Back to All Tutorials (5)
Convert HTML to PDF by using Visual Basic
In this tutorial we will cover how to implement asynchronous approach of Web Renderer. You only need to send HTML content to SubmitPDFFromHTMLTask or SubmitImageFromHTMLTask API methods to receive task identifier as response. There is also SubmitPDFFromUrlTask and SubmitImageFromUrlTask methods to render PDF or Image from public Web Uri.
After receiving task identifier you need to check task status by calling GetRenderingTaskStatus method. You need to call same method after a few seconds delay as long as task status equals to “Waiting”. Once you receive “Completed” from GetRenderingTaskStatus method you can call DownloadResult method to download final file. You can use the Visual Basic implementation below.
Imports System
Imports System.IO
Imports System.Net.Http
Module Program
Async Function SubmitPDFFromHTMLTask(htmlContent As String, uri As String, rapidApiKey As String) As Task(Of String)
Using httpClient As New HttpClient()
Using form As New MultipartFormDataContent()
form.Headers.Add("X-RapidAPI-Key", rapidApiKey)
form.Add(New StringContent(uri), "uri")
form.Add(New StringContent("false"), "useCompression")
form.Add(New StringContent("Home Page"), "pageLabel")
form.Add(New StringContent("Initial Capture"), "messageLabel")
form.Add(New StringContent("768"), "browserHeight")
form.Add(New StringContent("1024"), "browserWidth")
form.Add(New StringContent(htmlContent), "htmlContent")
Using response = Await httpClient.PostAsync("https://web-renderer.p.rapidapi.com/SubmitPDFFromHTMLTask", form)
response.EnsureSuccessStatusCode()
Return Await response.Content.ReadAsStringAsync()
End Using
End Using
End Using
End Function
Async Function GetRenderingTaskStatus(taskId As String, rapidApiKey As String) As Task(Of String)
Using httpClient As New HttpClient()
httpClient.DefaultRequestHeaders.Add("X-RapidAPI-Key", rapidApiKey)
Using response = Await httpClient.GetAsync($"https://web-renderer.p.rapidapi.com/GetRenderingTaskStatus?taskId={taskId}")
response.EnsureSuccessStatusCode()
Return Await response.Content.ReadAsStringAsync()
End Using
End Using
End Function
Async Function DownloadResult(taskId As String, rapidApiKey As String) As Task(Of Byte())
Using httpClient As New HttpClient()
httpClient.DefaultRequestHeaders.Add("X-RapidAPI-Key", rapidApiKey)
Using response = Await httpClient.GetAsync($"https://web-renderer.p.rapidapi.com/DownloadResult?taskId={taskId}")
response.EnsureSuccessStatusCode()
Return Await response.Content.ReadAsByteArrayAsync()
End Using
End Using
End Function
Public Async Function RenderHtmlAsync() As Task
Dim rapidApiKey = "<YOUR RAPIDAPI KEY HERE>"
Dim htmlContent = "<HTML CONTENT TO RENDER>"
Dim uriOfHtmlContent = "https://www.google.com?hl=en"
Dim taskId = Await SubmitPDFFromHTMLTask(htmlContent, uriOfHtmlContent, rapidApiKey)
Dim retryCount = 0
Do While (retryCount < 100)
retryCount += 1
Await Task.Delay(5000)
Dim status = Await GetRenderingTaskStatus(taskId, rapidApiKey)
If (status = "Completed") Then
Dim fileBytes = Await DownloadResult(taskId, rapidApiKey)
Await File.WriteAllBytesAsync("html_from_html.pdf", fileBytes)
Exit Do
ElseIf (status = "Waiting") Then
Continue Do
ElseIf (status = "Failed") Then
Throw New Exception("Cannot convert file")
Else
Throw New Exception("Invalid status")
End If
Loop
End Function
Sub Main(args As String())
RenderHtmlAsync().Wait()
End Sub
End Module