FAQ: TBarCode .NET

Caching Barcode Images in ASP.NET Applications
How To Encode Binary Data (2D Codes)
Using TBarCode ASP.NET in Web Farms (IIS 7.0)
How can I Create a Bitmap Optimized for Thermal Printers?
How can I Create a Readable PDF417 Bitmap with Constant Size?
How can I Optimize PDF417 Symbols in my Web Control?
How can I create a readable Code 39 bitmap?

File Based Caching

The CacheDirectory property only accepts virtual paths from the web server. It is not possible to use a physical path such as c:\temp. Temporary barcode images should be created within the local (virtual) application directory (where you can find the *.aspx files) or in a subdirectory.

Cache="Harddisk" 
CacheDirectory="." or CacheDirectory="barcodefiles"

Memory Based Caching

With the following setting all barcode images will be stored in the web server's cache memory:

Cache="Memory"

In order to use memory caching you must include a custom HTTP handler BarcodeHttpHandler in the <httpHandlers> section of your web.config file (you might need to create this section first, if it does not exist). It should look similar to this:

 <system.web>
  ...
  <httpHandlers>
    ...
    <add verb="GET" path="BarcodeHttpHandler.axd" 
               type="TECIT.TBarCode.Web.BarcodeHttpHandler,
               TECIT.TBarCode, 
               Version=9.0.1.0, Culture=neutral, 
               PublicKeyToken=1B5F4306B234B83D" />
    ...
  </httpHandlers>
  ...
 </system.web>

Based on the example shown above, you probably need to change the version number depending on your package. Under c:\windows\assembly, look for TECIT.TBarCode to find the correct version.

If you need more detailed instructions go to:

> Start Menu > TEC-IT TBarCode 9.0 > Developer Manuals >TBarCode .NET Developer Reference (BarcodeHttpHandler Class)

Even if you use an escape sequence for binary data the encoder will use Codepage Conversion (example: \x88 leads to a different value in Data Matrix as desired).

Solution:

• Switch off codepage conversion (use Encoding Mode LowByte)
• Force binary encoding mode if available (see PDF417 Encoding Mode, Data Matrix EnforceBinaryEncoding)

The following sample code in VB .NET generates a barcode image optimized for thermal printer output (resolutions such as 203 dpi).

Dim bc As New TECIT.TBarCode.Barcode()

bc.BarcodeType = TECIT.TBarCode.BarcodeType.EanUcc128
bc.Data = "1234567890123"

' set font size
bc.Font = New System.Drawing.Font("Arial", 15,
          System.Drawing.FontStyle.Bold, GraphicsUnit.Point)

bc.TextDistance = 1.1

bc.BearerBarType = TECIT.TBarCode.BearerBarType.TopAndBottom
bc.BearerBarWidth = 2.4

' adjust quiet zone in [Modules] (recommended for bitmaps)
bc.QuietZoneUnit = TECIT.TBarCode.QuietZoneUnit.Modules
bc.QuietZoneLeft = 12
bc.QuietZoneRight = 12

' important: set printer resolution of thermal printer
bc.Dpi = 203

' 203 dpi --> Module Width = 0.5005 = 4 Pixel per Module
Dim moduleWidth As New Single
moduleWidth = 0.5004926  'need exact value here!

bc.SizeMode = TECIT.TBarCode.SizeMode.CustomModuleWidth
bc.ModuleWidth = moduleWidth + 0.001
bc.AdjustModuleWidthToPixelRaster = True

Dim width As New Single
Dim height As New Single

' size in [mm]
width = bc.CalculateBarcodeWidth(Nothing)
height = 35

' convert size to [Pixels]
width = width / (25.4 / bc.Dpi)
height = height / (25.4 / bc.Dpi)

' adjust bitmap size
Dim drawBitmapRect As New Rectangle(0, 0, width, height)
bc.BoundingRectangle = drawBitmapRect

' output to file
bc.Draw("barcode.bmp", TECIT.TBarCode.ImageType.Bmp)

The following sample code in ASP .NET generates a PDF417 image with constant size.

