FAQ TBarCode .NET

How to Encode Binary Data (2D Codes)

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

Solution:

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

How Can I Control the Bar Code Size?

You can chose between two size modes:

• Size Mode Fit to Bounding Rectangle
  The barcode adapts to the bounding rectangle by auto-calculation of the module width. The module width property is just a Get/Set value and is not updated.
• Size Mode Custom Module Width
  The barcode size depends on the module width property which is set in [mm]. The barcode still adapts to the bounding rectangle in the dimension where the module width is not relevant (like the height in a linear code).

The Bounding Rectangle must be supplied in [mm] for doing Size calculations like with CalculateModuleWidth or CalculateBarcodeSize.

The Bounding Rectangle must be supplied in [Pixel] for any bitmap or device context related drawing operations.

Recommended Workflow

For any operations first set the rectangle, then do the operation or calculation.

It is recommended to do all in [mm] first and in case you draw to a bitmap, convert the mm to Pixel considering also the DPI you have adjusted.

• Set bar code and bar code data
• Set bounding rectangle in [mm], set the size mode and if applicable the module width
• Set the DPI if applicable
• If you use a custom module width: Do size retrieval / calculation functions (returned values are in mm). This is required because your bounding rectangle may not reflect the real bar code size.
• If you need a bitmap, convert the returned size to Pixel and set the bounding rectangle in Pixel

For creating bitmaps where the barcode size is not predefined by any specific requirements there is also the function CalculateOptimalBitmapSize. This function avoids quantization errors and improves the quality.

barcode.Dpi = 100;
barcode.SizeMode = SizeMode.FitToBoundingRectangle;
Size optimalSize = barcode.CalculateOptimalBitmapSize(null, 1, 1);  // 1 Module = 1 Pixel
barcode.BoundingRectangle = new Rectangle(0, 0, optimalSize.Width,  optimalSize.Height);
barcode.Draw(filename, ImageType.Jpg);

How Can I Control the Bitmap Transparency

When creating a barcode in bitmap format, there are two possibilities to adjust the background:

• IsBackgroundTransparent = TRUE → When drawing the barcode (DC, Graphics, Bitmap) only the bars are drawn, the rest remains free
• IsBackgroundTransparent = FALSE → When drawing the barcode (DC, Graphics, Bitmap) the background is filled first, then the bars are drawn

Recommended Workflow

If you want to create a bitmap barcode with a transparent background, you have to set the transparency color separately. To do this, first draw into a bitmap, set the transparency and then save it. Try one of the two following options:

Option #1

Draw the barcode with a white background:

• IsBackgroundTransparent := FALSE (→ the barcode library draws a white background)

Specify the transparency color:

• bitmap.MakeTransparent( Color.White ); //make be background transparent - this will be an index (rather than an alpha) transparency

Sample code in C#:

Barcode BC = new Barcode();
int width = 300;
int height = 150;

BC.BarcodeType = BarcodeType.Code128;
BC.Data = "12345";
BC.IsBackgroundTransparent = false;
BC.BoundingRectangle = new Rectangle(0, 0, width, height); // Pixel

Bitmap bitmap = new Bitmap(width, height);
Graphics gfx = Graphics.FromImage(bitmap);
BC.Draw(gfx);
bitmap.MakeTransparent(Color.White);
bitmap.Save("c:\\temp\\test1a.png", System.Drawing.Imaging.ImageFormat.Png);

Variant without graphics object:

Barcode BC = new Barcode();

int width = 300;
int height = 150;

BC.BarcodeType = BarcodeType.Code128;
BC.Data = "12345";
BC.IsBackgroundTransparent = false;
BC.BoundingRectangle = new Rectangle(0, 0, width, height); // Pixel

Bitmap bitmap = BC.DrawBitmap();
bitmap.MakeTransparent(Color.White);
bitmap.Save("c:\\temp\\test1b.png", System.Drawing.Imaging.ImageFormat.Png);       

Option #2

Draw the barcode without background:

• IsBackgroundTransparent := FALSE (→ the barcode library draws a white background)

Fill background with transparency:

• gfx.Clear(Color.Transparent);

