RE: gdk and vnc server/viewer at 16 bpp weirdness

[Vlad Harchev <hvv hippo ru>]

On Sun, 10 Sep 2000, Erik wrote:

 Hi,

> 
> On 10-Sep-2000 Vlad Harchev wrote:
> >  Hi,
> > 
> >  Have anybody used vnc server for X (running at 16 bpp, commandline option
> > '-depth 16') viewed with vncviewer (for any platform) running at 16 bpp too
> > (same commandline switch). I tried rather lot of combinations of vnc
> > server for X/(viewer,platform) and on all of them images that are displayed 
> > using gdk (probably using imlib, but I can be wrong) are displayed
> > totally incorrectly - some junk (looking like white noise + color) without
> > any
> > similarity to the original images. It's not a bug in vnc software since qt
> > and
> > motif apps look fine at showing pictures (netscape, kview). It seems there is
> > a nasty bug in gdk. More information: gcolorsel shows right colors, only
> > areas that were drawn by copying pixmap are broken (root window's image,
> > enlightnement's decorations, and (if pixmap theme is selected) every gtk 
> > widget. I've tried various versions of Xvnc (including most recent 3.3.3r1)
> > and vncviewer for X and Windows - both show the same. I used gtk-1.2.6 on
> > RH6.2 on x86.
> > 
> >  I've attached screenshot of gpanel. The current gtk theme is SatinBlack, so
> > everything should be dark shades of gray on the shot, but it looks like some
> > noise (though gradients are seen).
> > 
> >  Have anybody reported anything?
> >  
> >  Best regards,
> >   -Vlad
> 
> I've had no problems with vnc (16b or otherwise) doing gtk stuff. I've only
> used windows (95, 98, NT4, 2000) for clients, but I've used it on redhat(6.0?),
> debian, and fbsd without ill effects :/ Might want to check that you're using
> the same encoding on both sides?

 As I understand, the client and server  inform each other about
encoding they want, and some encoding is chosen by them - so there is no way
to use one encoding on server and another on client. Also, if it was encoding
problem, QT and motif apps wouldn't be displayed correctly.
 Also, research shows that this is imlib problem, not gdk's. GtkPixmap's are
displayed correctly. Only the places which are drawn using imlib are shown
incorrectly (and if you don't use pixmap engine-based theme, and don't view
images (using gqview for example) you won't see the problem (also, the problem
is seen by running gnome desktop - all icons are drawn using imlib, so you
should notice that problem).
 More details:
* Running vncserver and viewer at 8 bpp doesn't show the problem.
* Running vncserver at 16 bpp and vncviewer at 15 bpp shows another problem -
all colors are wrong (just as you look through the filter) - shades of brown
turn into shades of blue, yellow->gray.
* Running both server and client at 16 bpp produces results I've described
above.
 I repeat - there are no problems with any bpp combination for qt and motif
apps.

 One of the possible reasons for this problem could be incorrect color mask
and offset calculation in imlib I guess. Also, xdpyinfo reports unusual (IMO) 
things for Xvnc server running at 16bpp, compared to XFree86-3.3.1 server 
running at 16 bpp:
 For XFree:
------------
  default visual id:  0x20
  visual:
    visual id:    0x20
    class:    TrueColor
    depth:    16 planes
    available colormap entries:    64 per subfield
    red, green, blue masks:    0xf800, 0x7e0, 0x1f
    significant bits in color specification:    6 bits
------------
 For Xvnc:
  number of visuals:    1
  default visual id:  0x22
  visual:
    visual id:    0x22
    class:    TrueColor
    depth:    16 planes
    available colormap entries:    64 per subfield
    red, green, blue masks:    0x3f, 0x7c0, 0xf800
    significant bits in color specification:    8 bits
--------------
 Note value of "significant bits in color specification" - 6 for XFree, 8 for
Xvnc.
 To name a version of imlib, I used 1.9.5.

 So I cc'd to Raster.
 

>         -Erik <erik smluc org> [http://math.smsu.edu/~br0ke]
> 
> The opinions expressed by me are not necessarily opinions. In all
> probability, they are random rambling, and to be ignored. Failure to ignore
> may result in severe boredom or confusion. Shake well before opening. Keep
> Refrigerated.
>         
> 

 Best regards,
  -Vlad