Example E2732
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WinForms Data Grid - Draw a thick border under a data cell (PaintEx event)

This example shows how to draw a thick border around a grid cell under the mouse pointer:

The example handles the grid's PaintEx event to draw a border. The PaintEx event allows you to use DirectX-compatible APIs (e.Cache):

C#
private void GridControl_PaintEx(object sender, DevExpress.XtraGrid.PaintExEventArgs e) { DrawHotTrackedCell(e.Cache); } private void DrawHotTrackedCell(GraphicsCache cache) { Rectangle bounds = GetCellBounds(HotTrackedCell); cache.DrawRectangle(new Pen(Brushes.Black, _BorderWidth), bounds); }

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Example Code

Form1.cs(vb)
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; using DevExpress.XtraGrid.Views.Base; using DevExpress.XtraGrid.Views.Grid.ViewInfo; using DevExpress.Utils.Drawing; namespace WindowsApplication1 { public partial class Form1 : Form { private DataTable CreateTable(int RowCount) { DataTable tbl = new DataTable(); tbl.Columns.Add("Name", typeof(string)); tbl.Columns.Add("ID", typeof(int)); tbl.Columns.Add("Number", typeof(int)); tbl.Columns.Add("Date", typeof(DateTime)); for (int i = 0; i < RowCount; i++) tbl.Rows.Add(new object[] { String.Format("Name{0}", i), i, 3 - i, DateTime.Now.AddDays(i) }); return tbl; } public Form1() { InitializeComponent(); gridControl1.DataSource = CreateTable(20); new HotTrackCellHelper(gridView1); } } public class HotTrackCellHelper { public HotTrackCellHelper(GridView view) { _View = view; view.GridControl.PaintEx += GridControl_PaintEx; view.MouseMove += new MouseEventHandler(view_MouseMove); } private void GridControl_PaintEx(object sender, DevExpress.XtraGrid.PaintExEventArgs e) { DrawHotTrackedCell(e.Cache); } private int _BorderWidth = 4; private GridCell _HotTrackedCell; private readonly GridView _View; public GridCell HotTrackedCell { get { return _HotTrackedCell; } set { RefreshCell(_HotTrackedCell); _HotTrackedCell = value; } } public Rectangle GetCellBounds(GridCell cell) { if (cell == null) return Rectangle.Empty; GridViewInfo info = _View.GetViewInfo() as GridViewInfo; GridCellInfo cellInfo = info.GetGridCellInfo(cell.RowHandle, cell.Column); return cellInfo.Bounds; } private void UpdateHotTrackedCell(Point location) { GridHitInfo hi = _View.CalcHitInfo(location); if (hi.HitTest == GridHitTest.Row || hi.HitTest == GridHitTest.RowEdge) return; if (hi.InRowCell) { if (_View.IsRowVisible(hi.RowHandle) == RowVisibleState.Visible) { HotTrackedCell = new GridCell(hi.RowHandle, hi.Column); return; } } HotTrackedCell = null; } void view_MouseMove(object sender, MouseEventArgs e) { UpdateHotTrackedCell(e.Location); } private void RefreshCell(GridCell cell) { if (cell == null) return; Rectangle rect = GetCellBounds(cell); rect.Inflate(_BorderWidth, _BorderWidth); _View.InvalidateRect(rect); } private void DrawHotTrackedCell(GraphicsCache cache) { Rectangle bounds = GetCellBounds(HotTrackedCell); cache.DrawRectangle(new Pen(Brushes.Black, _BorderWidth), bounds); } } }
Program.cs(vb)
C#
using DevExpress.XtraEditors; using System; using System.Collections.Generic; using System.Windows.Forms; namespace WindowsApplication1 { static class Program { /// <summary> /// The main entry point for the application. /// </summary> [STAThread] static void Main() { Application.EnableVisualStyles(); Application.SetCompatibleTextRenderingDefault(false); Application.Run(new Form1()); } } }

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