B4X

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..

B4X

Dim success As Boolean = False

Dim bd As ChilkatBinData
bd.Initialize

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


'  Show GIF bytes as base64:
Log(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 ChilkatXml
xml.Initialize
success = xml.LoadXml(x)

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

Log(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")