C# Barcode Reader: Scan QR Code, Barcode in .NET Applications

• Add .net dll OnBarcode.Barcode.BarcodeScanner.dll from {Download package}/dll/NetStandard2.0/ to your .net project
• Add NuGet Package System.Drawing.Common from NuGet Package Manager to your .net project

• Add .net dll OnBarcode.Barcode.BarcodeScanner.Skia.dll from {Download package}/dll/NetStandard2.0/ to your .net project
• Add NuGet Package SkiaSharp from NuGet Package Manager to your .net project

• Add .net dll OnBarcode.Barcode.BarcodeScanner.dll from {Download package}/dll/net40/ or /net20/ to your C# project reference

public enum BarcodeType
{
    AustraliaPost = 0,        EAN8 = 7,                 ITF14 = 14,          RM4SCC = 21,    
    Codabar = 1,              EAN13 = 8,                Leitcode = 15,       UPCA = 22,   
    Code39 = 2,               Identcode = 9,            PatchCode = 16,      UPCE = 23,    
    Code39Extension = 3,      IntelligentMail = 10,     PDF417 = 17,         All = 999   
    Code93 = 4,               Interleaved2of5 = 11,     Planet = 18,                   
    Code128 = 5,              ISBN = 12,                Postnet = 19,
    DataMatrix = 6,           ISSN = 13,                QRCode = 20,                               
}

• Use method BarcodeScanner.Scan() to read all barcodes from an image file

string[] datas = BarcodeScanner.Scan("code128-barcode.png", BarcodeType.Code128);

BarcodeDetail[] datasInDetail = BarcodeScanner.ScanInDetails(
    "code128-barcode.png", BarcodeType.Code128);

• Use method BarcodeScanner.Scan() to read all barcodes from an image Stream object

string[] datas = BarcodeScanner.Scan(imageObject, BarcodeType.Code128);

BarcodeDetail[] datasInDetail = BarcodeScanner.ScanInDetails(
    imageObject, BarcodeType.Code128);

• Use method BarcodeScanner.ScanSingleBarcode() to read all barcodes from an image file

string[] barcodes = BarcodeScanner.ScanSingleBarcode(
    "code39-image.gif", BarcodeType.Code39); 

• SetScanRegions(): enable to scan specified regions inside the image file. It will speed up the reading speed, and improve the reading accuracy. View more details: How to read barcodes from specified regions in image in C#?
• SetMaxMultiThreadCount(): enable to scan barcodes using multi-threading in C#. View details here: How to scan, read barcodes in multithreading using C#?
• ScanSingle: enable to scan maximum one barcode per image file. It will improve the reading speed, if there is only one barcode in one image file.
• EnableGS1: enable to read and parse GS1 data elements from GS1 compatible barcodes, such as QR Code, Data Matrix, GS1-128, GS1 DataBar. More details, view here: How to read and parse GS1 barcode using C#?
• ScanDirection: Specify the barcode library image scanning direction to speed up the barcode reading speed.
• StepInterval: When defining the barcode search area, the scanning spacing is used, which indicates how many lines are scanned at a time.
• ZoomRatio: Valid range: 0.2F - 5.0F. Default is 1.0F. Apply scanned image zooming.

• Rotation: find the rotation angle about the scanned barcode.


• X1, Y1, X2, Y2, X3, Y3, X4, Y4: 8 properties which define the scanned barcode region on the image file.


• IsStructuredAppend: It is for QR Code and Data Matrix barcodes only. To identify whether the QR Code or Data Matrix barcode is in Structure Append mode. If so, you need combine the scanned barcode data with other barcodes from the same message. You can view the details here:
  How to read barcode data in Structure Append mode in C#.net?


• IsGS1Compitable: It is for QR Code, Data Matrix and Code 128 barcodes only. To identify whether the found barcode is GS1 compatible. Know more information, view here:
  How to read GS1 barcode data using C#?


• Method isMacroPDF417(): It is for PDF417 barcodes only. View more information about Macro PDF417 barcode reading in C#:
  How to read Macro PDF417 barcodes using C#?


• Method GetDataBytes(). You can get the read barcode data in byte array.


• Method GetMessage(), GetMessage(Encoding enc). You can get the scanned barcode data using default UTF8 encoding or your specified encoding format.

• The C# example code below explains how to get all QR Code barcodes from a png image file using C#

string[] datas = BarcodeScanner.Scan("qrcode-barcode.png", BarcodeType.QRCode);

• Using the following C# code, the barcode library will scan the specified region in the image only, and return all QR Code barcodes from the target area.

List<SRegion> region = new List<SRegion>();
region.Add(new SRegion(0, 0, 50, 60));

string[] barcodes = BarcodeScanner.ScanRegions(
    "qrcode-barcodes.png", BarcodeType.QRCode, region);

• Undefined. Default value is the same as All.
• LeftToRight. The library will scan the barcode image from left to right.
• TopToBottom. The library will scan the barcode image from top to bottom.
• RightToLeft. The library will scan the barcode image from right to left.
• BottomToTop. The library will scan the barcode image from bottom to top.
• Horizontal. Scan the barcode image from left to right, and right to left.
• Vertical. Scan the barcode image from top to bottom, and bottom to top.
• All. The barcode reader sdk will scan the barcode image from 4 different directions. Left to right, right to left, top to bottom, and bottom to top.

