Unit 'ExtCtrls' Package
[Overview][Types][Classes][Procedures and functions][Index] [#lcl]

TRadioGroup

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

TRadioGroup is a group of related but mutually exclusive radio buttons, requiring the user to select one of a set of alternatives.

Declaration

Source position: extctrls.pp line 740

type TRadioGroup = class(TCustomRadioGroup)

published

  property Align: TAlign;

  

Specifies the placement of the control on its Parent control.

  property Anchors: TAnchors;

  

The set of anchor definitions for this control.

  property AutoFill: Boolean;

  

Indicates if radio buttons are resized to fill the available space in the 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;

  

The text displayed for the control.

  property ChildSizing: TControlChildSizing;

  

Parameters for child control arrangement and spacing.

  property ClientHeight: Integer;

  

The height for the client area on the control.

  property ClientWidth: Integer;

  

The width of the client area for the control.

  property Color: TGraphicsColor;

  

The background color of the control.

  property ColumnLayout: TColumnLayout;

  

Fill direction for columns on the grouped control.

  property Columns: Integer;

  

Number of columns used to display radio buttons in the control.

  property Constraints: TSizeConstraints;

  

Contains the minimum and maximum Width and Height 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 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 ItemIndex: Integer;

  

The ordinal position in Items for the selected radio button in the group.

  property Items: TStrings;

  

Items - a string list containing the captions of the radio boxes.

  property OnChangeBounds: TNotifyEvent;

  

Event handler signalled when the Bounds for the control have been changed.

  property OnClick: TNotifyEvent;

  

Event called when the selected item is changed.

  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 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 OnItemEnter: TNotifyEvent;

  

Event handler signalled when a radio button in the group receives focus.

  property OnItemExit: TNotifyEvent;

  

Event handler signalled when a radio button in the group loses focus.

  property OnKeyDown: TKeyEvent;

  

Handler for keyboard key pressed.

  property OnKeyPress: TKeyPressEvent;

  

Handler for a character entered by the user.

  property OnKeyUp: TKeyEvent;

  

Event handler signalled when a key up event has occurred for the control.

  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 OnResize: TNotifyEvent;

  

Notification handler for a resize of the control.

  property OnSelectionChanged: TNotifyEvent;

  

Event called when the selected item changes.

  property OnStartDrag: TStartDragEvent;

  

Event handler for the start of a dragging operation.

  property OnUTF8KeyPress: TUTF8KeyPressEvent;

  

Handler for a character entered by the user.

  property ParentBackground: Boolean;

  

Indicates if the control uses the background for its Parent control.

  property ParentBidiMode: Boolean;

  

Indicates whether the BiDiMode settings in the Parent control are used.

  property ParentFont: Boolean;

  

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

  property ParentColor: Boolean;

  

Use the Color from the Parent control, when enabled.

  property ParentDoubleBuffered: Boolean;

  

Allows to reduce flicker in the painting of 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 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 Visible: Boolean;

  

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

end;

Inheritance

TRadioGroup

  

TRadioGroup is a group of related but mutually exclusive radio buttons, requiring the user to select one of a set of alternatives.

|

TCustomRadioGroup

  

TCustomRadioGroup is the base type for TRadioGroup.

|

TCustomGroupBox

  

The base class for TGroupBox, TRadioGroup and TCheckGroup.

|

TWinControl

  

Implements a windowed control which can contain other child controls.

|

TControl

  

The base class for visible controls.

|

TLCLComponent

  

|

TObject

Description

TRadioGroup: A group of related but mutually exclusive radio buttons, requiring the user to select one of a set of alternatives. As one button becomes selected, the remaining buttons in the group become automatically deselected.

To use this control, place it in the required position on the form, then in the Object Inspector select Items and click on the ellipsis (...) to open the string editor. Type in the captions to accompany each check box, then close the string editor and you will see a series of Radio Boxes with their captions displayed beside them. (Note - unlike TCheckGroup, there is no special RadioGroup editor).

Inherits properties from TCustomRadioGroup and TCustomGroupBox.

TRadioGroup behaves differently from a group of TRadioButton controls placed arbitrarily around a form.

In the case of TRadioButton, the mutual exclusivity is a feature that applies to any RadioButton anywhere in the Form, and the RadioButtons can be rearranged in any order or placed anywhere within the containing Form, while in TRadioGroup the exclusivity applies only to buttons within the Group, which are ordered strictly according to their ItemIndex within the Items for the control.

TRadioButton is an entity unto itself with a number of additional properties. In contrast, the buttons within TRadioGroup are not separate entities, but rather are simply entries in a list of strings, each of which is associated with the on-screen image of a RadioButton.

The example shows the difference between the use of TRadioButton and TRadioGroup.

See also

TRadioButton

  

Implement a radio button control.

How To Use Standard Controls

  

How to use StdCtrls, ComCtrls or ExtCtrls.

Example

{Using TRadioGroup with three entries in Items:
Index 0: Red
Index 1: Amber
Index 2: Green}

procedure TTrivialForm1.RadioGroup1Click(Sender: TObject);
begin
  case RadioGroup1.ItemIndex of
  0:   Shape1.brush.color := clRed;
  1:   Shape1.brush.color := clYellow;
  2:   Shape1.brush.color := clGreen
  end
end;



{Using three separate RadioButtons}

procedure TForm1.RadioButton1Click(Sender: TObject);
begin
  Shape1.brush.color := clRed
end;

procedure TForm1.RadioButton2Click(Sender: TObject);
begin
  Shape1.brush.color := clYellow
end;

procedure TForm1.RadioButton3Click(Sender: TObject);
begin
  Shape1.brush.color := clGreen
end;


CT Web help

CodeTyphon Studio