【C#中級】独自ボタンをユーザーコントロールで作成

using System;
using System.ComponentModel;
using System.ComponentModel.Design;
using System.Diagnostics;
using System.Drawing;
using System.Drawing.Design;
using System.Windows.Forms;

namespace WinFormsApp1
{
    public partial class ButtonImageUC : UserControl
    {
		public enum ButtonType
		{
			Button1,
		}

		private ButtonType type = ButtonImageUC.ButtonType.Button1;
		[Browsable(true)]
		public ButtonType Type
		{
			set
			{
				if (this.type == value) return;
				this.type = value;
				CreateBitmap();
			}
			get { return this.type; }
		}

		private bool selected = false;
		[Browsable(true)]
		public bool Selected
		{
			get { return this.selected; }
			set
			{
				if (this.selected == value) return;
				this.selected = value;
				OnSelectedChanged();
			}
		}

		[Bindable(true)]
		[Browsable(true)]
		[Localizable(true)]
		[DesignerSerializationVisibility(DesignerSerializationVisibility.Visible)]
		[EditorBrowsable(EditorBrowsableState.Always)]
		[Editor(typeof(MultilineStringEditor), typeof(UITypeEditor))]
		public override string Text { get; set; }
		public ButtonImageUC()
		{
			InitializeComponent();

			CreateBitmap();
			UpdateBitmap(); // デザイナでEnabledがfalseにされていた場合ここで更新。
		}

		private enum BitmapType
		{
			Default,
			Highlighted,
			Pressed,
			Selected,
			Disabled,
		}
		private BitmapType bitmapType = BitmapType.Default;

		private Bitmap[] bitmap;
		private Brush[] foreColor;

		private void CreateBitmap()
		{
			switch (this.Type)
			{
				case ButtonType.Button1:
					CreateGrayBitmap();
					break;
				default:
					Debug.Assert(false);
					CreateGrayBitmap();
					break;
			}
		}

		internal static readonly Color ForeColorDefault = Color.FromArgb(0x00, 0x00, 0x00);
		internal static readonly Color ForeColorHighlighted = Color.FromArgb(0x26, 0x26, 0x26);
		internal static readonly Color ForeColorPressed = Color.FromArgb(0x00, 0x00, 0x00);
		internal static readonly Color ForeColorSelected = Color.FromArgb(0xFF, 0xFF, 0xFF);
		internal static readonly Color ForeColorDisabled = Color.FromArgb(0xB2, 0xB2, 0xB2);

		private void CreateGrayBitmap()
		{
			DisposeBitmap();
			Debug.Assert(this.bitmap == null);
			this.bitmap = new Bitmap[Enum.GetValues(typeof(BitmapType)).Length];
			this.bitmap[(int)BitmapType.Default] = Resources.Default;
			this.bitmap[(int)BitmapType.Highlighted] = Resources.MouseOver;
			this.bitmap[(int)BitmapType.Pressed] = Resources.Press;
			this.bitmap[(int)BitmapType.Selected] = Resources.Select;
			this.bitmap[(int)BitmapType.Disabled] = Resources.Disable;

            this.foreColor = new Brush[Enum.GetValues(typeof(BitmapType)).Length];
            this.foreColor[(int)BitmapType.Default] = new SolidBrush(ButtonImageUC.ForeColorDefault);
            this.foreColor[(int)BitmapType.Highlighted] = new SolidBrush(ButtonImageUC.ForeColorHighlighted);
            this.foreColor[(int)BitmapType.Pressed] = new SolidBrush(ButtonImageUC.ForeColorPressed);
            this.foreColor[(int)BitmapType.Selected] = new SolidBrush(ButtonImageUC.ForeColorSelected);
            this.foreColor[(int)BitmapType.Disabled] = new SolidBrush(ButtonImageUC.ForeColorDisabled); // 現状の実装では反映されない。
        }

		private void DisposeBitmap()
		{
			if (this.bitmap != null) foreach (var target in this.bitmap) { target?.Dispose(); };
			this.bitmap = null;

			if (this.foreColor != null) foreach (var target in this.foreColor) { target?.Dispose(); }
			this.foreColor = null;
		}

		protected override void OnEnabledChanged(EventArgs e)
		{
			base.OnEnabledChanged(e);
			UpdateBitmap();
		}

		private void OnSelectedChanged()
		{
			UpdateBitmap();
		}

		private void button_Click(object sender, EventArgs e)
		{
			this.OnClick(e);
		}

		private bool highlited = false;
		private void button_MouseEnter(object sender, EventArgs e)
		{
			this.highlited = true;
			UpdateBitmap();
		}

		private void button_MouseLeave(object sender, EventArgs e)
		{
			this.highlited = false;
			UpdateBitmap();
		}

		private bool pressed = false;
		private void button_MouseDown(object sender, MouseEventArgs e)
		{
			this.pressed = true;
			UpdateBitmap();
		}

		private void button_MouseUp(object sender, MouseEventArgs e)
		{
			this.pressed = false;
			UpdateBitmap();
		}

		private void button_MouseCaptureChanged(object sender, EventArgs e)
		{
			this.pressed = false;
			UpdateBitmap();
		}

		private bool UpdateBitmap()
		{
			BitmapType current = GetCurrentBitmapType();
			if (this.bitmapType == current) return false;
			this.bitmapType = current;
			Invalidate();
			return true;
		}

		private BitmapType GetCurrentBitmapType()
		{
			if (this.selected) return BitmapType.Selected;
			if (!this.Enabled) return BitmapType.Disabled;
			if (this.pressed) return BitmapType.Pressed;
			if (this.highlited) return BitmapType.Highlighted;
			return BitmapType.Default;
		}

		private readonly StringFormat stringFormat = new StringFormat()
		{
			LineAlignment = StringAlignment.Center,
			Alignment = StringAlignment.Center,
			Trimming = StringTrimming.None,
		};

		private void ButtonImageUC_Paint(object sender, PaintEventArgs e)
		{
			if (!this.Visible) return;
			e.Graphics.DrawImage(this.bitmap[(int)this.bitmapType], this.ClientRectangle);
			e.Graphics.DrawString(this.Text, this.Font, this.foreColor[(int)this.bitmapType], this.ClientRectangle, this.stringFormat);
		}
	}
}

public enum ButtonType
{
	Button1,
　Button2,
　Button3,
}