png loader and text annotations

["Matthias Clasen" <Matthias Clasen poet de>]

I just glanced over the png 1.2 spec and noticed that there are actually
three different kinds of text chunks supported: tEXt (for ISO8859-1 
encoded text), 
zTXt  (for compressed IS=8859-1 encoded text) and iTXt (for UTF-8 encoded 
text).

The png loader stores annotations as tEXt chunks, which is ugly, since 
text
is generally UTF-8 in GTK. Wouldn't it be much more natural to store it as 
an
iTXt chunk ? From the libpng ChangeLog, it seems as if libpng has iTXt
support since 1.0.5 (Nov 99).

Now I seem to recall that the annotation support in the png loader was 
added
specifically for the thumbnailing stuff. Looking at the thumbnailing draft 
0.5, it
doesn't mention tEXt specifically, but links to the section about tEXt 
chunks in
the png 1.0 std. I think the thumbnail draft should be clarified to either 
allow
both tEXt or iTXt chunks or require iTXt.

Matthias