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# Drawing UPC-A Barcodes with C#

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Demonstrates a method to draw UPC-A barcodes using C#.

## Introduction

On almost every product sold, there is typically a UPC barcode of some type which is used to identify the product. The most common barcode used, in the United States and Canada, is the UPC-A barcode. In this article, we will look at the UPC-A specification and examine some code that can produce UPC-A barcodes.

## UPC-A Background

The UPC-A barcode is composed of 12 digits which are made up of the following sections:

• the first digit is the product type,
• the next five digits are the manufacturer code,
• the next five digits are the product code,
• the last digit is the checksum digit.

### Product Type

The product type is a one digit number which is used to describe the type of product.

Product Type NumberDescription
0Regular UPC codes
1Reserved
2Weight items marked at the store.
3National Drug/Health-related code.
4No format restrictions, in-store use on non-food items.
5Coupons
6Reserved
7Regular UPC codes
8Reserved
9Reserved

### Manufacturer code and product code

The manufacturer code is assigned by the Uniform Code Council, and is used to uniquely identify the product's manufacturer. The product code is used to identify the product.

### Checksum digit

The checksum digit is calculated using the product type, manufacturer's code, and the product code. The odd numbers are multiplied by 3 and added to the sum, while the even numbers are simply added to the sum. The modulus of 10 is then taken of the summed total. This is subtracted from 10 and the modulus of 10 is taken again.

 For example: UPC-A 01234567890 Product Type : 0 Manufacturer's Code : 12345 Product Code : 67890 The first digit '0' is odd, so multiple it by 3, the second digit 1 is even so just add it, etc... (0 * 3) + 1 + (2 * 3) + 3 + (4 * 3) + 5 + (6 * 3) + 7 + (8 * 3) + 9 + (0 * 3) = 85 85 % 10 = 5 ( ( 10 - 5 ) % 10 ) = 5

### Symbol size

The specifications for the UPC-A barcode specify the nominal size of a UPC symbol as 1.496" wide and 1.02" high. Based upon this nominal size the UPC symbol can be scaled by a magnification factor of 0.8 to 2.0. Scaling the barcode will produce a barcode between the minimal allowable size of 1.175" wide by .816" high and the maximum allowable size of 2.938" wide and 2.04" high.

### Digit patterns

Each digit in a UPC-A bar code is composed of a series of two spaces and two bars. Each digit is drawn within a space that is 7 modules wide. In addition to the 12 digits, which make up a UPC-A barcode, the barcode symbol also has two quite zones, a lead block, a separator, and a trailing block. Each quite zone is 9 modules wide, the lead and trailing blocks are a series of lines and spaces in the format of bar, space, bar. The separator is signified by the sequence space/bar/space/bar/space.

Special SymbolPattern
Quite Zone000000000
Separator01010

where '0' represents space and '1' denotes a bar.

In addition to the special symbol patterns listed above, the UPC-A barcode symbol uses two distinct digit patterns as well, the Left Digit pattern and the Right Digit pattern. The Left Digit pattern is used to draw the product type and the manufacturer code. The Right Digit pattern is used to draw the product code and the checksum digit. The Left Digit pattern starts with spaces and the Right Digit pattern starts with bars (see table below).

NumberLeft DigitsRight Digits
000011011110010
100110011100110
200100111101100
301111011000010
401000111011100
501100011001110
601011111010000
701110111000100
801101111001000
900010111110100

where a '0' denotes a space and '1' represents a bar.

## Using the code

First, we will examine how to use the `UpcA` class, and then we'll examine how the `UpcA` class works.

### Using the UpcA Class

The code excerpt below uses the `UpcA` class to draw a UPC-A barcode in a picture box control:

C#
```private void DrawUPC( )
{
System.Drawing.Graphics g = this.picBarcode.CreateGraphics( );

g.FillRectangle(new System.Drawing.SolidBrush(
System.Drawing.SystemColors.Control),
new Rectangle(0, 0, picBarcode.Width, picBarcode.Height));

// Create an instance of the UpcA Class.
upc = new UpcA( );

upc.ProductType = "0";
upc.ManufacturerCode = "21200";
upc.ProductCode = "10384";
upc.Scale =
(float)Convert.ToDecimal( cboScale.Items [cboScale.SelectedIndex] );

upc.DrawUpcaBarcode( g, new System.Drawing.Point( 0, 0 ) );

g.Dispose( );
}```

The first step for the `DrawUPC` function is to create an instance of the `UpcA` class, and then set the product type, manufacturer code, the product code, and the scale factor properties (the check sum will be calculated by the `UpcA` class). Once these properties are set, a call to the `DrawUpcaBarcode` function is made, passing a `Graphics` object and a `Point`, which indicates the starting position to draw at, this will cause the barcode to be drawn in the picture box starting at point (0, 0).

### The UpcA Class

The most significant variables are listed below:

C#
```// This is the nomimal size recommended by the UCC.
private float _fWidth = 1.469f;
private float _fHeight = 1.02f;
private float _fFontSize = 8.0f;
private float _fScale = 1.0f;