Sample Code in C#:

Barcode BC = new Barcode();

int width = 300;
int height = 150;

BC.BarcodeType = BarcodeType.Code128;
BC.Data = "12345";
BC.IsBackgroundTransparent = true;
BC.BoundingRectangle = new Rectangle(0, 0, width, height); // Pixel

Bitmap bitmap = new Bitmap(width, height);
Graphics gfx = Graphics.FromImage(bitmap);

gfx.Clear(Color.Transparent);
gfx.Flush();

BC.Draw(gfx);
bitmap.Save("c:\\temp\\test2.png", System.Drawing.Imaging.ImageFormat.Png); 

Notes

• Please note that the example barcode is not pixel-optimized.
• We recommend to use PNG images.
• Further information about transparency can be found here.

How Can I Create an ITF-14 Bitmap Optimized for Thermal Printers?

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

// Create an ITF-14 bar code for a label to be printed with 203 dpi
// Bearer bar width = 2 X (X = module width)
// We fine-tune the module width using AdjustModuleWidthToPixelRaster.

Barcode code = new Barcode ();
code.BarcodeType = TECIT.TBarCode.BarcodeType.ITF14;

code.Data = "1234567890123";

code.Font = new System.Drawing.Font("Arial", 15, System.Drawing.FontStyle.Bold, GraphicsUnit.Point);
code.TextDistance = 1.1F; // mm

// important: set printer resolution of thermal printer
code.Dpi = 203;

// 203 dpi --> Module Width = 0.5005 = 4 Pixel per Module
float moduleWidth = 0.5004926F; // use exact value!

code.SizeMode = TECIT.TBarCode.SizeMode.CustomModuleWidth;
code.ModuleWidth = moduleWidth + 0.001; // add delta to extend optimization range

code.AdjustModuleWidthToPixelRaster = true;

double modulesBearerBar = 2; // 2 X
code.BearerBarType = TECIT.TBarCode.BearerBarType.TopAndBottom;
code.BearerBarWidth = moduleWidth * modulesBearerBar;

// adjust quiet zone in [Modules] (recommended for bitmaps)
code.QuietZones.Unit = TECIT.TBarCode.QuietZoneUnit.Modules;
code.QuietZones.Left.Size = 10F;
code.QuietZones.Right.Size = 10F;

// for rectangular bearer bar having a width of 4.83 mm
// code.BearerBarWidth = 4.83F;
// double modulesBearerBar = Math.Round(code.BearerBarWidth / moduleWidth, MidpointRounding.AwayFromZero);
// code.QuietZones.Left.Size = 10F + modulesBearerBar;
// code.QuietZones.Right.Size = 10F + modulesBearerBar;

// size in [mm]
double width = code.CalculateBarcodeWidth(null);
double height = 35;

// convert size to [Pixels]
width = width / (25.4 / code.Dpi);
height = height / (25.4 / code.Dpi);

// adjust bitmap size
code.BoundingRectangleF = new RectangleF(0, 0, (float) width, (float) height);

// output to file
code.Draw("barcode-ITF-14-203dpi.bmp", TECIT.TBarCode.ImageType.Bmp);

How Can I Create a Readable PDF417 Bitmap with Constant Size?

The following sample code in C# 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);

How Can I Create a Bitmap with a Specific Bar Height?

The following sample code shows you how to create a bitmap with a particular bar height for EAN 13 (can be changed to other linear barcode types).

double dpi = 300;
double barHeightinMM = 23;
double symbolHeightinMM = 26;
double nominalNarrowBarWidthinMM = 0.33;

Graphics gfx = this.CreateGraphics(); // graphics of any screen DC

Barcode ean13 = new Barcode();
ean13.BarcodeType = BarcodeType.Ean13;
ean13.Data = "123456789012";
ean13.Dpi = dpi;

// 1 Pixel in mm
double PxtoMm = 25.4 / dpi; 

// how many Pixels are 0.33 mm => We have to round depending on DPI
int narrowBarinPx = (int) Math.Round (nominalNarrowBarWidthinMM / PxtoMm);
double narrowBarinMM = narrowBarinPx * PxtoMm;
System.Diagnostics.Debug.WriteLine("Narrow bar width in mm (rounded to full Pixels): " + narrowBarinMM);

