[Gaim-patches] [ gaim-Patches-1089195 ] Avatar format conversion causes unnecessary quality loss

[SourceForge.net <no...@so...>]

Patches item #1089195, was opened at 2004-12-21 12:22
Message generated for change (Comment added) made by thekingant
You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=300235&aid=1089195&group_id=235

Category: None
Group: None
>Status: Closed
Resolution: Accepted
Priority: 5
Submitted By: Graham Cole (chickens)
Assigned to: Mark Doliner (thekingant)
Summary: Avatar format conversion causes unnecessary quality loss

Initial Comment:
Here is a bug I've discovered with the way gaim
converts buddy icon images to be in the correct format
for the protocol:

Steps to reproduce:
1. Open the preferences window for an account that
supports buddy icons, e.g. an MSN account
2. Open an image to set as your icon, which although
acceptable to the protocol in size, is not in the
correct file format (e.g. a 96x96 JPEG image, where MSN
only supports PNG)

Expected result:
Image is losslessly converted to the PNG format and
displayed

*Actual* result:
Image is converted, but is very noticeably blurred

---

This is caused by an apparent bug in
gdk_pixbuf_scale_simple. Although it would seem safe to
ask the library to scale something to the same size, it
behaves oddly doing this when the chosen method of
scaling is GDK_INTERP_HYPER.

As the image is already the correct size in this case,
I would propose simply avoiding the attempt to scale
the image altogether!

Attached is my attempt at a patch for oldstatus -
unfortunately I'm unable to test it beyond compiling at
this point in (Christmas) time,... so take it with a
few handfuls of salt ;-)

----------------------------------------------------------------------

>Comment By: Mark Doliner (thekingant)
Date: 2004-12-24 11:45

Message:
Logged In: YES 
user_id=20979

Whoops, thanks.  Should be fixed now.

----------------------------------------------------------------------

Comment By: Graham Cole (chickens)
Date: 2004-12-24 06:18

Message:
Logged In: YES 
user_id=759914

The fix applied is not *quite* right:
It should not allow scaling when the size is equal to the
max or min values. This is especially important if the max
and min values are the same, as in MSN (not checked any others)

Patch to correct this attached

----------------------------------------------------------------------

Comment By: Mark Doliner (thekingant)
Date: 2004-12-23 20:33

Message:
Logged In: YES 
user_id=20979

I applied this to head.  And I inverted your logic some, but
it should have the same effect.  You might want to check to
make sure I got it right, though.

Thanks for the patch.

----------------------------------------------------------------------

Comment By: Graham Cole (chickens)
Date: 2004-12-22 17:02

Message:
Logged In: YES 
user_id=759914

Sorry if this wasn't crystal clear the first time round...

I'm not talking about scaling images which are too large/too
small, that's certainly very necessary (and works as
expected, from what I can tell). I'm talking about a tiny
detail in the logic of the gaim code, whereby images which
are *already* the correct size are still sent to be scaled,
to their original size no less! These come out the same size
but blurred, due to the GTK bug. When you have an image that
doesn't actually need anything done to it, might as well
leave it alone instead of putting it through the blurrifier :)

I did indeed post to the GTK bugzilla about this problem,
though kinda as an aside to an older bug...
http://bugzilla.gnome.org/show_bug.cgi?id=80927

... maybe I'll have a go at it myself sometime soonish :o)

----------------------------------------------------------------------

Comment By: Luke Schierer (lschiere)
Date: 2004-12-22 09:58

Message:
Logged In: YES 
user_id=28833

i am against accepting this patch. i think you should report
this to gtk, and it shoudl be fixed there.

not scaling images is not a good solution,
1)its not how the official client behaves
2)some people pick massive images for their avatar,
resulting in usably large dialogs (for any value of desktop
size). 

----------------------------------------------------------------------

You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=300235&aid=1089195&group_id=235