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 <devel.chm...@gmail.com> wrote:
> On Mon, Sep 24, 2012 at 10:41 AM, Tobias Leich <em...@froggs.de> 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 pdl.pl 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 pdl.pl is a var $ref, which is never used. Thats a bit confusing.
> 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.
> --Chris
>> 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/pdl.pl
>>> 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 pdl.pl 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.
>>> Regards,
>>> Chris
>>> On Sun, Sep 23, 2012 at 3:07 PM, Tobias Leich <em...@froggs.de> wrote:
>>>> Hi, Andrei asked some days ago how to load an image via PDL and but it
>>>> in a Surface to use it in SDL.
>>>> The example is here: https://gist.github.com/3772701
>>>> I'll put that in the examples folder too.
>>>> Cheers, Tobias

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