linear-app-launcher/RyzStudio/Windows/Forms/PanelBook.cs

namespace RyzStudio.Windows.Forms
{
    using System;
    using System.ComponentModel;
    using System.Windows.Forms;

    [ToolboxItem(true)]
    public partial class PanelBook : UserControl
    {
        protected PanelCollection panelCollection = null;

        public PanelBook()
        {
            InitializeComponent();

            panelCollection = new PanelCollection(this);

        }

        public Panel ActivePanel { get; set; } = null;

        [Category("Collection")]
        [DesignerSerializationVisibility(DesignerSerializationVisibility.Content)]
        public PanelCollection Pages
        {
            get { return panelCollection; }
        }

        [Category("Collection")]
        public int SelectedIndex
        {
            get
            {
                if (panelCollection.Count <= 0)
                {
                    return -1;
                }

                return panelCollection.IndexOf(this.ActivePanel);
            }
            set
            {
                if (panelCollection.Count <= 0)
                {
                    return;
                }

                if (value < 0)
                {
                    return;
                }

                if (value > (panelCollection.Count - 1))
                {
                    return;
                }

                if (value == this.SelectedIndex)
                {
                    return;
                }

                ActivatePanel(value);
            }
        }

        protected internal int PageIndex
        {
            get
            {
                return panelCollection.IndexOf(this.ActivePanel);
            }
            set
            {
                if (panelCollection.Count <= 0)
                {
                    ActivatePanel(-1);
                    return;
                }

                if ((value < -1) || (value >= panelCollection.Count))
                {
                    throw new ArgumentOutOfRangeException("PageIndex", value, "The page index must be between 0 and " + Convert.ToString(panelCollection.Count - 1));
                }

                ActivatePanel(value);
            }
        }

        protected internal void ActivatePanel(int index)
        {
            if ((panelCollection.Count == 0) && (index >= panelCollection.Count) && (index <= 0))
            {
                return;
            }

            Panel p = (Panel)panelCollection[index];

            ActivatePage(p);
        }

        protected internal void ActivatePage(Panel page)
        {
            if (this.ActivePanel != null)
            {
                this.ActivePanel.Visible = false;
            }

            this.ActivePanel = page;
            if (this.ActivePanel != null)
            {
                this.ActivePanel.Parent = this;
                if (!this.Contains(this.ActivePanel))
                {
                    this.Container.Add(this.ActivePanel);
                }

                this.ActivePanel.Dock = DockStyle.Fill;
                this.ActivePanel.Visible = true;
                this.ActivePanel.BringToFront();
            }

            if (this.ActivePanel != null)
            {
                this.ActivePanel.Invalidate();
            }
            else
            {
                this.Invalidate();
            }
        }

#if DEBUG

        protected override void OnResize(EventArgs e)
        {
            base.OnResize(e);

            if (this.DesignMode)
            {
                this.Invalidate();
            }
        }

#endif

        protected override void DestroyHandle()
        {
            base.DestroyHandle();

            foreach (Panel p in panelCollection)
            {
                p.Dispose();
            }
        }


    }
}