[Qt-embedded-interest] FW: Double Buffer Graphics Driver

[Bryce Salmi]

Tom,
     Thank you for the reply and I was hoping that wouldn't be the case.
Well, in this case it does look like I will have to write the driver as
you suggested which makes sense.  However, on the Qt documentation for
the accelerated graphics driver the example uses SVGAlibs which I do not
think applies to my board.  Is there another example of one that does
not use SVGAlibs that would be good to at least see another
implementation of the custom driver.  Maybe there are some other ideas
you may have or at least directions to point me in?  Thank you for your
time.




Sincerely,

Bryce Salmi 

-----Original Message-----
From: qt-embedded-interest-bounces at trolltech.com
[mailto:qt-embedded-interest-bounces at trolltech.com] On Behalf Of Tom
Cooksey
Sent: Wednesday, July 01, 2009 2:55 AM
To: qt-embedded-interest at trolltech.com
Subject: Re: [Qt-embedded-interest] Double Buffer Graphics Driver

> Qt List,
>      I am at a point where I am trying to get the Double Buffer
> Graphics Driver working.  I have been able to implement the driver
> and get it to at least be recognized by the program trying to be
> run.  However there is no display on the LCD from the program.  I
> know the programs run when I use the VNC display.  Here is what I
> did: Built the plug-in (all four files located either at
> QTDIR/examples/qws/dbscreen or on the link above) by invoking qmake
> without the -project option since there is already a .pro file, I
> then simply ran make resulting in the output file which was named
> "libdbscreen.so".  One way to use the plug-in was to create a
> directory in the application directory, so in my case I created
> analogclock/gfxdrivers and placed libdbscreen.so into it (make sure
> permissions are set).  At this point I could simply run the command
> in the application root directory:
>
> ./analogclock -qws -display dbscreen
>
> The resulting output was "blit_16(): Image format 0 not supported!"
> continuously being printed on the command line (once per second...
> maybe from the clock actually trying to update the area that
> changed?).  There were no LCD changes but at least the driver was
> recognized and could be run.
>
> I would like to figure this out and think that the blit could be
> manually set?  I simply need to copy over the buffer in memory to
> the /dev/fbo which I have accessed before in C.  There is no mmap
> support on my board (ARM) so the frame buffer test doesn't work... I
> was hoping that this would be a way to work around mmap problem.

The dbscreen driver still uses the regular LinuxFBScreen, which itself 
uses mmap. I think you need to take a look at the LinuxFBScreen class, 
in particular initDevice & connect and write your own screen driver 
which inherits QLinuxFBScreen and which re-implements initDevice, 
connect & blit.


Cheers,

Tom


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