XmTransferValue

library call

`XmTransferValue`

A toolkit function that transfers data to a destination

    #include <Xm/Xm.h>

    void XmTransferValue

    XtPointer transfer_id
    Atom target
    XtCallbackProc proc
    XtPointer client_data
    Time time

## DESCRIPTION

`XmTransferValue` converts a selection, transferring any data from the selection owner, in the context of an already-initiated data transfer operation. An application can call this routine from an `XmNdestinationCallback` procedure or any function called as a result.

The caller of `XmTransferValue` supplies the target to which the selection is converted. The caller also supplies a callback procedure to handle the data that results from the conversion.

`transfer_id`

- Specifies a unique indentifier for the data transfer operation. The value must be the same as the value of the `transfer_id` member of the XmDestinationCallbackStruct passed to the `XmNdestinationCallback` procedure.

target

- Specifies the target to which the selection is to be converted.

proc

- Specifies a callback procedure to be invoked when the selection has been converted and the data, if any, is available. This procedure is responsible for inserting or otherwise handling any data transferred. The procedure can also terminate the data transfer by calling `XmTransferDone`. The proc receives three arguments:

  - The widget that requested the conversion

  - The value of the client_data argument

  - A pointer to an XmSelectionCallbackStruct

  This procedure can be called before or after `XmTransferValue` returns.

client_data

- Specifies data to be passed to the callback procedure (the value of the proc argument) when the selection has been converted.

time

- Specifies the time of the XEvent that triggered the data transfer. You should typically set this field to `XtLastTimestampProcessed`.

The callback procedure (the value of the proc argument) receives a pointer to an XmSelectionCallbackStruct, which has the following definition:

    typedef struct
    {
            int reason;
            XEvent *event;
            Atom selection;
            Atom target;
            Atom type;
            XtPointer transfer_id;
            int flags;
            int remaining;
            XtPointer value;
            unsigned long length;
            int format;
    } XmSelectionCallbackStruct;

reason

- Indicates why the callback was invoked.

event

- Points to the XEvent that triggered the callback. It can be NULL.

selection

- Specifies the selection that has been converted.

target

- Specifies the target to which `XmTransferValue` requested conversion. The value is the same as the value of the target argument to `XmTransferValue`.

type

- Specifies the type of the selection value. This is not the target, but the type used to represent the target. The value XT_CONVERT_FAIL means that the selection owner did not respond to the conversion request within the Intrinsics selection timeout interval.

`transfer_id`

- Specifies a unique indentifier for the data transfer operation. The value is the same as the value of the `transfer_id` argument to `XmTransferValue`.

flags

- This member is currently unused. The value is always `XmSELECTION_DEFAULT`.

remaining

- Indicates the number of transfers remaining for the operation specified by `transfer_id`.

value

- Represents the data transferred by this request. The application is responsible for freeing the value by calling `XtFree`.

length

- Indicates the number of elements of data in value, where each element has the size symbolized by format. If value is NULL, length is 0.

format

- Indicates whether the data in value should be viewed as a list of char, short, or long quantities. Possible values are 8 (for a list of char), 16 (for a list of short), or 32 (for a list of long).

## RELATED

&cdeman.XmTransferSetParameters;, &cdeman.XmTransferSendRequest;, and &cdeman.XmTransferStartRequest;.