VB.NET

Decode Base64 Image String (GIF, JPG, etc.) and Save to File

I have an XML response that includes a base 64 encoded image string (UPS label). It's a huge string and I need to save it as a gif file on my users pc.

This example shows how to do it..

VB.NET

Dim success As Boolean = False

Dim bd As New Chilkat.BinData

' I created an extra-small GIF image for this example..
success = bd.LoadFile("qa_data/gif/xsmall.gif")
If (success <> True) Then
    Debug.WriteLine("Failed to load GIF image file.")
    Exit Sub
End If


' Show GIF bytes as base64:
Debug.WriteLine(bd.GetEncoded("base64"))

' This particular GIF in base64 is this:
' R0lGODlhBQAFAMQAAAAAAP////z8/PHx8evr6+jo6OHh4d7e3sPDw8LCwpqamo2NjWxsbGRkZFpaWk1NTUtLS0hISCwsLCQkJP///wAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAACH5BAEAABQALAAAAAAFAAUAAAUTYCAYQUBAU1lI0TIgztE8jFImIQA7

' Let's begin with an XML string:
Dim x As String = "<abc><def>R0lGODlhBQAFAMQAAAAAAP////z8/PHx8evr6+jo6OHh4d7e3sPDw8LCwpqamo2NjWxsbGRkZFpaWk1NTUtLS0hISCwsLCQkJP///wAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAACH5BAEAABQALAAAAAAFAAUAAAUTYCAYQUBAU1lI0TIgztE8jFImIQA7</def></abc>"

Dim xml As New Chilkat.Xml
success = xml.LoadXml(x)

' Get the base64 string:
Dim gifBase64 As String = xml.GetChildContent("def")

Debug.WriteLine(gifBase64)

' Load bd with the base64 decoded bytes.  
bd.Clear()
bd.AppendEncoded(gifBase64,"base64")

' Save to a GIF file.
success = bd.WriteFile("qa_output/xsmall.gif")