root/3rdparty/openexr/IlmImf/ImfTiledInputFile.cpp

DEFINITIONS

1. yTileCoords
2. wait
3. post
4. _sem
5. deleteStream
6. getTileBuffer
7. readTileData
8. readNextTileData
9. _tileBuffer
10. execute
11. initialize
12. fileName
13. header
14. version
15. setFrameBuffer
16. frameBuffer
17. isComplete
18. readTiles
19. readTiles
20. readTile
21. readTile
22. rawTileData
23. tileXSize
24. tileYSize
25. levelMode
26. levelRoundingMode
27. numLevels
28. numXLevels
29. numYLevels
30. isValidLevel
31. levelWidth
32. levelHeight
33. numXTiles
34. numYTiles
35. dataWindowForLevel
36. dataWindowForLevel
37. dataWindowForTile
38. dataWindowForTile
39. isValidTile

///////////////////////////////////////////////////////////////////////////
//
// Copyright (c) 2004, Industrial Light & Magic, a division of Lucas
// Digital Ltd. LLC
//
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
// *       Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// *       Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// *       Neither the name of Industrial Light & Magic nor the names of
// its contributors may be used to endorse or promote products derived
// from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//
///////////////////////////////////////////////////////////////////////////

//-----------------------------------------------------------------------------
//
//      class TiledInputFile
//
//-----------------------------------------------------------------------------

#include <ImfTiledInputFile.h>
#include <ImfTileDescriptionAttribute.h>
#include <ImfChannelList.h>
#include <ImfMisc.h>
#include <ImfTiledMisc.h>
#include <ImfStdIO.h>
#include <ImfCompressor.h>
#include "ImathBox.h"
#include <ImfXdr.h>
#include <ImfConvert.h>
#include <ImfVersion.h>
#include <ImfTileOffsets.h>
#include <ImfThreading.h>
#include "IlmThreadPool.h"
#include "IlmThreadSemaphore.h"
#include "IlmThreadMutex.h"
#include "ImathVec.h"
#include "Iex.h"
#include <string>
#include <vector>
#include <algorithm>
#include <assert.h>


namespace Imf {

using Imath::Box2i;
using Imath::V2i;
using std::string;
using std::vector;
using std::min;
using std::max;
using IlmThread::Mutex;
using IlmThread::Lock;
using IlmThread::Semaphore;
using IlmThread::Task;
using IlmThread::TaskGroup;
using IlmThread::ThreadPool;

namespace {

struct TInSliceInfo
{
    PixelType   typeInFrameBuffer;
    PixelType   typeInFile;
    char *      base;
    size_t      xStride;
    size_t      yStride;
    bool        fill;
    bool        skip;
    double      fillValue;
    int         xTileCoords;
    int         yTileCoords;

    TInSliceInfo (PixelType typeInFrameBuffer = HALF,
                  PixelType typeInFile = HALF,
                  char *base = 0,
                  size_t xStride = 0,
                  size_t yStride = 0,
                  bool fill = false,
                  bool skip = false,
                  double fillValue = 0.0,
                  int xTileCoords = 0,
                  int yTileCoords = 0);
};


TInSliceInfo::TInSliceInfo (PixelType tifb,
                            PixelType tifl,
                            char *b,
                            size_t xs, size_t ys,
                            bool f, bool s,
                            double fv,
                            int xtc,
                            int ytc)
:
    typeInFrameBuffer (tifb),
    typeInFile (tifl),
    base (b),
    xStride (xs),
    yStride (ys),
    fill (f),
    skip (s),
    fillValue (fv),
    xTileCoords (xtc),
    yTileCoords (ytc)
{
    // empty
}


struct TileBuffer
{
    const char *        uncompressedData;
    char *              buffer;
    int                 dataSize;
    Compressor *        compressor;
    Compressor::Format  format;
    int                 dx;
    int                 dy;
    int                 lx;
    int                 ly;
    bool                hasException;
    string              exception;

     TileBuffer (Compressor * const comp);
    ~TileBuffer ();

    inline void         wait () {_sem.wait();}
    inline void         post () {_sem.post();}

 protected:

    Semaphore _sem;
};


