NAME

XtGetSelectionValue − request the value of a selection. 

Synopsis

void XtGetSelectionValue(w, selection, target, callback, client_data, time)

    Widget w;
    Atom selection;
    Atom target;
    XtSelectionCallbackProc callback;
    XtPointer client_data;
    Time time;

Inputs

wSpecifies the widget that is making the request.  Must be of class Core or any subclass thereof. 

selectionSpecifies the particular selection desired (usually XA_PRIMARY or XA_SECONDARY). 

targetSpecifies the type of information about the selection that is being requested. 

callbackSpecifies the callback procedure to be called when the selection value has been obtained.  Note that this is how the selection value is communicated back to the client. 

client_data
Specifies an argument to be passed to callback when it is called. 

timeSpecifies the timestamp that indicates when the selection is desired.  This should be the timestamp of the event that triggered this request; the value CurrentTime is not acceptable. 

Description

XtGetSelectionValue() initiates an ICCCM-compliant request to the owner of the selection identified by selection to convert that selection to the type identified by target, and registers callback as the procedure to be called (with client_data as one of its arguments) when the converted value is ready.  callback will be called some time after XtGetSelectionValue() is called.  It may be called before or after XtGetSelectionValue() returns.  If there is no owner for the selection or if the owner could not convert to the requested type, callback will be called with a value of NULL and length zero.  If multiple calls to the server are required to get all the data, this will be transparent to the widget; the Intrinsics perform all the necessary fragmentation and reassembly of the selection.  See XtSelectionCallbackProc(2) for information on how to write a callback appropriate to register with this function. 

Usage

Because of the asynchronous nature of interclient communication, it is not possible to call a function that returns the value of the selection immediately.  When you need the value of the selection, to paste it into a widget, for example, you must call XtGetSelectionValue() and supply a callback which will be called at some later time.  It is in this callback that you can actually perform your paste.  To determine the target types that the selection owner will be willing to return, intern the string "TARGETS" using XInternAtom(), and send the corresponding Atom as target. To (atomically) request that a selection value be converted to several target types, use XtGetSelectionValues(). 

See Also

XtGetSelectionValues(1), XtGetSelectionValueIncremental(1), XtOwnSelection(1),
XtSelectionCallbackProc(2). 

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