通过

IViewObject::Freeze (Windows Embedded CE 6.0)

  • 项目

1/6/2010

Thismethod freezes a certain aspect of the object's presentation so that it does not change until the IViewObject::Unfreeze method is called.

Syntax

HRESULT Freeze( 
  DWORD dwAspect, 
  LONG lindex, 
  void* pvAspect, 
  DWORD* pdwFreeze
);

Parameters

  • dwAspect
    [in] Specifies how the object is to be represented.

    Representations include content, an icon, a thumbnail, or a printed document.

    Valid values are taken from the enumeration DVASPECT.

  • lindex
    [in] Portion of the object that is of interest for the draw operation.

    Its interpretation varies with dwAspect.

  • pvAspect
    [in] Pointer to additional information about the view of the object specified in dwAspect.

    Because none of the current aspects support additional information, pvAspect must always be NULL.

  • pdwFreeze
    [out] Pointer to where an identifying DWORD key is returned.

    This unique key is later used to cancel the freeze by calling Unfreeze.

    This key is an index that the default cache uses to keep track of which object is frozen.

Return Value

One of the values in the following table is returned.

Value Description

S_OK

The presentation was frozen.

VIEW_S_ALREADYFROZEN

Presentation was frozen.

The value of pdwFreeze is the identifying key of the frozen object.

OLE_E_BLANK

The presentation is not in cache.

DV_E_LINDEX

Invalid value for lindex; currently only -1 is supported.

DV_E_DVASPECT

Invalid value for dwAspect.

Remarks

The Freeze method causes the view object to freeze its drawn representation until a subsequent call to Unfreeze releases it. After calling Freeze, successive calls to IViewObject::Draw with the same parameters produce the same picture until Unfreeze is called.

Freeze is not part of the persistent state of the object and does not continue across unloads and reloads of the object.

The most common use of this method is for banded printing.

While in a frozen state, view notifications are not sent. Pending view notifications are deferred to the subsequent call to Unfreeze.

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

Requirements

Header Oleidl.h, oleidl.idl
Library oleaut32.lib, uuid.lib
Windows Embedded CE Windows CE 2.0 and later

See Also

Reference

IViewObject
DVASPECT
IViewObject::Draw
IViewObject::Unfreeze

Concepts

Determining Supported COM APIs