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The ShowImage.ashx handler contains only one method called ProcessRequest. This method
performs a data retrieval process and returns only the Image Content field as bytes of
array. The Image Content field is automatically pulled by the header to display in every
page.
The code sample that follows retrieves the banner from the database to display in the header.
C#: ShowImage.ashx
<%@ WebHandler Language="C#" Class="ShowImage" %>
using System;
using System.Configuration;
using System.Web;
using System.IO;
using System.Data;
using System.Data.SqlClient;
public class ShowImage : IHttpHandler
{
public void ProcessRequest(HttpContext context)
{
try
{
int compno;
if (!(context.Request.QueryString["cid"] == null))
{
compno = Convert.ToInt32(context.Request.QueryString["cid"]);
}
else
{
throw new ArgumentException("No parameter specified");
}
context.Response.ContentType = "image/jpeg"; // also works with gif
Stream strm = ShowEmpImage(compno);
byte[] buffer = new byte[4096];
int byteSeq = strm.Read(buffer, 0, 4096);
while ((byteSeq > 0))
{
context.Response.OutputStream.Write(buffer, 0, byteSeq);
byteSeq = strm.Read(buffer, 0, 4096);
}
}
catch
{
// Do Nothing
}
}
public Stream ShowEmpImage(int compno)
{
string conn = ConfigurationManager.AppSettings["DatabaseBanner1"];
SqlConnection connection = new SqlConnection(conn);
string sql = "SELECT HdrBanner FROM tblCompany WHERE CompanyID = @CID";
SqlCommand cmd = new SqlCommand(sql, connection);
cmd.CommandType = CommandType.Text;
cmd.Parameters.AddWithValue("@CID", compno);
connection.Open();
object img = cmd.ExecuteScalar();
try
{
return new MemoryStream((byte[])img);
}
catch
{
return null;
}
finally
{
connection.Close();
}
}
public bool IsReusable
{
get
{
return false;
}
}
}
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Visual Basic .NET: ShowImage.ashx
<%@ WebHandler Language="vb" Class="ShowImage" %>
Imports System
Imports System.Configuration
Imports System.Web
Imports System.IO
Imports System.Data
Imports System.Data.SqlClient
Public Class ShowImage
Implements IHttpHandler
Public Sub ProcessRequest(ByVal context As HttpContext) Implements IHttpHandler.ProcessRequest
Try
Dim compno As Integer
If Not context.Request.QueryString("cid") Is Nothing Then
compno = Convert.ToInt32(context.Request.QueryString("cid"))
Else
Throw New ArgumentException("No parameter specified")
End If
context.Response.ContentType = "image/jpeg" // also works with gif
Dim strm As Stream = ShowEmpImage(compno)
Dim buffer As Byte() = New Byte(4095) {}
Dim byteSeq As Integer = strm.Read(buffer, 0, 4096)
Do While byteSeq > 0
context.Response.OutputStream.Write(buffer, 0, byteSeq)
byteSeq = strm.Read(buffer, 0, 4096)
Loop
Catch
'Do Nothing
End Try
End Sub
Public Function ShowEmpImage(ByVal compno As Integer) As Stream
Dim conn As String = ConfigurationManager.AppSettings("DatabaseBanner1")
Dim connection As SqlConnection = New SqlConnection(conn)
Dim sql As String = "SELECT HdrBanner FROM tblCompany WHERE CompanyID = @CID"
Dim cmd As SqlCommand = New SqlCommand(sql, connection)
cmd.CommandType = CommandType.Text
cmd.Parameters.AddWithValue("@CID", compno)
connection.Open()
Dim img As Object = cmd.ExecuteScalar()
Try
Return New MemoryStream(CType(img, Byte()))
Catch
Return Nothing
Finally
connection.Close()
End Try
End Function
Public ReadOnly Property IsReusable() As Boolean Implements IHttpHandler.IsReusable
Get
Return False
End Get
End Property
End Class
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The call is done at the header’s LoadData() to display the banner in a synchronized fashion.
C#: Header.ascx.cs
public void LoadData()
{
LoadData_Base();
try
{
string userId = ((BaseApplicationPage)this.Page).SystemUtils.GetUserID();
VCompanyBannerRecord uC = VCompanyBannerView.GetRecord("UserID = " + userId);
int compid = uC.CompanyID;
if (uC.HdrBanner == null)
{
// Display the default banner from Images folder
PageHeader__Logo.ImageUrl = "../Images/logo.gif";
}
else
{
// Display the HeaderBanner from the database
PageHeader__Logo.ImageUrl = ("../Shared/ShowImage.ashx?cid=" + compid);
}
}
catch
{
// Do Nothing
}
}
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Visual Basic .NET: Header.ascx.vb
Public Sub LoadData()
LoadData_Base()
Try
Dim userId As String = (CType(Me.Page, BaseApplicationPage)).SystemUtils.GetUserID()
Dim uC As VCompanyBannerRecord = VCompanyBannerView.GetRecord("UserID = "
+ userId)
Dim compid As Integer = uC.CompanyID
If uC.HdrBanner Is Nothing Then
' Display the default banner from Images folder
PageHeader__Logo.ImageUrl = "../Images/et_headerbanner.jpg"
Else
' Display the HeaderBanner from the database
PageHeader__Logo.ImageUrl = "../Shared/ShowImage.ashx?cid=" & compid
End If
Catch
'Do Nothing
End Try
End Sub
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