RadioButton

Inheritance Hierarchy

          IComponent

          IControl

          IRadioButton

          RadioButton

Description

The RadioButton component is usually used together with other radio buttons to select one of the mutually exclusive alternatives.

Working with the Component

Only one radio button can be selected from the grouped radio buttons (using such components as GroupBox, Panel and others). When one of such radio buttons is selected, the others are automatically deselected. The radio buttons located directly on the form are also grouped.

The Text property of the component contains a text label located near the radio button (the place is defined by the Alignment property). In this component as well as in other components (Button, CheckBox) the text label may contain an ampersand symbol (&), which underlines the next symbol corresponding to an access hotkey.

The main property of the Checked component determines whether this radio button is selected by the user. Since it is often required that one of the radio buttons is selected by default, its Checked property must be set to True at the form creation stage.

Example

Properties of the RadioButton Component

  Property name Brief description
Align The Align property determines behavior of the component when its parent component is resized.
Alignment The Alignment property determines position of the radio button inside the component field.
AllowDrag The AllowDrag property determines whether an object can be dragged from the component.
AllowDrop The AllowDrop property determines whether the component can accept a dragged object.
Anchors The Anchors property returns settings that determine the percentage of the size change for the current component when the parent component is resized.
Brush The Brush property determines the brush that is used to fill component area.
Checked The Checked property determines a radio button status.
ClientHeight The ClientHeight property is used to receive or specify the height of the component’s client area.
ClientWidth The ClientWidth property is used to receive or specify the width of the component’s client area.
Color The Color property determines a component background color.
ComponentCount The ComponentCount property returns the number of child components.
Components The Components property returns the child component.
Cursor The Cursor property determines the look of the cursor over the component.
Data The Data property is used to store any custom data.
Enabled The Enabled property determines whether the component is available for the user.
Focused The Focused property returns True if the focus is set on the component.
Font The Font property determines the set of characteristics describing the font that is used to display text.
Height The Height property determines component height.
HelpContext The HelpContext property determines a unique index for the context help section for this component.
Hint The Hint property determines a component tooltip text.
Left The Left property determines the coordinate of the left border of the component.
Name The Name property determines a component name.
Parent The Parent property determines a parent component.
ParentColor The ParentColor property determines whether the component inherits the color of the parent component.
ParentFont The ParentFont property determines whether the component uses the font of the parent component.
ParentShowHint The ParentShowHint property determines whether a tooltip is displayed.
PopupMenu The PopupMenu property determines the context menu opened by clicking the component with the additional mouse button.
Scrolls The Scrolls property returns parameters of component's scrollbars.
ShowHint The ShowHint property enables and disables showing a component tooltip.
TabOrder The TabOrder property determines the component position in the tab order.
TabStop The TabStop property determines whether the component is focused when the TAB key is pressed.
Tag The Tag property is not used by the compiler. A user can change the value of the Tag property and use it as he wishes.
Text The Text property determines the row identifying a component for the user.
Top The Top property determines the coordinate of the top border of the component.
Visible The Visible property determines visibility of the component during execution.
Width The Width property determines component width.

Methods of the RadioButton Component

  Method name Brief description
BringToFront The BringToFront method brings a component to front.
ClientToScreen The ClientToScreen method converts the coordinates of a point specified relative to the component coordinate system into screen coordinates.
DoDragDrop The DoDragDrop method enables the user to start dragging operation.
GetImage The GetImage method returns the image of the component with all the child components.
ScreenToClient The ScreenToClient method converts screen coordinates of a point into coordinates specified relative to the component coordinate system.
SendToBack The SendToBack method sends a component to back.
SetFocus The SetFocus method sets focus to this component.

Events of the RadioButton Component

  Event name Brief description
OnBeginDrag The OnBeginDrag event occurs for a component when the user starts to drag an object from the component.
OnChange The OnChange event occurs when the selection status of the component changes.
OnClick The OnClick event occurs if the user clicks the component area.
OnDblClick The OnDblClick event occurs if the user double-clicks the component area.
OnDragDrop The OnDragDrop event occurs for the component if the user drops a dragged object over it.
OnDragEnter The OnDragEnter event occurs when a dragged object crosses the borders of this component.
OnDragLeave The OnDragLeave event occurs when a dragged object leaves the borders of this component.
OnDragOver The OnDragOver event occurs for the component when the user drags an object over it.
OnEnter The OnEnter event occurs when the component receives focus.
OnExit The OnExit event occurs when the component loses focus.
OnHScroll The OnHScroll event occurs when horizontal scrollbar slider changes its position.
OnKeyDown The OnKeyDown event occurs if the component is focused and a keyboard key is pressed.
OnKeyPress The OnKeyPress event occurs if the component is focused when the user presses a character key.
OnKeyPreview The OnKeyPreview event occurs prior to each event related to key pressing.
OnKeyUp The OnKeyUp event occurs if the component is focused and the user releases any button previously pressed.
OnMouseDown The OnMouseDown event occurs if the pointer is in component's area and a mouse key is pressed.
OnMouseEnter The OnMouseEnter event occurs when mouse cursor enters the component area.
OnMouseHover The OnMouseHover event occurs when mouse cursor is held in the component area.
OnMouseLeave The OnMouseLeave event occurs when mouse cursor leaves the component area.
OnMouseMove The OnMouseMove event occurs on moving the cursor over component.
OnMouseUp The OnMouseUp event occurs on releasing mouse button when the cursor is in component area.
OnMouseWheel The OnMouseWheel event occurs if the component is focused when the mouse wheel is rotated.
OnVScroll The OnVScroll event occurs when vertical scrollbar slider changes its position.

See also:

Standard Components