Dll e bin

using System;
using System.Collections;
using System.Web.UI.WebControls;
using System.Web.UI;
using System.Data;
using System.Diagnostics;

namespace ASPItalia.com
{

  public class MathColumn:System.Web.UI.WebControls.DataGridColumn
  {
    public MathColumn():base()
    {
    }

    private int columnIndex=0;
    private MathOperation operation=MathOperation.Sum;
    private string dataFields="";
    private string dataFormatString="{0}";
    private string[] fields=new string[0];

    public override void InitializeCell(TableCell cell,int columnIndex,ListItemType itemType)
    {
      //chiama il metodo base
      base.InitializeCell(cell,columnIndex,itemType);
      this.columnIndex=columnIndex;
    }

    private void onDataBound(object s, DataGridItemEventArgs e)
    {
      if (e.Item.DataItem!=null)
      {
        //riferimento al valore
        DataRowView r=e.Item.DataItem as DataRowView;
        if (r==null) return;
        //risultato
        float math=(operation==MathOperation.Min)?float.MaxValue:0f;
        foreach (string field in fields)
        {
          float v=Convert.ToSingle(r[field]);
          if ((operation==MathOperation.Min && v<math) ||
            (operation==MathOperation.Max && v>math))
            math=v;
          else if (operation==MathOperation.Sum || operation==MathOperation.Avg)
            math+=v;
        }
        if (operation==MathOperation.Avg)
          math/=fields.Length;
        e.Item.Cells[columnIndex].Text=string.Format(DataFormatString,math);
      }
    }

    public override void Initialize()
    {
      base.Initialize();
      Owner.ItemDataBound+=new DataGridItemEventHandler(onDataBound);
    }

    public MathOperation Operation
    {
      get
      {
        return operation;
      }
      set
      {
        operation=value;
      }
    }

    public string DataFormatString
    {
      get
      {
        return dataFormatString;
      }
      set
      {
        dataFormatString=value;
      }
    }

    public string DataFields
    {
      get
      {
        return dataFields;
      }
      set
      {
        dataFields=value;
        //preleva la lista dei campi
        fields=dataFields.Split(new Char[]{Convert.ToChar(",")});
      }
    }

  }

  public enum MathOperation
  {
    Sum,
    Avg,
    Min,
    Max
  }
}

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