/*=========================================================================

  Program:   Visualization Toolkit
  Module:    vtkVideoSource.cxx

  Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
  All rights reserved.
  See Copyright.txt or http://www.kitware.com/Copyright.htm for details.

     This software is distributed WITHOUT ANY WARRANTY; without even
     the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
     PURPOSE.  See the above copyright notice for more information.

=========================================================================*/
#include "vtkVideoSource.h"

#include "vtkDataArray.h"
#include "vtkImageData.h"
#include "vtkInformation.h"
#include "vtkInformationVector.h"
#include "vtkMultiThreader.h"
#include "vtkObjectFactory.h"
#include "vtkStreamingDemandDrivenPipeline.h"
#include "vtkTimerLog.h"
#include "vtkUnsignedCharArray.h"
#include "vtksys/SystemTools.hxx"

#include <mutex>

//---------------------------------------------------------------
// Important FrameBufferMutex rules:
//
// The frame grabs are generally done asynchronously, and it is necessary
// to ensure that when the frame buffer is valid when it is being written
// to or read from
//
// The following information can only be changed within a mutex lock,
// and the lock must not be released until the frame buffer agrees with the
// information.
//
// FrameBuffer
// FrameBufferTimeStamps
// FrameBufferSize
// FrameBufferIndex
// FrameBufferExtent
// FrameBufferBitsPerPixel
// FrameBufferRowAlignment
//
// After one of the above has been changed, and before the mutex is released,
// the following must be called to update the frame buffer:
//
// UpdateFrameBuffer()
//
// Likewise, the following function must only be called from within a
// mutex lock because it modifies FrameBufferIndex:
//
// AdvanceFrameBuffer()
//
// Any methods which might be called asynchronously must lock the
// mutex before reading the above information, and you must be very
// careful when accessing any information except for the above.
// These methods include the following:
//
// InternalGrab()
//
// Finally, when Execute() is reading from the FrameBuffer it must do
// so from within a mutex lock.  Otherwise tearing artifacts might result.

vtkStandardNewMacro(vtkVideoSource);

#if defined(_MSC_VER)
#pragma warning(disable : 4311)
#pragma warning(disable : 4312)
#endif

//------------------------------------------------------------------------------
vtkVideoSource::vtkVideoSource()
{
  int i;

  this->Initialized = 0;

  this->AutoAdvance = 1;

  this->FrameSize[0] = 320;
  this->FrameSize[1] = 240;
  this->FrameSize[2] = 1;

  for (i = 0; i < 6; i++)
  {
    this->FrameBufferExtent[i] = 0;
  }

  this->Playing = 0;
  this->Recording = 0;

  this->FrameRate = 30;

  this->FrameCount = 0;
  this->FrameIndex = -1;

  this->StartTimeStamp = 0;
  this->FrameTimeStamp = 0;

  this->OutputNeedsInitialization = 1;

  this->OutputFormat = VTK_LUMINANCE;
  this->NumberOfScalarComponents = 1;

  this->NumberOfOutputFrames = 1;

  this->Opacity = 1.0;

  for (i = 0; i < 3; i++)
  {
    this->ClipRegion[i * 2] = 0;
    this->ClipRegion[i * 2 + 1] = VTK_INT_MAX;
    this->OutputWholeExtent[i * 2] = 0;
    this->OutputWholeExtent[i * 2 + 1] = -1;
    this->DataSpacing[i] = 1.0;
    this->DataOrigin[i] = 0.0;
  }

  for (i = 0; i < 6; i++)
  {
    this->LastOutputExtent[i] = 0;
  }
  this->LastNumberOfScalarComponents = 0;

  this->FlipFrames = 0;

  this->PlayerThreader = vtkMultiThreader::New();
  this->PlayerThreadId = -1;

  this->FrameBufferSize = 0;
  this->FrameBuffer = nullptr;
  this->FrameBufferTimeStamps = nullptr;
  this->FrameBufferIndex = 0;
  this->SetFrameBufferSize(1);

  this->FrameBufferBitsPerPixel = 8;
  this->FrameBufferRowAlignment = 1;

  this->SetNumberOfInputPorts(0);
}

//------------------------------------------------------------------------------
vtkVideoSource::~vtkVideoSource()
{
  // we certainly don't want to access a virtual
  // function after the subclass has destructed!!
  this->vtkVideoSource::ReleaseSystemResources();

  this->SetFrameBufferSize(0);
  this->PlayerThreader->Delete();
}

//------------------------------------------------------------------------------
void vtkVideoSource::PrintSelf(ostream& os, vtkIndent indent)
{
  int idx;

  this->Superclass::PrintSelf(os, indent);

