BarcodeReadSymbologyEventArgs Class

Summary

Contains data for the ReadSymbology event.

Syntax

Objective-C

C++/CLI

Java

Python

public class BarcodeReadSymbologyEventArgs : EventArgs

@interface LTBarcodeReadSymbologyEventArgs : NSObject

public class BarcodeReadSymbologyEvent extends LeadEvent

public ref class BarcodeReadSymbologyEventArgs : public System.EventArgs

class BarcodeReadSymbologyEventArgs(EventArgs):

Remarks

You can use the ReadSymbology event to obtain information and set the status of the current barcode reading operation.

When reading barcodes using BarcodeReader.ReadBarcode or BarcodeReader.ReadBarcodes, the BarcodeReader object will fire the ReadSymbology event multiple times depending on the symbologies being read.

LEADTOOLS barcode reading is designed for speed and multiple barcode symbologies can be read (or searched for) in one operation as these barcodes share similar characteristics. Therefore, the symbologies being read are stored in a BarcodeSymbology array and can be obtained with the BarcodeReadSymbologyEventArgs.GetSymbologies method.

The following table lists the event members and their meanings:

Member	Description
Operation	Can be either BarcodeReadSymbologyOperation.PreRead if the BarcodeReader is about to try reading the symbologies or BarcodeReadSymbologyOperation.PreRead when the reader has finished reading the objects.
GetSymbologies	Will return the current symbologies being searched for or that have been read.
Options	The BarcodeReadOptions or one of its derived classes that specify the options being used to read the symbologies. This could be the options passed through the read methods or the default options set in BarcodeReader.
Data	A BarcodeData object that contains the data of the barcode found. Only valid if Operation is BarcodeReadSymbologyOperation.PostRead and no error occurred. Otherwise, it will be null (Nothing in Visual Basic).
Error	An Exception object that contains any error encountered during the current operation. If no errors are encountered, then this member will be null (Nothing in Visual Basic).
Status	The status of the operation. The BarcodeReader will always set this member to BarcodeReadSymbologyEventArgs.Continue, which means proceed to the next phase of the read operation. You can set this member to BarcodeReadSymbologyStatus.Skip to skip reading the current symbologies (only when Operation is BarcodeReadSymbologyOperation.PreRead) or to abort the whole read operation by setting it to BarcodeReadSymbologyStatus.Abort.

Example

Java

using Leadtools; 
using Leadtools.Codecs; 
using Leadtools.Barcode; 
using Leadtools.ImageProcessing; 
 
 
public void BarcodeReader_ReadSymbologyExample() 
{ 
   string imageFileName = Path.Combine(LEAD_VARS.ImagesDir, "Barcode1.tif"); 
 
   // Create a Barcode engine 
   BarcodeEngine engine = new BarcodeEngine(); 
 
   // Get the Barcode reader instance 
   BarcodeReader reader = engine.Reader; 
          
   // Load the image 
   using (RasterCodecs codecs = new RasterCodecs()) 
   { 
      using (RasterImage image = codecs.Load(imageFileName, 0, CodecsLoadByteOrder.BgrOrGray, 1, 1)) 
      { 
         // Subscribe to the ReadSymbology event 
         reader.ReadSymbology += new EventHandler<BarcodeReadSymbologyEventArgs>(reader_ReadSymbology); 
         // Read all barcodes in the image 
         reader.ReadBarcodes(image, LeadRect.Empty, 0, null); 
         reader.ReadSymbology -= new EventHandler<BarcodeReadSymbologyEventArgs>(reader_ReadSymbology); 
      } 
   } 
} 
 
private void reader_ReadSymbology(object sender, BarcodeReadSymbologyEventArgs e) 
{ 
   if (e.Operation == BarcodeReadSymbologyOperation.PreRead) 
   { 
      // Before reading, show the symbologies the engine is going to try to read 
      Console.WriteLine("Trying to read the following symbologies:"); 
      BarcodeSymbology[] symbologies = e.GetSymbologies(); 
      for (int i = 0; i < symbologies.Length; i++) 
      { 
         Console.Write(symbologies[i]); 
         if (i != (symbologies.Length - 1)) 
         { 
            Console.Write(", "); 
            Console.WriteLine(e.Options.FriendlyName); 
         } 
         else 
         { 
            Console.WriteLine(); 
         } 
      } 
   } 
   else if (e.Operation == BarcodeReadSymbologyOperation.PostRead) 
   { 
      if (e.Error == null) 
      { 
         // No errors 
         BarcodeData barcode = e.Data; 
         if (barcode != null) 
         { 
            // Found a barcode, show it 
            Console.WriteLine("  {0} at {1} with data {2}", barcode.Symbology, barcode.Bounds, barcode.Value); 
         } 
         else 
         { 
            Console.WriteLine("  No barcodes found"); 
         } 
      } 
      else 
      { 
         // Show the error 
         Console.WriteLine("Error: {0}", e.Error.Message); 
 
