Hmmm... well caught.

The DSCAPS_DOUBLE is because of the IDirectFBSurface_Window_Construct in idirectfbwindow.c containing it. However, this parameter is not used because a 'window' surface does not use IDirectFBSurface_Flip but instead uses IDirectFBSurface_Window_Flip as the 'Flip' implementation, which does not look at the caps field to determine flipping strategy - it simply reserves a single buffer always. I guess the DOUBLE is a remnant to convey the resulting behaviour rather than the actual implementation.

Not planning to change this, unless there is a need.

Greets
Niels

anders.bak...@nokia.com wrote:
_______________________________________
From: ext Niels Roest [ni...@directfb.org]
Sent: Saturday, March 27, 2010 3:16 AM
To: Bakken Anders (Nokia-D-Qt/RedwoodCity)
Cc: directfb-dev@directfb.org
Subject: Re: [directfb-dev] single buffered windows

How come you have double buffered windows?
Afaik, windows are default single buffered.
If you change the content of a window, the layer buffer is only updated
when you do a window->Flip after your change - this copies the updated
area from the window buffer to the layer buffer (generally the back
buffer followed by a implicit flip, if your layer is double buffered)

Greets
Niels

Hi Niels

That seems to what DirectFB is giving me. I use the attached example and the 
output is:

12 DSCAPS_DOUBLE 1

This is running 1.4.3 and system=x11

regards

Anders



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