[Overview][Constants][Types][Classes][Procedures and functions][Index] | Reference for unit 'DBCtrls' (#lcl)

# TDBCheckBox

[Properties (by Name)] [Methods (by Name)] [Events (by Name)]

Implements a data-aware check box control.

## Declaration

Source position: dbctrls.pp line 656

`type TDBCheckBox = class(TCustomCheckBox)`
`protected`
`function GetFieldCheckState; virtual;` |  | GetFieldCheckState - returns the check box state for the current field.
`procedure DataChange();` |  | Updates the control display value when the linked dataset is changed.
`procedure DoOnChange; override;` |  | Performs actions needed when the control is clicked.
`procedure UpdateData();` |  | UpdateData - examines the State to see whether it has changed.
`procedure Notification(); override;` |  | Handles notification events for components used in the class instance.
`public`
`constructor Create(); override;` |  | Constructor for the class instance.
`destructor Destroy; override;` |  | Destructor for the class instance.
`function ExecuteAction(); override;` |  | Implements support for TBasicAction in the data-aware control.
`function UpdateAction(); override;` |  | Updates the state for the specified action.
`property Checked: Boolean;` |  | Indicates the checked state for the control as a Boolean value.
`property Field: TField; [r]` |  | Provides access to the field definition for the data-aware control.
`property State: TCheckBoxState;` |  | The check, unchecked, or grayed state for the control.
`published`
`property Action: TBasicAction;` |  | The Action associated with the control.
`property Align: TAlign;` |  | Specifies the placement of the control on its Parent control.
`property Alignment: TLeftRight;` |  | Indicates the alignment for the caption text in the control.
`property AllowGrayed: Boolean;` |  | Allows the check box to use a "grayed" state.
`property Anchors: TAnchors;` |  | The set of anchor definitions for this control.
`property AutoSize: Boolean;` |  | Allows automatic adjustment of the size for the control, according to its content.
`property BiDiMode: TBiDiMode;` |  | Indicates whether text controls use in bi-directional reading.
`property BorderSpacing: TControlBorderSpacing;` |  | Determines the inner and outer border spacing for this control.
`property Caption: TCaption;` |  | Text displayed as the caption for the control.
`property Color: TColor;` |  | The background color for the control.
`property Constraints: TSizeConstraints;` |  | Contains the minimum and maximum Width and Height for the control.
`property DataField: string; [rw]` |  | The name (as a string) of the field with which the check box is to be associated.
`property DataSource: TDataSource; [rw]` |  | Provides access to the dataset with content for the control.
`property DoubleBuffered: Boolean;` |  | When enabled, it reduces flicker when the control is painted.
`property DragCursor: TCursor;` |  | The cursor shape shown during a drag operation.
`property DragKind: TDragKind;` |  | Indicates the action performed for a drag operation: drag-and-drop or drag-and-dock.
`property DragMode: TDragMode;` |  | Determines how a drag operation is started for the control.
`property Enabled: Boolean;` |  | Determines whether the control responds to mouse or keyboard input.
`property Font: TFont;` |  | The font to be used for text display in this control.
`property Hint: TTranslateString;` |  | The text to show in the Hint window for the control.
`property ParentBiDiMode: Boolean;` |  | Indicates whether the BiDiMode settings in the Parent control are used.
`property ParentColor: Boolean;` |  | Use the Color from the Parent control, when enabled.
`property ParentDoubleBuffered: Boolean;` |  | Value for the DoubleBuffered property in a Parent control.
`property ParentFont: Boolean;` |  | Indicates if the Font from the Parent control is used in the control.
`property ParentShowHint: Boolean;` |  | If True, the value of ShowHint for the control will be the same as the one from the Parent. Default is True.
`property PopupMenu: TPopupMenu;` |  | A context-sensitive menu that pops up when the right mouse button is clicked over this control.
`property ReadOnly: Boolean; [rw]` |  | ReadOnly - if True, data may be read but not written or modified (doesn't make much sense for a check-box unless the box is not Enabled).
`property ShowHint: Boolean;` |  | Enables Hint display for the control.
`property TabOrder: TTabOrder;` |  | Indicates the navigation order for the control when the user presses the Tab or Shift+Tab key.
`property TabStop: Boolean;` |  | Allows the user to navigate to / from the control by pressing the Tab or Shift+Tab keys.
`property ValueChecked: string; [rws]` |  | String representation for the check box value when the control is in its checked state.
`property ValueUnchecked: string; [rws]` |  | String representation for the check box value when the control is in its unchecked state.
`property Visible: Boolean;` |  | Indicates if the control is visible on its parent.
`property OnChange: TNotifyEvent;` |  | Event handler signalled when the button control is clicked.
`property OnClick: TNotifyEvent;` |  | Notification handler for mouse clicks.
`property OnContextPopup: TContextPopupEvent;` |  | Invoked when a context-sensitive pop-up menu is requested.
`property OnDragDrop: TDragDropEvent;` |  | Event handler signalled when an object is dropped onto the control.
`property OnDragOver: TDragOverEvent;` |  | Event handler signalled when a control is dragged over the control instance.
`property OnEndDrag: TEndDragEvent;` |  | Event handler signalled for the end of a drag-drop operation.
`property OnEnter: TNotifyEvent;` |  | Event handler signalled when the control receives focus.
`property OnExit: TNotifyEvent;` |  | Event handler signalled when the control loses focus.
`property OnMouseDown: TMouseEvent;` |  | Event handler signalled when a mouse down event is handled for the control.
`property OnMouseEnter: TNotifyEvent;` |  | Event handler signalled when the mouse pointer has entered the control.
`property OnMouseLeave: TNotifyEvent;` |  | Event handler signalled when the mouse pointer has left the control.
`property OnMouseMove: TMouseMoveEvent;` |  | Event handler signalled when the mouse pointer is moved in the control.
`property OnMouseUp: TMouseEvent;` |  | Event handler signalled when a mouse up event is handled for the control.
`property OnMouseWheel: TMouseWheelEvent;` |  | Event handler for mouse wheel turned.
`property OnMouseWheelDown: TMouseWheelUpDownEvent;` |  | Event handler signalled for a downward movement of the mouse wheel.
`property OnMouseWheelUp: TMouseWheelUpDownEvent;` |  | Event handler signalled for an upward movement of the mouse wheel.
`property OnStartDrag: TStartDragEvent;` |  | Event handler signalled for the start of a dragging operation.
`end;`

## Inheritance

`TDBCheckBox` |  | Implements a data-aware check box control.
`TCustomCheckBox` |  | The base class for a check box component.
`TButtonControl` |  | Specifies a base class for button controls.
`TWinControl` |  | Implements a windowed control which can contain other child controls.
`TControl` |  | The base class for visible controls.
`TLCLComponent` |  | The base class for LCL components which have an associated widget.
`TComponent`
?
`TObject`

## Description

TDBCheckBox implements a data-aware check box control for use with a logical field in a database. The dataset field can be represented using either a Boolean or a String data type.

TDBCheckBox is a TCustomCheckBox descendant, and provides support for a linked dataset with the value for the control. Internally, it uses a TFieldDataLink instance to maintain an association between the control and its DataSource and DataField.

Support for TBasicAction is also implemented in the control using its Action property.

Use the following properties to configure and control the data-aware check box control:

- DataSource
- DataField
- Field
- Checked
- ValueChecked
- ValueUnchecked
- Caption
- ReadOnly
- State

## See also

How To Use Data-aware Controls |  | HowToUseDataAwareControls - Hints for accessing databases.