EnumerateElements Method

Imports Leadtools
Imports Leadtools.Codecs
Imports Leadtools.Drawing
Imports Leadtools.Forms.DocumentWriters
Imports Leadtools.Svg

Private Shared Sub SvgDocumentEnumerateElementsExample()
   ' The source PDF file
   Dim sourceFile As String = "C:\Users\Public\Documents\LEADTOOLS Images\Leadtools.pdf"
   Dim beforeSvgFile As String = "C:\Users\Public\Documents\LEADTOOLS Images\Leadtools_before.svg"
   Dim afterSvgFile As String = "C:\Users\Public\Documents\LEADTOOLS Images\Leadtools_after.svg"
   ' Assume this is our Virtual Directory
   Dim virtualDirectory As String = "http://localhost/leadtools_images/svg/resources"
   ' Assume this phrysical directory maps to the Virtual Directory
   Dim physicalDirectory As String = "C:\Users\Public\Documents\LEADTOOLS Images\svg\resources"

   If Not Directory.Exists(physicalDirectory) Then Directory.CreateDirectory(physicalDirectory)

   ' Our SVG element enumartion callback
   Dim callback As SvgEnumerateElementsCallback = _
      Function(document As SvgDocument, node As SvgNodeHandle, userData As Object) As Boolean
         If node.ElementType = SvgElementType.Image Then
            ' Get the href
            Dim href As String = node.GetAttributeValue("xlink:href")
            If Not String.IsNullOrEmpty(href) Then
               ' Parse it as data URI
               Dim dataUri As SvgDataUri = SvgDataUri.Parse(href)
               ' Check if it is a data URI
               If dataUri.IsDataUri Then
                  ' Yes, create a new file in a virtual directory

                  ' Show the dataURI properties
                  Console.WriteLine("Replacing data URI")
                  Console.WriteLine("Format:" + dataUri.ImageFormat.ToString())
                  If dataUri.MediaLength > 0 Then Console.WriteLine("Media:" + dataUri.Href.Substring(dataUri.MediaOffset, dataUri.MediaLength))
                  If dataUri.CharSetOffset > 0 Then
                     Console.WriteLine("CharSet:" + dataUri.Href.Substring(dataUri.CharSetOffset, dataUri.CharSetLength))
                  Else
                     Console.WriteLine("CharSet: not set")
                  End If
                  Console.WriteLine("IsBase64:" + dataUri.IsBase64.ToString())
                  Console.WriteLine("ImageFormat:" + dataUri.ImageFormat.ToString())
                  Dim extension As String = dataUri.Extension
                  Console.WriteLine("Extension:" + dataUri.Extension)

                  ' Get a file name
                  Dim name As String = Guid.NewGuid().ToString().Replace("-", "") + "." + dataUri.Extension

                  ' Save it
                  ' Full physical path
                  Dim filePath As String = Path.Combine(physicalDirectory, name)
                  dataUri.DecodeToFile(filePath)

                  ' Alternatively you can save the data yourself using this code
                  ' Dim data As String = dataUri.Href.Substring(dataUri.ValueOffset, dataUri.ValueLength)
                  ' ' Save the data
                  ' Dim base64String As String = dataUri.Href.Substring(dataUri.ValueOffset, dataUri.ValueLength)
                  ' Dim rowData() As Byte = Convert.FromBase64String(base64String)
                  '
                  ' ' Save it to disk
                  ' File.WriteAllBytes(filePath, rawData)

                  ' Finally replace the attribute in the image element with the URI
                  Dim virtualPath As String = virtualDirectory + "/" + name
                  node.SetAttributeValue("xlink:href", virtualPath)
               Else
                  Console.WriteLine("Does not contain a valid data URI.")
               End If
            End If
         End If
         Return True

      End Function

   Using rasterCodecs As New RasterCodecs()
      ' Use 300 DPI when loading document images
      rasterCodecs.Options.RasterizeDocument.Load.Resolution = 300

      ' Load the first page as SVG
      Using svg As SvgDocument = CType(rasterCodecs.LoadSvg(sourceFile, 1, Nothing), SvgDocument)
         If Not svg.IsFlat Then svg.Flat(Nothing)
         If Not svg.Bounds.IsValid Then svg.CalculateBounds(False)

         ' Save this SVG to disk, report the size
         svg.SaveToFile(beforeSvgFile, Nothing)
         Console.WriteLine("Before unembedding the image, size is " + New FileInfo(beforeSvgFile).Length.ToString())

         ' Now enumerate the elements to replace each embedded image with a URL
         ' Since we are going to modify the SVG, call BeginUpdate/EndUpdate to speed up the process
         svg.BeginUpdate()
         Dim enumerationOptions As New SvgEnumerateOptions
         enumerationOptions.EnumerateDirection = SvgEnumerateDirection.TopToBottom
         svg.EnumerateElements(enumerationOptions, callback, Nothing)
         svg.EndUpdate()

         ' Save this SVG to disk again, report the size, should be alot smaller since the image are unembedded and stored as external resources
         svg.SaveToFile(afterSvgFile, Nothing)
         Console.WriteLine("Before unembedding the image, size is " + New FileInfo(afterSvgFile).Length.ToString())
      End Using
   End Using
End Sub