Combo Box

  • 项目

A combo box is a list box combined with a static control or an edit control that displays the currently selected item in the list box portion of the combo box. The list box portion of the control is displayed at all times or only drop down when the user selects the drop-down arrow (which is a push button) next to the control. If the selection field is an edit control, the user can enter information not in the list; otherwise, the user can only select items in the list.

The window class name for a combo box is "COMBOBOX".

The contents of the IAccessible properties depend on which of the following parts of the combo box is queried by the client:

  • The combo box window
  • The edit control or static text control
  • The drop-down arrow (which is a push button)
  • The list box
  • The list items in the list box

Supported Properties and Methods

  • accDoDefaultAction
    The following table shows the default action that the accDoDefaultAction method will perform for different parts of a combo box.

    Combo box part DoDefaultAction
    Combo box window None
    Edit control None
    Drop-down arrow Either drops down or closes the list
    List box None
    List item Selects the list item

  • accHitTest
    accLocation
    accNavigate
    accSelect
    get_accChild
    get_accChildCount
    The following table shows the child count value for different parts of the combo box.

    Combo box part ChildCount
    Combo box window 3
    Edit control 0
    Drop-down arrow 0
    List box The number of list items
    List item 0

  • get_accDefaultAction
    The following table shows the DefaultAction property for different parts of a combo box.

    Combo box part DefaultAction
    Combo box window None
    Edit control None
    Drop-down arrow "Open" or "Close" depending on the state of the drop-down list
    List box None
    List item "Double Click"

  • get_accDescription
    get_accFocus
    get_accHelp
    get_accHelpTopic
    get_accKeyboardShortcut
    The following table shows the KeyboardShortcut property for different parts of a combo box.

    Combo box part KeyboardShortcut
    Combo box window Access key of associated label
    Edit control None
    Drop-down arrow "Alt+Down Arrow"
    List box None
    List item None

    The access key for a combo box is the underlined character in the text from an associated static text control that labels the combo box. For example, on a standard Open dialog box that opens files, such as in WordPad, the combo box labeled "Files of type:" has the KeyboardShortcut "Alt+t".

  • get_accName
    The following table shows the Name property for different parts of a combo box.

    Combo box part Name
    Combo box window Static text control used as a label
    Edit control Static text control used as a label
    Drop-down arrow "Open" or "Close" depending on the state of the drop-down list
    List box Associated label
    List item Text of the list item

    The Name property of a combo box, its child edit control, and its child list box is the text from an associated static text control that labels the combo box. For example, on a standard Open dialog box that opens files, such as in WordPad, the Name properties for the two combo boxes are "Look in:" and "Files of type:".

  • get_accParent
    The following table shows the parent value for different parts of a combo box.

    Combo box part Parent
    Combo box window A window with the Role property of ROLE_SYSTEM_WINDOW that surrounds the combo box and has the same Name property and window class name as the combo box.
    Edit control (or static text control) The combo box window.
    Drop-down arrow The combo box window.
    List box parent window The combo box window. This window surrounds the list box.
    List box The list box parent window.
    List item The list box.

  • get_accRole
    The following table shows the Role property for different parts of a combo box.

    Combo box part Role
    Combo box window ROLE_SYSTEM_COMBOBOX
    Edit control (or static text control) ROLE_SYSTEM_TEXT or ROLE_SYSTEM_STATICTEXT
    Drop-down arrow ROLE_SYSTEM_PUSHBUTTON
    List box ROLE_SYSTEM_LIST
    List item ROLE_SYSTEM_LISTITEM

  • get_accState
    The following table shows the State property for different parts of a combo box.

    Combo box part Possible states
    Combo box window STATE_SYSTEM_INVISIBLE | STATE_SYSTEM_UNAVAILABLE | STATE_SYSTEM_FOCUSED | STATE_SYSTEM_FOCUSABLE | STATE_SYSTEM_NORMAL | STATE_SYSTEM_EXPANDED | STATE_SYSTEM_COLLAPSED
    Edit control STATE_SYSTEM_INVISIBLE | STATE_SYSTEM_UNAVAILABLE | STATE_SYSTEM_FOCUSED | STATE_SYSTEM_FOCUSABLE | STATE_SYSTEM_NORMAL
    Drop-down arrow 0, which means the button is visible and not pressed; or STATE_SYSTEM_PRESSED |

    STATE_SYSTEM_INVISIBLE | STATE_SYSTEM_NORMAL
    List box STATE_SYSTEM_INVISIBLE | STATE_SYSTEM_UNAVAILABLE | STATE_SYSTEM_FOCUSED | STATE_SYSTEM_FOCUSABLE | STATE_SYSTEM_FLOATING | STATE_SYSTEM_NORMAL
    List item STATE_SYSTEM_INVISIBLE | STATE_SYSTEM_FOCUSABLE | STATE_SYSTEM_FOCUSED | STATE_SYSTEM_SELECTABLE | STATE_SYSTEM_SELECTED | STATE_SYSTEM_NORMAL

  • get_accValue
    The following table shows the Value property for different parts of a combo box.

    Combo box part Value
    Combo box window Text of currently selected list item
    Edit control Text of currently selected list item
    Drop-down arrow None
    List box None
    List item None

Events Generated

EVENT_OBJECT_STATECHANGE

EVENT_OBJECT_VALUECHANGE

Remarks

When accNavigate is called with the NAVDIR_NEXT flag on the list box part of a combo box, it incorrectly navigates to the tray window when it should return VT_EMPTY.

See Also

IAccessible Interface