TweetDuck/video/Controls/LabelTooltip.cs

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

namespace TweetDuck.Video.Controls {
	sealed class LabelTooltip : Label {
		public LabelTooltip() {
			Visible = false;
		}

		public void AttachTooltip(Control control, bool followCursor, string tooltip) {
			AttachTooltip(control, followCursor, args => tooltip);
		}

		public void AttachTooltip(Control control, bool followCursor, Func<MouseEventArgs, string?> tooltipFunc) {
			control.MouseMove += (sender, args) => {
				SuspendLayout();

				Form? form = control.FindForm();
				Debug.Assert(form != null);

				string? text = tooltipFunc(args);

				if (text == null) {
					Visible = false;
					return;
				}

				Text = text;

				Point loc = form!.PointToClient(control.Parent.PointToScreen(new Point(control.Location.X + (followCursor ? args.X : control.Width / 2), 0)));
				loc.X = Math.Max(0, Math.Min(form.Width - Width, loc.X - Width / 2));
				loc.Y -= Height - Margin.Top + Margin.Bottom;
				Location = loc;

				ResumeLayout();
				Visible = true;
			};

			control.MouseLeave += control_MouseLeave;
		}

		private void control_MouseLeave(object sender, EventArgs e) {
			Visible = false;
		}
	}
}