Hi,

I'm having trouble fetching the XdndTypeList data. It works 100% on my 32-bit Linux laptop, but now trying on my 64-bit Linux desktop at work, the XGetWindowProperty() call under 64-bit linux for the XdndTypeList always returns count = 0, when in fact it should be 8, as my last section of the output shows. I simply forced count = 8, because I knew Nautilus has that many types, and wanted to see if my array of TAtom's actually contains the data - which it does! So it does seem to fetch the data, it just doesn't report it in the variables: actualformat, count, remaining.

Anybody got experience with this and know how I can resolve this problem?

type
  AtomArray = array [0..0] of TAtom;
  PAtomArray = ^AtomArray;
var
  s: string;
  actualtype: TAtom;
  actualformat: Integer;
  count, remaining, dummy: longword;
  xdndtypes: PAtomArray;
begin
...
        XGetWindowProperty(fpgApplication.Display, FSrcWinHandle,
            XdndTypeList, 0, dummy,
            TBool(False),
            AnyPropertyType,
            @actualtype, @actualformat, @count, @remaining,
            @xdndtypes);
        s := XGetAtomName(fpgApplication.Display, actualtype);
        writeln(Format('  ActualType: %s (%d)', [s, ActualType]));
        writeln('  Actualformat = ', ActualFormat);
        writeln('  count = ', count);
        writeln('  remaining = ', remaining);

------------ [ output of my test program ]-------------------- XdndEnter event received!
ver(4) check-XdndTypeList(True) data=1E0E816h,67108865,0,0,0
* We will be using XDND v4 protocol *
** We need to fetch XdndTypeList (>3 types)

Actual fetch: ---------------------
ActualType: ATOM (4)
Actualformat = 0
count = 0 <--- ???????????? remaining = 0

Force the count size to be eight: -------------------------- Format #1 = x-special/gnome-icon-list (564)
Format #2 = text/uri-list (531)
Format #3 = UTF8_STRING (283)
Format #4 = COMPOUND_TEXT (463)
Format #5 = TEXT (464)
Format #6 = STRING (31)
Format #7 = text/plain;charset=utf-8 (465)
Format #8 = text/plain (466)

--------------------------------

In our previous episode, Graeme Geldenhuys said:

You are not passing unix types, and are passing pointers to 32-bit types to parametesr that expect pointers to 64-bit types (pculong).

Since they are on the stack, they probably overwrite eachother. As always with 64-bit, pay great care to the typing.

You should use the ctypes here, since they'll change for 64 bit.

Henry

Marco van de Voort wrote

You are not passing unix types, and are passing pointers to 32-bit types to parametesr that expect pointers to 64-bit types (pculong).

Oops! Thanks Marco, changing them to ctypes solved the problem. I better double check my other X11 code too, I might be making the same mistake in a few more place. :-/

Finally got fpGUI-X11 drag-n-drop to work! :-)

Henry Vermaak wrote

You should use the ctypes here, since they'll change for 64 bit.

Thanks Henry, that was indeed the problem.