/*

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%                                                                             %

%                                                                             %

%                                                                             %

%              SSSSS  TTTTT  EEEEE   GGGG   AAA   N   N   OOO                 %

%              SS       T    E      G      A   A  NN  N  O   O                %

%               SSS     T    EEE    G  GG  AAAAA  N N N  O   O                %

%                 SS    T    E      G   G  A   A  N  NN  O   O                %

%              SSSSS    T    EEEEE   GGG   A   A  N   N   OOO                 %

%                                                                             %

%                                                                             %

%                       Write A Steganographic Image.                         %

%                                                                             %

%                              Software Design                                %

%                                   Cristy                                    %

%                                 July 1992                                   %

%                                                                             %

%                                                                             %

%  Copyright @ 1999 ImageMagick Studio LLC, a non-profit organization         %

%  dedicated to making software imaging solutions freely available.           %

%                                                                             %

%  You may not use this file except in compliance with the License.  You may  %

%  obtain a copy of the License at                                            %

%                                                                             %

%    https://imagemagick.org/license/                                         %

%                                                                             %

%  Unless required by applicable law or agreed to in writing, software        %

%  distributed under the License is distributed on an "AS IS" BASIS,          %

%  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.   %

%  See the License for the specific language governing permissions and        %

%  limitations under the License.                                             %

%                                                                             %

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%

%

*/

/*

  Include declarations.

*/

#include "MagickCore/studio.h"

#include "MagickCore/blob.h"

#include "MagickCore/blob-private.h"

#include "MagickCore/cache.h"

#include "MagickCore/colormap.h"

#include "MagickCore/constitute.h"

#include "MagickCore/exception.h"

#include "MagickCore/exception-private.h"

#include "MagickCore/image.h"

#include "MagickCore/image-private.h"

#include "MagickCore/list.h"

#include "MagickCore/magick.h"

#include "MagickCore/memory_.h"

#include "MagickCore/monitor.h"

#include "MagickCore/monitor-private.h"

#include "MagickCore/pixel-accessor.h"

#include "MagickCore/quantum-private.h"

#include "MagickCore/static.h"

#include "MagickCore/string_.h"

#include "MagickCore/module.h"

/*

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%                                                                             %

%                                                                             %

%                                                                             %

%   R e a d S T E G A N O I m a g e                                           %

%                                                                             %

%                                                                             %

%                                                                             %

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%

%  ReadSTEGANOImage() reads a steganographic image hidden within another

%  image type.  It allocates the memory necessary for the new Image structure

%  and returns a pointer to the new image.

%

%  The format of the ReadSTEGANOImage method is:

%

%      Image *ReadSTEGANOImage(const ImageInfo *image_info,

%        ExceptionInfo *exception)

%

%  A description of each parameter follows:

%

%    o image_info: the image info.

%

%    o exception: return any errors or warnings in this structure.

%

*/

static Image *ReadSTEGANOImage(const ImageInfo *image_info,

  ExceptionInfo *exception)

{

#define GetBit(alpha,i) (((size_t) (alpha) >> (size_t) (i)) & 0x01)

#define SetBit(i,set) SetPixelIndex(image,(Quantum) ((set) != 0 ? \

  (size_t) GetPixelIndex(image,q) | (one << (size_t) (i)) : \

  (size_t) GetPixelIndex(image,q) & ~(one << (size_t) (i))),q)

  Image

    *image,

    *watermark;

  ImageInfo

    *read_info;

  int

    c;

  MagickBooleanType

    status;

  PixelInfo

    pixel;

  Quantum

    *q;

  ssize_t

    x;

  size_t

    depth,

    one;

  ssize_t

    i,

    j,

    k,

    y;

  /*

    Initialize Image structure.

  */

  assert(image_info != (const ImageInfo *) NULL);

  assert(image_info->signature == MagickCoreSignature);

  assert(exception != (ExceptionInfo *) NULL);

  assert(exception->signature == MagickCoreSignature);

  if (IsEventLogging() != MagickFalse)

    (void) LogMagickEvent(TraceEvent,GetMagickModule(),"%s",

      image_info->filename);

  one=1;

  image=AcquireImage(image_info,exception);

  if ((image->columns == 0) || (image->rows == 0))

    ThrowReaderException(OptionError,"MustSpecifyImageSize");

  read_info=CloneImageInfo(image_info);

  SetImageInfoBlob(read_info,(void *) NULL,0);

  *read_info->magick='\0';

  watermark=ReadImage(read_info,exception);

  read_info=DestroyImageInfo(read_info);

  if (watermark == (Image *) NULL)

    return(DestroyImage(image));

  watermark->depth=MAGICKCORE_QUANTUM_DEPTH;

  if (AcquireImageColormap(image,MaxColormapSize,exception) == MagickFalse)

