Resort Companion

// Resort Companion Mobile Edition
// Copyright (c) 2004 Wolf Logan

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

namespace org.CircleCross.ResortCompanion.Mobile {
	/// <summary>
	/// A scrolling map control. Derived from a PictureBox, this control adds scrolling capabilities,
	/// both interactive and programmatic.
	/// </summary>
	public class ScrollMap: PictureBox {
		protected Point origin = new Point(0, 0);
		public Point Origin {
			get {
				return this.origin;
			}
			set {
				// clip the specified Origin to prevent scrolling off the edge of the image
				if(value.X > (this.Image.Width - this.Width)) {
					this.origin.X = (this.Image.Width - this.Width);
				} else if(value.X < 0) {
					this.origin.X = 0;
				} else {
					this.origin.X = value.X;
				}
				if(value.Y > (this.Image.Height - this.Height)) {
					this.origin.Y = (this.Image.Height - this.Height);
				} else if(value.Y < 0) {
					this.origin.Y = 0;
				} else {
					this.origin.Y = value.Y;
				}
			}
		}

		public ScrollMap(): base() {
		}

		/// <summary>
		/// OnPaint handler. Paints the visible portion of the image, based on the current origin.
		/// </summary>
		/// <param name="e"></param>
		protected override void OnPaint(PaintEventArgs e) {
			Rectangle src = new Rectangle(this.origin.X, this.origin.Y, this.ClientRectangle.Width, this.ClientRectangle.Height);
			e.Graphics.DrawImage(this.Image, this.ClientRectangle, src, GraphicsUnit.Pixel);
			
		}

		/// <summary>
		/// the initial point selected when the scrolling begins
		/// </summary>
		protected Point initialMouse = new Point(0, 0);

		/// <summary>
		/// the original origin before scrolling begins
		/// </summary>
		protected Point oldOrigin = new Point(0, 0);

		/// <summary>
		/// flag indicates whether we're currently scrolling
		/// </summary>
		protected bool isScrolling = false;

		/// <summary>
		/// OnMouseDown handler. Store the current Origin, and the current mouse position.
		/// </summary>
		/// <param name="e"></param>
		protected override void OnMouseDown(MouseEventArgs e) {
			this.initialMouse.X = e.X;
			this.initialMouse.Y = e.Y;
			this.oldOrigin = this.Origin;
			this.isScrolling = true;
			base.OnMouseDown (e);
		}

		/// <summary>
		/// OnMouseMove handler. Subtract the current mouse position from the initial position, 
		/// then move the Origin the same distance from the old Origin.
		/// </summary>
		/// <param name="e"></param>
		protected override void OnMouseMove(MouseEventArgs e) {
			if(this.isScrolling){
				Point delta = this.initialMouse;
				delta.Offset(-e.X, -e.Y);
				Point temp = this.oldOrigin;
				temp.Offset(delta.X, delta.Y);
				this.Origin = temp;
				Refresh();
			}
			base.OnMouseMove (e);
		}

		/// <summary>
		/// OnMouseUp handler. Clean up the scrolling flag when we're done.
		/// </summary>
		/// <param name="e"></param>
		protected override void OnMouseUp(MouseEventArgs e) {
			this.isScrolling = false;
			base.OnMouseUp (e);
		}
	}
}