using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Windows;

using Microsoft.Research.DynamicDataDisplay.Common;



namespace Microsoft.Research.DynamicDataDisplay.ViewportConstraints

{

	/// <summary>

	/// Represents a base class for all constraints that are being applied to viewport's visible rect.

	/// </summary>

	public abstract class ViewportConstraint

	{

		/// <summary>

		/// Applies the constraint.

		/// </summary>

		/// <param name="previousDataRect">Previous data rectangle.</param>

		/// <param name="proposedDataRect">Proposed data rectangle.</param>

		/// <param name="viewport">The viewport, to which current restriction is being applied.</param>

		/// <returns>New changed visible rectangle.</returns>

		public abstract DataRect Apply(DataRect previousDataRect, DataRect proposedDataRect, Viewport2D viewport);



		/// <summary>

		/// Raises the changed event.

		/// </summary>

		protected void RaiseChanged()

		{

			Changed.Raise(this);

		}

		/// <summary>

		/// Occurs when constraint changes.

		/// Causes update of <see cref="Viewport"/>'s Visible property.

		/// </summary>

		public event EventHandler Changed;

	}

}