I have a C++ DLL that exposes the following function. this function calls the callback function ( GetProperty
) immediately. I can not change the C++ DLL
// c++
DllExport unsigned int RegisterCallbackGetPropertyReal( bool (*GetProperty)( UINT property_identifer, float * value ) ) ;
I have a C# application that uses com.sun.jna to access this function of the DLL. I have gotten to the point where the callback function is being called correctly from the c++ DLL but I can't see to find a way to set the float * value
// Java
public class main {
public interface CBlargAPI extends Library {
interface GetPropertyReal_t extends Callback {
boolean invoke (int property_identifer, FloatByReference value);
}
int RegisterCallbackGetPropertyReal( GetPropertyReal_t getProperty ) ;
}
public static void main(String[] args) throws Exception
{
// Register call back functions
CBlargAPI.GetPropertyReal_t GetPropertyReal_fn = new CBACnetAPI.GetPropertyReal_t() {
@Override
public boolean invoke(int property_identifer, FloatByReference value) {
System.out.println("GetPropertyReal_t: " ) ;
value.setValue(97.5f);
return false; // [Edit] This is where the problem was. this should be `return true;` See my answer below.
}
};
CBlargAPI.INSTANCE.RegisterCallbackGetPropertyReal( GetPropertyReal_fn ) ;
}
}
What I would have expected is that the value should be set to 97.5f when it gets back to the c++ DLL. instead I get the default value of 0.000f
My question is:
This is a typo that no one else could have found. basicly if I return false on the GetPropertyReal_fn
callback the default value of 0.000f
would be used.
I have edited the question to show where the error was.
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