gui-cs.Terminal.Gui/Terminal.Gui/Views/Button.cs

//
// Button.cs: Button control
//
// Authors:
//   Miguel de Icaza ([email protected])
//

using System;
using System.Text;

namespace Terminal.Gui;
/// <summary>
///   Button is a <see cref="View"/> that provides an item that invokes raises the <see cref="Clicked"/> event.
/// </summary>
/// <remarks>
/// <para>
///   Provides a button showing text that raises the <see cref="Clicked"/> event when clicked on with a mouse
///   or when the user presses SPACE, ENTER, or the <see cref="View.HotKey"/>. The hot key is the first letter or digit following the first underscore ('_') 
///   in the button text. 
/// </para>
/// <para>
///   Use <see cref="View.HotKeySpecifier"/> to change the hot key specifier from the default of ('_'). 
/// </para>
/// <para>
///   If no hot key specifier is found, the first uppercase letter encountered will be used as the hot key.
/// </para>
/// <para>
///   When the button is configured as the default (<see cref="IsDefault"/>) and the user presses
///   the ENTER key, if no other <see cref="View"/> processes the key, the <see cref="Button"/>'s
///   <see cref="Clicked"/> event will will be fired.
/// </para>
/// </remarks>
public class Button : View {
	bool _isDefault;
	Rune _leftBracket;
	Rune _rightBracket;
	Rune _leftDefault;
	Rune _rightDefault;

	/// <summary>
	///   Initializes a new instance of <see cref="Button"/> using <see cref="LayoutStyle.Computed"/> layout.
	/// </summary>
	/// <remarks>
	///   The width of the <see cref="Button"/> is computed based on the
	///   text length. The height will always be 1.
	/// </remarks>
	public Button () : this (text: string.Empty, is_default: false) { }

	/// <summary>
	///   Initializes a new instance of <see cref="Button"/> using <see cref="LayoutStyle.Computed"/> layout.
	/// </summary>
	/// <remarks>
	///   The width of the <see cref="Button"/> is computed based on the
	///   text length. The height will always be 1.
	/// </remarks>
	/// <param name="text">The button's text</param>
	/// <param name="is_default">
	///   If <c>true</c>, a special decoration is used, and the user pressing the enter key 
	///   in a <see cref="Dialog"/> will implicitly activate this button.
	/// </param>
	public Button (string text, bool is_default = false) : base (text)
	{
		SetInitialProperties (text, is_default);
	}

	/// <summary>
	///   Initializes a new instance of <see cref="Button"/> using <see cref="LayoutStyle.Absolute"/> layout, based on the given text
	/// </summary>
	/// <remarks>
	///   The width of the <see cref="Button"/> is computed based on the
	///   text length. The height will always be 1.
	/// </remarks>
	/// <param name="x">X position where the button will be shown.</param>
	/// <param name="y">Y position where the button will be shown.</param>
	/// <param name="text">The button's text</param>
	public Button (int x, int y, string text) : this (x, y, text, false) { }

	/// <summary>
	///   Initializes a new instance of <see cref="Button"/> using <see cref="LayoutStyle.Absolute"/> layout, based on the given text.
	/// </summary>
	/// <remarks>
	///   The width of the <see cref="Button"/> is computed based on the
	///   text length. The height will always be 1.
	/// </remarks>
	/// <param name="x">X position where the button will be shown.</param>
	/// <param name="y">Y position where the button will be shown.</param>
	/// <param name="text">The button's text</param>
	/// <param name="is_default">
	///   If <c>true</c>, a special decoration is used, and the user pressing the enter key 
	///   in a <see cref="Dialog"/> will implicitly activate this button.
	/// </param>
	public Button (int x, int y, string text, bool is_default)
	    : base (new Rect (x, y, text.GetRuneCount () + 4 + (is_default ? 2 : 0), 1), text)
	{
		SetInitialProperties (text, is_default);
	}

