Vanara/Windows.Forms/Controls/CollapsiblePanelHeader.cs

using System;
using System.ComponentModel;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Windows.Forms;
using System.Windows.Forms.VisualStyles;
using Vanara.Extensions;

namespace Vanara.Windows.Forms
{
	internal class CollapsiblePanelHeader : Control
	{
		private const int tbpadding = 8;
		private const string bgClass = "LISTVIEW", btnClass = "TASKDIALOG", txtClass = btnClass;
		private const int bgPart = 6, btnPart = 13, txtPart = 2;
		private readonly VisualStyleRenderer bgRnd, btnRnd, txtRnd;
		private int headerHeight;
		private Size imgSz;
		private Rectangle buttonBounds;
		private Rectangle textBounds;

		public CollapsiblePanelHeader()
		{
			SetStyle(ControlStyles.OptimizedDoubleBuffer |
				ControlStyles.AllPaintingInWmPaint |
				ControlStyles.ResizeRedraw |
				ControlStyles.UserPaint, true);
			if (VisualStyleRenderer.IsSupported)
				try
				{
					bgRnd = new VisualStyleRenderer(bgClass, bgPart, 0);
					btnRnd = new VisualStyleRenderer(btnClass, btnPart, 0);
					txtRnd = new VisualStyleRenderer(txtClass, txtPart, 0);
				}
				catch { }
		}

		[DefaultValue(false)]
		public bool Collapsed { get; set; }

		internal PushButtonState ButtonState { get; set; } = PushButtonState.Normal;

		internal int HorzPadding { get; set; } = 12;

		/// <summary>
		/// Retrieves the default size for the control.
		/// </summary>
		/// <value></value>
		/// <returns>
		/// The default <see cref="T:System.Drawing.Size"/> of the control.
		/// </returns>
		protected override Size DefaultSize => new Size(200, 200);

		/// <summary>
		/// Retrieves the size of a rectangular area into which a control can be fitted.
		/// </summary>
		/// <param name="proposedSize">The custom-sized area for a control.</param>
		/// <returns>
		/// An ordered pair of type <see cref="T:System.Drawing.Size"/> representing the width and height of a rectangle.
		/// </returns>
		public override Size GetPreferredSize(Size proposedSize) => DefaultSize;

		protected override void OnClick(EventArgs e)
		{
			Collapsed = !Collapsed;
			base.OnClick(e);
		}

		/// <summary>
		/// Process Enabled property changed
		/// </summary>
		/// <param name="e">The <see cref="EventArgs"/> instance containing the event data.</param>
		protected override void OnEnabledChanged(EventArgs e)
		{
			ButtonState = Enabled ? PushButtonState.Normal : PushButtonState.Disabled;
			Invalidate();
			base.OnEnabledChanged(e);
		}

		/// <summary>
		/// Raises the <see cref="E:System.Windows.Forms.Control.GotFocus" /> event.
		/// </summary>
		/// <param name="e">The <see cref="EventArgs"/> instance containing the event data.</param>
		protected override void OnGotFocus(EventArgs e)
		{
			Invalidate();
			base.OnGotFocus(e);
		}

		/// <summary>
		/// Raises the <see cref="E:System.Windows.Forms.Control.LostFocus" /> event.
		/// </summary>
		/// <param name="e">The <see cref="EventArgs"/> instance containing the event data.</param>
		protected override void OnLostFocus(EventArgs e)
		{
			Invalidate();
			base.OnLostFocus(e);
		}

		/// <summary>
		/// Raises the <see cref="E:System.Windows.Forms.Control.MouseDown"/> event.
		/// </summary>
		/// <param name="e">A <see cref="T:System.Windows.Forms.MouseEventArgs"/> that contains the event data.</param>
		protected override void OnMouseDown(MouseEventArgs e)
		{
			if ((e.Button & MouseButtons.Left) != MouseButtons.Left) return;
			ButtonState = PushButtonState.Pressed;
			Invalidate();
			base.OnMouseDown(e);
		}

