ReadBarcode(RasterImage,LogicalRectangle,BarcodeSymbology,BarcodeReadOptions) Method

Read one barcode from an image with specified symbology and options.

Syntax

C#
Visual Basic
WinRT C#
Objective-C
Java
WinRT JavaScript
C++

public BarcodeData ReadBarcode( 
   RasterImage image,
   LogicalRectangle searchBounds,
   BarcodeSymbology symbology,
   BarcodeReadOptions options
)

'Declaration
 
Public Overloads Function ReadBarcode( _
   ByVal image As RasterImage, _
   ByVal searchBounds As LogicalRectangle, _
   ByVal symbology As BarcodeSymbology, _
   ByVal options As BarcodeReadOptions _
) As BarcodeData

'Usage
 
Dim instance As BarcodeReader
Dim image As RasterImage
Dim searchBounds As LogicalRectangle
Dim symbology As BarcodeSymbology
Dim options As BarcodeReadOptions
Dim value As BarcodeData
 
value = instance.ReadBarcode(image, searchBounds, symbology, options)

public BarcodeData ReadBarcode( 
   RasterImage image,
   LogicalRectangle searchBounds,
   BarcodeSymbology symbology,
   BarcodeReadOptions options
)

- (LTBarcodeData*)readBarcode:(LTRasterImage*)image 
                 searchBounds:(LeadRect)searchBounds 
                    symbology:(LTBarcodeSymbology)symbology 
                      options:(LTBarcodeReadOptions*)options 
                        error:(NSError**)outError;

public BarcodeData readBarcode(
  RasterImage image, 
  LeadRect searchBounds, 
  BarcodeSymbology symbology, 
  BarcodeReadOptions options
)

 function Leadtools.Barcode.BarcodeReader.ReadBarcode(RasterImage,LogicalRectangle,BarcodeSymbology,BarcodeReadOptions)( 
   image ,
   searchBounds ,
   symbology ,
   options 
)

public:
BarcodeData^ ReadBarcode( 
   RasterImage^ image,
   LogicalRectangle searchBounds,
   BarcodeSymbology symbology,
   BarcodeReadOptions^ options
)

Parameters

image: A Leadtools.RasterImage object that contains the image data. Must not be null (Nothing in Visual Basic).
searchBounds: A Leadtools.Forms.LogicalRectangle that specifies the region of interest area in the image where the barcode search and detection is performed. You can specify LogicalRectangle.Empty to indicate that the search must be performed on the whole image.
symbology: An BarcodeSymbology enumeration member that specifies the barcode symbology (type) to search for. You can pass BarcodeSymbology.Unknown to search for all available symbologies in this BarcodeReader.
options: An instance of a BarcodeReadOptions derived class that specifies the options to use.

Return Value

An instance of BarcodeData or one of its derived classes that contains the symbology, data, location, and any rotation angle of the barcode found. If no barcodes can be found, then this method will return null (Nothing in Visual Basic).

Remarks

Use these methods if you want to read a single barcode from the image, for example, a QR symbol by specifying BarcodeSymbology.QR or if you want to read any barcode found regardless of its type by using BarcodeSymbology.Unknown.

For more information on barcode reading, refer to BarcodeReader.

This method will use the default read options set in this BarcodeReader that correspond to symbology. If the value of this parameter is BarcodeSymbology.Unknown, then all the default read options might be used.

LEADTOOLS barcode read engine is optimized for speed and can search for multiple similar symbologies at the same time. This method simply returns the first barcode that is detected correctly using the symbology and current options.

This method will use the options in options when reading the barcode. If this parameter is null (Nothing in Visual Basic), then the default options for symbology (or all default options if BarcodeSymbology.Unknown is specified) will be used instead.

If options is not null (Nothing in Visual Basic) and symbology is not BarcodeSymbology.Unknown, then it must contain a derived class of BarcodeReadOptions that supports symbology.

The ReadSymbology event will occur before and after attempting to read any symbology. The read options being used whether the default or specified will be set in the BarcodeReadSymbologyEventArgs.Options property of the event data.

