VB.NET writing comments to jpeg file programmatically - vb.net

Question

I searched stackoverflow and I realized that GetPropertyItem and SetPropertyItem can edit comments in JPEG file
Dim images As Image = System.Drawing.Image.FromFile("C:\\Sample.jpeg")
Dim MSGF As New ArrayList
Dim ID() As String = {"hello ","i am here"}
Dim propItem As PropertyItem = images.GetPropertyItem(40092)
Dim encoderParameters As New EncoderParameters(1)
encoderParameters.Param(0) = New EncoderParameter(Encoder.Quality, 100L)
For i = 0 To ID.Length - 1
Dim TEMP As String = ID(i)
For II = 0 To TEMP.Length - 1
MSGF.Add(Convert.ToInt32(TEMP(II)))
Next
Next
For i = 0 To MSGF.Count - 1
propItem.Value.SetValue(Convert.ToByte(MSGF(i)), i)
Next
images.SetPropertyItem(propItem)
images.Save(TextBox1.Text & "\" & "1" & TextBox2.Text)
What I realized was I can get comments from jpeg file by GetPropertyItem. However, comments is based on the ascii code. Therefore, I was trying to convert comment that I wanted to insert to ascii code.
propItem.Value.SetValue(Convert.ToByte(MSGF(i)), i)
This part was actually changed comments which already existed in the jpeg file.
However, if there is no comments in jpeg file, propItem.value.setValue doesn't work because there is nothing to edit.
Is there anyway to just add comments to jpeg file?

Answer 1

Based on this answer in C#, it could be as simple as this:
Dim jpeg = New JpegMetadataAdapter(pathToJpeg)
jpeg.Metadata.Comment = "Some comments"
jpeg.Metadata.Title = "A title"
jpeg.Save()
' Saves the jpeg in-place
jpeg.SaveAs(someNewPath)
' Saves with a new path
Here is the class:
Public Class JpegMetadataAdapter
Private ReadOnly path As String
Private frame As BitmapFrame
Public ReadOnly Metadata As BitmapMetadata
Public Sub New(path As String)
Me.path = path
frame = getBitmapFrame(path)
Metadata = DirectCast(frame.Metadata.Clone(), BitmapMetadata)
End Sub
Public Sub Save()
SaveAs(path)
End Sub
Public Sub SaveAs(path As String)
Dim encoder As New JpegBitmapEncoder()
encoder.Frames.Add(BitmapFrame.Create(frame, frame.Thumbnail, Metadata, frame.ColorContexts))
Using stream As Stream = File.Open(path, FileMode.Create, FileAccess.ReadWrite)
encoder.Save(stream)
End Using
End Sub
Private Function getBitmapFrame(path As String) As BitmapFrame
Dim decoder As BitmapDecoder = Nothing
Using stream As Stream = File.Open(path, FileMode.Open, FileAccess.ReadWrite, FileShare.None)
decoder = New JpegBitmapDecoder(stream, BitmapCreateOptions.PreservePixelFormat, BitmapCacheOption.OnLoad)
End Using
Return decoder.Frames(0)
End Function
End Class