[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 checkbox control.

Declaration

Source position: dbctrls.pp line 651

type TDBCheckBox = class(TCustomCheckBox)

protected

  function GetFieldCheckState; virtual;

  

GetFieldCheckState - returns the checkbox 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.

  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 of 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 checkbox is to be associated.

  property DataSource: TDataSource; [rw]

  

Provides access to the dataset with content for the control.

  property DoubleBuffered: Boolean;

  

Allows to reduce flicker in the painting of the control.

  property DragCursor: TCursor;

  

The cursor shape shown while the control is dragged.

  property DragKind: TDragKind;

  

The operation when the control is dragged - Drag or Dock.

  property DragMode: TDragMode;

  

Allows the user to drag 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 OnChange: TNotifyEvent;

  

Event handler for changes to properties in the control.

  property OnClick: TNotifyEvent;

  

Notification handler for mouse clicks.

  property OnContextPopup: TContextPopupEvent;

  

Invoked when a context-sensitive pop-up menu is requested.

  property OnDragDrop: TDragDropEvent;

  

This handler determines the action on an drop onto this control, in a drag-drop operation.

  property OnDragOver: TDragOverEvent;

  

Event handler for a control being dragged over this control.

  property OnEndDrag: TEndDragEvent;

  

Notification handler for the end of a drag operation.

  property OnEnter: TNotifyEvent;

  

Handler for control receiving the focus.

  property OnExit: TNotifyEvent;

  

Handler for control losing the focus; This is a good place for checking the finished user input.

  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 for mouse movement within 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 for downward movement of mouse wheel.

  property OnMouseWheelUp: TMouseWheelUpDownEvent;

  

Event handler for upward movement of the mouse wheel.

  property OnStartDrag: TStartDragEvent;

  

Event handler for the start of a dragging operation.

  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;

  

If True, the Font of the control will be the same as the one from the Parent. Default is True.

  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; [rw]

  

ValueChecked is the value to use when the box is checked, for example True or 1.

  property ValueUnchecked: string; [rw]

  

ValueUnchecked is the value to use when the box is unchecked, for example False or 0.

  property Visible: Boolean;

  

Indicates if the control is visible on its parent.

end;

Inheritance

TDBCheckBox

  

Implements a data-aware checkbox 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 checkbox 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 checkbox control:

See also

How To Use Data-aware Controls

  

HowToUseDataAwareControls - Hints for accessing databases.