  os << indent << "FrameSize: (" << this->FrameSize[0] << ", " << this->FrameSize[1] << ", "
     << this->FrameSize[2] << ")\n";

  os << indent << "ClipRegion: (" << this->ClipRegion[0];
  for (idx = 1; idx < 6; ++idx)
  {
    os << ", " << this->ClipRegion[idx];
  }
  os << ")\n";

  os << indent << "DataSpacing: (" << this->DataSpacing[0];
  for (idx = 1; idx < 3; ++idx)
  {
    os << ", " << this->DataSpacing[idx];
  }
  os << ")\n";

  os << indent << "DataOrigin: (" << this->DataOrigin[0];
  for (idx = 1; idx < 3; ++idx)
  {
    os << ", " << this->DataOrigin[idx];
  }
  os << ")\n";

  os << indent << "OutputFormat: "
     << (this->OutputFormat == VTK_RGBA
            ? "RGBA"
            : (this->OutputFormat == VTK_RGB
                  ? "RGB"
                  : (this->OutputFormat == VTK_LUMINANCE_ALPHA
                        ? "LuminanceAlpha"
                        : (this->OutputFormat == VTK_LUMINANCE ? "Luminance" : "Unknown"))))
     << "\n";

  os << indent << "OutputWholeExtent: (" << this->OutputWholeExtent[0];
  for (idx = 1; idx < 6; ++idx)
  {
    os << ", " << this->OutputWholeExtent[idx];
  }
  os << ")\n";

  os << indent << "FrameRate: " << this->FrameRate << "\n";

  os << indent << "FrameCount: " << this->FrameCount << "\n";

  os << indent << "FrameIndex: " << this->FrameIndex << "\n";

  os << indent << "Recording: " << (this->Recording ? "On\n" : "Off\n");

  os << indent << "Playing: " << (this->Playing ? "On\n" : "Off\n");

  os << indent << "FrameBufferSize: " << this->FrameBufferSize << "\n";

  os << indent << "NumberOfOutputFrames: " << this->NumberOfOutputFrames << "\n";
  os << indent << "AutoAdvance: " << (this->AutoAdvance ? "On\n" : "Off\n");

  os << indent << "Opacity: " << this->Opacity << "\n";

  os << indent << "FlipFrames: " << this->FlipFrames << "\n";

  os << indent << "FrameBufferBitsPerPixel: " << this->FrameBufferBitsPerPixel << "\n";

  os << indent << "FrameBufferRowAlignment: " << this->FrameBufferRowAlignment << "\n";
}

//------------------------------------------------------------------------------
// Update the FrameBuffers according to any changes in the FrameBuffer*
// information.
// This function should always be called from within a FrameBufferMutex lock
// and should never be called asynchronously.
// It sets up the FrameBufferExtent
void vtkVideoSource::UpdateFrameBuffer()
{
  int i, oldExt;
  int ext[3];
  vtkDataArray* buffer;

  // clip the ClipRegion with the FrameSize
  for (i = 0; i < 3; i++)
  {
    oldExt = this->FrameBufferExtent[2 * i + 1] - this->FrameBufferExtent[2 * i] + 1;
    this->FrameBufferExtent[2 * i] = ((this->ClipRegion[2 * i] > 0) ? this->ClipRegion[2 * i] : 0);
    this->FrameBufferExtent[2 * i + 1] =
      ((this->ClipRegion[2 * i + 1] < this->FrameSize[i] - 1) ? this->ClipRegion[2 * i + 1]
                                                              : this->FrameSize[i] - 1);

    ext[i] = this->FrameBufferExtent[2 * i + 1] - this->FrameBufferExtent[2 * i] + 1;
    if (ext[i] < 0)
    {
      this->FrameBufferExtent[2 * i] = 0;
      this->FrameBufferExtent[2 * i + 1] = -1;
      ext[i] = 0;
    }

    if (oldExt > ext[i])
    { // dimensions of framebuffer changed
      this->OutputNeedsInitialization = 1;
    }
  }

  // total number of bytes required for the framebuffer
  int bytesPerRow = (ext[0] * this->FrameBufferBitsPerPixel + 7) / 8;
  bytesPerRow =
    ((bytesPerRow + this->FrameBufferRowAlignment - 1) / this->FrameBufferRowAlignment) *
    this->FrameBufferRowAlignment;
  int totalSize = bytesPerRow * ext[1] * ext[2];

  i = this->FrameBufferSize;

  while (--i >= 0)
  {
    buffer = reinterpret_cast<vtkDataArray*>(this->FrameBuffer[i]);
    if (buffer->GetDataType() != VTK_UNSIGNED_CHAR || buffer->GetNumberOfComponents() != 1 ||
      buffer->GetNumberOfTuples() != totalSize)
    {
      buffer->Delete();
      buffer = vtkUnsignedCharArray::New();
      this->FrameBuffer[i] = buffer;
      buffer->SetNumberOfComponents(1);
      buffer->SetNumberOfTuples(totalSize);
    }
  }
}

