WinForms Data Grid - Auto-scroll the grid during drag-and-drop

C#
using System;
using System.Collections.Generic;
using System.Text;
using System.Windows.Forms;
using DevExpress.XtraGrid;
using DevExpress.XtraGrid.Views.Grid;
using DevExpress.XtraGrid.Views.Grid.ViewInfo;
using System.Drawing;

namespace AutoScrollTimer {
    public class AutoScrollHelper {
        public AutoScrollHelper(GridView view) {
            fGrid = view.GridControl;
            fView = view;
            fScrollInfo = new ScrollInfo(this, view);
        }

        GridControl fGrid;
        GridView fView;
        ScrollInfo fScrollInfo;
        public int ThresholdInner = 20;
        public int ThresholdOutter = 100;
        public int HorizontalScrollStep = 10;
        public int ScrollTimerInterval {
            get {
                return fScrollInfo.scrollTimer.Interval;
            }
            set {
                fScrollInfo.scrollTimer.Interval = value;
            }
        }

        public void ScrollIfNeeded() {
            Point pt = fGrid.PointToClient(Control.MousePosition);
            Rectangle rect = fView.ViewRect;
            fScrollInfo.GoLeft = (pt.X > rect.Left - ThresholdOutter) && (pt.X < rect.Left + ThresholdInner);
            fScrollInfo.GoRight = (pt.X > rect.Right - ThresholdInner) && (pt.X < rect.Right + ThresholdOutter);
            fScrollInfo.GoUp = (pt.Y < rect.Top + ThresholdInner) && (pt.Y > rect.Top - ThresholdOutter);
            fScrollInfo.GoDown = (pt.Y > rect.Bottom - ThresholdInner) && (pt.Y < rect.Bottom + ThresholdOutter);
            Console.WriteLine("{0} {1} {2} {3} {4}", pt, fScrollInfo.GoLeft, fScrollInfo.GoRight, fScrollInfo.GoUp, fScrollInfo.GoDown);
        }

        internal class ScrollInfo {
            internal Timer scrollTimer;
            GridView view = null;
            bool left, right, up, down;

            AutoScrollHelper owner;
            public ScrollInfo(AutoScrollHelper owner, GridView view) {
                this.owner = owner;
                this.view = view;
                this.scrollTimer = new Timer();
                this.scrollTimer.Tick += new EventHandler(scrollTimer_Tick);
            }
            public bool GoLeft {
                get { return left; }
                set {
                    if(left != value) {
                        left = value;
                        CalcInfo();
                    }
                }
            }
            public bool GoRight {
                get { return right; }
                set {
                    if(right != value) {
                        right = value;
                        CalcInfo();
                    }
                }
            }
            public bool GoUp {
                get { return up; }
                set {
                    if(up != value) {
                        up = value;
                        CalcInfo();
                    }
                }
            }
            public bool GoDown {
                get { return down; }
                set {
                    if(down != value) {
                        down = value;
                        CalcInfo();
                    }
                }
            }
            private void scrollTimer_Tick(object sender, System.EventArgs e) {
                owner.ScrollIfNeeded();

                if(GoDown) 
                    view.TopRowIndex++;
                if(GoUp) 
                    view.TopRowIndex--;
                if(GoLeft) 
                    view.LeftCoord -= owner.HorizontalScrollStep;
                if(GoRight) 
                    view.LeftCoord += owner.HorizontalScrollStep;

                if((Control.MouseButtons & MouseButtons.Left) == MouseButtons.None)
                    scrollTimer.Stop();
            }
            void CalcInfo() {
                if(!(GoDown && GoLeft && GoRight && GoUp)) 
                    scrollTimer.Stop();

                if(GoDown || GoLeft || GoRight || GoUp) 
                    scrollTimer.Start();
            }
        }
    }
}

Visual Basic
Imports System
Imports System.Windows.Forms
Imports DevExpress.XtraGrid
Imports DevExpress.XtraGrid.Views.Grid
Imports System.Drawing

Namespace AutoScrollTimer

    Public Class AutoScrollHelper

        Public Sub New(ByVal view As GridView)
            fGrid = view.GridControl
            fView = view
            fScrollInfo = New ScrollInfo(Me, view)
        End Sub

        Private fGrid As GridControl

        Private fView As GridView

        Private fScrollInfo As ScrollInfo

        Public ThresholdInner As Integer = 20

        Public ThresholdOutter As Integer = 100

        Public HorizontalScrollStep As Integer = 10

        Public Property ScrollTimerInterval As Integer
            Get
                Return fScrollInfo.scrollTimer.Interval
            End Get

            Set(ByVal value As Integer)
                fScrollInfo.scrollTimer.Interval = value
            End Set
        End Property

        Public Sub ScrollIfNeeded()
            Dim pt As Point = fGrid.PointToClient(Control.MousePosition)
            Dim rect As Rectangle = fView.ViewRect
            fScrollInfo.GoLeft = pt.X > rect.Left - ThresholdOutter AndAlso pt.X < rect.Left + ThresholdInner
            fScrollInfo.GoRight = pt.X > rect.Right - ThresholdInner AndAlso pt.X < rect.Right + ThresholdOutter
            fScrollInfo.GoUp = pt.Y < rect.Top + ThresholdInner AndAlso pt.Y > rect.Top - ThresholdOutter
            fScrollInfo.GoDown = pt.Y > rect.Bottom - ThresholdInner AndAlso pt.Y < rect.Bottom + ThresholdOutter
            Console.WriteLine("{0} {1} {2} {3} {4}", pt, fScrollInfo.GoLeft, fScrollInfo.GoRight, fScrollInfo.GoUp, fScrollInfo.GoDown)
        End Sub

