mandi224
asked on
Displaying Base64 image in a user control
I have a Base64 encoded image stored in a session variable "EmrLabel" and I am trying to display the label-image in an .ascx control on an .aspx page.
The code below is bombing out on the line "Response.BinaryWrite(jpgS tream.ToAr ray());" with the error: OutputStream is not available when a custom TextWriter is used.
How do I correct this?
The code below is bombing out on the line "Response.BinaryWrite(jpgS
How do I correct this?
using System;
using System.Net;
using System.Web;
using System.Xml;
using System.Data;
using System.IO;
using System.Drawing;
using System.Drawing.Drawing2D;
namespace MB.UserControl
{
public partial class EmrLabel : System.Web.UI.UserControl
{
protected void Page_Load(object sender, EventArgs e)
{
string merchandiseReturnLabel = Session["EmrLabel"].ToString();
byte[] label = Convert.FromBase64String(merchandiseReturnLabel);
System.Drawing.Image imgTiff = default(System.Drawing.Image);
MemoryStream tiffStream = new MemoryStream();
MemoryStream jpgStream = new MemoryStream();
tiffStream.Write(label, 0, label.Length);
imgTiff = System.Drawing.Image.FromStream(tiffStream);
// Crop out crap.
imgTiff = CropAndResizeImage(imgTiff);
imgTiff.Save(jpgStream, System.Drawing.Imaging.ImageFormat.Jpeg);
Response.Clear();
Response.ContentType = "image/jpeg";
Response.BinaryWrite(jpgStream.ToArray());
Response.End();
}
private Image CropAndResizeImage(Image imgTiff)
{
// Crop image
Rectangle cropArea = new Rectangle();
cropArea.Width = 1520;
cropArea.Height = 1030;
cropArea.X = 50;
cropArea.Y = 50;
Bitmap bmpImage = new Bitmap(imgTiff);
Bitmap bmpCrop = bmpImage.Clone(cropArea, bmpImage.PixelFormat);
return (Image)bmpCrop;
}
}
}
ASKER
jensfiederer - thanks for your help. I hope I'm understanding correctly.
The way I had originally designed this, I had a page "ShippingPackingSlip.aspx" and on that page, I had
Where the EmrLabel.aspx page had the code above that I was attempting to put into a user control.
Problem was, when I open EmrLabel.aspx that way, Session["EmrLabel"] is null. (Even though it's NOT null in the codebehind on ShippingPackingSlip.aspx.
I also tried passing it as a querystring -- like EmrLabel.aspx?label=[Base6 4 Value] (which I didn't want to do) but it's too long (apparently?) and doesn't work either.
The way I had originally designed this, I had a page "ShippingPackingSlip.aspx"
Where the EmrLabel.aspx page had the code above that I was attempting to put into a user control.
Problem was, when I open EmrLabel.aspx that way, Session["EmrLabel"] is null. (Even though it's NOT null in the codebehind on ShippingPackingSlip.aspx.
I also tried passing it as a querystring -- like EmrLabel.aspx?label=[Base6
The original design sounds like the right way.
You are right, passing a query string with the Base64 value is much too long....a string with just enough info to retrieve (or generate) the value would be better....
But I gather that is what you wanted to do with Session["EmrLabel"] (presumably the contents are the Base64 string as in your current code).....I really don't see why Session["EmrLabel"] should be null. Where and how is Session["EmrLabel"] set to a value?
You are right, passing a query string with the Base64 value is much too long....a string with just enough info to retrieve (or generate) the value would be better....
But I gather that is what you wanted to do with Session["EmrLabel"] (presumably the contents are the Base64 string as in your current code).....I really don't see why Session["EmrLabel"] should be null. Where and how is Session["EmrLabel"] set to a value?
ASKER
Session["EmrLabel"] is the Base64 string, yes.
The user goes to ShippingMaterials.aspx -- clicks the order for the page they want to generate labels for.
It is on THIS page that I'm generating the label (so I can easily catch errors before actually printing the label) So I generate the label and add it to the session ... Session.Add("EmrLabel", merchandiseReturnLabel);
On that page, I check
If (Session["EmrLabel"] != null)
Then I go ahead and display ShippingPackingSlip.aspx which includes the
When I debug, Session["EmrLabel"] is not null on ShippingMaterials.aspx, it is not null on ShippingPackingSlip.aspx, but it is null on EmrLabel.aspx
The user goes to ShippingMaterials.aspx -- clicks the order for the page they want to generate labels for.
It is on THIS page that I'm generating the label (so I can easily catch errors before actually printing the label) So I generate the label and add it to the session ... Session.Add("EmrLabel", merchandiseReturnLabel);
On that page, I check
If (Session["EmrLabel"] != null)
Then I go ahead and display ShippingPackingSlip.aspx which includes the
When I debug, Session["EmrLabel"] is not null on ShippingMaterials.aspx, it is not null on ShippingPackingSlip.aspx, but it is null on EmrLabel.aspx
ASKER CERTIFIED SOLUTION
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When you program at the level of an individual CONTROL, you shouldn't be clearing the whole page. Just create an image with a specific URL, and then the Page_Load event for that entire page (URL) can do the same thing that you are currently trying to do for the Page_Load of a single control.