    {

      watermark=DestroyImage(watermark);

      ThrowReaderException(ResourceLimitError,"MemoryAllocationFailed");

    }

  if (image_info->ping != MagickFalse)

    {

      watermark=DestroyImage(watermark);

      (void) CloseBlob(image);

      return(GetFirstImageInList(image));

    }

  status=SetImageExtent(image,image->columns,image->rows,exception);

  if (status == MagickFalse)

    {

      watermark=DestroyImage(watermark);

      return(DestroyImageList(image));

    }

  for (y=0; y < (ssize_t) image->rows; y++)

  {

    q=QueueAuthenticPixels(image,0,y,image->columns,1,exception);

    if (q == (Quantum *) NULL)

      break;

    for (x=0; x < (ssize_t) image->columns; x++)

    {

      SetPixelIndex(image,0,q);

      q+=(ptrdiff_t) GetPixelChannels(image);

    }

    if (SyncAuthenticPixels(image,exception) == MagickFalse)

      break;

  }

  /*

    Get hidden watermark from low-order bits of image.

  */

  c=0;

  i=0;

  j=0;

  i=(ssize_t) (watermark->depth-1);

  depth=watermark->depth;

  for (k=image->offset; (i >= 0) && (j < (ssize_t) depth); i--)

  {

    for (y=0; (y < (ssize_t) image->rows) && (j < (ssize_t) depth); y++)

    {

      x=0;

      for ( ; (x < (ssize_t) image->columns) && (j < (ssize_t) depth); x++)

      {

        if ((k/(ssize_t) watermark->columns) >= (ssize_t) watermark->rows)

          break;

        (void) GetOneVirtualPixelInfo(watermark,UndefinedVirtualPixelMethod,

          k % (ssize_t) watermark->columns,k/(ssize_t) watermark->columns,

          &pixel,exception);

        q=GetAuthenticPixels(image,x,y,1,1,exception);

        if (q == (Quantum *) NULL)

          break;

        switch (c)

        {

          case 0:

          {

            SetBit(i,GetBit(pixel.red,j));

            break;

          }

          case 1:

          {

            SetBit(i,GetBit(pixel.green,j));

            break;

          }

          case 2:

          {

            SetBit(i,GetBit(pixel.blue,j));

            break;

          }

        }

        if (SyncAuthenticPixels(image,exception) == MagickFalse)

          break;

        c++;

        if (c == 3)

          c=0;

        k++;

        if (k == (ssize_t) (watermark->columns*watermark->rows))

          k=0;

        if (k == image->offset)

          j++;

      }

    }

    status=SetImageProgress(image,LoadImagesTag,(MagickOffsetType) i,depth);

    if (status == MagickFalse)

      break;

  }

  watermark=DestroyImage(watermark);

  (void) SyncImage(image,exception);

  return(GetFirstImageInList(image));

}

/*

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%                                                                             %

%                                                                             %

%                                                                             %

%   R e g i s t e r S T E G A N O I m a g e                                   %

%                                                                             %

%                                                                             %

%                                                                             %

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%

%  RegisterSTEGANOImage() adds attributes for the STEGANO image format to

%  the list of supported formats.  The attributes include the image format

%  tag, a method to read and/or write the format, whether the format

%  supports the saving of more than one frame to the same file or blob,

%  whether the format supports native in-memory I/O, and a brief

%  description of the format.

%

%  The format of the RegisterSTEGANOImage method is:

%

%      size_t RegisterSTEGANOImage(void)

%

*/

ModuleExport size_t RegisterSTEGANOImage(void)

{

  MagickInfo

    *entry;

  entry=AcquireMagickInfo("STEGANO","STEGANO","Steganographic image");

  entry->decoder=(DecodeImageHandler *) ReadSTEGANOImage;

  entry->format_type=ImplicitFormatType;

  (void) RegisterMagickInfo(entry);

  return(MagickImageCoderSignature);

}

/*

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%                                                                             %

%                                                                             %

%                                                                             %

%   U n r e g i s t e r S T E G A N O I m a g e                               %

%                                                                             %

%                                                                             %

%                                                                             %

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%

%  UnregisterSTEGANOImage() removes format registrations made by the

%  STEGANO module from the list of supported formats.

%

%  The format of the UnregisterSTEGANOImage method is:

%

%      UnregisterSTEGANOImage(void)

%

*/

ModuleExport void UnregisterSTEGANOImage(void)

{

  (void) UnregisterMagickInfo("STEGANO");

}