Re: [Pan-users] Re: Previews gone screwy

[walter s]

On 10/6/07, Greg Lee <address@hidden> wrote:
> On Sat, 06 Oct 2007 02:52:10 +0000, walt wrote:
> > ....something
> > in pan or gtk is being too fussy about decoding.  I'll see if I can find
> > the cause -- eventually :o)
>
> Is it the decoding? When I save the decoded jpeg files with Pan
> and view them with a different viewer program, they seem perfectly okay.

What pan actually does to display an attachment is complicated and I've
been studying the code all day to try to figure it out.  The real reason I'm
spending so much time on this is to teach myself gtk+ and it's actually
working :o)

I finally learned what gdk-pixbuf-query-loaders is actually telling us, which
I've wanted to know for years and was too lazy to find out.  It's listing all
the image loaders in /usr/lib/gtk-2.0/2.10.0/loaders.

In my /usr/lib/gtk-2.0/2.10.0/loaders/ I have a bunch of files like
libpixbufloader-jpeg.so, and that particular one does the actual dirty
work of 'decoding' a jpeg into a drawable bunch of pixels so that a
gtk-based application can display it on the screen.  That's what I
meant by the word 'decoding'.  (BTW, that pixbuf loader is the one
which was modified in gtk 2.11.x and is now causing us problems.)

The part that's still confusing me is that pan doesn't save the jpeg to
disk and then display it from there -- instead it seems to load the jpeg
into RAM and then calls pixbufloader-jpeg to render it from there.

How pan converts attachment(s) to a jpeg and loads it to RAM is still
confusing me -- but that seems to be the step which is failing somehow.

> ...
> I looked at some other 1 part images in this same newsgroup and
> found that all those with byte size <= 369052 displayed correctly,
> but all those with byte size >= 369361 displayed incorrectly.  Of
> the two dozen or so that I tried.

An interesting observation.  I'll keep it mind while I study this bug.
And while we all wait for Charles to fix it ;o)