On Jun 14, 2007, at 10:31 PM, Daniel Horowitz wrote:
So im trying to implement callbacks to java functions and I have
the honor of writing my own dll any which way I like. The problem
is that my dll depends on another dll which accepts a group of
callbacks as a struct.
How should my C function signature look to accept Java callback
methods? Should it be
int consume_callbacks(void *one, void *two, void *three)?
where one two and three are java functions?
I am running in to a wall here because the example uses a
predefined callback ( WNDENUMPROC lpEnumFunc ) type which you
overide with an interface (interface WNDENUMPROC extends
StdCallCallbac ). Should I simulate that instead, and typedef three
different types based on void*, then re-create those as interfaces
in java with callback methods?
ie
// C code
typedef void* one;
typedef void* two;
typedef void* three;
int consume_callbacks(one my_one, two my_two, three my_three)
//Java code
interface one extends Callback {
boolean callback(); }
Since the existing DLL uses stdcall callbacks (look at the definition
of WNDENUMPROC), you will need to define your callback interface the
same way.
While your C function *can* use void*, it is better to use the most
specific type you have, which is WNDENUMPROC. You need to declare
something of type Callback in your java interface, which effectively
gets converted to void* at the interface layer.
I believe one of the w32 API example libraries already has an
interface definition for WNDENUMPROC; you should duplicate or use
that one. It is critical that your java method interface for the
callback be identical w/r/t return type and argument count and type
as the C callback definition, or you will crash.
2 messages in net.java.dev.jna.usersRe: [jna-users] callbacks