//------------------------------------------------------------------------------
// Initialize() should be overridden to initialize the hardware frame grabber
void vtkVideoSource::Initialize()
{
  if (this->Initialized)
  {
    return;
  }
  this->Initialized = 1;

  this->UpdateFrameBuffer();
}

//------------------------------------------------------------------------------
// ReleaseSystemResources() should be overridden to release the hardware
void vtkVideoSource::ReleaseSystemResources()
{
  if (this->Playing || this->Recording)
  {
    this->Stop();
  }

  this->Initialized = 0;
}

//------------------------------------------------------------------------------
void vtkVideoSource::SetFrameSize(int x, int y, int z)
{
  if (x == this->FrameSize[0] && y == this->FrameSize[1] && z == this->FrameSize[2])
  {
    return;
  }

  if (x < 1 || y < 1 || z < 1)
  {
    vtkErrorMacro(<< "SetFrameSize: Illegal frame size");
    return;
  }

  if (this->Initialized)
  {
    this->FrameBufferMutex.lock();
    this->FrameSize[0] = x;
    this->FrameSize[1] = y;
    this->FrameSize[2] = z;
    this->UpdateFrameBuffer();
    this->FrameBufferMutex.unlock();
  }
  else
  {
    this->FrameSize[0] = x;
    this->FrameSize[1] = y;
    this->FrameSize[2] = z;
  }

  this->Modified();
}

//------------------------------------------------------------------------------
void vtkVideoSource::SetFrameRate(float rate)
{
  if (this->FrameRate == rate)
  {
    return;
  }

  this->FrameRate = rate;
  this->Modified();
}

//------------------------------------------------------------------------------
void vtkVideoSource::SetClipRegion(int x0, int x1, int y0, int y1, int z0, int z1)
{
  if (this->ClipRegion[0] != x0 || this->ClipRegion[1] != x1 || this->ClipRegion[2] != y0 ||
    this->ClipRegion[3] != y1 || this->ClipRegion[4] != z0 || this->ClipRegion[5] != z1)
  {
    this->Modified();
    if (this->Initialized)
    { // modify the FrameBufferExtent
      this->FrameBufferMutex.lock();
      this->ClipRegion[0] = x0;
      this->ClipRegion[1] = x1;
      this->ClipRegion[2] = y0;
      this->ClipRegion[3] = y1;
      this->ClipRegion[4] = z0;
      this->ClipRegion[5] = z1;
      this->UpdateFrameBuffer();
      this->FrameBufferMutex.unlock();
    }
    else
    {
      this->ClipRegion[0] = x0;
      this->ClipRegion[1] = x1;
      this->ClipRegion[2] = y0;
      this->ClipRegion[3] = y1;
      this->ClipRegion[4] = z0;
      this->ClipRegion[5] = z1;
    }
  }
}

//------------------------------------------------------------------------------
// Copy pseudo-random noise into the frames.  This function may be called
// asynchronously.
void vtkVideoSource::InternalGrab()
{
  int i, index;
  static int randsave = 0;
  int randNum;
  unsigned char* ptr;
  int* lptr;

  // get a thread lock on the frame buffer
  this->FrameBufferMutex.lock();

  if (this->AutoAdvance)
  {
    this->AdvanceFrameBuffer(1);
    if (this->FrameIndex + 1 < this->FrameBufferSize)
    {
      this->FrameIndex++;
    }
  }

  index = this->FrameBufferIndex % this->FrameBufferSize;
  while (index < 0)
  {
    index += this->FrameBufferSize;
  }

  int bytesPerRow =
    ((this->FrameBufferExtent[1] - this->FrameBufferExtent[0] + 1) * this->FrameBufferBitsPerPixel +
      7) /
    8;
  bytesPerRow =
    ((bytesPerRow + this->FrameBufferRowAlignment - 1) / this->FrameBufferRowAlignment) *
    this->FrameBufferRowAlignment;
  int totalSize = bytesPerRow * (this->FrameBufferExtent[3] - this->FrameBufferExtent[2] + 1) *
    (this->FrameBufferExtent[5] - this->FrameBufferExtent[4] + 1);

  randNum = randsave;

  // copy 'noise' into the frame buffer
  ptr = reinterpret_cast<vtkUnsignedCharArray*>(this->FrameBuffer[index])->GetPointer(0);

