TImageEnProc.ReadHiddenData

Declaration

function ReadHiddenData(data: PAnsiChar; maxlen: Integer): Integer;

Description

ReadHiddenText and ReadHiddenData return the hidden text or raw data written with WriteHiddenText or WriteHiddenData. Hidden information is stored inside the image (uses a pixel color modulation) and is independent of the image file format.
Use ReadHiddenText to read a simple string or ReadHiddenData to read a buffer of raw data.
If you set data to nil and maxlen to 0, ReadHiddenData will returns the length of data to read.

Note:
◼The hidden text will be lost if you save the image as Jpeg or if you subsample the colors
◼If the image PixelFormat is not ie24RGB, it will be converted

Example

// Hide image "alfa.jpg" within "beta.jpg", then save to "gamma.png"
procedure TForm1.Button2(Sender: TObject);
var
  ms: TMemoryStream;
begin
  ImageEnView1.IO.LoadFromFile('C:\beta.jpg');
  ms := TMemoryStream.Create();
  ms.LoadFromFile('C:\alfa.jpg');
  ImageEnView1.Proc.WriteHiddenData(ms.Memory, ms.Size);
  ms.Free();
  ImageEnView1.IO.SaveToFile('D:\gamma.png');
end;

// Read a hidden Jpeg image
procedure TForm1.Button1Click(Sender: TObject);
var
  ms: TMemoryStream;
begin
  ImageEnView1.IO.LoadFromFile('D:\gamma.png');
  ms := TMemoryStream.Create();
  ms.Size := ImageEnView1.Proc.ReadHiddenData(nil, 0) );
  ImageEnView1.Proc.ReadHiddenData(ms.Memory, ms.Size);
  ImageEnView2.IO.LoadFromStreamJpeg( ms );
  ms.Free();
end;

TImageEnProc.ReadHiddenData