ByteScout Cloud API Server – PDF To Image API – VB.NET – Convert PDF To PNG From Uploaded File

On-demand (REST Web API) version:
 Web API (on-demand version)

On-premise offline SDK for Windows:
 60 Day Free Trial (on-premise)

Module1.vb

      
Imports System.IO
Imports System.Net
Imports Newtonsoft.Json.Linq

' Please NOTE: In this sample we're assuming Cloud Api Server is hosted at "https://localhost". 
' If it's not then please replace this with with your hosting url.
Module Module1

 	' Source PDF file
	const SourceFile as String = ".\sample.pdf"
	' Comma-separated list of page indices (or ranges) to process. Leave empty for all pages. Example: '0,2-5,7-'.
	const Pages as String = ""
	' PDF document password. Leave empty for unprotected documents.
	const Password as String = ""
	
	Sub Main()

		' Create standard .NET web client instance
		Dim webClient As WebClient = New WebClient()

		' 1. RETRIEVE THE PRESIGNED URL TO UPLOAD THE FILE.
		' * If you already have the 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://localhost/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
				
				' 3. CONVERT UPLOADED PDF FILE TO PNG

				' Prepare URL for `PDF To PNG` API call
				query = Uri.EscapeUriString(String.Format(
					"https://localhost/pdf/convert/to/png?password={0}&pages={1}&url={2}",
					Password,
					Pages,
					uploadedFileUrl))

				' Execute request
				response = webClient.DownloadString(query)

				' Parse JSON response
				json = JObject.Parse(response)

				If json("error").ToObject(Of Boolean) = False Then
				
					' Download generated PNG files
					Dim page As Integer = 1
					For Each token As JToken In json("urls")
					
						Dim resultFileUrl As string = token.ToString()
						Dim localFileName As String = String.Format(".\page{0}.png", page)

						webClient.DownloadFile(resultFileUrl, localFileName)

						Console.WriteLine("Downloaded ""{0}"".", localFileName)
						page = page + 1

					Next

				Else 
					Console.WriteLine(json("message").ToString())
				End If

			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

End Module

    

ON-PREMISE OFFLINE SDK

60 Day Free Trial or Visit ByteScout Cloud API Server Home Page

Explore ByteScout Cloud API Server Documentation

Explore Samples

Sign Up for ByteScout Cloud API Server Online Training

ON-DEMAND REST WEB API

Get Your API Key

Explore Web API Docs

Explore Web API Samples

packages.config

      
<?xml version="1.0" encoding="utf-8"?>
<packages>
  <package id="Newtonsoft.Json" version="10.0.3" targetFramework="net40" />
</packages>
    

ON-PREMISE OFFLINE SDK

60 Day Free Trial or Visit ByteScout Cloud API Server Home Page

Explore ByteScout Cloud API Server Documentation

Explore Samples

Sign Up for ByteScout Cloud API Server Online Training

ON-DEMAND REST WEB API

Get Your API Key

Explore Web API Docs

Explore Web API Samples

ON-PREMISE OFFLINE SDK

60 Day Free Trial or Visit ByteScout Cloud API Server Home Page

Explore ByteScout Cloud API Server Documentation

Explore Samples

Sign Up for ByteScout Cloud API Server Online Training

ON-DEMAND REST WEB API

Get Your API Key

Explore Web API Docs

Explore Web API Samples