OpenAI Dall-E- Client

• Download vivacityDallEClient.zip - 481.5 KB

Introduction

The code send a request in JSON format to OpenAI image generation endpoint, composing a standard request to generate 1 single image using the Dall-E-2 model and standard quality size 512x512; the response in JSON format is deserialized, and the image URL is extracted and shown in a Picturebox

Using the code

The code is composed of a single long procedure that manages sending the request and getting the response; two minor procedures enable to manage the prompt textbox and to save the image to a local disk.

The code makes use of the following imports:

Imports System.Net
Imports System.IO
Imports System.Configuration
Imports System.Security.Cryptography
Imports System.Net.SecurityProtocolType
Imports System.Threading.Tasks
Imports System.ComponentModel

The dedicated form contains:

• a textbox for the prompt
• a textbox for the OpenAI API Key
• a pictureBox to show the image url
• a button to send the request
• a button to save the image
• a textbox showing the activity log (a sort of console)

The btnSend_Click event triggers all the magic!

The first operation is to set up the request and JSONify it:

logTxt.Text = "Sending request..." & vbCrLf

System.Net.ServicePointManager.SecurityProtocol = DirectCast(3072, System.Net.SecurityProtocolType)

Dim apiEndpoint As String = "https://api.openai.com/v1/images/generations"
Dim apiKey As String = ApiKeyTextBox.Text
Dim prompt As String = PromptTextBox.Text
Dim model As String = "dall-e-2"
Dim numberofimages As String = "1"
Dim imagesize As String = "512x512"

' Creation of HTTP request
Dim request As HttpWebRequest = WebRequest.Create(apiEndpoint)
request.Method = "POST"
request.ContentType = "application/json"
request.Headers.Add("Authorization", "Bearer " & apiKey)

' Creation of JSON request
Dim data As String = "{"
data += " ""model"": """ & model & ""","
data += " ""prompt"": """ & prompt & ""","
data += " ""n"": 1,"
data += " ""size"": """ & imagesize & """"
data += "}"
logTxt.Text += "Request grammar: " & data.ToString & vbCrLf
' Write body of request
Using streamWriter As New StreamWriter(request.GetRequestStream())
    streamWriter.Write(data)

End Using

The second step is to gather the response and deserialize it.

Dim response As HttpWebResponse = Nothing

Try
    response = CType(request.GetResponse(), HttpWebResponse)

    'Getting JSON format
    Dim responseStream As Stream = response.GetResponseStream()
    Dim reader As New StreamReader(responseStream)
    Dim jsonResponse As String = reader.ReadToEnd()
    logTxt.Text += "Receiving response..." & vbCrLf

    reader.Close()
    responseStream.Close()

    'Deserializing JSON response
    Dim oJavaScriptSerializer As New System.Web.Script.Serialization.JavaScriptSerializer
    Dim oJson As Hashtable = oJavaScriptSerializer.Deserialize(Of Hashtable)(jsonResponse)
    logTxt.Text += "Response received: " & jsonResponse.ToString & vbCrLf

Once done, we can intercept the image url and show it in the PictureBox:

'Extracting the image URL
Dim imageUrl As String = oJson("data")(0)("url").ToString()

' Visualizing the image
Dim imageClient As New WebClient()
Dim imageData As Byte() = imageClient.DownloadData(imageUrl)

Using ms As New MemoryStream(imageData)
    PictureBox1.Image = Image.FromStream(ms)
End Using
saveBtn.Visible = True

There is some simple error handling to be done:

Catch ex As WebException
    'simple error handling
    MessageBox.Show("Web error: " & ex.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error)

Finally
    If response IsNot Nothing Then
        response.Close()
    End If
End Try

For the sake of completeness, here is reported the routine to save the image to a local disc:

If PictureBox1.Image IsNot Nothing Then
    Dim saveDialog As New SaveFileDialog()
    saveDialog.Filter = "JPG Image|*.jpg"
    saveDialog.Title = "Save Image"

    If saveDialog.ShowDialog() = DialogResult.OK Then
        PictureBox1.Image.Save(saveDialog.FileName, Imaging.ImageFormat.Jpeg)
        MessageBox.Show("Imge saved correctly!", "Save Image", MessageBoxButtons.OK, MessageBoxIcon.Information)
    End If
Else
    MessageBox.Show("Image could not be saved.", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error)
End If

Points of Interest

The major interest in the code is to interrogate OpenAI API via VB.NET without having to depend on Python or NodeJS, the two main technologies used in this kind of operations and the only 2 supported by OpenAI in their documentation.

VB.NET still allows desktop developers to interact with modern technologies, especially without depending on 3rd-parties libraries.

History

Version 1.0 - May 13th 2024