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// 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.
//
//
//
// Description: DragEventArgs for drag-and-drop operation.
//
//
//
using System;
using System.Diagnostics;
using System.Windows.Media;
using System.Windows.Input;
using SR=MS.Internal.PresentationCore.SR;
namespace System.Windows
{
/// <summary>
/// The DragEventArgs class represents a type of RoutedEventArgs that
/// are relevant to all drag events(DragEnter/DragOver/DragLeave/DragDrop).
/// </summary>
public sealed class DragEventArgs : RoutedEventArgs
{
//------------------------------------------------------
//
// Constructors
//
//------------------------------------------------------
#region Constructors
/// <summary>
/// Constructs a DragEventArgs instance.
/// </summary>
/// <param name="data">
/// The data object used in this drag drop operation.
/// </param>
/// <param name="dragDropKeyStates">
/// The current state of the mouse button and modifier keys.
/// </param>
/// <param name="allowedEffects">
/// Allowed effects of a drag-and-drop operation.
/// </param>
/// <param name="target">
/// The target of the event.
/// </param>
/// <param name="point">
/// The current mouse position of the target.
/// </param>
internal DragEventArgs(IDataObject data, DragDropKeyStates dragDropKeyStates, DragDropEffects allowedEffects, DependencyObject target, Point point)
{
if (!DragDrop.IsValidDragDropKeyStates(dragDropKeyStates))
{
Debug.Assert(false, "Invalid dragDropKeyStates");
}
if (!DragDrop.IsValidDragDropEffects(allowedEffects))
{
Debug.Assert(false, "Invalid allowedEffects");
}
if (target == null)
{
Debug.Assert(false, "Invalid target");
}
this._data = data;
this._dragDropKeyStates = dragDropKeyStates;
this._allowedEffects = allowedEffects;
this._target = target;
this._dropPoint = point;
this._effects = allowedEffects;
}
#endregion Constructors
//------------------------------------------------------
//
// Public Methods
//
//------------------------------------------------------
#region Public Methods
/// <summary>
/// The point of drop operation that based on relativeTo.
/// </summary>
public Point GetPosition(IInputElement relativeTo)
{
Point dropPoint;
ArgumentNullException.ThrowIfNull(relativeTo);
dropPoint = new Point(0, 0);
if (_target != null)
{
// Translate the drop point from the drop target to the relative element.
dropPoint = InputElement.TranslatePoint(_dropPoint, _target, (DependencyObject)relativeTo);
}
return dropPoint;
}
#endregion Public Methods
//------------------------------------------------------
//
// Public Properties
//
//------------------------------------------------------
#region Public Properties
/// <summary>
/// The data object of drop operation
/// </summary>
public IDataObject Data
{
get { return _data; }
}
/// <summary>
/// The DragDropKeyStates that indicates the current states for
/// physical keyboard keys and mouse buttons.
/// </summary>
public DragDropKeyStates KeyStates
{
get { return _dragDropKeyStates; }
}
/// <summary>
/// The allowed effects of drag and drop operation
/// </summary>
public DragDropEffects AllowedEffects
{
get
{
return _allowedEffects;
}
}
/// <summary>
/// The effects of drag and drop operation
/// </summary>
public DragDropEffects Effects
{
get
{
return _effects;
}
set
{
if (!DragDrop.IsValidDragDropEffects(value))
{
throw new ArgumentException(SR.Format(SR.DragDrop_DragDropEffectsInvalid, "value"));
}
_effects = value;
}
}
#endregion Public Properties
#region Protected Methods
//------------------------------------------------------
//
// Protected Methods
//
//------------------------------------------------------
/// <summary>
/// The mechanism used to call the type-specific handler on the target.
/// </summary>
/// <param name="genericHandler">
/// The generic handler to call in a type-specific way.
/// </param>
/// <param name="genericTarget">
/// The target to call the handler on.
/// </param>
protected override void InvokeEventHandler(Delegate genericHandler, object genericTarget)
{
DragEventHandler handler = (DragEventHandler)genericHandler;
handler(genericTarget, this);
}
#endregion Protected Methods
//------------------------------------------------------
//
// Private Fields
//
//------------------------------------------------------
#region Private Fields
private IDataObject _data;
private DragDropKeyStates _dragDropKeyStates;
private DragDropEffects _allowedEffects;
private DragDropEffects _effects;
private DependencyObject _target;
private Point _dropPoint;
#endregion Private Fields
}
}
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