  // Somebody should check this:
  lptr = (int*)(((((intptr_t)ptr) + 3) / 4) * 4);
  i = totalSize / 4;

  while (--i >= 0)
  {
    randNum = 1664525 * randNum + 1013904223;
    *lptr++ = randNum;
  }
  unsigned char* ptr1 = ptr + 4;
  i = (totalSize - 4) / 16;
  while (--i >= 0)
  {
    randNum = 1664525 * randNum + 1013904223;
    *ptr1 = static_cast<unsigned char>(randNum);
    ptr1 += 16;
  }
  randsave = randNum;

  this->FrameBufferTimeStamps[index] = vtkTimerLog::GetUniversalTime();

  if (this->FrameCount++ == 0)
  {
    this->StartTimeStamp = this->FrameBufferTimeStamps[index];
  }

  this->Modified();

  this->FrameBufferMutex.unlock();
}

//------------------------------------------------------------------------------
// Sleep until the specified absolute time has arrived.
// You must pass a handle to the current thread.
// If '0' is returned, then the thread was aborted before or during the wait.
static int vtkThreadSleep(vtkMultiThreader::ThreadInfo* data, double time)
{
  // loop either until the time has arrived or until the thread is ended
  for (int i = 0;; i++)
  {
    double remaining = time - vtkTimerLog::GetUniversalTime();

    // check to see if we have reached the specified time
    if (remaining <= 0.0)
    {
      if (i == 0)
      {
        vtkGenericWarningMacro("Dropped a video frame.");
      }
      return 1;
    }
    // check the ActiveFlag at least every 0.1 seconds
    if (remaining > 0.1)
    {
      remaining = 0.1;
    }

    // check to see if we are being told to quit
    int activeFlag;
    {
      std::lock_guard<std::mutex> lockGuard(*data->ActiveFlagLock);
      activeFlag = *(data->ActiveFlag);
    }

    if (activeFlag == 0)
    {
      break;
    }

    vtksys::SystemTools::Delay(static_cast<unsigned int>(remaining * 1000.0));
  }

  return 0;
}

//------------------------------------------------------------------------------
// this function runs in an alternate thread to asynchronously grab frames
static void* vtkVideoSourceRecordThread(vtkMultiThreader::ThreadInfo* data)
{
  vtkVideoSource* self = (vtkVideoSource*)(data->UserData);

  double startTime = vtkTimerLog::GetUniversalTime();
  double rate = self->GetFrameRate();
  int frame = 0;

  do
  {
    self->InternalGrab();
    frame++;
  } while (vtkThreadSleep(data, startTime + frame / rate));

  return nullptr;
}

//------------------------------------------------------------------------------
// Set the source to grab frames continuously.
// You should override this as appropriate for your device.
void vtkVideoSource::Record()
{
  if (this->Playing)
  {
    this->Stop();
  }

  if (!this->Recording)
  {
    this->Initialize();

    this->Recording = 1;
    this->FrameCount = 0;
    this->Modified();
    this->PlayerThreadId =
      this->PlayerThreader->SpawnThread((vtkThreadFunctionType)&vtkVideoSourceRecordThread, this);
  }
}

//------------------------------------------------------------------------------
// this function runs in an alternate thread to 'play the tape' at the
// specified frame rate.
static void* vtkVideoSourcePlayThread(vtkMultiThreader::ThreadInfo* data)
{
  vtkVideoSource* self = (vtkVideoSource*)(data->UserData);

  double startTime = vtkTimerLog::GetUniversalTime();
  double rate = self->GetFrameRate();
  int frame = 0;

  do
  {
    self->Seek(1);
    frame++;
  } while (vtkThreadSleep(data, startTime + frame / rate));

  return nullptr;
}

//------------------------------------------------------------------------------
// Set the source to play back recorded frames.
// You should override this as appropriate for your device.
void vtkVideoSource::Play()
{
  if (this->Recording)
  {
    this->Stop();
  }

  if (!this->Playing)
  {
    this->Initialize();

    this->Playing = 1;
    this->Modified();
    this->PlayerThreadId =
      this->PlayerThreader->SpawnThread((vtkThreadFunctionType)&vtkVideoSourcePlayThread, this);
  }
}

//------------------------------------------------------------------------------
// Stop continuous grabbing or playback.  You will have to override this
// if your class overrides Play() and Record()
void vtkVideoSource::Stop()
{
  if (this->Playing || this->Recording)
  {
    this->PlayerThreader->TerminateThread(this->PlayerThreadId);
    this->PlayerThreadId = -1;
    this->Playing = 0;
    this->Recording = 0;
    this->Modified();
  }
}