// Left Hand Digits.
private string [] _aLeft = { "0001101", "0011001", "0010011", "0111101",
"0100011", "0110001", "0101111", "0111011",
"0110111", "0001011" };

// Right Hand Digits.
private string [] _aRight = { "1110010", "1100110", "1101100", "1000010",
"1011100", "1001110", "1010000", "1000100",
"1001000", "1110100" };

private string _sQuiteZone = "0000000000";
private string _sSeparator = "01010";```

The `_fWidth`, `_fHeight`, and the `_fScale` variables are initialized with the nominal size recommended by the Uniform Code Council. When the barcode is rendered, its actual size will be determined by the nominal size, and the scale factor, as discussed in the Symbol Size section of this article. The variables `_aLeft`, `_aRight`, `_sQuiteZone`, `_sLeadTail`, and `_sSeparator` are all string representations of the bar/space graphics, which represent the various parts of a UPC-A barcode. Essentially, a '1' represents a bar and a '0' represents a space, so `_sSeparator` would cause a space-bar-space-bar-space to be rendered. An alternate method to using a `string` could be to use a binary representation, where a 0 bit would be space and a 1 bit is a bar.

There are three primary functions which provide the majority of the functionality for the `UpcA` class. The workhorse of these functions is `DrawUpcaBarcode`. `DrawUpcaBarcode` uses the other two functions as helper functions. The two helper functions are: `CalculateChecksumDigit`, `ConvertToDigitPatterns` and these will be discussed first. There is also a fourth function, `CreateBitmap`, which provides an easy means for creating a bitmap image.

The first helper function `DrawUpcaBarcode` calls the `CalculateChecksumDigit` function, which uses the product type, manufacturer code, and product code to calculate the barcode's check sum.

C#
```public void CalculateChecksumDigit( )
{
string sTemp = this.ProductType + this.ManufacturerCode + this.ProductCode;
int iSum = 0;
int iDigit = 0;

// Calculate the checksum digit here.
for( int i = 1; i <= sTemp.Length; i++ )
{
iDigit = Convert.ToInt32( sTemp.Substring( i - 1, 1 ) );
if( i % 2 == 0 )
{    // even
iSum += iDigit * 1;
}
else
{    // odd
iSum += iDigit * 3;
}
}

int iCheckSum = ( 10 - ( iSum % 10 )  ) % 10;
this.ChecksumDigit = iCheckSum.ToString( );

}```

The `CalculateChecksumDigit` function calculates the check sum using the method discussed in the Checksum Digit section listed above.

The second helper function used is the `ConvertToDigitPatterns` function. This function takes the individual numbers of the manufacturer code, and the product number, and converts them to the string representation of the barcode graphics.

C#
```private string ConvertToDigitPatterns( string inputNumber, string [] patterns )
{
System.Text.StringBuilder sbTemp = new StringBuilder( );
int iIndex = 0;
for( int i = 0; i < inputNumber.Length; i++ )
{
iIndex = Convert.ToInt32( inputNumber.Substring( i, 1 ) );
sbTemp.Append( patterns[iIndex] );
}
return sbTemp.ToString( );
}```

The `ConvertToDigitPatterns` function requires two parameters:

• `inputNumber`
• `patterns`

The `inputNumber` will be either the manufacturer number or the product number, and the `patterns` will either be the `_aLeft` or the `_aRight` array depending on whether the `inputNumber` is the manufacturer number or the product number.

Finally the workhorse; the `DrawUpcaBarcode` handles the rendering of the barcode graphics and requires two parameters:

• `g`
• `pt`

This function begins by determining the width and height for the barcode, by scaling the nominal width and height by the scale factor. The `lineWidth` is based upon the total number of modules required to render a UPC-A barcode. The total number of modules, 113, is determined by the following: for example:

UPC-A code - 021900103841

Barcode SectionNumeric ValueGraphic RepresentationNumber of Modules
Quite ZoneN/A0000000009 modules
Product Type1 digit - "0"00011017 modules
Manufacturer Number5 digits = "21900"001001100110010001011000110100011015 digits * 7 modules = 35 modules
SeparatorN/A010105 modules
Product Number5 digits = "10384"110011011100101000010100100010111005 digits * 7 modules = 35 modules
Check Sum1 digit = "1"11001107 modules
TrailerN/A1013 modules
Quite ZoneN/A0000000009 modules

So, to determine the total module width, simply add the individual parts: 9 + 3 + 7 + 35 + 5 + 35 + 7 + 3 + 9 = 113.

