Drag and Drop in WPF using Behavior

Framework behavior starts the drag process. It records the queries for the dragged Data type.When framework behavior is dropped on the framework at the time operation start. It is a subclass of system.window.UIElement class. That we normally see on WPF.

When ListboxBehaviour is dropped on List box at that time operation will perform.

Treeview: In Treeview, every element is also a framework element. So in the XAML file in declaration framework behavior and framework element drop behavior are used.

CandidateView: The candidate is candidate framework element, using them we can do drag. The candidate is draping Listbox so for that it uses listboxDropBehaviour class.

The main purpose of dragging is to select the data which transfers it along with defining the data which passed by dragging and it decides the area when the mouse hovers around the screen the informs the system.

iDragabble interface the following:

interface IDragable
    {
        /// Type of the data item
        Type DataType{get;}
        /// Remove the object collection
                void Remove (object i);
    }

				

Remove method can be used to remove the source data which is a copy operation. Do not simply it. You can add it to your application according to your requirement and improve its performance.

Basic step to create attached behaviour

You will need a particular static object if you are handling drag and drop in WPF. This will help you to handle drag and drop.

Predefine data will be in the DataFormat class which will the data which is being dragged and drop. This is used to identify the data. If you are not familiar with the DataObject or iDataObject then you should first understand those concepts by which you can easily call the methods.

If you want to perform drag and drop then you should know which data you have to handle while you are performing drag and drop. You should have information that if selected data is being handled properly or not and what is the type of the selected data. You have an option to handle the behavior of the data behind the code. You can use the PreciewDrop event.

DropBehavior.cs
using System.Windows.Input;
using System.Windows;
namespace MVVM
{
    
				

Now you can add the data in the grid or the UI Element but cannot perform the drag and drop. If you try to drag and drop in the textbox then it will not work. The event will not be fired.

Example:

Add Dropbehavior to a user control and you can add the DropBehavior to a grid.

Implementing the ICommand in the ViewModel:

You will need the following code in the ViewModel

public ICommandPreviewDropCommand
{
    get { return _PreviewDropCommand ?? (_PreviewDropCommand = new RelayCommand(HandlePreviewDrop)); }
    set
    {
        _PreviewDropCommand = value;
    NotifyPropertyChanged("PreviewDropCommand");
    }
} 
  private ICommand _PreviewDropCommand;
  The method encapsulated in the relay command
  private void HandlePreviewDrop(object in object)
  {
    IDataObjectido = inObject as IDataObject;
    if (null == ido) return;
    // Get all the possible format
    string [] formats = ido.GetFormats();
 }
				

Below is iDraggable interface:

interface IDropable
    {