TcxCustomComboBox Class
The base class for all editors that allow users to select options in a drop-down window.
#Declaration
TcxCustomComboBox = class(
TcxCustomDropDownEdit,
IcxItemIndexHandler
)
#Remarks
A combo box editor combines a single-line text editor and a drop-down menu. If user input in the text edit box matches initial characters in a menu string, the combo box allows a user to autocomplete the current input with the full string.
The TcxCustomComboBox
class implements base functionality common to all editors that allow users to select options in a drop-down window.
#End-User Input Options
Up and Down arrow keys allow users to switch between combo box items, even when the drop-down menu is closed. Ctrl+PageUp and Ctrl+PageDown keystrokes select first and last items, respectively.
#Drop-Down Menu Interaction
Users can do the following to open or close the drop-down combo box menu:
- Click the drop-down button.
- Focus the combo box and press the Alt+Up Arrow or Alt+Down Arrow key.
- Focus the combo box and press the F4 key.
Note
You can invoke the drop-down menu only if it contains at least one value.
#Main API Members
The list below outlines key members of the TcxCustomComboBox
class that allow you to configure combo boxes and manage combo box items:
- Customize combo box settings (Properties).
- Assign a repository item as an external source of combo box settings (RepositoryItem).
- Identify active combo box settings (ActiveProperties).
- Disable or enable the combo box (Enabled).
- Switch between combo box items (ItemIndex).
- Manage the edit value (EditingValue, EditValue, EditingText, Clear, and ResetEditValue).
- Access and customize the drop-down menu (PopupWindow).
- Identify if the drop-down menu can be opened (CanDropDown).
- Open or close the drop-down window (DroppedDown and CloseUp).
- Specify a text hint for the combo box when it has no assigned edit value (TextHint).
- Manage content selection (SelStart, SelLength, SelText, SetSelection, SelectAll, and ClearSelection).
- Play the default system sound when a user confirms input (BeepOnEnter).
- Discard the last content change when the combo box has focus (Undo).
- Configure look & feel and base editor appearance settings (Style).
- Define individual appearance settings for different editor states (StyleDisabled, StyleFocused, and StyleHot).
- Change editor dimensions (Width and Height).
- Access individual styles applied to the combo box (Styles).
#Terminal TcxCustomComboBox Class Descendants
Terminal TcxCustomComboBox
class descendants include all unbound and data-aware editors that can display a list of options in a drop-down window.
Do not create TcxCustomComboBox
class instances. Use the following descendants instead:
#Unbound Combo Box Editors
You can use any unbound combo box editor as a standalone control or as an in-place editor embedded into a container control.
The ExpressEditors Library includes the following unbound combo box editors:
- TcxComboBox
- An unbound combo box.
- TcxCheckComboBox
- An unbound combo box editor that can display items with check boxes.
- TcxColorComboBox
- Represents a color combo box control.
- TcxExtLookupComboBox
- Represents a lookup editor displaying a grid View in its dropdown window.
- TcxFontNameComboBox
- Represents a combo box control containing font names available for selection.
- TcxImageComboBox
- An unbound combo box with support for images.
- TcxLookupComboBox
- Represents a lookup combo box control.
- TcxMRUEdit
- Represents a text editor displaying the list of most recently used items (MRU) within a dropdown window.
#Data-Aware Combo Box Editors
Data-aware combo box editors are designed to display and modify field values in the underlying dataset.
Note
If a combo box has both unbound and data-aware versions, you can only use its unbound version as an in-place editor.
The ExpressEditors Library ships with the following data-aware combo box editors:
- TcxDBComboBox
- A data-aware combo box.
- TcxDBCheckComboBox
- A data-aware combo box editor that can display items with check boxes.
- TcxDBColorComboBox
- Represents the data-aware version of the TcxColorComboBox.
- TcxDBExtLookupComboBox
- Represents a control to edit a dataset field by picking up a record in its dropdown data-aware View.
- TcxDBFontNameComboBox
- Represents a data-aware version of the TcxFontNameComboBox.
- TcxDBImageComboBox
- A data-aware image combo box.
- TcxDBLookupComboBox
- Represents a data-aware editor displaying a set of values from a lookup dataset used for editing values in another dataset.
- TcxDBMRUEdit
- Represents a data-aware text editor that stores the list of most recently used items and allows the selection of a value from this list.