Creating a Custom Web Server Control

In this article we will focus on:
1. How to Create Custom Web Server Control.
2. Adding the Custom Web Server Control to the Toolbox and using this newly created Custom Web Server Control from the Toolbox.
3. Consuming Custom Web Server Controls in a Website.

Why Custom Web Server Controls:
Easier to use than User Controls.
We can define a complete design time experience for the consumers of our Custom Web Server Control such as ToolBox support and designer functionality.
Only drawback is we will end up writing more code than the User Control code.
When to use Custom Web Server Control :
If you want to reuse a control across websites then go for Custom Web Server Control.

Creating a Custom Web Server Control:
1.A Custom Web Server Control is a control that inherits from either an existing Web Server control or from the WebControl class.
2.We can compile the control into a separate dll file that can be either be shared among applications or we can also deploy it into GAC.
3.There are two ways of creating a Create Custom Web Server Control :
a.Create a web server control that inherits from the WebControl class that provides a basic functionality. This way needs lot of work to develop this control.
b.Inherit from an existing Web Server control that provides the core features required for the control. Here we can focus on additional functionality required for the control.

In this article we will see both the approaches of creating a Web Server Control.
First Approach: Inheriting the Custom Web Server Control from an Existing ASP.NET Web Server Control.
Let us create a control that includes a Label and a TextBox. We will name this control as "UserCustomWebControl". User can set the Text of the Label which would label the TextBox(UserName and Password). We will allow the developer to set the text of the control(Label).

Step 1:
Open Microsoft Visual Studio -> Create a New Website ->Select Visual C# under Templates on the Left pane -> Select ASP.NET Web Forms Site -> name it "MyCustomControlDemo".


Step 2:Create Custom Web Server Control as a dll
Right Click the solution -> Add New Project -> Select "ClassLibrary" name it as: "MyCustomInputControl". Then Create a class "UserCustomWebControl" and add reference to System.Web assembly. ->Right click the "MyCustomInputControl" project and click on Add Reference-> Select System.Web and click on Ok. This adds reference to System.Web. Now add below namespace in the class
using System.Web.UI;
using System.Web.UI.WebControls;




Step 3:Inherit the class from the TextBox class.

 public class UserCustomWebControl : TextBox

 public string LabelText { get; set; }
 public int LabelWidth { get; set; }

 protected override void Render(HtmlTextWriter writer)
        {
            writer.Write(@"{1} ", LabelWidth, LabelText);
            base.Render(writer);
        }

 protected void Page_Init(object sender, EventArgs e)
    {
        ContentPlaceHolder content = (ContentPlaceHolder)this.Master.FindControl("MainContent");

        UserCustomWebControl cWebControl = new UserCustomWebControl();
        cWebControl.LabelText = "User Name";
        cWebControl.LabelWidth = 100;
        cWebControl.Width = 150;
         content.Controls.Add(cWebControl);
        LiteralControl br = new LiteralControl("
");
        content.Controls.Add(br);

        UserCustomWebControl cWebControl1 = new UserCustomWebControl();
       
        cWebControl1.LabelText = "Password";
        cWebControl1.LabelWidth = 100;
        cWebControl1.TextMode = TextBoxMode.Password;
        cWebControl1.Width = 150;

        content.Controls.Add(cWebControl1);
    }

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Web.UI.WebControls;

namespace MyWebsiteLogoControl
{
    public class SiteLogoControl : WebControl
    {
        public string SiteLogoPath { get; set; }
        public string SiteName { get; set; }

        public override void RenderBeginTag(System.Web.UI.HtmlTextWriter writer)
        {
            writer.RenderBeginTag("div");
        }

        protected override void RenderContents(System.Web.UI.HtmlTextWriter writer)
        {
            writer.Write(@"<img src=""{0}"" alt=""Website Logo"" /><br>>", SiteLogoPath);
            writer.Write(SiteName + "<br/>");
        }
    }
}

<%@ Register Assembly="MyWebsiteLogoControl" Namespace="MyWebsiteLogoControl"  TagPrefix="muc" %>

        <muc:SiteLogoControl runat="server" SiteLogoPath="Images/logo.png"  SiteName="DOT NET SPIDER" />