29/2012 06:39 AM, icgwh@tagyourself.com wrote:
>=20
> > That's very kind of you but I don't think it would be particularly fitt=
ed to my needs. The program I'm trying to code creates an image as an 2D ar=
ray of "pixels" which is defined by RGBA value. My program needs to access =
and modifies every component of every pixels in the image following a set o=
f rules, kind of like the game of life, only more complex.
>=20
> >
>=20
> > In fact I only need a library to "push" this array of pixels in a displ=
ayable format for the GUI and in PNG format to write the image to disk. I d=
on't need to do any fancy stuff with the image, just being able to display =
and write it.
>=20
> >
>=20
> >
>=20
> Then, actually, what I am suggesting was *almost* perfect.
>=20
> To do transparency, you need to write the portable any map (PAM) formatio=
n.
>=20
>=20
>=20
> Simply print a text header to a file which says:
>=20
>=20
>=20
> P7
>=20
> WIDTH 10
>=20
> HEIGHT 10
>=20
> DEPTH 4
>=20
> MAXVAL 255
>=20
> TUPLTYPE RGB_ALPHA
>=20
> ENDHDR
>=20
>=20
>=20
> And then dump your 2D array to that same file.
>=20
> A very quick example in 17 lines of code:
>=20
>=20
>=20
> io =3D open( "anyname.pam","w")
>=20
> x,y =3D 10,10
>=20
> gray=3D(128,128,128,255) # R,G,B,A value
>=20
> picture =3D [ [ gray ] * x ] * y # Make a blank gray canvas 2D array
>=20
>=20
>=20
> # Do whatever you want to the 2D picture array here!
>=20
>=20
>=20
> io.write( "P7\nWIDTH %d\nHEIGHT %d\nDEPTH 4\nMAXVAL 255\nTUPLTYPE=20
>=20
> RGB_ALPHA\nENDHDR\n" % (x,y) )
>=20
>=20
>=20
> for yi in xrange( y ):
>=20
>      for xi in xrange( x ):
>=20
>          pixel =3D picture[yi][xi]
>=20
>          io.write( chr(pixel[0]) ) # R value
>=20
>          io.write( chr(pixel[1]) ) # G value
>=20
>          io.write( chr(pixel[2]) ) # B value
>=20
>          io.write( chr(pixel[3]) ) # A value
>=20
>      io.flush()
>=20
>=20
>=20
> io.close()
>=20
>=20
>=20
> And that's it.  You may of course make this more efficient -- I'm just=20
>=20
> showing it this way for clarity.
>=20
> Many programs can read PAM directly; but for those that can't you can=20
>=20
> use nettools, or imagemagick, to convert it to PNG.

That's really interesting! Thank you so much! Never heard of PAM before... =
I  will try that!