		/// <summary>
		/// Raises the <see cref="M:System.Windows.Forms.Control.OnMouseEnter(System.EventArgs)"/> event.
		/// </summary>
		/// <param name="e">An <see cref="T:System.EventArgs"/> that contains the event data.</param>
		protected override void OnMouseEnter(EventArgs e)
		{
			ButtonState = PushButtonState.Hot;
			Invalidate();
			base.OnMouseEnter(e);
		}

		/// <summary>
		/// Raises the <see cref="E:System.Windows.Forms.Control.MouseLeave"/> event.
		/// </summary>
		/// <param name="e">An <see cref="T:System.EventArgs"/> that contains the event data.</param>
		protected override void OnMouseLeave(EventArgs e)
		{
			ButtonState = Enabled ? PushButtonState.Normal : PushButtonState.Disabled;
			Invalidate();
			base.OnMouseLeave(e);
		}

		/// <summary>
		/// Raises the <see cref="E:System.Windows.Forms.Control.MouseUp"/> event.
		/// </summary>
		/// <param name="e">A <see cref="T:System.Windows.Forms.MouseEventArgs"/> that contains the event data.</param>
		protected override void OnMouseUp(MouseEventArgs e)
		{
			if ((e.Button & MouseButtons.Left) != MouseButtons.Left) return;
			ButtonState = Enabled ? PushButtonState.Hot : PushButtonState.Disabled;
			Invalidate();
			base.OnMouseUp(e);
		}

		/// <summary>
		/// Raises the <see cref="E:System.Windows.Forms.Control.Paint"/> event.
		/// </summary>
		/// <param name="e">A <see cref="T:System.Windows.Forms.PaintEventArgs"/> that contains the event data.</param>
		protected override void OnPaint(PaintEventArgs e)
		{
			if (Visible)
			{
				var g = e.Graphics;
				g.SmoothingMode = SmoothingMode.HighQuality;
				g.CompositingQuality = CompositingQuality.HighQuality;
				g.InterpolationMode = InterpolationMode.HighQualityBicubic;

				if (bgRnd == null)
					try
					{
						e.Graphics.Clear(ButtonState == PushButtonState.Hot || ButtonState == PushButtonState.Pressed ? SystemColors.Highlight : SystemColors.Window);
						TextRenderer.DrawText(e.Graphics, Text, SystemFonts.CaptionFont, textBounds.Location, ButtonState == PushButtonState.Hot || ButtonState == PushButtonState.Pressed ? SystemColors.HighlightText : SystemColors.WindowText);
					}
					catch { }
				else
				{
					LayoutElements(e.Graphics, e.ClipRectangle);
					bgRnd.DrawBackground(e.Graphics, ClientRectangle);
					btnRnd.DrawBackground(e.Graphics, buttonBounds, null, this.GetRightToLeftProperty() == RightToLeft.Yes);
					var tff = TextFormatFlags.SingleLine;
					if (this.GetRightToLeftProperty() == RightToLeft.Yes)
						tff |= TextFormatFlags.RightToLeft;
					txtRnd.DrawText(e.Graphics, textBounds, Text, !Enabled, tff);
				}
				base.OnPaint(e);
			}
		}

		private void LayoutElements(IDeviceContext g, Rectangle clipRect)
		{
			if (btnRnd == null) return;
			var state = (int)ButtonState;
			if (state == 4)
				state = Collapsed ? 7 : 8;
			else if (!Collapsed)
				state += 3;
			btnRnd.SetState(state);
			state = (ButtonState == PushButtonState.Hot || ButtonState == PushButtonState.Pressed) ? 2 : 1;
			bgRnd.SetState(state);
			var r = txtRnd.GetTextExtent(g, "W", TextFormatFlags.Default);
			headerHeight = (tbpadding * 2) + r.Height;
			imgSz = new Size(btnRnd.GetInteger(IntegerProperty.Width), btnRnd.GetInteger(IntegerProperty.Height));
			buttonBounds = new Rectangle(clipRect.Width - imgSz.Width - HorzPadding, (headerHeight - imgSz.Height) / 2, imgSz.Width, imgSz.Height);
			textBounds = new Rectangle(HorzPadding, tbpadding, clipRect.Width - HorzPadding - imgSz.Width, tbpadding + r.Height);
			Height = headerHeight;
		}
	}
}