// calculate width in pixels by using the number of "modules" in the barcode
int symbolWidthinPixels = ean13.CalculateNumberOfModules() * narrowBarinPx;

// set font size to an automatic size based upon module width
double fontSizePt = 10 * Math.Round(narrowBarinMM, 3) / 0.339;
ean13.Font = new Font("Consolas", (float) fontSizePt);

// Case A: desired bar height is 23 mm
{
    int barHeightinPx = (int) Math.Round(barHeightinMM / PxtoMm, 0);
    System.Diagnostics.Debug.WriteLine("Bar height in Pixels : " + barHeightinPx);

    // calculate actual text area height
    float textAreaHeightMM = ean13.CalculateTextAreaHeight(null);
    int textAreaHeightPx = (int) (0.5 + textAreaHeightMM / PxtoMm);
    System.Diagnostics.Debug.WriteLine("Text height in Pixels: " + textAreaHeightPx);

    int symbolHeightinPx = barHeightinPx + textAreaHeightPx;

     // set bounding rectangle in Pixels
    ean13.BoundingRectangle = new Rectangle(0,0, symbolWidthinPixels, symbolHeightinPx);

    // Draw directly to bitmap file
    ean13.Draw(AppDomain.CurrentDomain.BaseDirectory + @"\EAN13-caseA.BMP", ImageType.Bmp, gfx, 1);

    // Draw to Picture Box

    // Option A
    // scale font depending on DPI ratio (required if internal DC is used)
    ean13.FontHeight = (int) (fontSizePt * dpi / gfx.DpiY);
    pictureBoxEAN13.Image = ean13.DrawBitmap();

    // Option B
    // ignore DC resolution + use Pt font size
    ean13.IgnoreDpiFromDC = true;
    ean13.FontHeight = (int) fontSizePt;
    pictureBoxEAN13.Image = ean13.DrawBitmap();
}

// Case B: desired symbol height (incl. text) is 26 mm
{
    int symbolHeightinPx = (int) Math.Round (symbolHeightinMM / PxtoMm, 0);
    System.Diagnostics.Debug.WriteLine("Symbol height in Pixels : " + symbolHeightinPx);

     // set bounding rectangle in Pixels
    ean13.BoundingRectangle = new Rectangle(0, 0, symbolWidthinPixels, symbolHeightinPx);

    // Draw directly to bitmap file
    ean13.Draw(AppDomain.CurrentDomain.BaseDirectory + @"\EAN13-caseB.BMP", ImageType.Bmp, gfx, 1);
}

DrawBitmap Creates a Very Small Font Size

If you want to create a high resolution bitmap (DPI >= 300), you may encounter a very small font size of the HRT in the resulting bitmap.

The following C# sample code demonstrates the influence of the screen DC (96 dpi) when you use DrawBitmap(). You can solve this issue either by using the Draw() export function or with IgnoreDPIFromDC.

Barcode code128 = new Barcode();
code128.BarcodeType = BarcodeType.Code128;
code128.Data = "HELLO";
code128.Dpi = 600;

code128.BoundingRectangle = new Rectangle(0, 0, code128.CalculateNumberOfModules() * 6, 600); // one module = 6 Pixel
code128.Draw(@"C:\temp\Draw-OK.bmp", ImageType.Bmp); // HRT is scaled correctly

Bitmap test1 = code128.DrawBitmap();
test1.Save(@"C:\temp\DrawBitmap-NOK.bmp"); // HRT is very small (scaled to 96 dpi screen resolution instead of 600)

code128.IgnoreDpiFromDC = true;
Bitmap test2 = code128.DrawBitmap();
test2.Save(@"C:\temp\DrawBitmap-OK.bmp"); // HRT is scaled to 600 dpi (Screen DC is ignored).

How Can I Add Additional Text to the Control?

This is possible by changing the active text index programmatically. The following sample code assumes a Barcode Control, which is drawn on a Graphics (gfx) in Pixel units and shows how to add additional text on the right side.