TileBuffer::TileBuffer (Compressor *comp):
    uncompressedData (0),
    dataSize (0),
    compressor (comp),
    format (defaultFormat (compressor)),
    dx (-1),
    dy (-1),
    lx (-1),
    ly (-1),
    hasException (false),
    exception (),
    _sem (1)
{
    // empty
}


TileBuffer::~TileBuffer ()
{
    delete compressor;
}

} // namespace


//
// struct TiledInputFile::Data stores things that will be
// needed between calls to readTile()
//

struct TiledInputFile::Data: public Mutex
{
    Header          header;                 // the image header
    TileDescription tileDesc;               // describes the tile layout
    int             version;                // file's version
    FrameBuffer     frameBuffer;            // framebuffer to write into
    LineOrder       lineOrder;              // the file's lineorder
    int             minX;                   // data window's min x coord
    int             maxX;                   // data window's max x coord
    int             minY;                   // data window's min y coord
    int             maxY;                   // data window's max x coord

    int             numXLevels;             // number of x levels
    int             numYLevels;             // number of y levels
    int *           numXTiles;              // number of x tiles at a level
    int *           numYTiles;              // number of y tiles at a level

    TileOffsets     tileOffsets;            // stores offsets in file for
                        // each tile

    bool            fileIsComplete;         // True if no tiles are missing
                            // in the file

    Int64           currentPosition;        // file offset for current tile,
                        // used to prevent unnecessary
                        // seeking

    vector<TInSliceInfo> slices;            // info about channels in file
    IStream *       is;                     // file stream to read from

    bool            deleteStream;           // should we delete the stream
                        // ourselves? or does someone
                        // else do it?

    size_t          bytesPerPixel;          // size of an uncompressed pixel

    size_t          maxBytesPerTileLine;    // combined size of a line
                        // over all channels


    vector<TileBuffer*> tileBuffers;        // each holds a single tile
    size_t          tileBufferSize;         // size of the tile buffers

     Data (bool deleteStream, int numThreads);
    ~Data ();

    inline TileBuffer * getTileBuffer (int number);
                        // hash function from tile indices
                        // into our vector of tile buffers
};


TiledInputFile::Data::Data (bool del, int numThreads):
    numXTiles (0),
    numYTiles (0),
    is (0),
    deleteStream (del)
{
    //
    // We need at least one tileBuffer, but if threading is used,
    // to keep n threads busy we need 2*n tileBuffers
    //

    tileBuffers.resize (max (1, 2 * numThreads));
}


TiledInputFile::Data::~Data ()
{
    delete [] numXTiles;
    delete [] numYTiles;

    if (deleteStream)
    delete is;

    for (size_t i = 0; i < tileBuffers.size(); i++)
        delete tileBuffers[i];
}


TileBuffer*
TiledInputFile::Data::getTileBuffer (int number)
{
    return tileBuffers[number % tileBuffers.size()];
}


namespace {

void
readTileData (TiledInputFile::Data *ifd,
          int dx, int dy,
          int lx, int ly,
              char *&buffer,
              int &dataSize)
{
    //
    // Read a single tile block from the file and into the array pointed
    // to by buffer.  If the file is memory-mapped, then we change where
    // buffer points instead of writing into the array (hence buffer needs
    // to be a reference to a char *).
    //

    //
    // Look up the location for this tile in the Index and
    // seek to that position if necessary
    //

    Int64 tileOffset = ifd->tileOffsets (dx, dy, lx, ly);

    if (tileOffset == 0)
    {
        THROW (Iex::InputExc, "Tile (" << dx << ", " << dy << ", " <<
                  lx << ", " << ly << ") is missing.");
    }

    if (ifd->currentPosition != tileOffset)
        ifd->is->seekg (tileOffset);

    //
    // Read the first few bytes of the tile (the header).
    // Verify that the tile coordinates and the level number
    // are correct.
    //

    int tileXCoord, tileYCoord, levelX, levelY;