	// TODO: v2 - Remove constructors with parameters
	/// <summary>
	/// Private helper to set the initial properties of the View that were provided via constructors.
	/// </summary>
	/// <param name="text"></param>
	/// <param name="is_default"></param>
	void SetInitialProperties (string text, bool is_default)
	{
		TextAlignment = TextAlignment.Centered;
		VerticalTextAlignment = VerticalTextAlignment.Middle;

		HotKeySpecifier = new Rune ('_');

		_leftBracket = CM.Glyphs.LeftBracket;
		_rightBracket = CM.Glyphs.RightBracket;
		_leftDefault = CM.Glyphs.LeftDefaultIndicator;
		_rightDefault = CM.Glyphs.RightDefaultIndicator;

		CanFocus = true;
		AutoSize = true;
		_isDefault = is_default;
		Text = text ?? string.Empty;

		OnResizeNeeded ();

		// Override default behavior of View
		// Command.Default sets focus
		AddCommand (Command.Accept, () => { OnClicked (); return true; });
		KeyBindings.Add (Key.Space, Command.Default, Command.Accept);
	}

	/// <summary>
	/// Gets or sets whether the <see cref="Button"/> is the default action to activate in a dialog.
	/// </summary>
	/// <value><c>true</c> if is default; otherwise, <c>false</c>.</value>
	public bool IsDefault {
		get => _isDefault;
		set {
			_isDefault = value;
			UpdateTextFormatterText ();
			OnResizeNeeded ();
		}
	}

	/// <summary>
	/// 
	/// </summary>
	public bool NoDecorations { get; set; }

	/// <summary>
	/// 
	/// </summary>
	public bool NoPadding { get; set; }

	/// <inheritdoc/>
	protected override void UpdateTextFormatterText ()
	{
		if (NoDecorations) {
			TextFormatter.Text = Text;
		} else
		if (IsDefault)
			TextFormatter.Text = $"{_leftBracket}{_leftDefault} {Text} {_rightDefault}{_rightBracket}";
		else {
			if (NoPadding) {
				TextFormatter.Text = $"{_leftBracket}{Text}{_rightBracket}";
			} else {
				TextFormatter.Text = $"{_leftBracket} {Text} {_rightBracket}";
			}
		}
	}

	bool AcceptKey ()
	{
		//if (!HasFocus) {
		//	SetFocus ();
		//}
		OnClicked ();
		return true;
	}

	/// <summary>
	/// Virtual method to invoke the <see cref="Clicked"/> event.
	/// </summary>
	public virtual void OnClicked ()
	{
		Clicked?.Invoke (this, EventArgs.Empty);
	}

	/// <summary>
	///   The event fired when the user clicks the primary mouse button within the Bounds of this <see cref="View"/>
	///   or if the user presses the action key while this view is focused. (TODO: IsDefault)
	/// </summary>
	/// <remarks>
	///   Client code can hook up to this event, it is
	///   raised when the button is activated either with
	///   the mouse or the keyboard.
	/// </remarks>
	public event EventHandler Clicked;

	///<inheritdoc/>
	public override bool MouseEvent (MouseEvent me)
	{
		if (me.Flags == MouseFlags.Button1Clicked) {
			if (CanFocus && Enabled) {
				if (!HasFocus) {
					SetFocus ();
					SetNeedsDisplay ();
					Draw ();
				}
				OnClicked ();
			}

			return true;
		}
		return false;
	}

	///<inheritdoc/>
	public override void PositionCursor ()
	{
		if (HotKey.IsValid && Text != "") {
			for (int i = 0; i < TextFormatter.Text.GetRuneCount (); i++) {
				if (TextFormatter.Text [i] == Text [0]) {
					Move (i, 0);
					return;
				}
			}
		}
		base.PositionCursor ();
	}

	///<inheritdoc/>
	public override bool OnEnter (View view)
	{
		Application.Driver.SetCursorVisibility (CursorVisibility.Invisible);

		return base.OnEnter (view);
	}
}