ScanOptions ops = new ScanOptions(BarcodeType.Code128);
ops.ScanDirection = ScanDirectionType.All;

ops.ScanDirection = ScanDirectionType.LeftToRight | ScanDirectionType.TopToBottom;

• ScanDirectionType.All. Scan bacode with all four different directions.
• ScanDirectionType.Horizontal. Scan barcode with two directions: from left to right, and from right to left.
• ScanDirectionType.LeftToRight. Scan with one direction only, from left to right.
• ScanDirectionType.LeftToRight | ScanDirectionType.TopToBottom. Scan with two diretions, from left to right, from top to bottom.

private static void readBarcodeSingleRound()
{
    ScanOptions ops = new ScanOptions(BarcodeType.Code128);
    ops.ScanDirection = ScanDirectionType.All;
    //ops.ScanDirection = ScanDirectionType.Horizontal;
    //ops.ScanDirection = ScanDirectionType.LeftToRight;
    //ops.ScanDirection = ScanDirectionType.LeftToRight | ScanDirectionType.TopToBottom;
    BarcodeDetail[] result = BarcodeScanner.Scan(
        "C:\\Input\\barcode-code128-demo-image.png", ops);
    if (result.Length > 0)
    {
         Debug.WriteLine("Count: " + result.Length);
         foreach (BarcodeDetail b in result)
         Debug.WriteLine("Message: '{0}'", b.GetMessage());
     }
     else
         Debug.WriteLine("No Barcode Found.");
}

System.Diagnostics.Stopwatch sw = new System.Diagnostics.Stopwatch();
sw.Start();
for (int round = 0; round < 10; round++)
    readBarcodeSingleRound();
float totalTime = (float)sw.ElapsedMilliseconds / 1000F;
Debug.WriteLine("Time: {0:F3}s; Ave.: {1:F3}s", totalTime, totalTime / 10F);

ScanDirectionType.All	ScanDirectionType.LeftToRight | ScanDirectionType.TopToBottom
ScanDirectionType.LeftToRight	ScanDirectionType.Horizontal

• Based on the rotation angle, the appropriate scanning direction needs to be selected for barcode recognition.
  
  For example, a bsarcode that has not been rotated requires the Left to Right scanning direction for recognition; a barcode rotated by 90 degrees needs the Top to Bottom scanning direction.


• Generally speaking, the more scanning directions are selected, the longer the time will be consumed.
  
  For instance, using Horizontal will scan in two directions, taking more time than one direction LeftToRight (0.205s vs 0.150s)


• The main time consumption lies in the inspection and identification of candidate barcodes.
  
  For example, scanning LeftToRight and TopToBottom can identify two Code 128 barcodes, with a time consumption of 0.235s, which is greater than 0.205s (Horizontal). While scanning all four directions takes 0.241s, which is not significantly different from 0.235s.

• StepInterval: Specify the scanning spacing, which indicates how many lines are scanned at a time.
  The minimum value is 1, and every row will be scanned.
  Default value: 5 (scan once every 5 lines)

ScanOptions ops = new ScanOptions(BarcodeType.Code128);
ops.ScanDirection = ScanDirectionType.LeftToRight;
ops.StepInterval = 5; // Default
//ops.StepInterval = 1;
//ops.StepInterval = 10;
//ops.StepInterval = 83;

StepInterval = 1	StepInterval = 5
StepInterval = 10	StepInterval = 83

• When searching for a barcode, a larger interval (assuming all other conditions are the same) usually results in less time consumption.
  
  For example, scanning each pixel line versus scanning every 5 lines, the time consumption comparison is 0.257s vs 0.151s.


• If the spacing is too large, the barcode may be skipped, resulting in no barcodes detected from the image. (Whether it will be skipped depends on two factors: the height and position of the barcode.).
  
  For example, the demo image uses StepInterval = 83 for scanning, and the barcode library cannot detect the barcode.

• Create a ScanOptions with barcode format to scane
• Set maximum 3 threads through method SetMaxMultiThreadCount() in ScanOptions
• Using Scan() method in BarcodeScanner to read barcodes customized with ScanOptions

            ScanOptions options = new ScanOptions(BarcodeType.QRCode);
            //  Set maximum number of threads could be used in the scanning.
            //  The valud must be non-negative.
            //  0: disable multi-thread (Default Value)
            //  >0: using multi-thread
            options.SetMaxMultiThreadCount(3);
            BarcodeDetail[] result = BarcodeScanner.Scan(
                new String[] {
                    "SourceImage01.png",
                    "SourceImage02.png",
                    "SourceImage03.png"
                }, options);

            foreach (BarcodeDetail obj in result)
            {
                //  Report result ... 
            }