JNI - How to find native handle for a JInternalFrame

Question

use (and works) this code on a C DLL to interface with JNI and JAVA to obtain a native handle for a JFrame:
JAWT awt;
JAWT_DrawingSurface *ds;
JAWT_DrawingSurfaceInfo *dsi;
JAWT_Win32DrawingSurfaceInfo *dsi_win;
jboolean result;
jint lock;
awt.version = JAWT_VERSION_1_4;
result = JAWT_GetAWT(env, &awt);
assert(result != JNI_FALSE);
ds = awt.GetDrawingSurface(env, javacomponent);
assert(ds != NULL);
lock = ds->Lock(ds);
assert((lock & JAWT_LOCK_ERROR) == 0);
dsi = ds->GetDrawingSurfaceInfo(ds);
dsi_win = (JAWT_Win32DrawingSurfaceInfo*)dsi->platformInfo;
nativeHanle = dsi_win->hwnd;
ds->FreeDrawingSurfaceInfo(dsi);
ds->Unlock(ds);
awt.FreeDrawingSurface(ds);
This code works fine if javacomponent is a Canvas or a JFrame, but if it is a JInternalFrame, locking the drawing surface gives error (lines 'lock = ds->Lock(ds);' and 'assert((lock & JAWT_LOCK_ERROR) == 0);')
Thanks in advance.

Answer 1

Hello,
I'm not sure about what you're trying to achieve but, as far as I know, JInternalFrames don't have a native counterpart (peer) as other top level swing components or as awt components in general. They are just painted over their Container (usually a JDesktopPane).