Microsoft Foundation Classes (mfc.hlp) (
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class CComboBox
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Description
The CComboBox class provides the functionality of a Windows combo box. A
combo box consists of an edit control plus a list box. The list box may
be displayed at all times or may be dropped down when the user selects a
drop-down arrow next to the edit control, depending on the ◄style► of
the combo box.
Depending on the style of the combo box, the user may or may not be able
to edit the contents of the edit control. If the list box is visible,
typing characters into the edit control will cause the first list-box
entry that matches the characters typed to be highlighted. Conversely,
selecting an item in the list box displays the selected text in the edit
control.
You create a combo box in two steps. First call the constructor
CComboBox to construct the CComboBox object, then call the ◄Create►
member function to create the button control and attach it to the
CComboBox object.
Construction can be a one-step process in a class derived from
CComboBox. Write a constructor for the derived class and call Create
from within the constructor.
If you want to handle the Windows notification messages sent by a
CComboBox object to its parent (usually a class derived from CDialog or
CModalDialog), add the appropriate message-map entries and
message-handler member functions to the parent class to handle the
messages you want to process. Potential message-map entries are:
ON_COMMAND
ON_CBN_KILLFOCUS
ON_CBN_SETFOCUS
ON_CBN_DROPDOWN
ON_CBN_DBLCLK
ON_CBN_ERRSPACE
ON_CBN_SELCHANGE
ON_CBN_EDITCHANGE
ON_CBN_EDITUPDATE
If you create a CComboBox object within a dialog box (through a dialog
resource), the CComboBox is automatically destroyed when the user closes
the dialog box.
If you create a CComboBox object within a window, you may also need to
destroy it. If you create the CComboBox object on the stack, it is
destroyed automatically. If you create the CComboBox object on the heap
by using the new function, you must call delete on the object to destroy
it when the user terminates the Windows combo box.
If you allocate any memory in the CComboBox object, override the
CComboBox destructor to dispose of the allocations.
See Also
◄CWnd►, ◄CButton►, ◄CEdit►, ◄CListBox►, ◄CScrollBar►, ◄CStatic►,
◄CModalDialog►, ◄CDialog►
Public Members
Construction/Destruction
◄CComboBox► Constructs a CComboBox object.
Initialization
◄Create► Creates the combo box and attaches it to the CComboBox
object.
General Operations
◄GetCount► Retrieves the number of items in the list box of a
combo box.
◄GetCurSel► Retrieves the index of the currently selected item, if
any, in the list box of a combo box.
◄SetCurSel► Selects a string in the list box of a combo box.
◄GetEditSel► Gets the starting and ending character positions of the
current selection in the edit control of a combo box.
◄LimitText► Limits the length of the text that the user may enter
into the edit control of a combo box.
◄SetEditSel► Select characters in the edit control of a combo box.
◄GetItemData► Retrieves the application-supplied 32-bit value
associated with the specified combo-box item.
◄SetItemData► Sets the 32-bit value associated with the specified
item in a combo box.
◄GetLBText► Gets a string from the list box of a combo box.
◄GetLBTextLen► Gets the length of a string in the list box of a combo
box.
◄ShowDropDown► Shows or hides the list box of a combo box that has the
CBS_DROPDOWN or CBS_DROPDOWNLIST ◄style►.
◄Clear► Deletes (clears) the current selection (if any) in the
edit control.
◄Copy► Copies the current selection (if any) onto the
Clipboard in CF_TEXT format.
◄Cut► Deletes (cuts) the current selection (if any) in the
edit control, and copies the deleted text onto the
Clipboard in CF_TEXT format.
◄Paste► Inserts the data from the Clipboard into the edit
control at the current cursor position. Data is
inserted only if the Clipboard contains data in CF_TEXT
format.
String Operations
◄AddString► Adds a string to the end of the list in the list box of
a combo box, or at the sorted position for list boxes
with the CBS_SORT style.
◄DeleteString► Deletes a string from the list box of a combo box.
◄InsertString► Inserts a string into the list box of a combo box.
◄ResetContent► Removes all items from the list box and edit control of
a combo box.
◄Dir► Adds a list of filenames to the list box of a combo
box.
◄FindString► Finds the first string that contains the specified
prefix in the list box of a combo box.
◄SelectString► Searches for a string in the list box of a combo box
and, if the string is found, selects the string in the
list box and copies the string to the edit control.
Windows 3.1 Functions
◄SetItemHeight► Sets the height of list items in a combo box
or the height of the edit-control (or
static-text) portion of a combo box.
◄GetItemHeight► Retrieves the height of list items in a combo
box.
◄FindStringExact► Finds the first listbox string (in a combo
box) that matches the specified string.
◄SetExtendedUI► Selects either the default user interface or
the extended user interface for a combo box
that has the ◄CBS_DROPDOWN► or
◄CBS_DROPDOWNLIST► style.
◄GetExtendedUI► Determines whether a combo box has the default
user interface or the extended user
interface.
◄GetDroppedControlRect► Retrieves the screen coordinates of the
visible (dropped-down) list box of a drop-down
combo box.
◄GetDroppedState► Determines whether the list box of a drop-down
combo box is visible (dropped down).
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