Add a reference to the System.Design.dll assembly to your application. using System; using System.Web.UI; using System.Web.UI.WebControls; using System.Web.UI.Design; using System.ComponentModel; using System.Drawing; namespace myControls { [Designer(typeof(GradientPanelDesigner))] [ParseChildren(false)] public class GradientPanel : WebControl { private GradientDirection _direction = GradientDirection.Horizontal; private Color _startColor = Color.DarkBlue; private Color _endColor = Color.White; public GradientDirection Direction { get { return _direction; } set { _direction = value; } } public Color StartColor { get { return _startColor; } set { _startColor = value; } } public Color EndColor { get { return _endColor; } set { _endColor = value; } } protected override void AddAttributesToRender(HtmlTextWriter writer) { writer.AddStyleAttribute(HtmlTextWriterStyle.Filter, this. GetFilterString()); base.AddAttributesToRender(writer); } public string GetFilterString() { return String.Format("progid:DXImageTransform.Microsoft.Gradient (gradientType={0},startColorStr={1},endColorStr={2})", _direction.ToString("d"), ColorTranslator.ToHtml(_startColor), ColorTranslator.ToHtml(_endColor)); } public GradientPanel() { this.Width = Unit.Parse("500px"); } protected override HtmlTextWriterTag TagKey { get { return HtmlTextWriterTag.Div; } } } public enum GradientDirection { Vertical = 0, Horizontal = 1 } public class GradientPanelDesigner : ContainerControlDesigner { protected override void AddDesignTimeCssAttributes(System.Collections. IDictionary styleAttributes) { GradientPanel gPanel = (GradientPanel)this.Component; styleAttributes.Add("filter", gPanel.GetFilterString()); base.AddDesignTimeCssAttributes(styleAttributes); } } }
Open the page in Design view in either Visual Web Developer or Visual Studio .NET. File: ShowGradientPanel.aspx <%@ Page Language="C#" %> <%@ Register TagPrefix="custom" Namespace="myControls" %> "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> Show GradientPanel