Add interface with native Java type argument - awt

Question

I want to use swig to create a JNI interface not in the common way that the C++ function exists. I want to add a method/function with an java class argument.
File : test.i
%typemap(javaimports) A %{
import java.awt.Component;
%}
%extend(java) A {
void Attach( Component awt)
{
// here I Want to retrieve XDisplay, Window, Screen from
// /usr/lib/jvm/java-1.7.0-openjdk-1.7.0.25.x86_64/include/jawt.h
// I need canvas of type jobject.
// with this information I call Attach( XDisplay * dpy, Window win);
}
}
class A
{
public:
void Attach( XDisplay * dpy, Window win);
};

Answer 1

You'll need a few typemaps to have a java.awt.Component passed through to an extended method as a jobject:
%module test
%typemap(jstype) jobject *awtcomponent "java.awt.Component";
%typemap(jtype) jobject *awtcomponent "java.awt.Component";
%typemap(jni) jobject *awtcomponent "jobject";
%typemap(javain) jobject *awtcomponent "$javainput";
%extend A {
void attach(jobject awtcomponent) {
// Call whatever JNI functions you want with this jobject
// (which is always an AWT component)
// Then:
$self->Attach(arg1, arg2);
}
}
%inline %{
struct A {
};
%}
Given that you already have a member function you can in fact skip the %extend entirely and use a typemap to deal with that directly:
%module test
%typemap(jstype) (XDisplay * dpy, Window win) "java.awt.Component";
%typemap(jtype) (XDisplay * dpy, Window win) "java.awt.Component";
%typemap(jni) (XDisplay * dpy, Window win) "jobject";
%typemap(javain) (XDisplay * dpy, Window win) "$javainput";
%typemap(in,numinputs=1) (XDisplay * dpy, Window win) {
// some JNI to convert $input (jobject) into $1 (dpy) and $2 (win)
}
%inline %{
struct A {
void Attach(XDisplay * dpy, Window win) {}
};
%}
These typemaps have the added benefit of working everywhere you have a XDisplay, Window pairing with no extra effort.
The completed example, derived from the jawt.h example, with all the JNI filled out becomes:
%module test
%{
#include <X11/Xlib.h>
#include <jawt.h>
#include <jawt_md.h>
#include <cassert>
%}
%typemap(jstype) (Display * dpy, Window win) "java.awt.Component";
%typemap(jtype) (Display * dpy, Window win) "java.awt.Component";
%typemap(jni) (Display * dpy, Window win) "jobject";
%typemap(javain) (Display * dpy, Window win) "$javainput";
%typemap(in,noblock=1,numinputs=1) (Display * dpy, Window win) {
// some JNI to convert $input (jobject) into $1 (dpy) and $2 (win)
JAWT awt;
JAWT_DrawingSurface* ds;
JAWT_DrawingSurfaceInfo *dsi;
JAWT_X11DrawingSurfaceInfo* dsi_x11;
jboolean result;
jint lock;
awt.version = JAWT_VERSION_1_3;
result = JAWT_GetAWT(jenv, &awt);
assert(result != JNI_FALSE);
ds = awt.GetDrawingSurface(jenv, $input);
assert(ds != NULL);
lock = ds->Lock(ds);
assert((lock & JAWT_LOCK_ERROR) == 0);
dsi = ds->GetDrawingSurfaceInfo(ds);
dsi_x11 = (JAWT_X11DrawingSurfaceInfo*)dsi->platformInfo;
$1 = dsi_x11->display;
$2 = dsi_x11->drawable;
}
%typemap(freearg) (Display * dpy, Window win) {
ds->FreeDrawingSurfaceInfo(dsi);
ds->Unlock(ds);
awt.FreeDrawingSurface(ds);
}
%inline %{
struct A {
void Attach(Display * dpy, Window win) {}
};
%}
The two notable changes are the added freearg typemap which runs after the call to cleanup and the noblock=1 to make the local temporary variables visible to the freearg.