        Friend Class ScrollInfo

            Friend scrollTimer As Timer

            Private view As GridView = Nothing

            Private left, right, up, down As Boolean

            Private owner As AutoScrollHelper

            Public Sub New(ByVal owner As AutoScrollHelper, ByVal view As GridView)
                Me.owner = owner
                Me.view = view
                scrollTimer = New Timer()
                AddHandler scrollTimer.Tick, New EventHandler(AddressOf scrollTimer_Tick)
            End Sub

            Public Property GoLeft As Boolean
                Get
                    Return left
                End Get

                Set(ByVal value As Boolean)
                    If left <> value Then
                        left = value
                        CalcInfo()
                    End If
                End Set
            End Property

            Public Property GoRight As Boolean
                Get
                    Return right
                End Get

                Set(ByVal value As Boolean)
                    If right <> value Then
                        right = value
                        CalcInfo()
                    End If
                End Set
            End Property

            Public Property GoUp As Boolean
                Get
                    Return up
                End Get

                Set(ByVal value As Boolean)
                    If up <> value Then
                        up = value
                        CalcInfo()
                    End If
                End Set
            End Property

            Public Property GoDown As Boolean
                Get
                    Return down
                End Get

                Set(ByVal value As Boolean)
                    If down <> value Then
                        down = value
                        CalcInfo()
                    End If
                End Set
            End Property

            Private Sub scrollTimer_Tick(ByVal sender As Object, ByVal e As EventArgs)
                owner.ScrollIfNeeded()
                If GoDown Then view.TopRowIndex += 1
                If GoUp Then view.TopRowIndex -= 1
                If GoLeft Then view.LeftCoord -= owner.HorizontalScrollStep
                If GoRight Then view.LeftCoord += owner.HorizontalScrollStep
                If(Control.MouseButtons And MouseButtons.Left) = MouseButtons.None Then scrollTimer.Stop()
            End Sub

            Private Sub CalcInfo()
                If Not(GoDown AndAlso GoLeft AndAlso GoRight AndAlso GoUp) Then scrollTimer.Stop()
                If GoDown OrElse GoLeft OrElse GoRight OrElse GoUp Then scrollTimer.Start()
            End Sub
        End Class
    End Class
End Namespace

C#
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using DevExpress.XtraGrid.Views.Grid.ViewInfo;

namespace AutoScrollTimer {
    public partial class Form1 : Form {
        public Form1() {
            InitializeComponent();
        }

        AutoScrollHelper autoScrollHelper;
        private void Form1_Load(object sender, EventArgs e) {
            gridControl1.DataSource = GetDataTable();
            autoScrollHelper = new AutoScrollHelper(gridView1);
        }

        private DataTable GetDataTable() {
            const int ColCount = 40;
            const int RowCount = 100;
            DataTable table = new DataTable();
            for(int i = 0; i < ColCount; i++)
                table.Columns.Add();
            for(int j = 0; j < RowCount; j++) {
                DataRow row = table.NewRow();
                for(int i = 0; i < ColCount; i++)
                    row[i] = string.Format("row {0} / col {1}", j, i);
                table.Rows.Add(row);
            }
            table.AcceptChanges();
            return table;
        }

        private void simpleButton1_MouseMove(object sender, MouseEventArgs e) {
            simpleButton1.DoDragDrop("test", DragDropEffects.Move);
        }

        private void gridControl1_DragOver(object sender, DragEventArgs e) {
            e.Effect = DragDropEffects.Move;
            autoScrollHelper.ScrollIfNeeded();
        }

        private void gridControl1_DragLeave(object sender, EventArgs e) {
            
        }
    }
}

Visual Basic
Imports System
Imports System.ComponentModel
Imports System.Data
Imports System.Drawing
Imports System.Windows.Forms

Namespace AutoScrollTimer

    Public Partial Class Form1
        Inherits Form

        Public Sub New()
            InitializeComponent()
        End Sub

        Private autoScrollHelper As AutoScrollHelper

        Private Sub Form1_Load(ByVal sender As Object, ByVal e As EventArgs)
            gridControl1.DataSource = GetDataTable()
            autoScrollHelper = New AutoScrollHelper(gridView1)
        End Sub

        Private Function GetDataTable() As DataTable
            Const ColCount As Integer = 40
            Const RowCount As Integer = 100
            Dim table As DataTable = New DataTable()
            For i As Integer = 0 To ColCount - 1
                table.Columns.Add()
            Next

            For j As Integer = 0 To RowCount - 1
                Dim row As DataRow = table.NewRow()
                For i As Integer = 0 To ColCount - 1
                    row(i) = String.Format("row {0} / col {1}", j, i)
                Next

                table.Rows.Add(row)
            Next

            table.AcceptChanges()
            Return table
        End Function

        Private Sub simpleButton1_MouseMove(ByVal sender As Object, ByVal e As MouseEventArgs)
            simpleButton1.DoDragDrop("test", DragDropEffects.Move)
        End Sub

        Private Sub gridControl1_DragOver(ByVal sender As Object, ByVal e As DragEventArgs)
            e.Effect = DragDropEffects.Move
            autoScrollHelper.ScrollIfNeeded()
        End Sub

        Private Sub gridControl1_DragLeave(ByVal sender As Object, ByVal e As EventArgs)
        End Sub
    End Class
End Namespace