TestForm.cs

using FluentDragDrop;
using FluentDragDrop.Effects;
using FluentTransitions;
using System;
using System.Drawing;
using System.Drawing.Imaging;
using System.Linq;
using System.Windows.Forms;

namespace FluentDragDropExample
{
	public partial class TestForm : Form
	{
		private bool _listCompatibilityTraditionalMouseDown;

		public TestForm()
		{
			InitializeComponent();
		}

		private void picNoPreview_MouseDown(object sender, MouseEventArgs e)
		{
			var pic = (PictureBox)sender;
			pic.InitializeDragAndDrop()
				.Copy()
				.Immediately()
				.WithData(pic.Image)
				.WithoutPreview()
				.To(PreviewBoxes, (target, data) => target.Image = data);
		}

		#region ImmediateUsage
		private void picControlPreviewBehindCursor_MouseDown(object sender, MouseEventArgs e)
		{
			var pic = (PictureBox)sender;

			pic.InitializeDragAndDrop()
				.Copy()
				.Immediately()
				.WithData(pic.Image)
				.WithPreview().BehindCursor()
				.To(PreviewBoxes, (target, data) => target.Image = data);

			// Copy(), Move() or Link() to define allowed effects
			// Immediately() or OnMouseMove() for deferred start on mouse move
			// WithData() to pass any object you like
			// WithPreview() to define your preview and how it should behave
			//     BehindCursor() or RelativeToCursor() to define the preview placement
			// To() to define target controls and how the dragged data should be used on drop
		}
		#endregion

		private void picCustomPreviewWindowsExplorerStyle_MouseDown(object sender, MouseEventArgs e)
		{
			var pic = (PictureBox)sender;

			// Image: Custom
			// Drag style: Like Windows Explorer

			pic.InitializeDragAndDrop()
				.Copy()
				.OnMouseMove()
				.WithData(() => pic.Image)
				.WithPreview(() => Grayscale((Bitmap)pic.Image)).LikeWindowsExplorer()
				.To(PreviewBoxes, (target, data) => target.Image = data);
		}

		private void picUpdatingPreviewRelativeToCursor_MouseDown(object sender, MouseEventArgs e)
		{
			var pic = (PictureBox)sender;

			pic.InitializeDragAndDrop()
				.Copy()
				.Immediately()
				.WithData(pic.Image)
				.WithPreview((img, _) => new UpdatablePreview(img, Control.MousePosition)).RelativeToCursor()
				.To(PreviewBoxes, (target, data) => target.Image = data);
		}

		#region DelayedUsage
		private void CountryList_MouseDown(object sender, MouseEventArgs e)
		{
			var source = (ListView)sender;
			var target = source.Equals(listLeft) ? listRight : listLeft;

			source.InitializeDragAndDrop()
				.Move()
				.OnMouseMove()
				.If(() => source.SelectedIndices.Count > 0)
				.WithData(() => source.SelectedItems.OfType<ListViewItem>().ToArray())
				.WithPreview((_, data) => RenderPreview(data)).BehindCursor()
				.To(target, MoveItems);
		}
		#endregion

		private void linkCompatibilityBrowser_MouseDown(object sender, MouseEventArgs e)
		{
			linkCompatibilityBrowser.InitializeDragAndDrop()
				.Link()
				.Immediately()
				.WithData("https://twitter.com/waescher");
		}

		private void listCompatibilityFluent_MouseDown(object sender, MouseEventArgs e)
		{
			listCompatibilityFluent.InitializeDragAndDrop()
				.Copy()
				.OnMouseMove()
				.If(() => listCompatibilityFluent.SelectedItems.OfType<ListViewItem>().ToArray().Any())
				.WithData(() => listCompatibilityFluent.SelectedItems.OfType<ListViewItem>().ToArray())
				.WithPreview((_, data) => RenderPreview(data)).BehindCursor();
			//.To(listCompatibilityTarget, CopyItems) -> doubles items if used, because listCompatibilityTarget handles the drop input already
		}

		private void listCompatibilityTraditional_MouseDown(object sender, MouseEventArgs e)
		{
			_listCompatibilityTraditionalMouseDown = true;
		}

		private void listCompatibilityTraditional_MouseUp(object sender, MouseEventArgs e)
		{
			_listCompatibilityTraditionalMouseDown = false;
		}

		private void listCompatibilityTraditional_MouseMove(object sender, MouseEventArgs e)
		{
			if (!_listCompatibilityTraditionalMouseDown)
				return;

