TDBCheckBox class

In unit DBCtrls

Implements a data-aware check box control.

Declaration

pascal

TDBCheckBox = class(TCustomCheckBox)

Inheritance

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

Properties

`Checked`	public	Indicates the checked state for the control as a Boolean value.
`Field`	public	Provides access to the field definition for the data-aware control.
`State`	public	The check, unchecked, or grayed state for the control.
`Action`	published	The Action associated with the control.
`Align`	published	Specifies the placement of the control on its Parent control.
`Alignment`	published	Indicates the alignment for the caption text in the control.
`AllowGrayed`	published	Allows the check box to use a "grayed" state.
`Anchors`	published	The set of anchor definitions for this control.
`AutoSize`	published	Allows automatic adjustment of the size for the control, according to its content.
`BiDiMode`	published	Indicates whether text controls use in bi-directional reading.
`BorderSpacing`	published	Determines the inner and outer border spacing for this control.
`Caption`	published	Text displayed as the caption for the control.
`Color`	published	The background color for the control.
`Constraints`	published	Contains the minimum and maximum Width and Height for the control.
`DataField`	published	The name (as a string) of the field with which the check box is to be associated.
`DataSource`	published	Provides access to the dataset with content for the control.
`DoubleBuffered`	published	When enabled, it reduces flicker when the control is painted.
`DragCursor`	published	The cursor shape shown during a drag operation.
`DragKind`	published	Indicates the action performed for a drag operation: drag-and-drop or drag-and-dock.
`DragMode`	published	Determines how a drag operation is started for the control.
`Enabled`	published	Determines whether the control responds to mouse or keyboard input.
`Font`	published	The font to be used for text display in this control.
`Hint`	published	The text to show in the Hint window for the control.
`ParentBiDiMode`	published	Indicates whether the BiDiMode settings in the Parent control are used.
`ParentColor`	published	Use the Color from the Parent control, when enabled.
`ParentDoubleBuffered`	published	Value for the DoubleBuffered property in a Parent control.
`ParentFont`	published	Indicates if the Font from the Parent control is used in the control.
`ParentShowHint`	published	If True, the value of ShowHint for the control will be the same as the one from the Parent. Default is True.
`PopupMenu`	published	A context-sensitive menu that pops up when the right mouse button is clicked over this control.
`ReadOnly`	published	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).
`ShowHint`	published	Enables Hint display for the control.
`TabOrder`	published	Indicates the navigation order for the control when the user presses the Tab or Shift+Tab key.
`TabStop`	published	Allows the user to navigate to / from the control by pressing the Tab or Shift+Tab keys.
`ValueChecked`	published	String representation for the check box value when the control is in its checked state.
`ValueUnchecked`	published	String representation for the check box value when the control is in its unchecked state.
`Visible`	published	Indicates if the control is visible on its parent.

Methods

`GetFieldCheckState`	protected	GetFieldCheckState - returns the check box state for the current field.
`DataChange`	protected	Updates the control display value when the linked dataset is changed.
`DoOnChange`	protected	Performs actions needed when the control is clicked.
`UpdateData`	protected	UpdateData - examines the State to see whether it has changed.
`Notification`	protected	Handles notification events for components used in the class instance.
`Create`	public	Constructor for the class instance.
`Destroy`	public	Destructor for the class instance.
`ExecuteAction`	public	Implements support for TBasicAction in the data-aware control.
`UpdateAction`	public	Updates the state for the specified action.

Events

`OnChange`	published	Event handler signalled when the button control is clicked.
`OnClick`	published	Notification handler for mouse clicks.
`OnContextPopup`	published	Invoked when a context-sensitive pop-up menu is requested.
`OnDragDrop`	published	Event handler signalled when an object is dropped onto the control.
`OnDragOver`	published	Event handler signalled when a control is dragged over the control instance.
`OnEndDrag`	published	Event handler signalled for the end of a drag-drop operation.
`OnEnter`	published	Event handler signalled when the control receives focus.
`OnExit`	published	Event handler signalled when the control loses focus.
`OnMouseDown`	published	Event handler signalled when a mouse down event is handled for the control.
`OnMouseEnter`	published	Event handler signalled when the mouse pointer has entered the control.
`OnMouseLeave`	published	Event handler signalled when the mouse pointer has left the control.
`OnMouseMove`	published	Event handler signalled when the mouse pointer is moved in the control.
`OnMouseUp`	published	Event handler signalled when a mouse up event is handled for the control.
`OnMouseWheel`	published	Event handler for mouse wheel turned.
`OnMouseWheelDown`	published	Event handler signalled for a downward movement of the mouse wheel.
`OnMouseWheelUp`	published	Event handler signalled for an upward movement of the mouse wheel.
`OnStartDrag`	published	Event handler signalled for the start of a dragging operation.