Read QR Code - VB.NET
Barcode Reader sample in VB.NET demonstrating ‘Read QR Code’
Module1.vb
Imports System.IO
Imports System.Net
Imports System.Threading
Imports Newtonsoft.Json
Imports Newtonsoft.Json.Linq
Module Module1
' The authentication key (API Key).
' Get your own by registering at https://app.pdf.co
Const API_KEY As String = "*********************************"
' Source file name
Const SourceFile As String = ".\QRCode.png"
' Comma-separated list of barcode types to search.
' See valid barcode types in the documentation https://apidocs.pdf.co
Const BarcodeTypes As String = "QRCode"
' Comma-separated list of page indices (or ranges) to process. Leave empty for all pages. Example: '0,2-5,7-'.
Const Pages As String = ""
' (!) Make asynchronous job
Const Async As Boolean = True
Sub Main()
' Create standard .NET web client instance
Dim webClient As WebClient = New WebClient()
' Set API Key
webClient.Headers.Add("x-api-key", API_KEY)
' 1. RETRIEVE THE PRESIGNED URL TO UPLOAD THE FILE.
' * If you already have a direct file URL, skip to the step 3.
' Prepare URL for `Get Presigned URL` API call
Dim query As String = Uri.EscapeUriString(String.Format(
"https://api.pdf.co/v1/file/upload/get-presigned-url?contenttype=application/octet-stream&name={0}",
Path.GetFileName(SourceFile)))
Try
' Execute request
Dim response As String = webClient.DownloadString(query)
' Parse JSON response
Dim json As JObject = JObject.Parse(response)
If json("error").ToObject(Of Boolean) = False Then
' Get URL to use for the file upload
Dim uploadUrl As String = json("presignedUrl").ToString()
' Get URL of uploaded file to use with later API calls
Dim uploadedFileUrl As String = json("url").ToString()
' 2. UPLOAD THE FILE TO CLOUD.
webClient.Headers.Add("content-type", "application/octet-stream")
webClient.UploadFile(uploadUrl, "PUT", SourceFile) ' You can use UploadData() instead if your file is byte array or Stream
' Set JSON content type
webClient.Headers.Add("Content-Type", "application/json")
' 3. READ BARCODES FROM UPLOADED FILE
' Prepare URL for `Barcode Reader` API call
Dim url As String = "https://api.pdf.co/v1/barcode/read/from/url"
' Prepare requests params as JSON
' See documentation: https : //apidocs.pdf.co
Dim parameters As New Dictionary(Of String, Object)
parameters.Add("types", BarcodeTypes)
parameters.Add("pages", Pages)
parameters.Add("url", uploadedFileUrl)
parameters.Add("async", Async)
' Convert dictionary of params to JSON
Dim jsonPayload As String = JsonConvert.SerializeObject(parameters)
Try
' Execute POST request with JSON payload
response = webClient.UploadString(url, jsonPayload)
' Parse JSON response
json = JObject.Parse(response)
If json("error").ToObject(Of Boolean) = False Then
' Asynchronous job ID
Dim jobId As String = json("jobId").ToString()
' URL of generated JSON file with decoded barcodes that will available after the job completion
Dim resultFileUrl As String = json("url").ToString()
' Check the job status in a loop.
' If you don't want to pause the main thread you can rework the code
' to use a separate thread for the status checking and completion.
Do
Dim status As String = CheckJobStatus(jobId) ' Possible statuses: "working", "failed", "aborted", "success".
' Display timestamp and status (for demo purposes)
Console.WriteLine(DateTime.Now.ToLongTimeString() + ": " + status)
If status = "success" Then
' Download generated JSON results file as string
Dim jsonFileString As String = webClient.DownloadString(resultFileUrl)
Dim jsonFoundBarcodes As JArray = JArray.Parse(jsonFileString)
' Display found barcodes in console
For Each token As JToken In jsonFoundBarcodes
Console.WriteLine("Found barcode:")
Console.WriteLine(" Type: " + token("TypeName").ToString())
Console.WriteLine(" Value: " + token("Value").ToString())
Console.WriteLine(" Document Page Index: " + token("Page").ToString())
Console.WriteLine(" Rectangle: " + token("Rect").ToString())
Console.WriteLine(" Confidence: " + token("Confidence").ToString())
Console.WriteLine()
Next
Exit Do
ElseIf status = "working" Then
' Pause for a few seconds
Thread.Sleep(3000)
Else
Console.WriteLine(status)
Exit Do
End If
Loop
Else
Console.WriteLine(json("message").ToString())
End If
Catch ex As WebException
Console.WriteLine(ex.ToString())
End Try
End If
Catch ex As WebException
Console.WriteLine(ex.ToString())
End Try
webClient.Dispose()
Console.WriteLine()
Console.WriteLine("Press any key...")
Console.ReadKey()
End Sub
''' <summary>
''' Check Job Status
''' </summary>
Function CheckJobStatus(jobId As String) As String
Using webClient As WebClient = New WebClient()
' Set API Key
webClient.Headers.Add("x-api-key", API_KEY)
Dim url As String = "https://api.pdf.co/v1/job/check?jobid=" + jobId
Dim response As String = webClient.DownloadString(url)
Dim json As JObject = JObject.Parse(response)
Return Convert.ToString(json("status"))
End Using
End Function
End Module
Resources.Designer.vb
'------------------------------------------------------------------------------
' <auto-generated>
' This code was generated by a tool.
