RadioButton

Inheritance Hierarchy

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 Aligment 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 to be displayed on right-click on the component.
	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 with the main mouse button.
	OnDblClick	The OnDblClick event occurs if the user double-clicks a component area with the mouse button.
	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 the 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.