[PD-dev] Opening patches from libpd without accessing filesystem?

[Miller Puckette]

I'm not sure if you can make calls directly into Pd, but if so, you
can do what Pd does to create a couple of invosoble canvases it leeds.
Look in teh Pd source for garray_init() (g_array.c) to see how it's
done.

Perhaps this would be a good thing for libpd to support directly at some point.

Also, I've been thinking for a long time about how patches could include their
own abstractions for easier distribution... I haven't been able to figure out
the best way to do this yet (fake a filesystem?  Or include dependencies
directly in the Pd file? dunno...)

cheers
Miller

On Mon, May 04, 2020 at 04:46:05PM -0400, Andi McClure wrote:
> Hi. I am embedding libpd into a video game. The video game targets
> Android and so will be shipped in a configuration where assets are
> bundled into a zip file (the APK) and decoded at runtime. Code does
> not access the filesystem directly.
> 
> Looking at the libpd C sample, and also the documentation, it appears
> the only way to get it to open a patch is `void *libpd_openfile(const
> char *name, const char *dir)`. This appears to take an on-disk path to
> the patch file directly and it appears sometimes it will open other
> files from disk too (I guess pd files can reference external sound
> files?). However, again, none of the files I will want it to open are
> on the disk so it will not find them.
> 
> Is there a way around this? For example is there a backdoor to give
> libpd a buffer in memory containing an already-loaded file? Or
> callbacks to replace libpd's open/read file functions?
> 
> If this is not possible, it looks like I might be able to alter libpd
> to add virtual filesystem abilities (for example, letting the library
> user provide a table of surrogate openFile, readFile, closeFile
> function pointers). It looks(?) like the filesystem access is pretty
> neatly contained in s_path.c and m_binbuf.c. If I do this, would there
> be interest in accepting the patch back upstream?
> 
> 
> 
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