The BarcodeReader provides the following barcode read methods:

Method	Description
ReadBarcode(RasterImage image, LogicalRectangle searchBounds, BarcodeSymbology symbology) and ReadBarcode(RasterImage image, LogicalRectangle searchBounds, BarcodeSymbology symbology, BarcodeReadOptions options)	Read one barcode from an image with specified symbology and default or specific options. Use these methods if you want to read a single barcode from the image, for example, a QR symbol by specifying BarcodeSymbology.QR or if you want to read any barcode found regardless of its type by using BarcodeSymbology.Unknown.
ReadBarcode(RasterImage image, LogicalRectangle searchBounds, BarcodeSymbology[] symbologies) and ReadBarcode(RasterImage image, LogicalRectangle searchBounds, BarcodeSymbology[] symbologies, BarcodeReadOptions[] options)	Read one barcode from an image with a symbology from a specified group and default or specific options. Use these methods if you want to read a single barcode from a known group. For example, to read a barcode that can be of any UPC type, pass an array of BarcodeSymbology.UPCA and BarcodeSymbology.UPCE.
ReadBarcodes(RasterImage image, LogicalRectangle searchBounds, int maximumBarcodes, BarcodeSymbology[] symbologies) and ReadBarcodes(RasterImage image, LogicalRectangle searchBounds, int maximumBarcodes, BarcodeSymbology[] symbologies, BarcodeReadOptions[] options)	Read multiple barcodes from an image with symbologies from a specified group and default or specific options. Use these methods if you want to read multiple barcodes of the same or multiple symbologies.

Example

C#
Visual Basic
WinRT C#
WinRT JavaScript
Silverlight C#
Silverlight VB

Copy Code

Imports Leadtools
Imports Leadtools.Codecs
Imports Leadtools.Forms
Imports Leadtools.Barcode
Imports Leadtools.ImageProcessing

Public Sub BarcodeReader_ReadBarcodeExample2()
   Dim imageFileName As String = Path.Combine(LEAD_VARS.ImagesDir, "Barcode2.tif")

   ' Create a Barcode engine
   Dim engine As New BarcodeEngine()

   ' Get the Barcode reader instance
   Dim reader As BarcodeReader = engine.Reader

   Using codecs As New RasterCodecs()
      Using image As RasterImage = codecs.Load(imageFileName, 0, CodecsLoadByteOrder.BgrOrGray, 1, 1)
         ' Invert the image
         Console.WriteLine("Inverting the image")
         Dim invert As New Leadtools.ImageProcessing.Color.InvertCommand()
         invert.Run(image)

         ' All barcodes have default options of black foreground color and white background color, so
         ' reading the barcode with default options should not return any barcodes right now

         ' Read the QR barcode from this image using default options
         Console.WriteLine("Reading using default options")
         Dim barcode As BarcodeData = reader.ReadBarcode(image, LogicalRectangle.Empty, BarcodeSymbology.QR, Nothing)

         ' Show its location and data if found
         ' This will print out "Not found"
         If Not IsNothing(barcode) Then
            Console.WriteLine("Found at {0}, data:\n{1}", barcode.Bounds, barcode.Value)
         Else
            Console.WriteLine("Not found")
         End If

         ' Now create QR read options to have white foreground color and black background color
         Dim qrReadOptions As New QRBarcodeReadOptions()
         qrReadOptions.ForeColor = RasterColor.FromKnownColor(RasterKnownColor.White)
         qrReadOptions.BackColor = RasterColor.FromKnownColor(RasterKnownColor.Black)

         ' And use it to try to read the QR barcode again
         Console.WriteLine("Reading using specific options that instruct the engine to look for white on black barcodes")
         barcode = reader.ReadBarcode(image, LogicalRectangle.Empty, BarcodeSymbology.QR, qrReadOptions)

         ' Show its location and data if found
         ' This will find the barcode and print its information now
         If Not IsNothing(barcode) Then
            Console.WriteLine("Found at {0}, data:\n{1}", barcode.Bounds, barcode.Value)
         Else
            Console.WriteLine("Not found")
         End If
      End Using
   End Using
End Sub