//------------------------------------------------------------------------------
// Rewind back to the frame with the earliest timestamp.
void vtkVideoSource::Rewind()
{
  this->FrameBufferMutex.lock();

  double* stamp = this->FrameBufferTimeStamps;
  double lowest = 0;
  int i, j;

  if (this->FrameBufferSize)
  {
    lowest = stamp[this->FrameBufferIndex];
  }
  for (i = 0; i < this->FrameBufferSize; i++)
  {
    j = (this->FrameBufferIndex + i + 1) % this->FrameBufferSize;
    if (stamp[j] != 0.0 && stamp[j] <= lowest)
    {
      lowest = stamp[j];
    }
    else
    {
      break;
    }
  }
  j = (this->FrameBufferIndex + i) % this->FrameBufferSize;
  if (stamp[j] != 0.0 && stamp[j] < 980000000.0)
  {
    vtkWarningMacro("Rewind: bogus time stamp!");
  }
  else
  {
    this->AdvanceFrameBuffer(-i);
    this->FrameIndex = (this->FrameIndex - i) % this->FrameBufferSize;
    while (this->FrameIndex < 0)
    {
      this->FrameIndex += this->FrameBufferSize;
    }
  }

  this->FrameBufferMutex.unlock();
}

//------------------------------------------------------------------------------
// Fast-forward to the frame with the latest timestamp.
void vtkVideoSource::FastForward()
{
  this->FrameBufferMutex.lock();

  double* stamp = this->FrameBufferTimeStamps;
  double highest = 0;
  int i, j;

  if (this->FrameBufferSize)
  {
    highest = stamp[this->FrameBufferIndex];
  }
  for (i = 0; i < this->FrameBufferSize; i++)
  {
    j = (this->FrameBufferIndex - i - 1) % this->FrameBufferSize;
    while (j < 0)
    {
      j += this->FrameBufferSize;
    }
    if (stamp[j] != 0.0 && stamp[j] >= highest)
    {
      highest = stamp[j];
    }
    else
    {
      break;
    }
  }
  j = (this->FrameBufferIndex - i) % this->FrameBufferSize;
  while (j < 0)
  {
    j += this->FrameBufferSize;
  }
  if (stamp[j] != 0.0 && stamp[j] < 980000000.0)
  {
    vtkWarningMacro("FastForward: bogus time stamp!");
  }
  else
  {
    this->AdvanceFrameBuffer(i);
    this->FrameIndex = (this->FrameIndex + i) % this->FrameBufferSize;
    while (this->FrameIndex < 0)
    {
      this->FrameIndex += this->FrameBufferSize;
    }
  }

  this->FrameBufferMutex.unlock();
}

//------------------------------------------------------------------------------
// Rotate the buffers
void vtkVideoSource::Seek(int n)
{
  this->FrameBufferMutex.lock();
  this->AdvanceFrameBuffer(n);
  this->FrameIndex = (this->FrameIndex + n) % this->FrameBufferSize;
  while (this->FrameIndex < 0)
  {
    this->FrameIndex += this->FrameBufferSize;
  }
  this->FrameBufferMutex.unlock();
  this->Modified();
}

//------------------------------------------------------------------------------
// The grab function, which should (of course) be overridden to do
// the appropriate hardware stuff.  This function should never be
// called asynchronously.
void vtkVideoSource::Grab()
{
  // ensure that the hardware is initialized.
  this->Initialize();

  this->InternalGrab();
}

//------------------------------------------------------------------------------
// Override this and provide checks to ensure an appropriate number
// of components was asked for (i.e. 1 for greyscale, 3 for RGB,
// or 4 for RGBA)
void vtkVideoSource::SetOutputFormat(int format)
{
  if (format == this->OutputFormat)
  {
    return;
  }

  this->OutputFormat = format;

  // convert color format to number of scalar components
  int numComponents = 1;

  switch (this->OutputFormat)
  {
    case VTK_RGBA:
      numComponents = 4;
      break;
    case VTK_RGB:
      numComponents = 3;
      break;
    case VTK_LUMINANCE_ALPHA:
      numComponents = 2;
      break;
    case VTK_LUMINANCE:
      numComponents = 1;
      break;
    default:
      vtkErrorMacro(<< "SetOutputFormat: Unrecognized color format.");
      break;
  }
  this->NumberOfScalarComponents = numComponents;

  if (this->FrameBufferBitsPerPixel != numComponents * 8)
  {
    this->FrameBufferMutex.lock();
    this->FrameBufferBitsPerPixel = numComponents * 8;
    if (this->Initialized)
    {
      this->UpdateFrameBuffer();
    }
    this->FrameBufferMutex.unlock();
  }

