How to select multiple controls by mouse-dragging over them

C#

namespace WindowsFormsApplication5 { using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using System.Text; using System.Windows.Forms; using System.Drawing.Drawing2D; /// <summary> /// Main application form /// </summary> public partial class Form1 : Form { /// <summary> /// Initializes a new instance of the WindowsFormsApplication5.Form1 class /// </summary> public Form1() { InitializeComponent(); DoubleBuffered = true; } private Point selectionStart; private Point selectionEnd; private Rectangle selection; private bool mouseDown; private void GetSelectedTextBoxes() { List<TextBox> selected = new List<TextBox>(); foreach (Control c in Controls) { if (c is TextBox) { if (selection.IntersectsWith(c.Bounds)) { selected.Add((TextBox)c); } } } // Replace with your input box MessageBox.Show("You selected " + selected.Count + " textbox controls."); } protected override void OnMouseDown(MouseEventArgs e) { selectionStart = PointToClient(MousePosition); mouseDown = true; } protected override void OnMouseUp(MouseEventArgs e) { mouseDown = false; SetSelectionRect(); Invalidate(); GetSelectedTextBoxes(); } protected override void OnMouseMove(MouseEventArgs e) { if (!mouseDown) { return; } selectionEnd = PointToClient(MousePosition); SetSelectionRect(); Invalidate(); } protected override void OnPaint(PaintEventArgs e) { base.OnPaint(e); if (mouseDown) { using (Pen pen = new Pen(Color.Black, 1F)) { pen.DashStyle = DashStyle.Dash; e.Graphics.DrawRectangle(pen, selection); } } } private void SetSelectionRect() { int x, y; int width, height; x = selectionStart.X > selectionEnd.X ? selectionEnd.X : selectionStart.X; y = selectionStart.Y > selectionEnd.Y ? selectionEnd.Y : selectionStart.Y; width = selectionStart.X > selectionEnd.X ? selectionStart.X - selectionEnd.X : selectionEnd.X - selectionStart.X; height = selectionStart.Y > selectionEnd.Y ? selectionStart.Y - selectionEnd.Y : selectionEnd.Y - selectionStart.Y; selection = new Rectangle(x, y, width, height); } } } <textarea> 

vb.net

''' <summary> ''' ''''''''''''''''''''''''''''''''''''''''''''''''''''''''FP MouseDragging Select ''' </summary> Private selectionStart As Point Private selectionEnd As Point Private selection As Rectangle Private mouseDown As Boolean Public Sub DesignF() Mycontrols.ozSC_M.SplitterDistance = 84 Mycontrols.ozSC.SplitterDistance = 200 Mycontrols.ozSC_Seg.SplitterDistance = 120 End Sub Private Sub FPMouseDown(sender As FlowLayoutPanel, e As MouseEventArgs) selectionStart = sender.PointToClient(System.Windows.Forms.Control.MousePosition) mouseDown = True End Sub Private Sub FPMouseUP(sender As FlowLayoutPanel, e As MouseEventArgs) mouseDown = False SetSelectionRect() GetSelectedItems(sender) Mycontrols.ozTLP1.Invalidate() End Sub Private Sub FPPaint(sender As Object, e As PaintEventArgs) If (mouseDown) Then Using p As Pen = New Pen(Color.Black, 1F) p.DashStyle = System.Drawing.Drawing2D.DashStyle.Dash e.Graphics.DrawRectangle(p, selection) End Using End If End Sub Private Sub GetSelectedItems(sender As FlowLayoutPanel) For Each c As RItem In sender.Controls If selection.IntersectsWith(c.Bounds) Then msgbox(c.NM) End If Next End Sub Private Sub FPMouseMove(sender As FlowLayoutPanel, e As MouseEventArgs) If Not mouseDown Then Return End If selectionEnd = sender.PointToClient(System.Windows.Forms.Control.MousePosition) SetSelectionRect() Mycontrols.ozTLP1.Invalidate() End Sub Private Sub SetSelectionRect() Dim x As Integer, y As Integer Dim width As Integer, height As Integer If selectionStart.X > selectionEnd.X Then x = selectionEnd.X width = selectionStart.X - selectionEnd.X Else x = selectionStart.X width = selectionEnd.X - selectionStart.X End If If selectionStart.Y > selectionEnd.Y Then y = selectionEnd.y height = selectionStart.Y - selectionEnd.Y Else y = selectionStart.y height = selectionEnd.Y - selectionStart.Y End If selection = New Rectangle(x, y, width, height) End Sub