// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
 
namespace System.Windows.Controls.Primitives
{
    /// <summary>
    /// This DragDeltaEventArgs class contains additional information about the
    /// DragDeltaEvent event.
    /// </summary>
    /// <seealso cref="Thumb.DragDeltaEvent" />
    /// <seealso cref="RoutedEventArgs" />
    public class DragDeltaEventArgs: RoutedEventArgs
    {
        /// <summary>
        /// This is an instance constructor for the DragDeltaEventArgs class.  It
        /// is constructed with a reference to the event being raised.
        /// </summary>
        /// <returns>Nothing.</returns>
        public DragDeltaEventArgs(double horizontalChange, double verticalChange) : base()
        {
            _horizontalChange = horizontalChange;
            _verticalChange = verticalChange;
            RoutedEvent=Thumb.DragDeltaEvent;
        }
 
        /// <value>
        /// Read-only access to the horizontal change.
        /// </value>
        public double HorizontalChange
        {
            get { return _horizontalChange; }
        }
 
        /// <value>
        /// Read-only access to the vertical change.
        /// </value>
        public double VerticalChange
        {
            get { return _verticalChange; }
        }
 
        /// <summary>
        /// This method is used to perform the proper type casting in order to
        /// call the type-safe DragDeltaEventHandler delegate for the DragDeltaEvent event.
        /// </summary>
        /// <param name="genericHandler">The handler to invoke.</param>
        /// <param name="genericTarget">The current object along the event's route.</param>
        /// <returns>Nothing.</returns>
        /// <seealso cref="Thumb.DragDeltaEvent" />
        /// <seealso cref="DragDeltaEventHandler" />
        protected override void InvokeEventHandler(Delegate genericHandler, object genericTarget)
        {
            DragDeltaEventHandler handler = (DragDeltaEventHandler)genericHandler;
 
            handler(genericTarget, this);
        }
 
        private double _horizontalChange;
        private double _verticalChange;
    }
 
    /// <summary>
    ///     This delegate must used by handlers of the DragDeltaEvent event.
    /// </summary>
    /// <param name="sender">The current element along the event's route.</param>
    /// <param name="e">The event arguments containing additional information about the event.</param>
    /// <returns>Nothing.</returns>
    public delegate void DragDeltaEventHandler(object sender, DragDeltaEventArgs e);
}