Public NotInheritable Class LEAD_VARS
Public Const ImagesDir As String = "C:\Users\Public\Documents\LEADTOOLS Images"
End Class

using Leadtools;
using Leadtools.Codecs;
using Leadtools.Forms;
using Leadtools.Barcode;
using Leadtools.ImageProcessing;

public void BarcodeReader_ReadBarcodeExample2()
{
   string imageFileName = Path.Combine(LEAD_VARS.ImagesDir, "Barcode2.tif");

   // Create a Barcode engine
   BarcodeEngine engine = new BarcodeEngine();

   // Get the Barcode reader instance
   BarcodeReader reader = engine.Reader;

   using(RasterCodecs codecs = new RasterCodecs())
   {
      using(RasterImage image = codecs.Load(imageFileName, 0, CodecsLoadByteOrder.BgrOrGray, 1, 1))
      {
         // Invert the image
         Console.WriteLine("Inverting the image");
         Leadtools.ImageProcessing.Color.InvertCommand invert = new Leadtools.ImageProcessing.Color.InvertCommand();
         invert.Run(image);

         // All barcodes have default options of black foreground color and white background color, so
         // reading the barcode with default options should not return any barcodes right now

         // Read the QR barcode from this image using default options
         Console.WriteLine("Reading using default options");
         BarcodeData barcode = reader.ReadBarcode(image, LogicalRectangle.Empty, BarcodeSymbology.QR, null);

         // Show its location and data if found
         // This will print out "Not found"
         if(barcode != null)
         {
            Console.WriteLine("Found at {0}, data:\n{1}", barcode.Bounds, barcode.Value);
         }
         else
         {
            Console.WriteLine("Not found");
         }

         // Now create QR read options to have white foreground color and black background color
         QRBarcodeReadOptions qrReadOptions = new QRBarcodeReadOptions();
         qrReadOptions.ForeColor = RasterColor.FromKnownColor(RasterKnownColor.White);
         qrReadOptions.BackColor = RasterColor.FromKnownColor(RasterKnownColor.Black);

         // And use it to try to read the QR barcode again
         Console.WriteLine("Reading using specific options that instruct the engine to look for white on black barcodes");
         barcode = reader.ReadBarcode(image, LogicalRectangle.Empty, BarcodeSymbology.QR, qrReadOptions);

         // Show its location and data if found
         // This will find the barcode and print its information now
         if(barcode != null)
         {
            Console.WriteLine("Found at {0}, data:\n{1}", barcode.Bounds, barcode.Value);
         }
         else
         {
            Console.WriteLine("Not found");
         }
      }
   }
}

static class LEAD_VARS
{
public const string ImagesDir = @"C:\Users\Public\Documents\LEADTOOLS Images";
}

using Leadtools;
using Leadtools.Codecs;
using Leadtools.Forms;
using Leadtools.Barcode;
using Leadtools.ImageProcessing;
using Leadtools.Examples;

public void BarcodeReader_ReadBarcodeExample2(RasterImage image)
{
   // Create a Barcode engine
   BarcodeEngine engine = new BarcodeEngine();
   // Get the Barcode reader instance
   BarcodeReader reader = engine.Reader;

   RasterCodecs codecs = new RasterCodecs();

   // Invert the image
   Console.WriteLine("Inverting the image");
   Leadtools.ImageProcessing.Color.InvertCommand invert = new Leadtools.ImageProcessing.Color.InvertCommand();
   invert.Run(image);

   // All barcodes have default options of black foreground color and white background color, so
   // reading the barcode with default options should not return any barcodes right now

   // Read the QR barcode from this image using default options
   Console.WriteLine("Reading using default options");
   BarcodeData barcode = reader.ReadBarcode(image, LogicalRectangle.Empty, BarcodeSymbology.QR, null);

   // Show its location and data if found
   // This will print out "Not found"
   if(barcode != null)
   {
      Console.WriteLine("Found at {0}, data:\n{1}", barcode.Bounds, barcode.Value);
   }
   else
   {
      Console.WriteLine("Not found");
   }