Barcode tbc = barcodeControl1.Barcode;

Graphics gfx = this.CreateGraphics();
SizeF barcodeSizeMM = tbc.CalculateBarcodeSize(gfx);
double pixelSizeMM = 25.4F / gfx.DpiX;
int barcodeWidthPx = Convert.ToInt32(0.5 + barcodeSizeMM.Width / pixelSizeMM);
int barcodeHeightPx = Convert.ToInt32(0.5 + barcodeSizeMM.Height / pixelSizeMM);

// first add a quiet zone for our text area
tbc.QuietZones.Right.Size = 100;
tbc.QuietZones.Unit = QuietZoneUnit.Pixel;

// set barcode data (+ normal HRT) in text area #0
tbc.ActiveTextIndex = 0;
tbc.BarcodeType = BarcodeType.Code128;
tbc.Data = "1234567890";
tbc.IsTextVisible = false;

// change text index to (auxiliary) text area #1
tbc.ActiveTextIndex = 1;

// now adjust all settings for text area #1
tbc.HumanReadableText ="My Label Text";
tbc.Font = new Font("Arial", 10, FontStyle.Regular, GraphicsUnit.Point);
tbc.TextClipping = false;
tbc.IsTextVisible = true;
tbc.TextPositionTop = (barcodeHeightPx - (int) tbc.Font.GetHeight(gfx)) / 2 ;
tbc.TextPositionLeft = barcodeWidthPx - (int)tbc.QuietZones.Right.Size + 10;

// reset text index back to barcode text
tbc.ActiveTextIndex = 0;

The text area #1 can be set to any text, but also to your bar code data. You have to take care on the dimensions and need to center / align the text with your own coordinates.

How Can I Create a 26x26 Data Matrix for DP Premiumadress?

The following sample code for C# .NET shows you how to adjust the settings for Data Matrix:

Barcode barcode = new TECIT.TBarCode.Barcode();
      
barcode.BarcodeType = BarcodeType.DataMatrix;
barcode.DataMatrix.Size = DataMatrixSize.Square26x26;
barcode.DataMatrix.Format = DataMatrixFormat.Default;
barcode.DataMatrix.ShallEnforceBinaryEncoding = true;

barcode.SizeMode = SizeMode.CustomModuleWidth;
barcode.ModuleWidth = 0.423;

barcode.EncodingMode = EncodingMode.Hexadecimal;
// set preformatted data (Bytes = Hex codes)
barcode.Data = "444541080D02540BE3FF0052232D242D000065000000010100015A313031000000000000000000000000";

How Can I Create a Data Matrix with 1BPP and 1200 DPI?

The following sample code for C# .NET shows you how to create a TIFF with 1 bpp (B/W) and 1200 dpi.

Barcode barcode = new TECIT.TBarCode.Barcode();
//barcode.License(…)
barcode.BarcodeType = BarcodeType.DataMatrix;
barcode.Dpi = -1;  // Use DPI from screen DC
barcode.SizeMode = SizeMode.FitToBoundingRectangle;
barcode.Data = "TEST 1234";

float dpi = 1200;
int nScale = 12; // 1 Dot = 12 Pixel  (at 1200 dpi, this is 0.254 mm)
// Calculate bounding rectangle using a scaled module width adapted to Pixel boundaries
Size sizePx = barcode.CalculateOptimalBitmapSize(null, nScale, nScale);
barcode.BoundingRectangleF = new RectangleF(0, 0, sizePx.Width, sizePx.Height);

Bitmap myBarcode = barcode.DrawBitmap();
//myBarcode.SetResolution(dpi, dpi);
//myBarcode.Save("c:\\temp\\ExportedFile.jpg", System.Drawing.Imaging.ImageFormat.Jpeg);
Bitmap converted = myBarcode.Clone(new Rectangle(0, 0, myBarcode.Width, myBarcode.Height), System.Drawing.Imaging.PixelFormat.Format1bppIndexed);
converted.SetResolution(dpi, dpi);
converted.Save("c:\\temp\\ExportedFile.tif", System.Drawing.Imaging.ImageFormat.Tiff);

How Can I Create a 2D Mailmark ™ Type 7?

