Re: Allow a PNG to begin with a #! line

In terms of binary, a #! "line" is just a "#!", followed by arbitrary 
non-\x0A bytes, followed by a single \x0A byte.

A #! is not a proper "line" in the sense that it can only exist on a 
file with "lines", a #! is simply what I described above. Ocaml uses #! 
with (binary) bytecode files, as weird as that may sound.

(Sad that I need to give up on backwards compatibility to have 
executable esolang[1] images. We do what we have to, I guess.)

[1]: Lots of image-based esolangs:
      - http://esolangs.org/wiki/Piet
      - http://esolangs.org/wiki/Brainloller
      - http://esolangs.org/wiki/Braincopter (variation of the above)
      - http://esolangs.org/wiki/Mycelium
      - etc, you get the idea.

On 01/11/16 10:01 PM, Glenn Randers-Pehrson wrote:
> A PNG file does not have "lines"; it's binary.  But you could do 
> something like
> this, with the "#!something" followed by a base64-encoded PNG (like a 
> "data URL"):
>
> $ cat blue.epng
> #!/usr/local/bin/display_epng
> data:image/png;base64,
> iVBORw0KGgoAAAANSUhEUgAAABAAAAAQAQMAAAAlPW0iAAAABGdBTUEAALGPC/xhBQAAACBjSFJN
> AAB6JgAAgIQAAPoAAACA6AAAdTAAAOpgAAA6mAAAF3CculE8AAAABlBMVEUAAP////973JksAAAA
> AWJLR0QB/wIt3gAAAAd0SU1FB+ALARMzAYjwr9kAAAAMSURBVAjXY2AgDQAAADAAAceqhY4AAAAl
> dEVYdGRhdGU6Y3JlYXRlADIwMTYtMTEtMDFUMTk6NTE6MDEtMDQ6MDBvJnzcAAAAJXRFWHRkYXRl
> Om1vZGlmeQAyMDE2LTExLTAxVDE5OjUxOjAxLTA0OjAwHnvEYAAAAABJRU5ErkJggg==
>
> That wouldn't require defining a PNG-2.0, the data can contain a 
> regular PNG as demonstrated above.  So,
> an EPNG is simply a #-delimited header followed by a data URL 
> containing image data.
>
> Glenn
>
> On Tue, Nov 1, 2016 at 4:43 PM, Soni L. <[email protected] 
> <mailto:[email protected]>> wrote:
>
>     EPNG was a bust, so, can PNG be changed so that a #! line at the start
>     of a PNG is ignored/skipped?
>
>     This breaks backwards compatibility, so might need to be delayed
>     until a
>     "PNG 2.0".
>
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