         // Tell the reader top stop reading barcodes 
         e.Status = BarcodeReadSymbologyStatus.Abort; 
      } 
   } 
} 
 
static class LEAD_VARS 
{ 
   public const string ImagesDir = @"C:\LEADTOOLS23\Resources\Images"; 
}

 
import java.io.File; 
import java.io.IOException; 
import java.util.*; 
import java.util.concurrent.ExecutorService; 
import java.util.concurrent.Executors; 
 
import org.junit.*; 
import org.junit.Test; 
import org.junit.runner.JUnitCore; 
import org.junit.runner.Result; 
import org.junit.runner.notification.Failure; 
import static org.junit.Assert.*; 
 
import leadtools.*; 
import leadtools.barcode.*; 
import leadtools.codecs.*; 
import leadtools.imageprocessing.*; 
import leadtools.internal.ManualResetEvent; 
 
 
public void barcodeReaderReadSymbologyExample() { 
   final String LEAD_VARS_IMAGES_DIR = "C:\\LEADTOOLS23\\Resources\\Images"; 
   String imageFileName = combine(LEAD_VARS_IMAGES_DIR, "barcode1.tif"); 
 
   // Create a Barcode engine 
   BarcodeEngine engine = new BarcodeEngine(); 
 
   // Get the Barcode reader instance 
   BarcodeReader reader = engine.getReader(); 
 
   // Load the image 
   RasterCodecs codecs = new RasterCodecs(); 
 
   RasterImage image = codecs.load(imageFileName, 0, CodecsLoadByteOrder.BGR_OR_GRAY, 1, 1); 
   codecs.save(image, "Result.jpg", RasterImageFormat.JPEG, 0); 
 
   // Subscribe to the ReadSymbology event 
   reader.addReadSymbologyListener(readerReadSymbology); 
 
   // Read all barcodes in the image 
   reader.readBarcodes(image, LeadRect.getEmpty(), 0, null); 
   reader.removeReadSymbologyListener(readerReadSymbology); 
 
   assertTrue("Image unsuccessfully saved", (new File("Result.jpg")).exists()); 
   System.out.printf("Image loaded and saved to %s%n", new File("Result.jpg")); 
} 
 
BarcodeReadSymbologyListener readerReadSymbology = new BarcodeReadSymbologyListener() { 
 
   @Override 
   public void onReadSymbologyEvent(BarcodeReadSymbologyEvent arg0) { 
 
      if (arg0.getOperation() == BarcodeReadSymbologyOperation.PRE_READ) { 
 
         // Before reading, show the symbologies the engine is going to try to read 
         System.out.println("Trying to read the following symbologies:"); 
         BarcodeSymbology[] symbologies = arg0.getSymbologies(); 
 
         for (int i = 0; i < symbologies.length; i++) { 
            System.out.print(symbologies[i]); 
 
            if (i != (symbologies.length - 1)) { 
               System.out.print(", "); 
               System.out.println(arg0.getOptions().getFriendlyName()); 
 
            } else { 
               System.out.println(" "); 
            } 
         } 
      } 
 
      else if (arg0.getOperation() == BarcodeReadSymbologyOperation.POST_READ) { 
 
         if (arg0.getError() == null) { 
 
            // No errors 
            BarcodeData barcode = arg0.getData(); 
 
            if (barcode != null) { 
 
               // Found a barcode, show it 
               System.out.printf("  %1s at %2s with data %3s%n", barcode.getSymbology(), barcode.getBounds(), 
                     barcode.getValue()); 
            } else { 
               System.out.println("  No barcodes found"); 
            } 
         } else { 
            // Show the error 
            System.out.printf("Error: %1s%n", arg0.getError().getMessage()); 
 
            // Tell the reader top stop reading barcodes 
            arg0.setStatus(BarcodeReadSymbologyStatus.ABORT); 
         } 
      } 
   } 
 
};

Requirements

Target Platforms

Reference

BarcodeReadSymbologyEventArgs Members

Leadtools.Barcode Namespace

BarcodeReader.ReadSymbology

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Help Version 23.0.2024.2.29

Leadtools.Barcode Assembly

Introduction

Getting Started

Namespaces

Leadtools.Barcode Namespace

Assemblies