[directfb-dev] Re: how to CreateSurface on CRTC2 layer for G400

[Ville Syrjälä <syrjala@sci.fi>]

On Sun, Dec 15, 2002 at 10:46:06AM -0500, a40e8119bbddbe7b3d281db117f19b32@interlinx.bc.ca wrote:
> On Sun, Dec 15, 2002 at 05:22:42PM +0200, Ville Syrjälä wrote:
> > On Sun, Dec 15, 2002 at 09:37:30AM -0500, a40e8119bbddbe7b3d281db117f19b32@interlinx.bc.ca wrote:
> > > I have tried to replace the CreateSurface() with a GetSurface() but I
> > > wind up getting a segfault in the application.  Should a
> > > GetSurface(layer, ...) be substitutable for a
> > > CreateSurface(DFBContext, ...) or is it more complicated than that?
> > 
> > Yes if CreateSurface() had DSCAPS_PRIMARY.
> 
> Yes it's more complicated than that or yes it should be substituable?

Yes it whould work.

> > Perhaps the code assumes something about the surface
> > size.
> 
> Just prior to the CreateSurface there is a:
> 
>   SetVideoMode(dfb, width, height, bpp)

This will only affect the primary layer.

> Where the latter 3 parameters are passed in from config values.  So
> the only assumption is that the surface is the same size as the user
> set in the config file.

Bad assumption. I recommend you use GetSize() to get the actual surface
size. This guarantees that you're code will work with PAL and NTSC without
forcing the user to edit some config files.

> > CRTC2 surface has a fixed size so you'll have to make sure the code
> > understands that. 
> 
> I set the user-configurable size to 768x486 (it was 800x600).

The layer size is 720x486 so there's your segfault.

> P.S.  With this being the 2nd graphics layer I have had to hack to be
> able to use CRTC2 instead of DLID_PRIMARY, have any ideas about how to
> make this sort of thing user-selectable been thought up?  I guess a
> new /etc/directfbrc option could be introduced to specify the layer
> you want to work on.

A small change to IDirectFB_Construct() would do the trick I think. At
least apps depending on EnumVideoModes() returning something useful will
fail. There might be other problems too.

I don't have time to go through the code right now so I'm not sure if it
actually works. Can you try hardcoding the layer in IDirectFB_Construct()
in idirectfb.c?

- data->layer = dfb_layer_at( DLID_PRIMARY );
+ data->layer = dfb_layer_at( 2 );

-- 
Ville Syrjälä
syrjala@sci.fi
http://www.sci.fi/~syrjala/


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