    Xdr::read <StreamIO> (*ifd->is, tileXCoord);
    Xdr::read <StreamIO> (*ifd->is, tileYCoord);
    Xdr::read <StreamIO> (*ifd->is, levelX);
    Xdr::read <StreamIO> (*ifd->is, levelY);
    Xdr::read <StreamIO> (*ifd->is, dataSize);

    if (tileXCoord != dx)
        throw Iex::InputExc ("Unexpected tile x coordinate.");

    if (tileYCoord != dy)
        throw Iex::InputExc ("Unexpected tile y coordinate.");

    if (levelX != lx)
        throw Iex::InputExc ("Unexpected tile x level number coordinate.");

    if (levelY != ly)
        throw Iex::InputExc ("Unexpected tile y level number coordinate.");

    if (dataSize > (int) ifd->tileBufferSize)
        throw Iex::InputExc ("Unexpected tile block length.");

    //
    // Read the pixel data.
    //

    if (ifd->is->isMemoryMapped ())
        buffer = ifd->is->readMemoryMapped (dataSize);
    else
        ifd->is->read (buffer, dataSize);

    //
    // Keep track of which tile is the next one in
    // the file, so that we can avoid redundant seekg()
    // operations (seekg() can be fairly expensive).
    //

    ifd->currentPosition = tileOffset + 5 * Xdr::size<int>() + dataSize;
}


void
readNextTileData (TiledInputFile::Data *ifd,
          int &dx, int &dy,
          int &lx, int &ly,
                  char * & buffer,
          int &dataSize)
{
    //
    // Read the next tile block from the file
    //

    //
    // Read the first few bytes of the tile (the header).
    //

    Xdr::read <StreamIO> (*ifd->is, dx);
    Xdr::read <StreamIO> (*ifd->is, dy);
    Xdr::read <StreamIO> (*ifd->is, lx);
    Xdr::read <StreamIO> (*ifd->is, ly);
    Xdr::read <StreamIO> (*ifd->is, dataSize);

    if (dataSize > (int) ifd->tileBufferSize)
        throw Iex::InputExc ("Unexpected tile block length.");

    //
    // Read the pixel data.
    //

    ifd->is->read (buffer, dataSize);

    //
    // Keep track of which tile is the next one in
    // the file, so that we can avoid redundant seekg()
    // operations (seekg() can be fairly expensive).
    //

    ifd->currentPosition += 5 * Xdr::size<int>() + dataSize;
}


//
// A TileBufferTask encapsulates the task of uncompressing
// a single tile and copying it into the frame buffer.
//

class TileBufferTask : public Task
{
  public:

    TileBufferTask (TaskGroup *group,
                    TiledInputFile::Data *ifd,
            TileBuffer *tileBuffer);

    virtual ~TileBufferTask ();

    virtual void                execute ();

  private:

    TiledInputFile::Data *      _ifd;
    TileBuffer *                _tileBuffer;
};


TileBufferTask::TileBufferTask
    (TaskGroup *group,
     TiledInputFile::Data *ifd,
     TileBuffer *tileBuffer)
:
    Task (group),
    _ifd (ifd),
    _tileBuffer (tileBuffer)
{
    // empty
}


TileBufferTask::~TileBufferTask ()
{
    //
    // Signal that the tile buffer is now free
    //

    _tileBuffer->post ();
}


void
TileBufferTask::execute ()
{
    try
    {
        //
        // Calculate information about the tile
        //

        Box2i tileRange = Imf::dataWindowForTile (_ifd->tileDesc,
                                                  _ifd->minX, _ifd->maxX,
                                                  _ifd->minY, _ifd->maxY,
                                                  _tileBuffer->dx,
                                                  _tileBuffer->dy,
                                                  _tileBuffer->lx,
                                                  _tileBuffer->ly);

        int numPixelsPerScanLine = tileRange.max.x - tileRange.min.x + 1;

        int numPixelsInTile = numPixelsPerScanLine *
                            (tileRange.max.y - tileRange.min.y + 1);

        int sizeOfTile = _ifd->bytesPerPixel * numPixelsInTile;


        //
        // Uncompress the data, if necessary
        //

        if (_tileBuffer->compressor && _tileBuffer->dataSize < sizeOfTile)
        {
            _tileBuffer->format = _tileBuffer->compressor->format();

