IDataAdviseHolder::Advise method

Creates a connection between an advise sink and a data object for receiving notifications.

Syntax


HRESULT Advise(
  [in]   IDataObject *pDataObject,
  [in]   FORMATETC *pFetc,
  [in]   DWORD advf,
  [in]   IAdviseSink *pAdvise,
  [out]  DWORD *pdwConnection
);

Parameters

pDataObject [in]

A pointer to the IDataObject interface on the data object for which notifications are requested. If data in this object changes, a notification is sent to the advise sinks that have requested notification.

pFetc [in]

A pointer to a FORMATETC structure that contains the specified format, medium, and target device that is of interest to the advise sink requesting notification. For example, one sink may want to know only when the bitmap representation of the data in the data object changes. Another sink may be interested in only the metafile format of the same object. Each advise sink is notified when the data of interest changes. This data is passed back to the advise sink when notification occurs.

advf [in]

A group of flags that control the advisory connection. Possible values are from the ADVF enumeration. However, only some of the possible ADVF values are relevant for this method. The following table briefly describes the relevant values; a more detailed description can be found in the description of the ADVF enumeration.

ValueMeaning
ADVF_NODATA

Asks that no data be sent along with the notification.

ADVF_ONLYONCE

Causes the advisory connection to be destroyed after the first notification is sent. An implicit call to IDataAdviseHolder::Unadvise is made on behalf of the caller to remove the connection.

ADVF_PRIMEFIRST

Causes an initial notification to be sent regardless of whether data has changed from its current state.

ADVF_DATAONSTOP

When specified with ADVF_NODATA, this flag causes a last notification with the data included to be sent before the data object is destroyed. When ADVF_NODATA is not specified, this flag has no effect.

 

pAdvise [in]

A pointer to the IAdviseSink interface on the advisory sink that receives the change notification.

pdwConnection [out]

A pointer to a variable that receives a token that identifies this connection. The calling object can later delete the advisory connection by passing this token to IDataAdviseHolder::Unadvise. If this value is zero, the connection was not established.

Return value

This method returns S_OK on success.

Remarks

Through the connection established through this method, the advisory sink can receive future notifications in a call to IAdviseSink::OnDataChange.

An object issues a call to IDataObject::DAdvise to request notification on changes to the format, medium, or target device of interest. This data is specified in the pFormatetc parameter. The DAdvise method is usually implemented to call IDataAdviseHolder::Advise to delegate the task of setting up and tracking a connection to the advise holder. When the format, medium, or target device in question changes, the data object calls IDataAdviseHolder::SendOnDataChange to send the necessary notifications.

The established connection can be deleted by passing the value in pdwConnection in a call to IDataAdviseHolder::Unadvise.

Requirements

Minimum supported client

Windows 2000 Professional [desktop apps only]

Minimum supported server

Windows 2000 Server [desktop apps only]

Header

ObjIdl.h

IDL

ObjIdl.idl

IID

IID_IDataAdviseHolder is defined as 00000110-0000-0000-C000-000000000046

See also

CreateDataAdviseHolder
IDataAdviseHolder
IDataObject::DAdvise

 

 

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