IOleObject::DoVerb

A version of this page is also available for

Windows Embedded CE 6.0 R3

4/8/2010

This method requests an object to perform an action in response to an end-user's action. The possible actions are enumerated for the object in IOleObject::EnumVerbs.

Syntax

HRESULT DoVerb( 
  LONG iVerb, 
  LPMSG lpmsg, 
  IOleClientSite* pActiveSite, 
  LONG lindex, 
  HWND hwndParent, 
  LPCRECT lprcPosRect 
);

Parameters

• iVerb
  [in] Number assigned to the verb in the OLEVERB structure returned by EnumVerbs.

• lpmsg
  [in] Long pointer to the MSG structure describing the event that invoked the verb.

  The caller should pass the MSG structure unmodified, without attempting to interpret or alter the values of any of the members of lpmsg.

• pActiveSite
  [in] Pointer to the IOleClientSite interface on the object's active client site, where the event occurred that invoked the verb.

• lindex
  [in] Reserved for future use; set to zero.

• hwndParent
  [in] Handle to the document window that contains the object.

  This and lprcPosRect make it possible to open a temporary window for an object, where hwndParent is the parent window in which the object's window is to be displayed, and lprcPosRect defines the area available for displaying the object window within that parent.

  A temporary window is useful, for example, to a multimedia object that opens itself for playback but not for editing.

• lprcPosRect
  [in] Long pointer to the RECT structure that contains the coordinates, in pixels, that define an object's bounding rectangle in hwndParent.

  This and hwndParent together enable opening multimedia objects for playback but not for editing.

Return Value

One of the values in the following table is returned.

Remarks

A verb is an action that an OLE object takes in response to a message from its container. An object's container, or a client linked to the object, normally calls DoVerb in response to some user action, such as double-clicking the object.

The various actions available for a given object are enumerated in an OLEVERB structure, which the container obtains by calling EnumVerbs.

DoVerb matches the value of iVerb against the iVerb member of the structure to determine which verb to invoke.

Through EnumVerbs, an object, rather than its container, determines which verbs (actions) it supports.

OLE 2 defines seven verbs that are available, but not necessarily useful, to all objects. In addition, each object can define additional verbs that are unique to it.

The following verbs are defined by OLE:

• OLEIVERB_PRIMARY (0L)
  Specifies the action that occurs when a user double-clicks the object in its container. The object, not the container, determines this action.

  If the object supports in-place activation, the primary verb usually activates the object in place.

• OLEIVERB_SHOW (–1)
  Instructs an object to show itself for editing or viewing. Called to display newly inserted objects for initial editing and to show link sources. Usually an alias for some other object-defined verb.

• OLEIVERB_OPEN (–2)
  Instructs an object, including one that otherwise supports in-place activation, to open itself for editing in a window separate from that of its container.

  If the object does not support in-place activation, this verb has the same semantics as OLEIVERB_SHOW.

• OLEIVERB_HIDE (–3)
  Causes an object to remove its user interface from the view. Applies only to objects that are activated in-place.

• OLEIVERB_UIACTIVATE (–4)
  Activates an object in place, along with its full set of user-interface tools, including menus, toolbars, and its name in the title bar of the container window.

  If the object does not support in-place activation, it should return E_NOTIMPL.

• OLEIVERB_INPLACEACTIVATE (–5)
  Activates an object in place without displaying tools, such as menus and toolbars, that users need to change the behavior or appearance of the object.

  Single-clicking such an object causes it to negotiate the display of its user-interface tools with its container. If the container refuses, the object remains active but without its tools displayed.

• OLEIVERB_DISCARDUNDOSTATE (–6)
  Used to tell objects to discard any undo state that they might be maintaining without deactivating the object.

To determine whether the platform supports this interface, see Determining Supported COM APIs.

Note to Callers

Containers call DoVerb as part of initializing a newly created object.

Before making the call, containers should do the following:

• Call IOleObject::SetClientSite to inform the object of its display location
• Call IOleObject::SetHostNames to alert the object that it is an embedded object and to trigger appropriate changes to the user interface of the object application in preparation for opening an editing window.

Like the OleActivate function in OLE 1, DoVerb automatically runs the OLE server application. If an error occurs during verb execution, the object application is shut down.

If a user invokes a verb by some means other than selecting a command from a menu (say, by double-clicking or, more rarely, single-clicking an object), the object's container should pass a pointer (lpmsg)to a Windows MSG structure that contains the appropriate message.

For example, if the user invokes a verb by double-clicking the object, the container should pass a MSG structure that contains WM_LBUTTONDBLCLK, WM_MBUTTONDBLCLK, or WM_RBUTTONDBLCLK.

If the container passes no message, lpmsg should be set to NULL.

The object should ignore the hwnd member of the passed MSG structure, but can use all other MSG members.

If the object's embedding container calls DoVerb, the client-site pointer (pClientSite) passed to DoVerb is the same as that of the embedding site. If the embedded object is a link source, the pointer passed to DoVerb is that of the linking client's client site.

When DoVerb is invoked on an OLE link, it can return OLE_E_CLASSDIFF or MK_CONNECTMANUALLY:

• The link object returns OLE_E_CLASSDIFF when the link source has been subjected to some sort of conversion while the link was passive.
• The link object returns MK_CONNECTMANUALLY when the link source is on a network drive that is not connected to the caller's computer.

Container applications that do not support general in-place activation can still use the hwndParent and lprcPosRect parameters to support in-place playback of multimedia files. Containers must pass valid hwndParent and lprcPosRect parameters to DoVerb.

Some code samples pass a lindex value of –1 instead of zero. The value –1 works but should be avoided in favor of zero.

The lindex parameter is reserved, and for reasons of consistency Microsoft recommends assigning a zero value to all reserved parameters.

Notes to Implementers

In addition to the above verbs, an object can define in its OLEVERB structure additional verbs that are specific to itself. Positive numbers designate these object-specific verbs.

An object should treat an unknown positive verb number as if it were the primary verb and return OLE_S_INVALIDVERB to the calling function.

The object should ignore verbs with negative numbers that it does not recognize and return E_NOTIMPL.

If the verb being executed places the object in the running state, register the object in the Running Object Table (ROT) even if its server application does not support linking. Registration is important because the object might at some point serve as the source of a link in a container that supports links to embeddings.

Registering the object with the ROT enables the link client to get a pointer to the object directly, instead of having to go through the object's container.

To perform the registration, do the following:

1. Call IOleClientSite::GetMoniker to get the full moniker of the object,
2. Call the GetRunningObjectTable function to get a pointer to the ROT, and then
3. Call IRunningObjectTable::Register.

When showing a window as a result of DoVerb, it is very important for the object to explicitly call SetForegroundWindow on its editing window. This ensures that the object's window is visible to the user even if another process originally obscured it.

For more information about SetForegroundWindow and SetActiveWindow, see the Windows SDK.

Requirements

See Also

Reference

IOleObject
GetRunningObjectTable
IOleClientSite
IOleClientSite::GetMoniker
IOleObject::EnumVerbs
IOleObject::SetClientSite
IOleObject::SetHostNames
IRunningObjectTable::Register
OLEVERB

Concepts

Determining Supported COM APIs

Other Resources

MSG
RECT
SetActiveWindow
SetForegroundWindow