How to open a pdf Or image file in a new browser window

In the Default.aspx page, in a button click or any other events
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ScriptManager.RegisterStartupScript(this, this.GetType(), "s", "window.open('Default2.aspx?FileName=PO0005_R.pdf',null,'height=500, width=500,status= no,resizable= no, scrollbars=no,toolbar=no,menubar=no');", true);

In the Defult2.aspx page
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using System.Net;

protected void Page_Load(object sender, EventArgs e)
{
ReadPdfFile(Request.QueryString["FileName"].ToString());
}
private void ReadPdfFile(string FileName)
{
string path = Server.MapPath("PO0005_R.pdf");
WebClient client = new WebClient();
Byte[] buffer = client.DownloadData(path);

if (buffer != null)
{
Response.ContentType = "application/pdf";
Response.AddHeader("content-length", buffer.Length.ToString());
Response.BinaryWrite(buffer);
}

}

How to get datakeyNames ( Gridview )

GridViewRow row = ((GridViewRow)((Control)e.CommandSource).Parent.Parent);

lblPopGRNNo.Text = grvGRNList.DataKeys[row.RowIndex]["GrnNumber"].ToString();

lblGRNDate.Text = (Convert.ToDateTime(grvGRNList.DataKeys[row.RowIndex]["GrnDate"])).ToString("dd MMM yyyy");

lblSupplierName.Text = grvGRNList.DataKeys[row.RowIndex]["SupplierName"].ToString();

lblSuratJalanNumber.Text = grvGRNList.DataKeys[row.RowIndex]["SuratJalanNumber"].ToString();

System colors to dropdownlist

using System.Drawing;

string[] names = System.Enum.GetNames(typeof(System.Drawing.KnownColor));
Array values = System.Enum.GetValues(typeof(System.Drawing.KnownColor));
for (int i = 27; i <= names.Length - 8; i++)
{
ListItem item = new ListItem(names[i], values.GetValue(i).ToString());
ddlColorPicker.Items.Add(item);
ddlColorPicker.Items[i - 26].Attributes.Add("style", "background-color :" + values.GetValue(i).ToString() + "");
}

Filtering dataset

grvItem.DataSource = dataset1.Tables[0].DefaultView;
DataView myView = dataset1.Tables[0].DefaultView;
myView.RowFilter = "Name like '" + txtSearch.Text + "%'";
grvItem.DataSource = myView;
grvItem.DataBind();