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

TDBMemo

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

TDBMemo - a data-aware Memo box to process the multi-line text of a single field in a dataset.

Declaration

Source position: dbctrls.pp line 985

type TDBMemo = class(TCustomMemo)

protected

  function GetReadOnly; override;

  

Gets the value for the ReadOnly property.

  procedure SetReadOnly(); override;

  

Sets the value for the ReadOnly property.

  procedure DataChange();

  

DataChange - if Data changed, loads the new data into the appropriate part of the Field.

  procedure Notification(); override;

  

Handles the notification when a component is added or removed from the control.

  procedure UpdateData();

  

UpdateData - if data changed, copy new text via the datalink.

  procedure Change; override;

  

Performs actions needed when the value for the control has been changed.

  procedure KeyDown(); override;

  

Handles key down events in the data-aware control.

  procedure KeyPress(); override;

  

Invokes the OnKeyPress handler.

  procedure WndProc(); override;

  

The general message handler for this control.

  class procedure WSRegisterClass; override;

  

Registers the widgetset class created for new instances of the control.

public

  constructor Create(); override;

  

Constructor for the class instance.

  destructor Destroy; override;

  

Destroy - destructor for TDBMemo: frees datalinks then calls inherited Destroy.

  procedure EditingDone; override;

  

Called when editing has been completed in the control.

  procedure LoadMemo; virtual;

  

Loads the lines of text for the memo from the field in the linked data set.

  function ExecuteAction(); override;

  

Provides support for TBasicAction in the control.

  function UpdateAction(); override;

  

Updates the specified action to reflect the current state in the linked dataset.

  property Field: TField; [r]

  

Provides access to the field definition for the data-aware control.

published

  property Align: TAlign;

  

Specifies the placement of the control inside its Parent.

  property Alignment: TAlignment;

  

The horizontal alignment for the text in the control (left, right, or centered).

  property Anchors: TAnchors;

  

The set of anchor definitions for this control.

  property AutoDisplay: Boolean; [rw]

  

AutoDisplay - if True, automatically displays the data when loaded from the linked dataset.

  property BiDiMode: TBiDiMode;

  

Customization (of text controls) in bidirectional reading environments.

  property BorderSpacing: TControlBorderSpacing;

  

Determines the inner and outer border spacing for this control.

  property BorderStyle: TBorderStyle;

  

Indicates if borders are displayed around the control.

  property CharCase: TEditCharCase;

  

Controls the character case applied to values entered in the control.

  property Color: TColor;

  

The background color of the control.

  property Constraints: TSizeConstraints;

  

The minimum and maximum Width and Height for the control.

  property DataField: string; [rw]

  

The name of the field, as a string (i.e. cannot be referred to as an Index).

  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 reacts on mouse or keyboard input.

  property Font: TFont;

  

The font to be used for text display in this control.

  property MaxLength: Integer;

  

The maximum length of the value entered in Text, or 0 (zero) for unlimited length.

  property OnChange: TNotifyEvent;

  

Event handler signalled when the text for the control is changed.

  property OnClick: TNotifyEvent;

  

Notification handler for mouse clicks.

  property OnContextPopup: TContextPopupEvent;

  

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

  property OnDblClick: TNotifyEvent;

  

Event Handler for double mouse clicks.

  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 OnEditingDone: TNotifyEvent;

  

Event handler signalled when editing is done.

  property OnEndDrag: TEndDragEvent;

  

Notification handler for the end of a dragging operation.

  property OnEnter: TNotifyEvent;

  

Handler for control receiving the focus.

  property OnExit: TNotifyEvent;

  

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

  property OnKeyDown: TKeyEvent;

  

Handler for keyboard key pressed.

  property OnKeyPress: TKeyPressEvent;

  

Handler for a character entered by the user.

  property OnKeyUp: TKeyEvent;

  

Handler for keyboard key released.

  property OnMouseDown: TMouseEvent;

  

Event handler for mouse button going down.

  property OnMouseEnter: TNotifyEvent;

  

Event handler for mouse entering the area of the control.

  property OnMouseLeave: TNotifyEvent;

  

Event handler for mouse leaving the area of the control.

  property OnMouseMove: TMouseMoveEvent;

  

Event handler for mouse movement within the control.

  property OnMouseUp: TMouseEvent;

  

Event handler for mouse button going up.

  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 OnResize: TNotifyEvent;

  

Notification handler for a resize of the control.

  property OnStartDrag: TStartDragEvent;

  

Event handler for the start of a dragging operation.

  property OnUTF8KeyPress: TUTF8KeyPressEvent;

  

Handler for a character entered by the user.

  property ParentBiDiMode: Boolean;

  

Allows to use the BiDiMode settings in the Parent control. Default is true.

  property ParentDoubleBuffered: Boolean;

  

Value from 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]

  

Indicates that the text in the control cannot be modified.

  property ScrollBars: TScrollStyle;

  

Defines the vertical and/or horizontal scrollbars used in the control.

  property ShowHint: Boolean;

  

Enables the Hint display.

  property TabOrder: TTabOrder;

  

Determines the sequence of control navigation when the user presses the Tab key.

  property Tabstop: Boolean;

  

Allows the user to navigate to this control, by pressing the Tab key.

  property Visible: Boolean;

  

Allows the control, and all of its children, to be displayed or hidden.

  property WantReturns: Boolean;

  

Allows the user to insert Return characters (line breaks) into the text.

  property WantTabs: Boolean;

  

Allows Tab characters to be entered into the text.

  property WordWrap: Boolean;

  

Allows long lines (paragraphs) to wrap into multiple display lines.

end;

Inheritance

TDBMemo

  

TDBMemo - a data-aware Memo box to process the multi-line text of a single field in a dataset.

|

TCustomMemo

  

The base class for multi-line text controls.

|

TCustomEdit

  

The base class for controls presenting editable text.

|

TWinControl

  

The base class for controls 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

TDBMemo is a TCustomMemo descendant which implements a data-aware memo control. Like its ancestor, TDBMemo can be used to display or edit multi-line textual content. It extends the ancestor class to provide properties which define the datasource and field name with the value maintained in the control. For situations where data-awareness is not needed, use the TMemo control.

Internally, the control uses a TFieldDataLink to maintain an association between the control and its datasource, dataset, and field.

Use DataSource to assign the component with the linked dataset for the control.

Use DataField to specify the name of the field in the linked dataset with the value for the control.

Use the AutoDisplay property to control whether the field content is automatically displayed during record navigation in the linked dataset. When AutoDisplay is set to False, the DisplayLabel for the Field is shown in the control and it content must be loaded by calling the LoadMemo method.

See also

TCustomMemo

  

The base class for multi-line text controls.

How To Use Data-aware Controls

  

HowToUseDataAwareControls - Hints for accessing databases.

The latest version of this document can be found at lazarus-ccr.sourceforge.net.