How to handle AssetManager using JavaCpp?

[Clement-Devevey]

I have a c++ library that needs access to the java Android AssetManager. (android.content.res.AssetManager)
To pass it to the library, I am using a custom JNI that takes this AssetManager as a jobect and then converts it to the equivalent c++ class AAssetManager (defines in android/asset_manager.h) using AAssetManager_fromJava(jobject*)

I was wondering how to handle this using javacpp?

I tried to do infoMap.put(new Info("AAssetManager").javaNames("AssetManager").define())
but the generated NativeLibrary.java doesn't define the AssetManager class.

[saudet]

How are you including asset_manager.h?

[Clement-Devevey]

#include <android/asset_manager.h>
#include <android/asset_manager_jni.h>

[saudet]

You'll also need to include it in Java

[Clement-Devevey]

Ok looks like I've been able to build by doing so:

• include the files in java (android_manager.h and android_manager_jni.h, need to check if both are required)
• add infoMap.put(new Info("off64_t").javaNames("long").define())
• add infoMap.put(new Info("AAssetManager_fromJava").skip()
• add infoMap.put(new Info("AAsset_openFileDescriptor64").skip()

I had to skip AAssetManager_fromJava otherwise it would have require to also include the whole jni.h file which seems to be so overkill?
But I am not sure I'll be able to create a AAssetManager without AAssetManager_fromJava ...

The c++ method I'm trying to call is a static one, so I think I will stick to the old way for this method only as it seems overkill to include all jni.h, what do you think?

[saudet]

Well JavaCPP is based on JNI. To use those objects, use the @Raw annotation:
http://bytedeco.org/javacpp/apidocs/org/bytedeco/javacpp/annotation/Raw.html

[Clement-Devevey]

Thanks for the pointer!
I am sorry I couldn't find any usage example, could you explain how is it intended to be used please? 🙏

[saudet]

There's a couple of examples here:
https://github.com/bytedeco/javacpp/blob/master/src/main/java/org/bytedeco/javacpp/Loader.java#L2067-L2079