  this->Modified();
}

//------------------------------------------------------------------------------
// set or change the circular buffer size
// you will have to override this if you want the buffers
// to be device-specific (i.e. something other than vtkDataArray)
void vtkVideoSource::SetFrameBufferSize(int bufsize)
{
  int i;
  void** framebuffer;
  double* timestamps;

  if (bufsize < 0)
  {
    vtkErrorMacro(<< "SetFrameBufferSize: There must be at least one framebuffer");
  }

  if (bufsize == this->FrameBufferSize && bufsize != 0)
  {
    return;
  }

  this->FrameBufferMutex.lock();

  if (this->FrameBuffer == nullptr)
  {
    if (bufsize > 0)
    {
      this->FrameBufferIndex = 0;
      this->FrameIndex = -1;
      this->FrameBuffer = new void*[bufsize];
      this->FrameBufferTimeStamps = new double[bufsize];
      for (i = 0; i < bufsize; i++)
      {
        this->FrameBuffer[i] = vtkUnsignedCharArray::New();
        this->FrameBufferTimeStamps[i] = 0.0;
      }
      this->FrameBufferSize = bufsize;
      this->Modified();
    }
  }
  else
  {
    if (bufsize > 0)
    {
      framebuffer = new void*[bufsize];
      timestamps = new double[bufsize];
    }
    else
    {
      framebuffer = nullptr;
      timestamps = nullptr;
    }

    // create new image buffers if necessary
    for (i = 0; i < bufsize - this->FrameBufferSize; i++)
    {
      framebuffer[i] = vtkUnsignedCharArray::New();
      timestamps[i] = 0.0;
    }
    // copy over old image buffers
    for (; i < bufsize; i++)
    {
      framebuffer[i] = this->FrameBuffer[i - (bufsize - this->FrameBufferSize)];
    }

    // delete image buffers we no longer need
    for (i = 0; i < this->FrameBufferSize - bufsize; i++)
    {
      reinterpret_cast<vtkDataArray*>(this->FrameBuffer[i])->Delete();
    }

    delete[] this->FrameBuffer;
    this->FrameBuffer = framebuffer;
    delete[] this->FrameBufferTimeStamps;
    this->FrameBufferTimeStamps = timestamps;

    // make sure that frame buffer index is within the buffer
    if (bufsize > 0)
    {
      this->FrameBufferIndex = this->FrameBufferIndex % bufsize;
      if (this->FrameIndex >= bufsize)
      {
        this->FrameIndex = bufsize - 1;
      }
    }
    else
    {
      this->FrameBufferIndex = 0;
      this->FrameIndex = -1;
    }

    this->FrameBufferSize = bufsize;
    this->Modified();
  }

  if (this->Initialized)
  {
    this->UpdateFrameBuffer();
  }

  this->FrameBufferMutex.unlock();
}

//------------------------------------------------------------------------------
// This function MUST be called only from within a FrameBufferMutex.lock()
void vtkVideoSource::AdvanceFrameBuffer(int n)
{
  int i = (this->FrameBufferIndex - n) % this->FrameBufferSize;
  while (i < 0)
  {
    i += this->FrameBufferSize;
  }
  this->FrameBufferIndex = i;
}

//------------------------------------------------------------------------------
double vtkVideoSource::GetFrameTimeStamp(int frame)
{
  double timeStamp;

  this->FrameBufferMutex.lock();

  if (this->FrameBufferSize <= 0)
  {
    return 0.0;
  }

  timeStamp = this->FrameBufferTimeStamps[(this->FrameBufferIndex + frame) % this->FrameBufferSize];
  this->FrameBufferMutex.unlock();

  return timeStamp;
}

//------------------------------------------------------------------------------
// This method returns the largest data that can be generated.
int vtkVideoSource::RequestInformation(vtkInformation* vtkNotUsed(request),
  vtkInformationVector** vtkNotUsed(inputVector), vtkInformationVector* outputVector)
{
  // get the info objects
  vtkInformation* outInfo = outputVector->GetInformationObject(0);

  int i;
  int extent[6];

  // ensure that the hardware is initialized.
  this->Initialize();

  for (i = 0; i < 3; i++)
  {
    // initially set extent to the OutputWholeExtent
    extent[2 * i] = this->OutputWholeExtent[2 * i];
    extent[2 * i + 1] = this->OutputWholeExtent[2 * i + 1];
    // if 'flag' is set in output extent, use the FrameBufferExtent instead
    if (extent[2 * i + 1] < extent[2 * i])
    {
      extent[2 * i] = 0;
      extent[2 * i + 1] = this->FrameBufferExtent[2 * i + 1] - this->FrameBufferExtent[2 * i];
    }
    this->FrameOutputExtent[2 * i] = extent[2 * i];
    this->FrameOutputExtent[2 * i + 1] = extent[2 * i + 1];
  }

  int numFrames = this->NumberOfOutputFrames;
  if (numFrames < 1)
  {
    numFrames = 1;
  }
  if (numFrames > this->FrameBufferSize)
  {
    numFrames = this->FrameBufferSize;
  }

