IAccessible::get_accKeyboardShortcut

發行項
03/28/2008

The IAccessible::get_accKeyboardShortcut method retrieves the specified object's shortcut key or access key, also known as the mnemonic. All objects that have a shortcut key or an access key support this property.

HRESULT get_accKeyboardShortcut(
VARIANTvarID,BSTR* pszKeyboardShortcut);

Parameters

varID
[in] Specifies whether the keyboard shortcut retrieved is that of the object or one of the object's child elements. This parameter is either CHILDID_SELF (to obtain information about the object) or a child ID (to obtain information about the object's child element). For more information about initializing the VARIANT structure, see How Child IDs Are Used in Parameters.
pszKeyboardShortcut
[out, retval] Address of a BSTR that receives a localized string that identifies the keyboard shortcut, or NULL if no keyboard shortcut is associated with the specified object.

Return Values

If successful, returns S_OK.

If not successful, returns one of the following values or another standard COM error code. Although servers return these values, clients must always check output parameters to ensure that they contain valid values. For more information, see Checking IAccessible Return Values.

Error	Description
S_FALSE	The object does not have an associated keyboard shortcut.
E_INVALIDARG	An argument is invalid.
DISP_E_MEMBERNOTFOUND	The object does not support this property.

Remarks

An access key is an underlined character in the text of a menu, menu item, or label of a button or some other control. For example, a user can display a menu by pressing the ALT key while also pressing the indicated underlined key, such as ALT+F to open the File menu. To use the access key of a menu item, the menu that contains the item must be active.

Controls such as toolbar buttons and menu items often have an associated shortcut key, also known as a keyboard accelerator. Some menu items may have both an access key and a shortcut key, and some may have only one. For example, a menu item called New has an access key N and a shortcut key CTRL+N. The menu does not have to be active for the shortcut key to work.

Note to client developers If this property returns a single character, you cannot assume it is an access key or a keyboard shortcut. With standard menu items, the access key is returned by IAccessible::get_accKeyboardShortcut, and the shortcut key is returned as part of the menu item name returned from IAccessible::get_accName. In general, access keys tend to be defined as ALT + <letter>, and keyboard shortcuts tend to be CTRL + <letter>.

Note to server developers If the user interface (UI) element can receive keyboard focus, then you should expose the access key for the element. If the UI element cannot receive keyboard focus (such as toolbar icons), then you should display the shortcut key.

Because shortcut keys are usually determined by the application rather than by the control itself, servers can usually return the value obtained from the standard accessible object for the window.

Client Example

The following example function retrieves the keyboard shortcut for the specified accessible object, or one of its children, and prints it to the console.

HRESULT PrintShortcut(IAccessible* pAcc, long child)
{
    if (pAcc == NULL)
    {
        return E_INVALIDARG;
    }
    BSTR bstrShortcut;
    VARIANT varObj;
    varObj.vt = VT_I4;
    varObj.lVal = child;
    HRESULT hr = pAcc->get_accKeyboardShortcut(varObj, &bstrShortcut;);
    if (hr == S_OK)
    {
        printf("Shortcut: %S\n", bstrShortcut);
        SysFreeString(bstrShortcut);
    }
    return hr;
}

Requirements

**  Windows NT/2000/XP/Server 2003:** Included in Windows 2000 and later.
**  Windows 95/98/Me:** Included in Windows 98 and later.
**  Redistributable:** Requires Active Accessibility 1.3 RDK on Windows NT 4.0 SP6 and Windows 95.
**  Header:** Declared in Oleacc.h.
**  Library:** Use Oleacc.lib.

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