C#
```public void DrawUpcaBarcode(System.Drawing.Graphics g,System.Drawing.Point pt)
{

float width = this.Width * this.Scale;
float height = this.Height * this.Scale;

// A upc-a excluding 2 or 5 digit supplement information
// should be a total of 113 modules wide.
// Supplement information is typically
// used for periodicals and books.
float lineWidth = width / 113f;

// Save the GraphicsState.
System.Drawing.Drawing2D.GraphicsState gs = g.Save( );

// Set the PageUnit to Inch because all of
// our measurements are in inches.
g.PageUnit = System.Drawing.GraphicsUnit.Inch;

// Set the PageScale to 1, so an inch will represent a true inch.
g.PageScale = 1;

System.Drawing.SolidBrush brush =
new System.Drawing.SolidBrush( System.Drawing.Color.Black );

float xPosition = 0;

System.Text.StringBuilder strbUPC = new System.Text.StringBuilder( );

float xStart = pt.X;
float yStart = pt.Y;
float xEnd = 0;

System.Drawing.Font font =
new System.Drawing.Font( "Arial", this._fFontSize * this.Scale );

// Calculate the Check Digit.
this.CalculateChecksumDigit( );

// Build the UPC Code.
strbUPC.AppendFormat( "{0}{1}{2}{3}{4}{5}{6}{1}{0}",
ConvertToDigitPatterns( this.ProductType, this._aLeft ),
ConvertToDigitPatterns( this.ManufacturerCode, this._aLeft ),
this._sSeparator,
ConvertToDigitPatterns( this.ProductCode, this._aRight ),
ConvertToDigitPatterns( this.ChecksumDigit, this._aRight ) );

string sTempUPC = strbUPC.ToString( );

float fTextHeight = g.MeasureString( sTempUPC, font ).Height;

// Draw the barcode lines.
for( int i = 0; i < strbUPC.Length; i++ )
{
if( sTempUPC.Substring( i, 1 ) == "1" )
{
if( xStart == pt.X )
xStart = xPosition;

// Save room for the UPC number below the bar code.
if( ( i > 19 && i < 56 ) || ( i > 59 && i < 95 ) )
// Draw space for the number
g.FillRectangle( brush, xPosition, yStart,
lineWidth, height - fTextHeight );
else
// Draw a full line.
g.FillRectangle( brush, xPosition, yStart, lineWidth, height );
}

xPosition += lineWidth;
xEnd = xPosition;
}

// Draw the upc numbers below the line.
xPosition = xStart - g.MeasureString( this.ProductType, font ).Width;
float yPosition = yStart + ( height - fTextHeight );

// Draw Product Type.
g.DrawString( this.ProductType, font, brush,
new System.Drawing.PointF( xPosition, yPosition ) );

// Each digit is 7 modules wide, therefore the MFG_Number
// is 5 digits wide so
// 5 * 7 = 35, then add 3 for the LeadTrailer
// Info and another 7 for good measure,
// that is where the 45 comes from.
xPosition +=
g.MeasureString( this.ProductType, font ).Width + 45 * lineWidth -
g.MeasureString( this.ManufacturerCode, font ).Width;

// Draw MFG Number.
g.DrawString( this.ManufacturerCode, font, brush,
new System.Drawing.PointF( xPosition, yPosition ) );

// Add the width of the MFG Number and 5 modules for the separator.
xPosition += g.MeasureString( this.ManufacturerCode, font ).Width +
5 * lineWidth;

// Draw Product ID.
g.DrawString( this.ProductCode, font, brush,
new System.Drawing.PointF( xPosition, yPosition ) );

// Each digit is 7 modules wide, therefore
// the Product Id is 5 digits wide so
// 5 * 7 = 35, then add 3 for the LeadTrailer
// Info, + 8 more just for spacing
// that is where the 46 comes from.
xPosition += 46 * lineWidth;

// Draw Check Digit.
g.DrawString( this.ChecksumDigit, font, brush,
new System.Drawing.PointF( xPosition, yPosition ) );

// Restore the GraphicsState.
g.Restore( gs );

}```

The function uses the `CalculateChecksumDigit` function to calculate the correct check sum digit, and then uses the `ConvertToDigitPatterns` function to convert the various numeric parts of the UPC-A barcode number to a string representation. Once the number has been converted over to a string representation, the code uses the string representation to render the barcode, 1 will cause a rectangle to be drawn, and 0 will cause the code to skip drawing a rectangle. If the code draws a rectangle, it also takes into consideration whether it needs to shorten the rectangle to allow space for the manufacturer's number and the product number. Once the barcode is completely rendered, the code then determines the position, and draws the product type number, the manufacturer's number, the product number, and the check sum digit.

The `CreateBitmap` function simply creates a `Bitmap` object, and uses the `DrawUpcaBarcode` function to render the barcode to the `Bitmap` object, and then it returns the `Bitmap`.

C#
```public System.Drawing.Bitmap CreateBitmap( )
{
float tempWidth = ( this.Width * this.Scale ) * 100 ;
float tempHeight = ( this.Height * this.Scale ) * 100;

