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Advanced JPEG Conversation Options | VB.NET
Module1.vb:
VB
Imports System.IO Imports System.Net Imports System.Threading Imports Newtonsoft.Json Imports Newtonsoft.Json.Linq ' Cloud API asynchronous "PDF To JPEG" job example. ' Allows to avoid timeout errors when processing huge or scanned PDF documents. ' The following options are available through profiles: ' (JSON can be single/double-quoted and contain comments.) ' { ' "profiles": [ ' { ' "profile1": { ' "TextSmoothingMode": "HighQuality", // Valid values: "HighSpeed", "HighQuality" ' "VectorSmoothingMode": "HighQuality", // Valid values: "HighSpeed", "HighQuality" ' "ImageInterpolationMode": "HighQuality", // Valid values: "HighSpeed", "HighQuality" ' "RenderTextObjects": true, // Valid values: true, false ' "RenderVectorObjects": true, // Valid values: true, false ' "RenderImageObjects": true, // Valid values: true, false ' "RenderCurveVectorObjects": true, // Valid values: true, false ' "JPEGQuality": 85, // from 0 (lowest) to 100 (highest) ' "TIFFCompression": "LZW", // Valid values: "None", "LZW", "CCITT3", "CCITT4", "RLE" ' "RotateFlipType": "RotateNoneFlipNone", // RotateFlipType enum values from here: https://docs.microsoft.com/en-us/dotnet/api/system.drawing.rotatefliptype?view=netframework-2.0 ' "ImageBitsPerPixel": "BPP24", // Valid values: "BPP1", "BPP8", "BPP24", "BPP32" ' "OneBitConversionAlgorithm": "OtsuThreshold", // Valid values: "OtsuThreshold", "BayerOrderedDithering" ' "FontHintingMode": "Default", // Valid values: "Default", "Stronger" ' "NightMode": false // Valid values: true, false ' } ' } ' ] ' } Module Module1 ' The authentication key (API Key). ' Get your own by registering at https://app.pdf.co/documentation/api Const API_KEY As String = "***********************************" ' Source PDF file Const SourceFileUrl As String = "https://bytescout-com.s3.amazonaws.com/files/demo-files/cloud-api/pdf-to-image/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 = "" ' (!) Make asynchronous job Const Async As Boolean = True ' Advanced options Const Profiles As String = "{ 'profiles': [ { 'profile1': { 'JPEGQuality': '25' } } ] }" 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) ' Set JSON content type webClient.Headers.Add("Content-Type", "application/json") ' Prepare URL for `PDF To JPEG` API call Dim url As String = "https://api.pdf.co/v1/pdf/convert/to/jpg" ' Prepare requests params as JSON ' See documentation: https : //apidocs.pdf.co Dim parameters As New Dictionary(Of String, Object) parameters.Add("password", Password) parameters.Add("pages", Pages) parameters.Add("url", SourceFileUrl) parameters.Add("async", Async) parameters.Add("profiles", Profiles) ' Convert dictionary of params to JSON Dim jsonPayload As String = JsonConvert.SerializeObject(parameters) Try ' Execute POST request with JSON payload Dim response As String = webClient.UploadString(url, jsonPayload) ' Parse JSON response Dim json As JObject = 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 available after the job completion; it will contain URLs of result JPEG files. Dim resultJsonFileUrl 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 JSON file as string Dim jsonFileString As String = webClient.DownloadString(resultJsonFileUrl) Dim resultFilesUrls As JArray = JArray.Parse(jsonFileString) ' Download generated JPEG files Dim page As Integer = 1 For Each token As JToken In resultFilesUrls Dim resultFileUrl As String = token.ToString() Dim localFileName As String = String.Format(".\page{0}.jpg", page) webClient.DownloadFile(resultFileUrl, localFileName) Console.WriteLine("Downloaded ""{0}"".", localFileName) page = page + 1 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 webClient.Dispose() Console.WriteLine() Console.WriteLine("Press any key...") Console.ReadKey() End Sub 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