The following sample code for VB .NET shows you how to adjust the settings for 2D Mailmark Type 7 bitmap file:

' 2D Mailmark Type 7 - 24x24 matrix size
' Module size 0.508 mm (300 dpi), total size 12.2 x 12.2 mm

Dim myBarcode As New TECIT.TBarCode.Barcode
myBarcode.BarcodeType = TECIT.TBarCode.BarcodeType.Mailmark_2D
myBarcode.DataMatrix.Size = TECIT.TBarCode.DataMatrixSize.Square24x24

myBarcode.SizeMode = TECIT.TBarCode.SizeMode.CustomModuleWidth
myBarcode.ModuleWidth = 0.508F
myBarcode.Dpi = 300

myBarcode.Data = "JGB 012100123412345678AB19XY1A 0             123456"

' retrieve final size in [mm]
Dim finalSizeMM As SizeF
finalSizeMM = myBarcode.CalculateBarcodeSize(Nothing) ' will return [mm]

Dim widthPx As Integer
Dim heightPx As Integer

' convert to Pixel
widthPx = finalSizeMM.Width * myBarcode.Dpi / 25.4
heightPx = finalSizeMM.Height * myBarcode.Dpi / 25.4

' adjust bitmap size and save as BMP
myBarcode.BoundingRectangleF = New RectangleF(0, 0, widthPx, heightPx)
myBarcode.Draw("C:\temp\2DMailmark.bmp", TECIT.TBarCode.ImageType.Bmp)

Why I See a Different Font in EPS and AI Export?

TBarCode SDK does not embed the fonts into EPS and AI. It just references the font by specifying the font name. So it depends on the output device or graphics suite if the font is available and how the font is rendered.

For EPS only font names which are standard in PostScript or font names, which do not contain any blanks/spaces in the referenced font name are allowed.

EPS: In order to avoid problems on printers, which do not have Arial installed, we convert references to Arial always to Helvetica, which looks similar and is a standard PS font (available in all printers). If this is not desired, you have an option, which controls if there is a font replacement applied or not. This is the UseDeviceFonts option.

Here is sample code for EAN13 SC2 – 100%:

Export to EPS with Standard Postscript Fonts (Arial ⇒ Helvetica)

Barcode barcode = new Barcode();
barcode.BarcodeType = BarcodeType.Ean13;

barcode.BoundingRectangleF = new RectangleF(0, 0, 37.29F, 25.91F); // SC2 size
barcode.SizeMode = SizeMode.CustomModuleWidth;
barcode.ModuleWidth = 0.330F; // SC2 module width

barcode.Data = "123456789012";
barcode.Font = new Font("Arial", 9);
barcode.UseDeviceFonts = true;

barcode.Draw("c:\\temp\\TestFile.eps", ImageType.Eps);
barcode.Draw("c:\\temp\\TestFile.ai", ImageType.Ai);

If you open the exported EPS file with a text editor, you see Helvetica instead of Arial:

This is how it looks if you open the EPS file with a PostScript viewer (like GSView):

If you open the exported AI file with a text editor, you see:

Export to EPS and Keep the Adjusted Font (Arial ⇒ Arial)

The printer or the graphics software must support “Arial”! Font names must not contain blanks/spaces!

Barcode barcode = new Barcode();
barcode.BarcodeType = BarcodeType.Ean13;

barcode.BoundingRectangleF = new RectangleF(0, 0, 37.29F, 25.91F);
barcode.SizeMode = SizeMode.CustomModuleWidth;
barcode.ModuleWidth = 0.330F;

barcode.Data = "123456789012";
barcode.Font = new Font("Arial", 9);
barcode.UseDeviceFonts = false;

barcode.Draw("c:\\temp\\TestFile.eps", ImageType.Eps);
barcode.Draw("c:\\temp\\TestFile.ai", ImageType.Ai);

If you open the exported EPS file with a text editor, you see:

If you open the exported AI file with a text editor you see:

Summary

In order to use the adjusted font for the export, you can set UseDeviceFonts = false. It depends also what you want to do with the EPS file. If you want to send the file just “as is” to a printer or printing system, it is maybe better to use Helvetica with UseDeviceFonts = true. We recommend to try printing first before you make a decision about DeviceFonts.

