Volume 6A: Motif Programming Manual

"STRING", data, length+1, &recvd, NULL);

while (status == ClipboardLocked);

if (status != ClipboardSuccess || recvd != length) {

printf ("Failed to receive all clipboard data0);

XtFree (data);

}

else

printf ("Retrieved

}

18.2 Copy by Name

As discussed earlier, there are cases where data should not be c-opied to the clipboard until it is requested. It is

possible to copy data by name, so that the owner of the data is notified through a callback function when the data is

needed by the clipboard. Since copying large amounts of data may be expensive, time−consuming, or even impossible

due to other constraints in an application, copying data by name may be the only option available. The technique is

especially advantageous if the data is never requested, since time and resources are saved.

The procedure for copying data by name is quite similar to the procedure for normal copying. The application first

calls XmClipboardStartCopy(), but unlike a normal copy operation, the callback and widget parameters

are specified. These values indicate that the data is to be copied by name. The callback parameter specifies the

routine that is called when the data is requested by another client. The widget parameter specifies the widget that

receives the messages requesting the data. Since the toolkit handles the messages, any valid widget ID can be used.

XmClipboardCopy() is then called with a buffer value of NULL. XmClipboardEndCopy() is called as

usual. When a client requests the data from the clipboard, ...