IUIAutomation4::AddChangesEventHandler method (uiautomationclient.h)

Article
02/22/2024

Registers a method that handles change events.

Note Before implementing an event handler, you should be familiar with the threading issues described in Understanding Threading Issues.

Syntax

HRESULT AddChangesEventHandler(
  [in] IUIAutomationElement             *element,
       TreeScope                        scope,
  [in] int                              *changeTypes,
  [in] int                              changesCount,
  [in] IUIAutomationCacheRequest        *pCacheRequest,
  [in] IUIAutomationChangesEventHandler *handler
);

Parameters

[in] element

Type: IUIAutomationElement*

A pointer to the UI Automation element associated with the event handler.

scope

[in] changeTypes

Type: int*

A pointer to a list of integers that indicate the change types the event represents.

[in] changesCount

Type: int

The number of changes that occurred in this event.

[in] pCacheRequest

Type: IUIAutomationCacheRequest*

A pointer to a cache request, or NULL if no caching is wanted.

[in] handler

Type: IUIAutomationChangesEventHandler*

A pointer to the object that handles the changes event.

Return value

Type: HRESULT

If this method succeeds, it returns S_OK. Otherwise, it returns an HRESULT error code.

Remarks

A Microsoft UI Automation client should not use multiple threads to add or remove event handlers. Unexpected behavior can result if one event handler is being added or removed while another is being added or removed in the same client process.

Requirements

Requirement	Value
Minimum supported client	Windows 10, version 1607 [desktop apps only]
Minimum supported server	Windows Server 2016 [desktop apps only]
Target Platform	Windows
Header	uiautomationclient.h (include UIAutomation.h)