  // multiply Z extent by number of frames to output
  extent[5] = extent[4] + (extent[5] - extent[4] + 1) * numFrames - 1;

  outInfo->Set(vtkStreamingDemandDrivenPipeline::WHOLE_EXTENT(), extent, 6);

  // set the spacing
  outInfo->Set(vtkDataObject::SPACING(), this->DataSpacing, 3);

  // set the origin.
  outInfo->Set(vtkDataObject::ORIGIN(), this->DataOrigin, 3);

  // set default data type (8 bit greyscale)
  vtkDataObject::SetPointDataActiveScalarInfo(
    outInfo, VTK_UNSIGNED_CHAR, this->NumberOfScalarComponents);

  return 1;
}

//------------------------------------------------------------------------------
// The UnpackRasterLine method should be overridden if the framebuffer uses
// unusual pixel packing formats, such as XRGB XBRG BGRX BGR etc.
// The version below assumes that the packing of the framebuffer is
// identical to that of the output.
void vtkVideoSource::UnpackRasterLine(char* outPtr, char* rowPtr, int start, int count)
{
  char* inPtr = rowPtr + start * this->NumberOfScalarComponents;
  memcpy(outPtr, inPtr, count * this->NumberOfScalarComponents);
  if (this->OutputFormat == VTK_RGBA)
  { // RGBA image: need to copy in the opacity
    unsigned char alpha = (unsigned char)(this->Opacity * 255);
    int k;
    outPtr += 3;
    for (k = 0; k < count; k++)
    {
      outPtr[4 * k] = alpha;
    }
  }
}

//------------------------------------------------------------------------------
// The Execute method is fairly complex, so I would not recommend overriding
// it unless you have to.  Override the UnpackRasterLine() method instead.
// You should only have to override it if you are using something other
// than 8-bit vtkUnsignedCharArray for the frame buffer.
int vtkVideoSource::RequestData(vtkInformation* vtkNotUsed(request),
  vtkInformationVector** vtkNotUsed(inputVector), vtkInformationVector* outputVector)
{
  vtkInformation* outInfo = outputVector->GetInformationObject(0);
  vtkImageData* data = this->AllocateOutputData(vtkImageData::GetData(outInfo), outInfo);
  int i, j;

  int outputExtent[6];     // will later be clipped in Z to a single frame
  int saveOutputExtent[6]; // will possibly contain multiple frames
  data->GetExtent(outputExtent);
  for (i = 0; i < 6; i++)
  {
    saveOutputExtent[i] = outputExtent[i];
  }
  // clip to extent to the Z size of one frame
  outputExtent[4] = this->FrameOutputExtent[4];
  outputExtent[5] = this->FrameOutputExtent[5];

  int frameExtentX = this->FrameBufferExtent[1] - this->FrameBufferExtent[0] + 1;
  int frameExtentY = this->FrameBufferExtent[3] - this->FrameBufferExtent[2] + 1;
  int frameExtentZ = this->FrameBufferExtent[5] - this->FrameBufferExtent[4] + 1;

  int extentX = outputExtent[1] - outputExtent[0] + 1;
  int extentY = outputExtent[3] - outputExtent[2] + 1;
  int extentZ = outputExtent[5] - outputExtent[4] + 1;

  // if the output is more than a single frame,
  // then the output will cover a partial or full first frame,
  // several full frames, and a partial or full last frame

  // index and Z size of the first frame in the output extent
  int firstFrame = (saveOutputExtent[4] - outputExtent[4]) / extentZ;
  int firstOutputExtent4 = saveOutputExtent[4] - extentZ * firstFrame;

  // index and Z size of the final frame in the output extent
  int finalFrame = (saveOutputExtent[5] - outputExtent[4]) / extentZ;
  int finalOutputExtent5 = saveOutputExtent[5] - extentZ * finalFrame;

  char* outPtr = (char*)data->GetScalarPointer();
  char* outPtrTmp;

  int inIncY = (frameExtentX * this->FrameBufferBitsPerPixel + 7) / 8;
  inIncY = ((inIncY + this->FrameBufferRowAlignment - 1) / this->FrameBufferRowAlignment) *
    this->FrameBufferRowAlignment;
  int inIncZ = inIncY * frameExtentY;

  int outIncX = this->NumberOfScalarComponents;
  int outIncY = outIncX * extentX;
  int outIncZ = outIncY * extentY;

