[Pan-users] Re: Previews gone screwy

[walt]

On Fri, 19 Oct 2007 23:39:25 -0400, Dave Chand wrote:

> On Oct 6, 2007, at 6:58 PM, Greg Lee wrote:
> 
>> 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...

> I have been experimenting with gdk-pixbuf. What I find is the following:
> in the file gtk+2.12.x/gdk-pixbuf/io-jpeg.c there is the statement
> #define JPEG_PROG_BUF_SIZE 65536
> if you change its value to something significantly higher, such as
> #JPEG_PROG_BUF_SIZE 500000
> then it seems the decoding problems go away.

I just sent this question to Matthias Clasen, who increased that number
from 4096 back in 2002.  It seems that a pixbuf sets an arbitrary size
limit on how much data can be loaded in a single chunk.  The real
question is whether that limit is intentional or merely a bug.

Meanwhile, Brian Downing posted a patch to the pan bugreport:
http://bugzilla.gnome.org/attachment.cgi?id=96917&action=view

His patch explicitly limits the amount of data Pan sends in one
chunk, and this is the correct fix at least until we know if this
size problem is a gdk bug or not.