            _tileBuffer->dataSize = _tileBuffer->compressor->uncompressTile
        (_tileBuffer->buffer, _tileBuffer->dataSize,
         tileRange, _tileBuffer->uncompressedData);
        }
        else
        {
            //
            // If the line is uncompressed, it's in XDR format,
            // regardless of the compressor's output format.
            //

            _tileBuffer->format = Compressor::XDR;
            _tileBuffer->uncompressedData = _tileBuffer->buffer;
        }

        //
        // Convert the tile of pixel data back from the machine-independent
    // representation, and store the result in the frame buffer.
        //

        const char *readPtr = _tileBuffer->uncompressedData;
                                                        // points to where we
                                                        // read from in the
                                                        // tile block

        //
        // Iterate over the scan lines in the tile.
        //

        for (int y = tileRange.min.y; y <= tileRange.max.y; ++y)
        {
            //
            // Iterate over all image channels.
            //

            for (unsigned int i = 0; i < _ifd->slices.size(); ++i)
            {
                const TInSliceInfo &slice = _ifd->slices[i];

                //
                // These offsets are used to facilitate both
                // absolute and tile-relative pixel coordinates.
                //

                int xOffset = slice.xTileCoords * tileRange.min.x;
                int yOffset = slice.yTileCoords * tileRange.min.y;

                //
                // Fill the frame buffer with pixel data.
                //

                if (slice.skip)
                {
                    //
                    // The file contains data for this channel, but
                    // the frame buffer contains no slice for this channel.
                    //

                    skipChannel (readPtr, slice.typeInFile,
                                 numPixelsPerScanLine);
                }
                else
                {
                    //
                    // The frame buffer contains a slice for this channel.
                    //

                    char *writePtr = slice.base +
                                     (y - yOffset) * slice.yStride +
                                     (tileRange.min.x - xOffset) *
                                     slice.xStride;

                    char *endPtr = writePtr +
                                   (numPixelsPerScanLine - 1) * slice.xStride;

                    copyIntoFrameBuffer (readPtr, writePtr, endPtr,
                                         slice.xStride,
                                         slice.fill, slice.fillValue,
                                         _tileBuffer->format,
                                         slice.typeInFrameBuffer,
                                         slice.typeInFile);
                }
            }
        }
    }
    catch (std::exception &e)
    {
        if (!_tileBuffer->hasException)
        {
            _tileBuffer->exception = e.what ();
            _tileBuffer->hasException = true;
        }
    }
    catch (...)
    {
        if (!_tileBuffer->hasException)
        {
            _tileBuffer->exception = "unrecognized exception";
            _tileBuffer->hasException = true;
        }
    }
}


TileBufferTask *
newTileBufferTask
    (TaskGroup *group,
     TiledInputFile::Data *ifd,
     int number,
     int dx, int dy,
     int lx, int ly)
{
    //
    // Wait for a tile buffer to become available,
    // fill the buffer with raw data from the file,
    // and create a new TileBufferTask whose execute()
    // method will uncompress the tile and copy the
    // tile's pixels into the frame buffer.
    //

    TileBuffer *tileBuffer = ifd->getTileBuffer (number);

    try
    {
    tileBuffer->wait();

    tileBuffer->dx = dx;
    tileBuffer->dy = dy;
    tileBuffer->lx = lx;
    tileBuffer->ly = ly;

    tileBuffer->uncompressedData = 0;

    readTileData (ifd, dx, dy, lx, ly,
              tileBuffer->buffer,
              tileBuffer->dataSize);
    }
    catch (...)
    {
    //
    // Reading from the file caused an exception.
    // Signal that the tile buffer is free, and
    // re-throw the exception.
    //

    tileBuffer->post();
    throw;
    }

    return new TileBufferTask (group, ifd, tileBuffer);
}


} // namespace


TiledInputFile::TiledInputFile (const char fileName[], int numThreads):
    _data (new Data (true, numThreads))
{
    //
    // This constructor is called when a user
    // explicitly wants to read a tiled file.
    //

    try
    {
    _data->is = new StdIFStream (fileName);
    _data->header.readFrom (*_data->is, _data->version);
    initialize();
    }
    catch (Iex::BaseExc &e)
    {
    delete _data;