  int inPadX = 0;
  int inPadY = 0;
  int inPadZ; // do inPadZ later

  int outPadX = -outputExtent[0];
  int outPadY = -outputExtent[2];
  int outPadZ; // do outPadZ later

  if (outPadX < 0)
  {
    inPadX -= outPadX;
    outPadX = 0;
  }

  if (outPadY < 0)
  {
    inPadY -= outPadY;
    outPadY = 0;
  }

  int outX = frameExtentX - inPadX;
  int outY = frameExtentY - inPadY;
  int outZ; // do outZ later

  if (outX > extentX - outPadX)
  {
    outX = extentX - outPadX;
  }
  if (outY > extentY - outPadY)
  {
    outY = extentY - outPadY;
  }

  // if output extent has changed, need to initialize output to black
  for (i = 0; i < 3; i++)
  {
    if (saveOutputExtent[i] != this->LastOutputExtent[i])
    {
      this->LastOutputExtent[i] = saveOutputExtent[i];
      this->OutputNeedsInitialization = 1;
    }
  }

  // ditto for number of scalar components
  if (data->GetNumberOfScalarComponents() != this->LastNumberOfScalarComponents)
  {
    this->LastNumberOfScalarComponents = data->GetNumberOfScalarComponents();
    this->OutputNeedsInitialization = 1;
  }

  // initialize output to zero only when necessary
  if (this->OutputNeedsInitialization)
  {
    memset(outPtr, 0,
      (saveOutputExtent[1] - saveOutputExtent[0] + 1) *
        (saveOutputExtent[3] - saveOutputExtent[2] + 1) *
        (saveOutputExtent[5] - saveOutputExtent[4] + 1) * outIncX);
    this->OutputNeedsInitialization = 0;
  }

  // we have to modify the outputExtent of the first frame,
  // because it might be complete (it will be restored after
  // the first frame has been copied to the output)
  int saveOutputExtent4 = outputExtent[4];
  outputExtent[4] = firstOutputExtent4;

  this->FrameBufferMutex.lock();

  int index = this->FrameBufferIndex;
  this->FrameTimeStamp = this->FrameBufferTimeStamps[index % this->FrameBufferSize];

  int frame;
  for (frame = firstFrame; frame <= finalFrame; frame++)
  {
    if (frame == finalFrame)
    {
      outputExtent[5] = finalOutputExtent5;
    }

    vtkDataArray* frameBuffer =
      reinterpret_cast<vtkDataArray*>(this->FrameBuffer[(index + frame) % this->FrameBufferSize]);

    char* inPtr = reinterpret_cast<char*>(frameBuffer->GetVoidPointer(0));
    char* inPtrTmp;

    extentZ = outputExtent[5] - outputExtent[4] + 1;
    inPadZ = 0;
    outPadZ = -outputExtent[4];

    if (outPadZ < 0)
    {
      inPadZ -= outPadZ;
      outPadZ = 0;
    }

    outZ = frameExtentZ - inPadZ;

    if (outZ > extentZ - outPadZ)
    {
      outZ = extentZ - outPadZ;
    }

    if (this->FlipFrames)
    { // apply a vertical flip while copying to output
      outPtr += outIncZ * outPadZ + outIncY * outPadY + outIncX * outPadX;
      inPtr += inIncZ * inPadZ + inIncY * (frameExtentY - inPadY - outY);

      for (i = 0; i < outZ; i++)
      {
        inPtrTmp = inPtr;
        outPtrTmp = outPtr + outIncY * outY;
        for (j = 0; j < outY; j++)
        {
          outPtrTmp -= outIncY;
          if (outX > 0)
          {
            this->UnpackRasterLine(outPtrTmp, inPtrTmp, inPadX, outX);
          }
          inPtrTmp += inIncY;
        }
        outPtr += outIncZ;
        inPtr += inIncZ;
      }
    }
    else
    { // don't apply a vertical flip
      outPtr += outIncZ * outPadZ + outIncY * outPadY + outIncX * outPadX;
      inPtr += inIncZ * inPadZ + inIncY * inPadY;

      for (i = 0; i < outZ; i++)
      {
        inPtrTmp = inPtr;
        outPtrTmp = outPtr;
        for (j = 0; j < outY; j++)
        {
          if (outX > 0)
          {
            this->UnpackRasterLine(outPtrTmp, inPtrTmp, inPadX, outX);
          }
          outPtrTmp += outIncY;
          inPtrTmp += inIncY;
        }
        outPtr += outIncZ;
        inPtr += inIncZ;
      }
    }
    // restore the output extent once the first frame is done
    outputExtent[4] = saveOutputExtent4;
  }

  this->FrameBufferMutex.unlock();

  return 1;
}