//PDF417
Barcode barcode = new Barcode();
barcode.Data = strMyData;
barcode.BarcodeType = BarcodeType.Pdf417;
barcode.Pdf417.EncodingMode = PdfEncodingMode.Binary;

// with dpi = 100 we get 1 Pixel = 0.254 mms
barcode.Dpi = 100;

 // we should specify the number of horizontal data columns
 // this inhibits the symbol to change its horizontal size regardless of data
 barcode.Pdf417.NumberOfColumns = 16; // use a value, which fits to your available space !!

 // now calculate optimal bitmap size for the bar code
 barcode.SizeMode = SizeMode.FitToBoundingRectangle;
 Size optimalSize = barcode.CalculateOptimalBitmapSize(null, 1, 1);

 // we already could use this optimal Size for saving the image
 // barcode.BoundingRectangle = new Rectangle(0, 0, optimalSize.Width,  optimalSize.Height);
 // barcode.Draw(filename, ImageType.Jpg);

 // but we want a constant bitmap size,
 // which fits exactly into your predefined space

 Size finalSize = new Size(350, 200); // final bitmap size in Pixel

 // so we have to add empty spaces around the symbol via adding a quiet zone
 barcode.QuietZoneUnit = QuietZoneUnit.Pixel;

 // calculate the required empty quiet zone we have to add

if (finalSize.Width > optimalSize.Width)
  barcode.QuietZoneRight = finalSize.Width - optimalSize.Width;
else
  // should not occur!! Reduce the Pdf417.NumberOfColumns
  finalSize.Width = optimalSize.Width;
            
if (finalSize.Height > optimalSize.Height)
  barcode.QuietZoneBottom = finalSize.Height - optimalSize.Height;
else
  // should not occur!! Increase final bitmap size
  finalSize.Height = optimalSize.Height;

barcode.BoundingRectangle = new Rectangle(0, 0, finalSize.Width, finalSize.Height);
barcode.Draw(filename, ImageType.Jpg);

Option #1

Add the following attributes to your TBarCode .NET Web Control. This will generate an optimized symbol, which fits into a 120 x 120 pixel matrix. Increase both the Width/Height and the NumberOfColumns attribute if required.

<cc2:BarcodeControl id="BarcodeControl1"
  Width="120" Height="120"
  Barcode-Dpi="96" 
  Barcode-SizeMode="MinimalModuleWidth" 
  Barcode-Pdf417-NumberOfColumns="3"                        
  Barcode-MustFit="True" ErrorHandling="ShowMessage" 
  Barcode-BarcodeType="Pdf417" 

Option #2

In the Page Load event or after you have set the bar code data apply the following calculation. This code will use width/height ratio of 1:3 for the graphical modules.

Barcode barcode = BarcodeControl1.Barcode;
barcode.SizeMode = SizeMode.FitToBoundingRectangle;  
System.Drawing.Size optimalSize = barcode.CalculateOptimalBitmapSize(null, 1, 1);

BarcodeControl1.Width = new Unit(optimalSize.Width, UnitType.Pixel);
BarcodeControl1.Height = new Unit(optimalSize.Height, UnitType.Pixel);  

BarcodeControl1.Refresh();

The following sample code in ASP .NET generates a Code 39 image.

//Code 39
Barcode barcode = new Barcode();
barcode.Data = "10030000007611107871900002199908";
barcode.BarcodeType = BarcodeType.Code39;

// with dpi = 100 we get 1 Pixel = 0.254 mms
barcode.Dpi = 100;

// now calculate optimal bitmap size for the bar code
barcode.SizeMode = SizeMode.FitToBoundingRectangle;

// set default size of symbol (define the default height)
barcode.BoundingRectangle = new Rectangle(0, 0, 254, 100 /* = 1 inch */);
                
// now calculate optimal bitmap size for the bar code
Size optimalSize = barcode.CalculateOptimalBitmapSize(null, 1, 1);

barcode.BoundingRectangle  = new Rectangle(0, 0, optimalSize.Width, optimalSize.Height);
barcode.Draw(filename, ImageType.Jpg);