			_listCompatibilityTraditionalMouseDown = false;

			if (listCompatibilityTraditional.SelectedItems.Count == 0)
				return;

			var newItems = listCompatibilityTraditional.SelectedItems.OfType<ListViewItem>().ToArray();
			listCompatibilityTraditional.DoDragDrop(newItems, DragDropEffects.Copy | DragDropEffects.Move);
		}

		private void listCompatibilityTarget_DragEnter(object sender, DragEventArgs e)
		{
			e.Effect = DragDropEffects.Copy;
		}

		private void listCompatibilityTarget_DragDrop(object sender, DragEventArgs e)
		{
			var items = e.Data.GetData(typeof(ListViewItem[])) as ListViewItem[];
			if (items != null)
			{
				var newItems = items.Select(i => new ListViewItem { Text = i.Text, ImageIndex = i.ImageIndex }).ToArray();
				listCompatibilityTarget.Items.AddRange(newItems);
			}
		}

		private void picDragOverHook_MouseDown(object sender, MouseEventArgs e)
		{
			picDragOverHook.InitializeDragAndDrop()
				.Copy()
				.OnMouseMove()
				.WithData(() => picDragOverHook.Image);
		}

		private void picDragOverHookGiveFeedback_MouseDown(object sender, MouseEventArgs e)
		{
			picDragOverHookGiveFeedback.InitializeDragAndDrop()
				.Copy()
				.OnMouseMove()
				.WithData(() => picDragOverHookGiveFeedback.Image)
				.WithoutMouseHooks();
		}

		private void MoveItems(ListView targetListView, ListViewItem[] draggedItems)
		{
			var newItems = draggedItems.Select(i => new ListViewItem { Text = i.Text, ImageIndex = i.ImageIndex }).ToArray();
			targetListView.Items.AddRange(newItems);

			var sourceListView = draggedItems[0].ListView;

			foreach (var item in draggedItems)
				sourceListView.Items.Remove(item);
		}

		private Bitmap Grayscale(Bitmap image)
		{
			var result = new Bitmap(image.Width, image.Height);

			using (var graphics = Graphics.FromImage(result))
			{
				var colorMatrix = new ColorMatrix(new float[][]
				{
					new float[] {.3f, .3f, .3f, 0, 0},
					new float[] {.59f, .59f, .59f, 0, 0},
					new float[] {.11f, .11f, .11f, 0, 0},
					new float[] {0, 0, 0, 1, 0},
					new float[] {0, 0, 0, 0, 1}
				});

				using (var attributes = new ImageAttributes())
				{
					attributes.SetColorMatrix(colorMatrix);
					graphics.DrawImage(image, new Rectangle(0, 0, result.Width, result.Height), 0, 0, image.Width, image.Height, GraphicsUnit.Pixel, attributes);
				}
			}
			return result;
		}

		private Bitmap RenderPreview(ListViewItem[] items)
		{
			var itemHeight = 23;
			var image = new Bitmap(120, itemHeight * items.Length);
			var borderBounds = new Rectangle(Point.Empty, image.Size);
			borderBounds.Width--;
			borderBounds.Height--;

			using (var graphics = Graphics.FromImage(image))
			{
				graphics.Clear(Color.White);
				graphics.DrawRectangle(Pens.Black, borderBounds);

				using (var format = new StringFormat())
				{
					format.Alignment = StringAlignment.Near;
					format.LineAlignment = StringAlignment.Center;
					format.FormatFlags = StringFormatFlags.NoWrap;
					format.Trimming = StringTrimming.EllipsisCharacter;

					for (int i = 0; i < items.Length; i++)
					{
						var itemY = itemHeight * i;

						var itemImage = imlSmall.Images[items[i].ImageIndex];
						var imagePadding = (itemHeight - itemImage.Height) / 2;
						graphics.DrawImage(itemImage, new Point(imagePadding, itemY + imagePadding));

						var textX = itemImage.Width + imagePadding;
						var textBounds = new Rectangle(textX, itemY, image.Width - textX, itemHeight);
						graphics.DrawString(items[i].Text, listLeft.Font, Brushes.Black, textBounds, format);
					}
				}
			}

			return image;
		}

		private PictureBox[] PreviewBoxes => new[] { picNoPreview, picControlPreviewBehindCursor, picCustomPreviewWindowsExplorerStyle, picUpdatingPreviewRelativeToCursor, picEmpty1, picEmpty2, picEmpty3, picEmpty4 };

		private void picReturnOnCancel_MouseDown(object sender, MouseEventArgs e)
		{
			picReturnOnCancel
				.InitializeDragAndDrop()
				.Move()
				.Immediately()
				.WithData("")
				.WithPreview().RelativeToCursor()
				.FadeInOnStart()
				.ReturnToStartOnCancel()
				.WithDropEffects(new MorphToTargetEffect(), new FlashSourceControlEffect())
				.To(picEffectsTarget, null);
		}

		internal class FlashSourceControlEffect : IEffect
		{
			public void Start(IEffect.Arguments arguments)
			{
				if (arguments?.TargetControl is null)
					throw new ArgumentNullException($"Target control cannot be null for this {nameof(FlashSourceControlEffect)}");

				Transition
					.With(arguments.TargetControl, nameof(arguments.TargetControl.BackColor), Color.LightSeaGreen)
					.Bounce(TimeSpan.FromSeconds(1.2));
			}
		}

		private void picTransparency1_MouseDown(object sender, MouseEventArgs e)
		{
			var pic = (PictureBox)sender;
			pic.InitializeDragAndDrop()
			   .Move()
			   .Immediately()
			   .WithData(pic.Image)
			   .WithPreview(() => (Bitmap)pic.Image).RelativeToCursor()
			   .To(picTransparencyDrop, (target, image) => target.Image = image);
		}
	}
}