   // Now create QR read options to have white foreground color and black background color
   QRBarcodeReadOptions qrReadOptions = new QRBarcodeReadOptions();
   qrReadOptions.ForeColor = RasterColor.FromKnownColor(RasterKnownColor.White);
   qrReadOptions.BackColor = RasterColor.FromKnownColor(RasterKnownColor.Black);

   // And use it to try to read the QR barcode again
   Console.WriteLine("Reading using specific options that instruct the engine to look for white on black barcodes");
   barcode = reader.ReadBarcode(image, LogicalRectangle.Empty, BarcodeSymbology.QR, qrReadOptions);

   // Show its location and data if found
   // This will find the barcode and print its information now
   if(barcode != null)
   {
      Console.WriteLine("Found at {0}, data:\n{1}", barcode.Bounds, barcode.Value);
   }
   else
   {
      Console.WriteLine("Not found");
   }
}

Imports Leadtools
Imports Leadtools.Codecs
Imports Leadtools.Forms
Imports Leadtools.Barcode
Imports Leadtools.ImageProcessing
Imports Leadtools.ImageProcessing.Color

Public Sub BarcodeReader_ReadBarcodeExample2(ByVal image As RasterImage)
   ' Create a Barcode engine
   Dim engine As BarcodeEngine = New BarcodeEngine()
   ' Get the Barcode reader instance
   Dim reader As BarcodeReader = engine.Reader

   Dim codecs As RasterCodecs = New RasterCodecs()

   ' Invert the image
   Console.WriteLine("Inverting the image")
   Dim invert As InvertCommand = New InvertCommand()
   invert.Run(image)

   ' All barcodes have default options of black foreground color and white background color, so
   ' reading the barcode with default options should not return any barcodes right now

   ' Read the QR barcode from this image using default options
   Console.WriteLine("Reading using default options")
   Dim barcode As BarcodeData = reader.ReadBarcode(image, LogicalRectangle.Empty, BarcodeSymbology.QR, Nothing)

   ' Show its location and data if found
   ' This will print out "Not found"
   If Not barcode Is Nothing Then
      Console.WriteLine("Found at {0}, data:" & Constants.vbLf & "{1}", barcode.Bounds, barcode.Value)
   Else
      Console.WriteLine("Not found")
   End If

   ' Now create QR read options to have white foreground color and black background color
   Dim qrReadOptions As QRBarcodeReadOptions = New QRBarcodeReadOptions()
   qrReadOptions.ForeColor = RasterColor.FromKnownColor(RasterKnownColor.White)
   qrReadOptions.BackColor = RasterColor.FromKnownColor(RasterKnownColor.Black)

   ' And use it to try to read the QR barcode again
   Console.WriteLine("Reading using specific options that instruct the engine to look for white on black barcodes")
   barcode = reader.ReadBarcode(image, LogicalRectangle.Empty, BarcodeSymbology.QR, qrReadOptions)

   ' Show its location and data if found
   ' This will find the barcode and print its information now
   If Not barcode Is Nothing Then
      Console.WriteLine("Found at {0}, data:" & Constants.vbLf & "{1}", barcode.Bounds, barcode.Value)
   Else
      Console.WriteLine("Not found")
   End If
End Sub

Requirements

Target Platforms

Reference

BarcodeReader Class
BarcodeReader Members
Overload List
ReadBarcode(RasterImage image, LogicalRectangle searchBounds, BarcodeSymbology symbology)
ReadBarcode(RasterImage image, LogicalRectangle searchBounds, BarcodeSymbology[] symbologies)
ReadBarcode(RasterImage image, LogicalRectangle searchBounds, BarcodeSymbology[] symbologies, BarcodeReadOptions[] options)
ReadBarcodes(RasterImage image, LogicalRectangle searchBounds, int maximumBarcodes, BarcodeSymbology[] symbologies)
ReadBarcodes(RasterImage image, LogicalRectangle searchBounds, int maximumBarcodes, BarcodeSymbology[] symbologies, BarcodeReadOptions[] options)
Programming with LEADTOOLS Barcode
Supported Barcode Symbologies
Unlocking Barcode Support
Reading Barcodes Tutorial