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<p>Hi Clayton<br>
interacting with JNI code has few issues:<br>
<br>
1. you need a JNIEnv* segment<br>
2. you need to be able to wrap Java objects as JNI references (so
that they can be passed as pointers to native calls)<br>
3. expose some way to map method names into JNI mangled names (so
that we can look those up using a symbol lookup)<br>
</p>
<p>This is something on our radar and we will like to address this
use case at some point (but it is possible this might be addressed
_after_ the FFM API is finalized). Two possible approaches are:</p>
<p>* a set of static helper functions which allow to obtain JNIEnv
segment, as well as create, dereference and destroy JNI refs. We
might even expose JNI functions here (think of a JNIUtils class)<br>
* a true JNILinker <: Linker - this might allow a tighter
coupling with JNI functions (as the JNIEnv will be passed
automatically)<br>
</p>
<p>I think the former approach is quite attractive in terms of bang
for bucks. It doesn't add a lot of complexity to the API, and adds
the minimum functionality that is required in order to allow the
native linker to deal with JNI functions as well (even though
developers will need to take some extra care when doing so).</p>
<p>In the meantime, I think it might be possible to define a small
JNI library which takes care of the missing functionalities - e.g.
it could return/accept JNI references as "jlong" (an hack, I know)
so, something like this:<br>
</p>
<p>native long makeGlobalRef(Object o) // call NewGlobalRef, cast
result to jlong and return<br>
native void destroyGlobalRef(long ref) // cast to jobject, then
call DeleteGlobalRef<br>
native Object readGlobalRef(long ref) // cast to jobject, return<br>
native long getEnv(); // cast env parameter to jlong and return<br>
</p>
<p>I've tried something along those lines and it seems to work as
expected. But I agree that it would be convenient if this "just
worked" out of the box.</p>
<p>Cheers<br>
Maurizio<br>
</p>
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<div class="moz-cite-prefix">On 24/05/2023 18:28, Clayton Walker
wrote:<br>
</div>
<blockquote type="cite" cite="mid:CAEwKcDK9K9BpSJ=VjfM9g+PWbw9qXGjg_4vWjAMbKHWOAybUkA@mail.gmail.com">
<div dir="ltr">I am working on a project with one of the goals
being able to use a swing component as a render target. From the
documentation <a href="https://docs.oracle.com/javase/8/docs/technotes/guides/awt/AWT_Native_Interface.html" moz-do-not-send="true">here</a> I assume we need jni in order
to access the native PlatformInfo struct. My question is the
same as asked in <a href="https://stackoverflow.com/questions/75620948/how-do-i-get-the-hwnd-of-a-canvas-using-panama" moz-do-not-send="true">this stackoverflow question</a>, is it
possible to use panama to get the HWND of a swing window?</div>
</blockquote>
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