Re: [Perldl] PDL image to SDL::Surface

2012-09-26 Thread Chris Marshall
This was for Strawberry Perl on windows so the
device should be whatever the default is for windows.
If it needs X11, then the build probably did not
configure correctly for the platform.  It looks like
libSDL does support windows and MinGW and
the docs do not indicate that X11 is a prerequisite
for that.


On Mon, Sep 24, 2012 at 7:03 PM, Kartik Thakore wrote:
 Can you select a videodriver for SDL by exporting SDL_VIDEODRIVER
 either fbcon or x11 may fix this. If not then your SDL were not compiled
 with X11 libs. Install those.

 On Mon, Sep 24, 2012 at 6:36 PM, Sisyphus wrote:

 - Original Message - From: Chris Marshall
 To: Kartik Thakore
 Cc: Tobias Leich; sdl-devel
 Sent: Tuesday, September 25, 2012 2:46 AM
 Subject: Re: [Perldl] PDL image to SDL::Surface

 Hi Kartik-

 I don't have a working SDL module install that I could
 check things out on.

 Hi guys,

 Chris, 'cpan -fi SDL' should install SDL-2.54 on your SPP. (You need force
 because a couple of the SDL tests fail.)
 During the 'perl' stage of Alien::SDL you'll be prompted to
 select which library package to install. I took option 1 because it was
 RECOMMENDED, though option 2 is probably more recent.

 I've run the demo at but that just

 No available video device at
 C:/_32/strawberry516/perl/site/lib/SDLx/ line 123, DATA line 206.
 SDLx::App::new('SDLx::App', 'title', 'PDL and SDL aplication', 'width',
 640, 'height', 640, 'eoq', 1, ...) called at line 12

 And same error for

 I don't know what needs to be done in order that a video device becomes
 available. (I'm probably not the sharpest tool in the shed to be using for
 this ;-)


Re: PDL image to SDL::Surface

2012-09-26 Thread Chris Marshall
On Mon, Sep 24, 2012 at 12:46 PM, Chris Marshall wrote:
 Hi Kartik-

 I don't have a working SDL module install that I could
 check things out on.  The posted gist seemed like a
 regression of using direct PDL manipulation to read and
 copy the image data to an SDL surface.

 The example seemed ok to me until I tried looking
 at the latest XS code where it seemed that the SDL module
 doesn't not accept a packed string data as input to the
 surface from routines.

Still don't have an SDL install but reviewing objects/Surface.xs
a bit more it appears that the -get_pixels_ptr() does return a
scalar perl reference to a PV with the string pointer being the
pointer to the pixel data.

However, the -new_from() method appears to assume the
pixel pointer is actually poked into the RV slot of the dereferenced
SV rather than the PV string.  This seems inconsistent.


 On Mon, Sep 24, 2012 at 12:39 PM, Kartik Thakore wrote:
 Whats wrong with ?

 On Mon, Sep 24, 2012 at 12:36 PM, Chris Marshall

 Looking back through the code to the original SDL_Perl
 I found version 2.0.5 which allows one to actually create
 an SDL surface from pixel data.  More recent versions
 appear to copy the data and as far as I can tell, there is
 no way to directly create an SDL surface from external

 If that is the case (that SDL_CreateRGBSurfaceFrom is
 not accessible from the perl API), have you implemented
 another approach to achieve this?


 On Mon, Sep 24, 2012 at 12:07 PM, Chris Marshall
  On Mon, Sep 24, 2012 at 10:41 AM, Tobias Leich wrote:
  Hi Chris,
  The performance is poor of course.
  I tried to use the piddle's pointer (-dataref or so) but it looks like
  it is not pointing to a usable memory area.
  $piddle-get_dataref returns a scalar reference to a perl
  PV whose string content _is_ the data block.  You should
  be able to get the starting location for the pixel data (i.e.,
  the string) via SvPV.
  It looks like there are more than 4 bytes per pixel, and libSDL can't
  handle that.
  Per the above, the get_dataref returns an RV to an Sv with
  the data in the string.  It is just a contiguous block of memory.
  As far as I know, all the SDL memory buffers are just
  contiguous blocks of memory (ignoring variations due to
  stride, alignment,...)
  The example is working, I see colored squares.
  I don't know what the output should look like.  I'm
  cc-ing our PDL mailing list in the hopes that someone
  with access to both PDL and SDL can give it a try.
  Is there a cygwin install of SDL and libSDL?
  I think we should need to improve our examples btw, there is not a
  single comment, thats bad.
  In the is a var $ref, which is never used. Thats a bit
  I think the ref is from a previous iteration in the code
  trying to get things working.
  Speaking of documentation, do you have any on the
  actual perl-libSDL bindings an data structures?  Trying
  to read XS is not the simplest way to sort things out---
  especially since I am far for an expert on some of the
  tricky XS technologies.
  Cheers, Tobias
  Am 24.09.2012 16:09, schrieb Chris Marshall:
  I took a look at the gist and it looks reasonable
  (I can't run it because I don't have the SDL module
  and lib installed on my system), however...
  I would expect the performance to be *very* poor
  since the image data is essentially being converted
  from packed byte data to a perl list and then poked
  a byte at a time into the SDL surface data.
  The better approach would be to wrap a PDL object
  (a.k.a. piddle) into an SDL surface.  Then you could
  just lock, copy the data via a PDL direct assignment,
  unlock and use SDL.  There is an examples/
  that shows how to do the wrapping.
  BUT, I took a look at the xs code and it appears
  that your SDL_Surface objects no longer use a
  packed-string representation for the SDL surface
  data.  If that is the case, I would be surprised if
  the example works at all now.
  If someone could verify this, I would appreciate it.
  If that is the case, it should be straightforward to
  modify the SDL_CreateRGBSurfaceFrom routine
  to allow for a SvPV for pixel data as one alternative.
  Given the power of PDL for whole-image data
  manipulation, allowing for easy interoperability
  with the current SDL module would benefit both
  our user and developer communities.
  On Sun, Sep 23, 2012 at 3:07 PM, Tobias Leich wrote:
  Hi, Andrei asked some days ago how to load an image via PDL and but
  in a Surface to use it in SDL.
  The example is here:
  I'll put that in the examples folder too.
  Cheers, Tobias