Check out this pull request, and try it out if you have a chance.  I'm curious 
if it solves the problem for you.

https://github.com/OpenImageIO/oiio/pull/621


On Jun 17, 2013, at 4:54 PM, Jonathan Egstad wrote:

> Thanks!
> 
> -jonathan
> 
> On Jun 17, 2013, at 4:22 PM, Larry Gritz wrote:
> 
>> I think I can make things easier for you on this front.  Let me see what I 
>> can throw together.  Stay tuned.
>> 
>> In the mean time, I think you can probably make headway by compiling OIIO 
>> with a simple modification to src/libOpenImageIO/CMakeLists.txt -- just 
>> comment out line 123 that adds the two exr*.cpp files to the embedded list.  
>> Then it should find your plugin just fine (although it's not a "stock" 
>> libOpenImageIO at that point).
>> 
>>      -- lg
>> 
>> 
>> On Jun 17, 2013, at 3:17 PM, Jonathan Egstad wrote:
>> 
>>> Without getting into too much detail we've codec modifications to the 
>>> OpenEXR format that (hopefully soon!) will get rolled in to the standard 
>>> distribution.  Until then we do need a customized plugin that has small 
>>> modifications to the codec enumerations and is linked against our OpenEXR 
>>> build.
>>> 
>>> So it sounds like our near-term solution is to build oiio without embedded 
>>> plugins.
>>> 
>>> However I do think it would be a worthwhile fix if it's trivial enough to 
>>> do as it would make plugin management more flexible.
>>> If you don't want to change the API you could trap for a token in the 
>>> search path like '<builtins>:/tmp/oiio/plugins' that would determine where 
>>> to insert the embedded paths.
>>> 
>>> -jonathan
>>> 
>>> On Jun 17, 2013, at 2:06 PM, Larry Gritz wrote:
>>> 
>>>> The idea of the plugins was to extend the set of supported file formats at 
>>>> runtime.  An example would be if an application that uses OIIO wanted to 
>>>> support for GIF files (we don't, natively), they could write their own 
>>>> gif.imageio.so (or .dll) to extend support, rather than create a 
>>>> customized libOpenImageIO.  Another example would be if there was a truly 
>>>> proprietary format (internal to one company, or one application), they 
>>>> could easily extend OIIO to support it just by writing that one DLL/DSO 
>>>> without cluttering the public distribution or without revealing to the 
>>>> world the details of their proprietary format.
>>>> 
>>>> (Aside: In truth, although I always thought of the plugin mechanism as an 
>>>> important feature in an image library, it's not clear to me whether anyone 
>>>> at all uses the ability to extend format support at runtime.  I started 
>>>> out with *all* formats supported via DSO/DLL's, even the ones that come 
>>>> with OIIO.  It was user demand that led to format support being embedded 
>>>> in the library rather than DSO's.  People overwhelmingly found the build 
>>>> and distribution simpler with one library rather than a dozen or more 
>>>> plugins.)
>>>> 
>>>> I admit that I never really considered the case of somebody who wanted to 
>>>> *replace* an existing format module, rather than extend the set of file 
>>>> formats.  So it's not surprising that the library always considers the 
>>>> built-in (embedded) implementations first, and only checks the DSO/DLL's 
>>>> if none of the embedded readers are able to open the file.
>>>> 
>>>> If it's important to you, I think we could fix this pretty easily.  I'm 
>>>> not sure I'd want it to be the default, but we could certainly make it an 
>>>> option to check for DSOs first, i.e., reverse the priority.
>>>> 
>>>> Out of curiosity, what does your OpenEXR reader do that the standard one 
>>>> does not?  Is a more productive route to propose an improvement to the 
>>>> built-in exr reader?
>>>> 
>>>>    -- lg
>>>> 
>>>> 
>>>> On Jun 17, 2013, at 12:54 PM, Jonathan Egstad wrote:
>>>> 
>>>>> Sorry if this has been answered before, I can't find a relevant mail.
>>>>> 
>>>>> We've built oiio with embedded plugins and now we're attempting to 
>>>>> override the exr plugin with a customized one.
>>>>> Unfortunately the plugin_searchpath string passed to 
>>>>> ImpageInput::create() does not appear to take precedence during the 
>>>>> cataloging of available plugins which means the embedded openexr plugin 
>>>>> appears to always be found first.
>>>>> 
>>>>> Is this the expected behavior or am I doing something wrong?
>>>>> 
>>>>> The custom exr plugin is handicapped so the plugin's open() method will 
>>>>> produce an assert error, but no assert is occurring so I'm assuming the 
>>>>> embedded openexr plugin is getting called instead.
>>>>> 
>>>>> From my reading of imageioplugin.cpp the catalog_all_plugins() method 
>>>>> first calls catalog_builtin_plugins() before the searchpath string is 
>>>>> being parsed (I haven't yet built oiio with debug prints to see what's 
>>>>> going on in there, but that was going to be my next step.)
>>>>> 
>>>>> 
>>>>> Thanks for any help,
>>>>> 
>>>>> -jonathan
>>>>> 
>>>>> 
>>>>> #include <OpenImageIO/imageio.h>
>>>>> 
>>>>> using namespace OIIO_NAMESPACE;
>>>>> 
>>>>> const char* plugin_searchpath = "/tmp/oiio/plugins";
>>>>> const char* read_path = "/tmp/oiio/plugins/test.exr";
>>>>> 
>>>>> int main(int argc, char* argv[]) {
>>>>> ImageSpec spec;
>>>>> ImageInput* reader = ImageInput::create(read_path, plugin_searchpath);
>>>>> if (!reader) return 1;
>>>>> if (!reader->open(read_path, spec)) {
>>>>>  std::cerr << "Unable to open file '" << read_path << "'" << std::endl;
>>>>>  return 1;
>>>>> }
>>>>> 
>>>>> std::cout << spec.width << "x" << spec.height << std::endl;
>>>>> 
>>>>> return 0;
>>>>> }
>>>>> 
>>>>> _______________________________________________
>>>>> Oiio-dev mailing list
>>>>> [email protected]
>>>>> http://lists.openimageio.org/listinfo.cgi/oiio-dev-openimageio.org
>>>> 
>>>> --
>>>> Larry Gritz
>>>> [email protected]
>>>> 
>>>> 
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>>> 
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>> 
>> --
>> Larry Gritz
>> [email protected]
>> 
>> 
>> _______________________________________________
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>> http://lists.openimageio.org/listinfo.cgi/oiio-dev-openimageio.org
> 
> _______________________________________________
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--
Larry Gritz
[email protected]


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