Custom Control Property Collections

Question

Hey All

I am trying to write a custom control that has one of its properties as a collection of panel controls. These panel controls are to go inside a main panel inside the custom control. How can I get the designer to add the collection of panel controls to the main panel control?

Thanks in advance.

Answer 1

Add a variable in the Custom Control as
public IList<Panel> Items = new List<Panel>();

Render those using the virtual method as
protected override void Render(HtmlTextWriter writer)

In the designer use it as
MyControl.Items.Add(new Panel(){ID="Panel1".....});

Thanks

---

Anirban Bhattacharya (Lead Consultant - ESSPL)

Answer 2

Thanks for your reply

I'm not quite sure what you mean by " Render those using the virtual method as" and "In the designer use it as"...

Basically I want to get the added panels to show up at design time....

Could you elaborate further? Thanks!

(This is a C# WinForms application, FYI)

Answer 3

Hi,

If you are creating a Custom Control inheriting WebControl there is always a virtual method available to make sure that it's Childs are rendered properly.

Here is a simplete custom control. Where you can set the main Panel and add child panels as TestControl1.Items.Add(new Panel(){ID="this..."});

Hope this explains.

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Collections.Generic;

namespace MiscControls
{
  [ToolboxData(@"<{0}:TestControl runat=""server"" \>")]
  public class TestControl : WebControl
  {
    public IList<Panel> Items = new List<Panel>();

    //Main Panel
    Panel MainPanel{get; set;}
    //Auto PostBack
    public bool AutoPostBack { get; set; }

    //Child Controls
    protected override void CreateChildControls()
    {
      base.CreateChildControls();
      if (MainPanel != null)
      {
        foreach(Panel pnl in Items)
          MainPanel.Controls.Add(pnl);
      }
    }

    //Render
    protected override void Render(HtmlTextWriter writer)
    {
      base.Render(writer);
      //You can write your own render process here.
    }
  }

}

 

 

---

Anirban Bhattacharya (Lead Consultant - ESSPL)

Answer 4

Anirban,

This is a WinForms C# application. Is there an equivalent for the code you posted?

 

Thanks so far :)

Answer 5

Hey, it's much easier in WinForm Controls. Hope this detailed explanation will make it clear. Simple difference is instead of "Render" you need to use "OnPaint"

The Control Class

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;

namespace TestWinFormApp
{
  public class TestControl : Control
  {
    public IList<Panel> Items = new List<Panel>();
        

    //Component
    private System.ComponentModel.Container com = null;
    
    //Constructor
    public TestControl()
    {
      
    }

    //This is instead of Render method
    protected override void OnPaint(PaintEventArgs e)
    {
      base.OnPaint(e);
      //Add your custom rendering or painting here
      //Ex:
      foreach (Panel pnl in this.Items)
      {
        this.Controls.Add(pnl);
      }
    }

    //Dispose
    protected override void Dispose(bool disposing)
    {
      if (disposing)
      {
        if (com != null)
          com.Dispose();
      }
      base.Dispose(disposing);
    }


  }
}

The Initializer where you are using...

//Test Control
    private TestControl tc;


private void InitializeComponent()
    {
      
      this.SuspendLayout();
      tc = new TestControl();
      
      // 
      // Form1
      // 
      this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);
      this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
      this.ClientSize = new System.Drawing.Size(428, 262);
      this.Name = "Form1";
      this.Text = "Form1";
      this.Load += new System.EventHandler(this.Form1_Load);
      this.ResumeLayout(false);

      //Server Control. Here I have added the style of the control
      this.tc.BackColor = System.Drawing.Color.Brown;
      tc.Width = 300;
      tc.Height = 200;
      this.Controls.Add(tc);
    }

 

Adding childing controls to it...

public Form1()
    {
      InitializeComponent();
      tc.Items.Add(new Panel() { BackColor = Color.Black, Width = 100, Height = 100 });
    }

 

 

 

 

---

Anirban Bhattacharya (Lead Consultant - ESSPL)

Answer 6

Perfect. Bit more tinkering from myself and that'll do it.

Thanks a bunch!