TCustomCheckCombo class

In unit ComboEx

Base class for a combo-box which displays check boxes for Items in the control.

Declaration

pascal

TCustomCheckCombo = class(TCustomComboBox)

Inheritance

Descends from it: TCheckComboBox

Description

TCustomCheckCombo is a TCustomComboBox descendant which defines the base class for a combo-box which displays check boxes for the Items in the control. It behaves like an ordinary combo-box with a drop-down using a customizable number of visible rows.

TCustomCheckCombo provides additional properties, methods, and events which allow the checked state for values in Items to be specified as either a Boolean or a TCheckBoxState value. An OnItemChange event handler is added to perform custom actions when the Checked value for an item is changed. Convenience methods are included which allow check boxes to be added or deleted, or toggle their value.

TCustomCheckCombo is the ancestor for the TCheckComboBox control.

Properties

`AllowGrayed`	public	Indicates if check boxes can be drawn in the indeterminate state.
`Count`	public	Reflects the number of check boxes defined for the control.
`Checked`	public	Provides indexed access to the Boolean value for a check box defined in Items.
`ItemEnabled`	public	Provides indexed access to the Boolean enabled value for a check box defined in Items.
`Objects`	public	Provides indexed access to the Data for a check box defined in Items.
`State`	public	Provides indexed access to the checked State for a check box defined in Items.

Methods

`CMBiDiModeChanged`	protected	Performs actions needed when the BiDiMode setting is changed for the control.
`ClearItemStates`	protected	Removes all state classes allocated for the check boxes in the control.
`CloseUp`	protected	Closes the drop down displayed for the control.
`DrawItem`	protected	Draws a check box item defined in the combo-box control.
`DropDown`	protected	Displays the drop down for the combo-box.
`FontChanged`	protected	Performs actions needed when the font for the control has been changed.
`InitializeWnd`	protected	Initializes the window handle for the control.
`InitItemStates`	protected	Initializes check box state information for items in the control.
`CheckItemStates`	protected	Ensures that check box item state classes have been allocated for items in the control.
`QueueCheckItemStates`	protected	Queues an asynchronous call to AsyncCheckItemStates in the Application singleton.
`KeyDown`	protected	Handles key down events for the control.
`Loaded`	protected	Performs actions needed when the component has finished loading from the LCL streaming mechanism.
`MouseLeave`	protected	Deactivates tracking the highlighted check box when the mouse leaves the control.
`MouseMove`	protected	Tracks changes to the mouse position for the highlighted check box in the control.
`SetItemHeight`	protected	Sets the value for the ItemHeight property.
`SetItems`	protected	Sets the value for the Items property.
`Select`	protected	Toggles the value for the current item selected in the control.
`Create`	public	Constructor for the class instance.
`Destroy`	public	Destructor for the class instance.
`AddItem`	public	Adds a check box with the specified settings to the Items property.
`AssignItems`	public	Assigns the content in the specified TStringList to the Items in the control.
`Clear`	public	Removes the values stored in the Items property.
`DeleteItem`	public	Deletes the check box at the specified position.
`CheckAll`	public	Sets the state for all check boxes defined in the control meeting the specified criteria.
`Toggle`	public	Toggles the checked state for the check box at the specified position.

Events

OnItemChange public Event handler signalled when the state for a check box in the control is changed.

Fields

`FCheckHighlight`	protected	Internal member used to to track the highlighting state.
`FCheckSize`	protected	Internal member used to track size adjusts needed for them services.
`FDropped`	protected	Internal members used to track the state for the drop down in the control.
`FHilightedIndex`	protected	Internal member used to track the item highlighted in the control.
`FHiLiteLeft`	protected	Internal member used to track the left coordinate for the highlight.
`FHiLiteRight`	protected	Internal member used to track the right coordinate for the highlight.
`FNeedMeasure`	protected	Internal member used to track whether the text height has been calculated for items in the control.
`FRejectDropDown`	protected	Internal member used to track whether drop down requests should be rejected; i. e. the drop down is already visible.
`FRejectToggleOnSelect`	protected	Internal member used to track whether the current check box selection can toggle its value; i. e. whether the drop down is visible.
`FRightToLeft`	protected	Internal member used to track the BiDi status for the control.
`FTextHeight`	protected	Internal member used to track the text height for check boxes in the control.