OpAtom Find Function. Finds specified types of OpAtom entries in an array. ABCpdf .NET PDF Library.

Finds specified types of OpAtom entries in an array

[C#]
IList<Tuple<string, int>> Find(ArrayAtom atom)
IList<Tuple<string, int>> Find(ArrayAtom atom, string[] names)

[Visual Basic]
Function Find(atom As ArrayAtom) As IList(Of Tuple(Of string, int))
Function Find(atom As ArrayAtom, names() As String) As IList(Of Tuple(Of string, int))


Finds specified types of OpAtom entries in an array.

If you specify no names then the positions and text of all the OpAtoms in the ArrayAtom will be returned. If you are only interested in a particular set of operators then you can specify an array of those types to restrict the number of items returned.

This example shows how to use the Array.FromContentStream function to parse a content stream and then use the Find method to search for certain types of color operators and replace them with other color operators. In this example this has the effect of converting some black parts of the PDF to red.

[C#]
using (Doc doc = new Doc()) {
  doc.Read("spaceshuttle.pdf");
  doc.RemapPages(new int[] { 1, 1 });
  doc.PageNumber = 2;
  Page page = doc.ObjectSoup[doc.Page] as Page;
  StreamObject[] layers = page.GetLayers();
  MemoryStream st = new MemoryStream();
  foreach (StreamObject layer in layers) {
    if (!layer.Decompress())
      throw new Exception("Unable to decompress stream.");
    byte[] data = layer.GetData();
    st.Write(data, 0, data.Length);
    layer.CompressFlate();
  }
  ArrayAtom array = ArrayAtom.FromContentStream(st.ToArray());
  if (true) {
    var items = OpAtom.Find(array, new string[] { "k" });
    foreach (var pair in items) { // make red
      Atom[] args = OpAtom.GetParameters(array, pair.Item2);
      if (args != null) {
        ((NumAtom)args[0]).Real = 0;
        ((NumAtom)args[1]).Real = 1;
        ((NumAtom)args[2]).Real = 1;
        ((NumAtom)args[3]).Real = 0;
      }
    }
  }
  if (true) {
    var items = OpAtom.Find(array, new string[] { "rg" });
    foreach (var pair in items) { // make green
      Atom[] args = OpAtom.GetParameters(array, pair.Item2);
      if (args != null) {
        ((NumAtom)args[0]).Real = 0;
        ((NumAtom)args[1]).Real = 1;
        ((NumAtom)args[2]).Real = 0;
      }
    }
  }
  byte[] arrayData = array.GetData();
  StreamObject so = new StreamObject(doc.ObjectSoup);
  so.SetData(arrayData, 1, arrayData.Length - 2);
  doc.SetInfo(page.ID, "/Contents:Del", "");
  page.AddLayer(so);
  doc.Save("ReplaceColors.pdf");
}

[Visual Basic]
Sub ...
  Using doc As New Doc()
    doc.RemapPages(New Integer[] { 1, 1 })
    doc.PageNumber = 2
    Dim page As Page = TryCast(doc.ObjectSoup(doc.Page), Page)
    Dim layers As StreamObject() = page.GetLayers()
    Dim st As New MemoryStream()
    For Each layer As StreamObject In layers
      If Not layer.Decompress() Then
        Throw New Exception("Unable to decompress stream.")
      End If
      Dim data As Byte() = layer.GetData()
      st.Write(data, 0, data.Length)
      layer.CompressFlate()
    Next
    Dim array As ArrayAtom = ArrayAtom.FromContentStream(st.ToArray())
    If True Then
      Dim items = OpAtom.Find(array, New String() {"k"})
      For Each pair As var In items
        ' make red
        Dim args As Atom() = OpAtom.GetParameters(array, pair.Item2)
        If args IsNot Nothing Then
          DirectCast(args(0), NumAtom).Real = 0
          DirectCast(args(1), NumAtom).Real = 1
          DirectCast(args(2), NumAtom).Real = 1
          DirectCast(args(3), NumAtom).Real = 0
        End If
      Next
    End If
    If True Then
      Dim items = OpAtom.Find(array, New String() {"rg"})
      For Each pair As var In items
        ' make green
        Dim args As Atom() = OpAtom.GetParameters(array, pair.Item2)
        If args IsNot Nothing Then
          DirectCast(args(0), NumAtom).Real = 0
          DirectCast(args(1), NumAtom).Real = 1
          DirectCast(args(2), NumAtom).Real = 0
        End If
      Next
    End If
    Dim arrayData As Byte() = array.GetData()
    Dim so As New StreamObject(doc.ObjectSoup)
    so.SetData(arrayData, 1, arrayData.Length - 2)
    doc.SetInfo(page.ID, "/Contents:Del", "")
    page.AddLayer(so)
    doc.Save("ReplaceColors.pdf")
  End Using
End Sub


ReplaceColors.pdf [Page 1]

ReplaceColors.pdf [Page 2]