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

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

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>
///         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
{
    private readonly Rune _leftBracket;
    private readonly Rune _leftDefault;
    private readonly Rune _rightBracket;
    private readonly Rune _rightDefault;
    private bool _isDefault;

    /// <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 ()
    {
        TextAlignment = TextAlignment.Centered;
        VerticalTextAlignment = VerticalTextAlignment.Middle;

        HotKeySpecifier = new Rune ('_');

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

        // Ensures a height of 1 if AutoSize is set to false
        Height = 1;

        CanFocus = true;
        AutoSize = true;

        // Override default behavior of View
        // Command.Default sets focus
        AddCommand (
                    Command.Accept,
                    () =>
                    {
                        OnClicked ();

                        return true;
                    }
                   );
        KeyBindings.Add (Key.Space, Command.Default, Command.Accept);
        KeyBindings.Add (Key.Enter, 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; }

    /// <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;
    }

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

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

        return base.OnEnter (view);
    }

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

                    return;
                }
            }
        }

        base.PositionCursor ();
    }

    /// <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}";
            }
        }
    }
}