AccessibleObjectFromPoint function

Retrieves the address of the IAccessible interface pointer for the object displayed at a specified point on the screen.

Syntax

HRESULT AccessibleObjectFromPoint(
  POINT       ptScreen,
  IAccessible **ppacc,
  VARIANT     *pvarChild
);

Parameters

ptScreen

Specifies, in physical screen coordinates, the point that is examined.

ppacc

Address of a pointer variable that receives the address of the object's IAccessible interface.

pvarChild

Address of a VARIANT structure that specifies whether the IAccessible interface pointer that is returned in ppacc belongs to the object displayed at the specified point, or to the parent of the element at the specified point. The vt member of the VARIANT is always VT_I4. If the lVal member is CHILDID_SELF, then the IAccessible interface pointer at ppacc belongs to the object at the point. If the lVal member is not CHILDID_SELF, ppacc is the address of the IAccessible interface of the child element's parent object. Clients must call VariantClear on the retrieved VARIANT parameter when finished using it.

Return Value

If successful, returns S_OK.

If not successful, returns one of the following or another standard COM error code.

Return code Description
E_INVALIDARG
An argument is not valid.

Remarks

This function retrieves the lowest-level accessible object in the object hierarchy at a given point. If the element at the point is not an accessible object (that is, does not support IAccessible), then the function retrieves the IAccessible interface of the parent object. The parent object must provide information about the child element through the IAccessible interface. Call IAccessible::accHitTest to identify the child element at the specified screen coordinates.

As with other IAccessible methods and functions, clients might receive errors for IAccessible interface pointers because of a user action. For more information, see Receiving Errors for IAccessible Interface Pointers.

Client Example

The following example function selects the item at a specified point on the screen. It is assumed that a single selection is wanted.

HRESULT SelectItemAtPoint(POINT point)
{
    VARIANT varItem;
    IAccessible* pAcc;
    HRESULT hr = AccessibleObjectFromPoint(point, &pAcc, &varItem);
    if ((hr == S_OK))
    {
        hr = pAcc->accSelect((SELFLAG_TAKEFOCUS | SELFLAG_TAKESELECTION), varItem);
        VariantClear(&varItem);
        pAcc->Release();
    }
    return hr;
}

Requirements

   
Minimum supported client Windows 2000 Professional [desktop apps only]
Minimum supported server Windows Server 2003 [desktop apps only]
Target Platform Windows
Header oleacc.h
Library Oleacc.lib
DLL Oleacc.dll
Redistributable Active Accessibility 1.3 RDK on Windows NT 4.0 with SP6 and later and Windows 95

See Also

AccessibleObjectFromEvent

AccessibleObjectFromWindow

Active Accessibility and Windows Vista Screen Scaling

IAccessible

VARIANT Structure