PDF Export without HRT

For PDF export, there is no font rendering included in the TBarCode SDK - that is why you don’t get any font or text output if you chose PDF export format.

If you need PDF export with font embedding, you may use our TFORMer Label Printing SDK. The TFORMer SDK supports the same barcodes as the TBarCode SDK. Or - you can also use Barcode Studio in command line mode – you call BCStudio.exe from your own program code and pass the barcode data and file name to BCStudio (for the available command line parameters see the BCStudio user manual). Alternatively - if you want to use PDF libraries from third party vendors, you may use the Callback drawing mechanism of TBarCode SDK – here you get the coordinates of the bars and of the text and with these coordinates you implement the barcode with the drawing and font / text rendering functions of the PDF library. Samples for how to use the Callback drawing are included in the SDK.

Error "Catastrophic Failure" During Licensing

On specific systems (e.g. W2012R2, IIS8.5) you may encounter an error if you apply the license key immediately after creating an instance of the bar code object. This occurs because the underlying (native) TBarCode DLL has not been initialized at this point - possibly due to delayed loading of dependency DLLs or another timing issue.

As a workaround try to set any property before applying the license - see below:

TECIT.TBarCode.Barcode oBC = new TECIT.TBarCode.Barcode();
oBC.BarcodeType = TECIT.TBarCode.BarcodeType.Code128; // set a property of the object
oBC.License("Licensee", TECIT.TBarCode.LicenseType.DeveloperOrWeb, 1, "Key", TECIT.TBarCode.TBarCodeProduct.Barcode2D);

Lack of Barcode After Deployment to Microsoft Azure

TBarCode employs Windows GDI API calls for drawing lines and rendering text output. However, a problem arises on Azure due to the Web App sandbox's blocking of GDI. This blockage is implemented for security reasons, as Microsoft restricts calls to the video/screen driver owing to security concerns. Consequently, the barcode is either drawn in a fragmented manner or is entirely absent. The complete functionality of GDI functions is only achievable with a server hosted on-premise.

Solution: Utilize the Custom Drawing Callback interface as an alternative to GDI API calls.

• Download the QR Code Web App Sample for .NET 6 (see folder ASPNETCoreWebApp).
• Refer to BarcodeController.cs: GetQRCodeImgNoGDI, which utilizes .NET functions through the Callback interface to draw the barcode. This method is suitable for Azure Services where GDI is inaccessible.
• If you are utilizing the SDK's precompiled Barcode Service (WebDeploy package), update to the latest version and set the UseGDI=false parameter.

Issues with Font Size on Azure

If your intention involves creating a linear barcode with human-readable text, text output via the Callback interface is also necessary (code is included in the ASP.NET Core sample linked above). Sometimes we saw an unwanted font scaling on Azure, in this case you have to use a font, which is installed and set the size.

Performance: Caching Barcode Images in ASP.NET Applications

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)

Using TBarCode ASP.NET in Web Farms (IIS 7.0)

If you use TBarCode ASP.NET Web Control in a Web Farm you may encounter the following exception:

Exception Type: System.ApplicationException
Message: The requested image is no longer cached.

The TBarCode .NET Web Control uses the HttpContext.Cache object to store the generated barcode image. Since http requests are load balanced within a web farm it can occur that a specific Web Control receives a request for an image, which has been generated on a different application server (and therefore is not available in its local cache).

To overcome this problem you could

• Synchronize the HttpContext.Cache object on all servers in the web farm (="distributed caches"). This could be done with extra programming or additional third party software.
• or simply use Client Affinity in IIS 7.0 (recommended)

Having client affinity enabled all requests are tagged with a cookie so that subsequent requests (from the same client) are routed to the same server in the web farm.

See Application Request Routing (Step 3 – Configure client affinity)

Application Request Routing provides a client affinity feature that maps a client to a content server behind Application Request Routing for the duration of a client session. When this feature is enabled, the load balancing algorithm is applied only for the very first request from the client.