IWDFDriver::CreateWdfObject method (wudfddi.h)

Article
10/21/2021

[Warning: UMDF 2 is the latest version of UMDF and supersedes UMDF 1. All new UMDF drivers should be written using UMDF 2. No new features are being added to UMDF 1 and there is limited support for UMDF 1 on newer versions of Windows 10. Universal Windows drivers must use UMDF 2. For more info, see Getting Started with UMDF.]

The CreateWdfObject method creates a custom (or user) WDF object from a parent WDF object.

Syntax

HRESULT CreateWdfObject(
  [in, optional] IUnknown   *pCallbackInterface,
  [in, optional] IWDFObject *pParentObject,
  [out]          IWDFObject **ppWdfObject
);

Parameters

[in, optional] pCallbackInterface

A pointer to the IUnknown interface that the framework uses to determine the object-related event callback functions that the driver subscribes to on the newly created custom object. This parameter is optional. The driver can pass NULL if the driver does not require notification. If the driver passes a valid pointer, the framework will call QueryInterface on the IUnknown interface for the IObjectCleanup interface. If the framework obtains the driver's IObjectCleanup interface, the framework can subsequently call the driver's IObjectCleanup::OnCleanup method to notify the driver that the custom object is cleaned up.

[in, optional] pParentObject

A pointer to the IWDFObject interface for the parent WDF object. If NULL, the driver object becomes the default parent.

[out] ppWdfObject

A pointer to a buffer that receives a pointer to the IWDFObject interface for the newly created WDF object.

Return value

CreateWdfObject returns S_OK if the operation succeeds. Otherwise, this method returns one of the error codes that are defined in Winerror.h.

Remarks

The driver can call CreateWdfObject to create a general framework base object for its own use. The driver can associate context memory, assign a parent object, and register an IObjectCleanup interface. The framework subsequently calls the IObjectCleanup::OnCleanup method to clean up the child object.

If no parent object is specified at the pParentObject parameter, the driver becomes the default parent. Therefore, when the driver object is deleted, the framework cleans up the child object.

If a parent object is assigned, the child object is deleted when the parent object is deleted. In other words, the lifetime of a child object is scoped within that of the parent.

If the driver must clean up the child object before the parent object is deleted, the driver can call the IWDFObject::DeleteWdfObject method.

Requirements

Requirement	Value
End of support	Unavailable in UMDF 2.0 and later.
Target Platform	Desktop
Minimum UMDF version	1.5
Header	wudfddi.h (include Wudfddi.h)
DLL	WUDFx.dll