Question

I have an ASP Image control that I want to save to a specific folder.

Image1.ImageUrl = "~/fa/barcode.aspx?d=" + Label1.Text.ToUpper();

This is basically what barcode.aspx does:

 Bitmap oBitmap = new Bitmap(w, 100);

        // then create a Graphic object for the bitmap we just created.
        Graphics oGraphics = Graphics.FromImage(oBitmap);

        oGraphics.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.None;
        oGraphics.TextRenderingHint = TextRenderingHint.SingleBitPerPixel;


        // Let's create the Point and Brushes for the barcode
        PointF oPoint = new PointF(2f, 2f);
        SolidBrush oBrushWrite = new SolidBrush(Color.Black);
        SolidBrush oBrush = new SolidBrush(Color.White);

        // Now lets create the actual barcode image
        // with a rectangle filled with white color
        oGraphics.FillRectangle(oBrush, 0, 0, w, 100);

        // We have to put prefix and sufix of an asterisk (*),
        // in order to be a valid barcode
        oGraphics.DrawString("*" + Code + "*", oFont, oBrushWrite, oPoint);
Response.ContentType = "image/jpeg";
oBitmap.Save(Response.OutputStream, ImageFormat.Jpeg);

How do I save it to a folder (~/fa/barcodeimages/)? So far here’s what I tried:

WebClient webClient = new WebClient();
                string remote = "http://" + Request.Url.Authority.ToString() + "/fa/barcode.aspx?d=" + Label1.Text.ToUpper();
                string local = Server.MapPath("barcodeimages/" + Label1.Text.ToUpper() + ".jpeg");
                webClient.DownloadFile(remote, local);

But it does not work, I always get a corrupted .jpeg file. And it seems inefficient.

Answer 1

It looks like the problem is that your business logic – the code required to generate a barcode image – is in the wrong place.

You should keep that business logic away from the presentation logic of your aspx page (which is about serving an image to respond to a URL), and move the Bitmap creation logic to somewhere that both the “serve a barcode” and “save a barcode to disk” code can get at it. That could be in a different business logic assembly, or it could simply be in a separate class within the same project. The main thing is that you want it in a reusable place.

At that point, your aspx code changes to something like:

Response.ContentType = "image/jpeg";
using (Bitmap bitmap = barcodeGenerator.Generate(Code))
{
    bitmap.Save(Response.OutputStream, ImageFormat.Jpeg);
}

and your saving code changes to something like:

// TODO: Validate that the text here doesn't contain dots, slashes etc
string code = Label1.Text.ToUpper();
string file = Server.MapPath("barcodeimages/" + code + ".jpeg");
using (Bitmap bitmap = barcodeGenerator.Generate(code))
{
    bitmap.Save(file, ImageFormat.Jpeg);
}

Here, barcodeGenerator would ideally be a depedency-injected instance of your BarcodeGenerator class (or whatever it turns out to be). If you’re not using dependency injection, you could create a new instance directly, specifying the font etc each time – it’s not as pleasant, but it should work okay.