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List:       vnc-list
Subject:    Re: VNC viewer ignores -truecolor
From:       Grant McDorman <grant.mcdorman () cedara ! com>
Date:       2003-06-23 14:00:07
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On June 20, 2003 10:25 pm, Fred Ma wrote:
> Grant McDorman wrote:
> > > I am using TightVNC connect from sunbox to
> > > sunbox.  The remote VNC server is 24-bit
> > > true color, while the local machine's
> > > display has 6 visuals, one of which is
> > > 24-bit true color.  When I try to start
> > > the vncviewer with -truecolor, it always
> > > says that it is using 8-bit pseudocolor.

> Hi, Grant,
>
> Actually, your comment sent me off on some more
> sleuthing.  The problems seems to be that -owncmap
> is being specified (I forgot that I had vncviewer
> aliased to always specify -owncmap).  If I specify
> -truecolor without -owncmap, the viewer uses a true
> color visual of depth 8.  Funny, but I still get
> flashing colors when moving the mouse pointer in
> and out of the viewer.

Colourmap flashing occurs when the hardware colourmap needs to be reloaded. In 
your case, presumably the hardware cannot display TrueColour and PseudoColour 
(8-bit colour-mapped) simultaneously. Some hardware can (such as my Creator 
3D); most can't.

> The illuminating thing is that if I specify -truecolor
> and '-depth 24', the viewer complains that it can't
> find a matching visual.  It uses "default colormap" and
> translates from BGR233.

Yep, you don't have a 24-bit TrueColour visual.

> At least
> with the default colormap, I don't get messed up colors
> when I put the viewer in fullscreen (it seems that the
> fullscreen uses the nonprivate color map when the
> viewer is started with -owncmap!).

Sounds like a bug.

> The reason for not finding a true color visual of
> depth 24 is obvious when I reexamine the xdpyinfo:
>
>     visual id:    0x26
>     class:    TrueColor
>     depth:    8 planes
>     available colormap entries:    8 per subfield
>     red, green, blue masks:    0x7, 0x38, 0xc0
>     significant bits in color specification:    8 bits

24 bit truecolour looks like this:
  visual:
    visual id:    0x2c
    class:    TrueColor
    depth:    24 planes
    available colormap entries:    256 per subfield
    red, green, blue masks:    0xff, 0xff00, 0xff0000
    significant bits in color specification:    8 bits

- -- 

Grant McDorman <grant.mcdorman@cedara.com>, Sr. Software Design Consultant
Cedara Software Corp.  <URL:http://www.cedara.com>
  (formerly I.S.G. Technologies Inc.)
Mississauga, Ontario, Canada

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