Class Button

Button is a View that provides an item that invokes an System.Action when activated by the user.
Inheritance
System.Object
Responder
View
Button
Implements
System.IDisposable
System.ComponentModel.ISupportInitializeNotification
System.ComponentModel.ISupportInitialize
Inherited Members
Namespace: Terminal.Gui
Assembly: Terminal.Gui.dll
Syntax
public class Button : View
Remarks

Provides a button showing text invokes an System.Action when clicked on with a mouse or when the user presses SPACE, ENTER, or hotkey. The hotkey is the first letter or digit following the first underscore ('_') in the button text.

Use HotKeySpecifier to change the hotkey specifier from the default of ('_').

If no hotkey specifier is found, the first uppercase letter encountered will be used as the hotkey.

When the button is configured as the default (IsDefault) and the user presses the ENTER key, if no other View processes the KeyEvent, the Button's System.Action will be invoked.

Constructors

Button()

Initializes a new instance of Button using Computed layout.
Declaration
public Button()
Remarks
The width of the Button is computed based on the text length. The height will always be 1.

Button(ustring, Boolean)

Initializes a new instance of Button using Computed layout.
Declaration
public Button(ustring text, bool is_default = false)
Parameters
Type Name Description
NStack.ustring text The button's text
System.Boolean is_default If true, a special decoration is used, and the user pressing the enter key in a Dialog will implicitly activate this button.
Remarks
The width of the Button is computed based on the text length. The height will always be 1.

Button(Int32, Int32, ustring)

Initializes a new instance of Button using Absolute layout, based on the given text
Declaration
public Button(int x, int y, ustring text)
Parameters
Type Name Description
System.Int32 x X position where the button will be shown.
System.Int32 y Y position where the button will be shown.
NStack.ustring text The button's text
Remarks
The width of the Button is computed based on the text length. The height will always be 1.

Button(Int32, Int32, ustring, Boolean)

Initializes a new instance of Button using Absolute layout, based on the given text.
Declaration
public Button(int x, int y, ustring text, bool is_default)
Parameters
Type Name Description
System.Int32 x X position where the button will be shown.
System.Int32 y Y position where the button will be shown.
NStack.ustring text The button's text
System.Boolean is_default If true, a special decoration is used, and the user pressing the enter key in a Dialog will implicitly activate this button.
Remarks
The width of the Button is computed based on the text length. The height will always be 1.

Properties

HotKey

Gets or sets the HotKey defined for this view. A user pressing HotKey on the keyboard while this view has focus will cause the Clicked event to fire.
Declaration
public override Key HotKey { get; set; }
Property Value
Type Description
Key
Overrides

IsDefault

Gets or sets whether the Button is the default action to activate in a dialog.
Declaration
public bool IsDefault { get; set; }
Property Value
Type Description
System.Boolean true if is default; otherwise, false.

Methods

MouseEvent(MouseEvent)

Method invoked when a mouse event is generated
Declaration
public override bool MouseEvent(MouseEvent me)
Parameters
Type Name Description
MouseEvent me
Returns
Type Description
System.Boolean true, if the event was handled, false otherwise.
Overrides

OnClicked()

Virtual method to invoke the Clicked event.
Declaration
public virtual void OnClicked()

OnEnter(View)

Method invoked when a view gets focus.
Declaration
public override bool OnEnter(View view)
Parameters
Type Name Description
View view The view that is losing focus.
Returns
Type Description
System.Boolean true, if the event was handled, false otherwise.
Overrides

PositionCursor()

Positions the cursor in the right position based on the currently focused view in the chain.
Declaration
public override void PositionCursor()
Overrides

ProcessColdKey(KeyEvent)

This method can be overwritten by views that want to provide accelerator functionality (Alt-key for example), but without interefering with normal ProcessKey behavior.
Declaration
public override bool ProcessColdKey(KeyEvent kb)
Parameters
Type Name Description
KeyEvent kb
Returns
Type Description
System.Boolean
Overrides
Remarks

After keys are sent to the subviews on the current view, all the view are processed and the key is passed to the views to allow some of them to process the keystroke as a cold-key.

This functionality is used, for example, by default buttons to act on the enter key. Processing this as a hot-key would prevent non-default buttons from consuming the enter keypress when they have the focus.

ProcessHotKey(KeyEvent)

This method can be overwritten by view that want to provide accelerator functionality (Alt-key for example).
Declaration
public override bool ProcessHotKey(KeyEvent kb)
Parameters
Type Name Description
KeyEvent kb
Returns
Type Description
System.Boolean
Overrides
Remarks

Before keys are sent to the subview on the current view, all the views are processed and the key is passed to the widgets to allow some of them to process the keystroke as a hot-key.

For example, if you implement a button that has a hotkey ok "o", you would catch the combination Alt-o here. If the event is caught, you must return true to stop the keystroke from being dispatched to other views.

ProcessKey(KeyEvent)

If the view is focused, gives the view a chance to process the keystroke.
Declaration
public override bool ProcessKey(KeyEvent kb)
Parameters
Type Name Description
KeyEvent kb
Returns
Type Description
System.Boolean
Overrides
Remarks

Views can override this method if they are interested in processing the given keystroke. If they consume the keystroke, they must return true to stop the keystroke from being processed by other widgets or consumed by the widget engine. If they return false, the keystroke will be passed using the ProcessColdKey method to other views to process.

The View implementation does nothing but return false, so it is not necessary to call base.ProcessKey if you derive directly from View, but you should if you derive other View subclasses.

UpdateTextFormatterText()

Can be overridden if the Text has different format than the default.
Declaration
protected override void UpdateTextFormatterText()
Overrides

Events

Clicked

Clicked System.Action, raised when the user clicks the primary mouse button within the Bounds of this View or if the user presses the action key while this view is focused. (TODO: IsDefault)
Declaration
public event Action Clicked
Event Type
Type Description
System.Action
Remarks
Client code can hook up to this event, it is raised when the button is activated either with the mouse or the keyboard.

Implements

System.IDisposable
System.ComponentModel.ISupportInitializeNotification
System.ComponentModel.ISupportInitialize