System.Drawing.Bitmap bmp =
new System.Drawing.Bitmap( (int)tempWidth, (int)tempHeight );

System.Drawing.Graphics g = System.Drawing.Graphics.FromImage( bmp );
this.DrawUpcaBarcode( g, new System.Drawing.Point( 0, 0 ) );
g.Dispose( );
return bmp;
}```

## Points of interest

The United States and Canada are the only two countries that use the UPC-A barcode system, the rest of the world uses the EAN barcode system. So, as of January 1, 2005, the Uniform Code Council, UCC, has mandated that all U.S. and Canadian point-of-sale companies must be able to scan and process EAN-8, and EAN-13 barcodes, in addition to the UPC-A barcodes (this is called the 2005 Sunrise). The UCC has also began to push a new bar code system, known as the Global Trade Item Numbers (GTINs), basically a GTIN is a 14 digit number which conforms to the UPC-A, and EAN-13 symbol standards but uses additional digits to store country of origin information. If you want more information, go to UCC: 2005 Sunrise.

## History

• Version 1.0 - Initial application.

A list of licenses authors might use can be found here

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 First PrevNext
 Usage in products Member 114312555-Feb-15 16:58 Member 11431255 5-Feb-15 16:58
 Good article about a method to draw UPC-A barcodes using C#. Volynsky Alex20-Apr-14 22:35 Volynsky Alex 20-Apr-14 22:35
 UPC-A Barcode VB.NET version? laxi3005-Oct-11 8:29 laxi300 5-Oct-11 8:29
 barcode in code 39 Member 79252208-Jul-11 22:28 Member 7925220 8-Jul-11 22:28
 My vote of 5 dl4gbe8-Aug-10 9:34 dl4gbe 8-Aug-10 9:34
 Barcode does not show up if placed in Window directory BHHNVB18-Sep-09 7:01 BHHNVB 18-Sep-09 7:01
 NOT PRODUCING AN ACCURATE BAR CODE! [modified] Chris Marcan16-Jul-09 7:43 Chris Marcan 16-Jul-09 7:43
 When scale is 1, bar codes will scan, but not very well. When I compare with a bar code from a packaged product with the same upc created with this code, I notice that some of the lines have a different thickness. When looking at the binary string and comparing it to the lines in the bar code, some of the single lines (example: 010) are thicker than the others, even though the line width is the same value for every line. Some kinda rounding or scaling issue. When scale is changed to 2, all the single thickness lines are the same thickness and they scan perfectly. How to fix this? I have no idea. modified on Thursday, July 16, 2009 1:50 PM
 Re: NOT PRODUCING AN ACCURATE BAR CODE! [modified] Chris Marcan16-Jul-09 8:36 Chris Marcan 16-Jul-09 8:36
 Re: NOT PRODUCING AN ACCURATE BAR CODE! muppaluri23-Oct-09 4:53 muppaluri 23-Oct-09 4:53
 quistion beeshooo9-Feb-09 7:21 beeshooo 9-Feb-09 7:21
 Message Closed 3-Mar-13 16:41 Thomasssss 3-Mar-13 16:41
 help lakshmi priya.t.n29-Jan-09 17:33 lakshmi priya.t.n 29-Jan-09 17:33
 Message Closed 3-Mar-13 17:11 Thomasssss 3-Mar-13 17:11
 This saves me \$\$\$ David Tum27-Jan-07 5:53 David Tum 27-Jan-07 5:53
 UPC-E Bill Daugherty II1-Jan-06 8:59 Bill Daugherty II 1-Jan-06 8:59
 Re: UPC-E rainman_633-Jan-06 2:46 rainman_63 3-Jan-06 2:46
 Re: UPC-E Bill Daugherty II3-Jan-06 8:04 Bill Daugherty II 3-Jan-06 8:04
 Just some inforamtion. Bill Daugherty II1-Jan-06 8:56 Bill Daugherty II 1-Jan-06 8:56
 runnign code as webapp... walkerla27-Sep-05 15:26 walkerla 27-Sep-05 15:26
 Re: runnign code as webapp... rainman_6328-Sep-05 4:37 rainman_63 28-Sep-05 4:37