' Runtime Version:4.0.30319.42000
'
' Changes to this file may cause incorrect behavior and will be lost if
' the code is regenerated.
' </auto-generated>
'------------------------------------------------------------------------------
Option Strict On
Option Explicit On
Namespace My.Resources
'This class was auto-generated by the StronglyTypedResourceBuilder
'class via a tool like ResGen or Visual Studio.
'To add or remove a member, edit your .ResX file then rerun ResGen
'with the /str option, or rebuild your VS project.
'''<summary>
''' A strongly-typed resource class, for looking up localized strings, etc.
'''</summary>
<Global.System.CodeDom.Compiler.GeneratedCodeAttribute("System.Resources.Tools.StronglyTypedResourceBuilder", "4.0.0.0"), _
Global.System.Diagnostics.DebuggerNonUserCodeAttribute(), _
Global.System.Runtime.CompilerServices.CompilerGeneratedAttribute(), _
Global.Microsoft.VisualBasic.HideModuleNameAttribute()> _
Friend Module Resources
Private resourceMan As Global.System.Resources.ResourceManager
Private resourceCulture As Global.System.Globalization.CultureInfo
'''<summary>
''' Returns the cached ResourceManager instance used by this class.
'''</summary>
<Global.System.ComponentModel.EditorBrowsableAttribute(Global.System.ComponentModel.EditorBrowsableState.Advanced)> _
Friend ReadOnly Property ResourceManager() As Global.System.Resources.ResourceManager
Get
If Object.ReferenceEquals(resourceMan, Nothing) Then
Dim temp As Global.System.Resources.ResourceManager = New Global.System.Resources.ResourceManager("ByteScoutWebApiExample.Resources", GetType(Resources).Assembly)
resourceMan = temp
End If
Return resourceMan
End Get
End Property
'''<summary>
''' Overrides the current thread's CurrentUICulture property for all
''' resource lookups using this strongly typed resource class.
'''</summary>
<Global.System.ComponentModel.EditorBrowsableAttribute(Global.System.ComponentModel.EditorBrowsableState.Advanced)> _
Friend Property Culture() As Global.System.Globalization.CultureInfo
Get
Return resourceCulture
End Get
Set(ByVal value As Global.System.Globalization.CultureInfo)
resourceCulture = value
End Set
End Property
End Module
End Namespace
Settings.Designer.vb
'------------------------------------------------------------------------------
' <auto-generated>
' This code was generated by a tool.
' Runtime Version:4.0.30319.42000
'
' Changes to this file may cause incorrect behavior and will be lost if
' the code is regenerated.
' </auto-generated>
'------------------------------------------------------------------------------
Option Strict On
Option Explicit On
Namespace My
<Global.System.Runtime.CompilerServices.CompilerGeneratedAttribute(), _
Global.System.CodeDom.Compiler.GeneratedCodeAttribute("Microsoft.VisualStudio.Editors.SettingsDesigner.SettingsSingleFileGenerator", "11.0.0.0"), _
Global.System.ComponentModel.EditorBrowsableAttribute(Global.System.ComponentModel.EditorBrowsableState.Advanced)> _
Partial Friend NotInheritable Class MySettings
Inherits Global.System.Configuration.ApplicationSettingsBase
Private Shared defaultInstance As MySettings = CType(Global.System.Configuration.ApplicationSettingsBase.Synchronized(New MySettings), MySettings)
#Region "My.Settings Auto-Save Functionality"
#If _MyType = "WindowsForms" Then
Private Shared addedHandler As Boolean
Private Shared addedHandlerLockObject As New Object
<Global.System.Diagnostics.DebuggerNonUserCodeAttribute(), Global.System.ComponentModel.EditorBrowsableAttribute(Global.System.ComponentModel.EditorBrowsableState.Advanced)> _
Private Shared Sub AutoSaveSettings(ByVal sender As Global.System.Object, ByVal e As Global.System.EventArgs)
If My.Application.SaveMySettingsOnExit Then
My.Settings.Save()
End If
End Sub
#End If
#End Region
Public Shared ReadOnly Property [Default]() As MySettings
Get
#If _MyType = "WindowsForms" Then
If Not addedHandler Then
SyncLock addedHandlerLockObject
If Not addedHandler Then
AddHandler My.Application.Shutdown, AddressOf AutoSaveSettings
addedHandler = True
End If
End SyncLock
End If
#End If
Return defaultInstance
End Get
End Property
End Class
End Namespace
Namespace My
<Global.Microsoft.VisualBasic.HideModuleNameAttribute(), _
Global.System.Diagnostics.DebuggerNonUserCodeAttribute(), _
Global.System.Runtime.CompilerServices.CompilerGeneratedAttribute()> _
Friend Module MySettingsProperty
<Global.System.ComponentModel.Design.HelpKeywordAttribute("My.Settings")> _
Friend ReadOnly Property Settings() As Global.ByteScoutWebApiExample.My.MySettings
Get
Return Global.ByteScoutWebApiExample.My.MySettings.Default
End Get
End Property
End Module
End Namespace
PDF.co Web API: the Web API with a set of tools for documents manipulation, data conversion, data extraction, splitting and merging of documents. Includes image recognition, built-in OCR, barcode generation and barcode decoders to decode bar codes from scans, pictures and pdf.