    REPLACE_EXC (e, "Cannot open image file "
            "\"" << fileName << "\". " << e);
    throw;
    }
    catch (...)
    {
    delete _data;
        throw;
    }
}


TiledInputFile::TiledInputFile (IStream &is, int numThreads):
    _data (new Data (false, numThreads))
{
    //
    // This constructor is called when a user
    // explicitly wants to read a tiled file.
    //

    try
    {
    _data->is = &is;
    _data->header.readFrom (*_data->is, _data->version);
    initialize();
    }
    catch (Iex::BaseExc &e)
    {
    delete _data;

    REPLACE_EXC (e, "Cannot open image file "
            "\"" << is.fileName() << "\". " << e);
    throw;
    }
    catch (...)
    {
    delete _data;
        throw;
    }
}


TiledInputFile::TiledInputFile
    (const Header &header,
     IStream *is,
     int version,
     int numThreads)
:
    _data (new Data (false, numThreads))
{
    //
    // This constructor called by class Imf::InputFile
    // when a user wants to just read an image file, and
    // doesn't care or know if the file is tiled.
    //

    _data->is = is;
    _data->header = header;
    _data->version = version;
    initialize();
}


void
TiledInputFile::initialize ()
{
    if (!isTiled (_data->version))
    throw Iex::ArgExc ("Expected a tiled file but the file is not tiled.");

    _data->header.sanityCheck (true);

    _data->tileDesc = _data->header.tileDescription();
    _data->lineOrder = _data->header.lineOrder();

    //
    // Save the dataWindow information
    //

    const Box2i &dataWindow = _data->header.dataWindow();
    _data->minX = dataWindow.min.x;
    _data->maxX = dataWindow.max.x;
    _data->minY = dataWindow.min.y;
    _data->maxY = dataWindow.max.y;

    //
    // Precompute level and tile information to speed up utility functions
    //

    precalculateTileInfo (_data->tileDesc,
              _data->minX, _data->maxX,
              _data->minY, _data->maxY,
              _data->numXTiles, _data->numYTiles,
              _data->numXLevels, _data->numYLevels);

    _data->bytesPerPixel = calculateBytesPerPixel (_data->header);

    _data->maxBytesPerTileLine = _data->bytesPerPixel * _data->tileDesc.xSize;

    _data->tileBufferSize = _data->maxBytesPerTileLine * _data->tileDesc.ySize;

    //
    // Create all the TileBuffers and allocate their internal buffers
    //

    for (size_t i = 0; i < _data->tileBuffers.size(); i++)
    {
        _data->tileBuffers[i] = new TileBuffer (newTileCompressor
                          (_data->header.compression(),
                           _data->maxBytesPerTileLine,
                           _data->tileDesc.ySize,
                           _data->header));

        if (!_data->is->isMemoryMapped ())
            _data->tileBuffers[i]->buffer = new char [_data->tileBufferSize];
    }

    _data->tileOffsets = TileOffsets (_data->tileDesc.mode,
                      _data->numXLevels,
                      _data->numYLevels,
                      _data->numXTiles,
                      _data->numYTiles);

    _data->tileOffsets.readFrom (*(_data->is), _data->fileIsComplete);

    _data->currentPosition = _data->is->tellg();
}


TiledInputFile::~TiledInputFile ()
{
    if (!_data->is->isMemoryMapped())
        for (size_t i = 0; i < _data->tileBuffers.size(); i++)
            delete [] _data->tileBuffers[i]->buffer;

    delete _data;
}


const char *
TiledInputFile::fileName () const
{
    return _data->is->fileName();
}


const Header &
TiledInputFile::header () const
{
    return _data->header;
}


int
TiledInputFile::version () const
{
    return _data->version;
}


void
TiledInputFile::setFrameBuffer (const FrameBuffer &frameBuffer)
{
    Lock lock (*_data);

    //
    // Set the frame buffer
    //

    //
    // Check if the new frame buffer descriptor is
    // compatible with the image file header.
    //

    const ChannelList &channels = _data->header.channels();

    for (FrameBuffer::ConstIterator j = frameBuffer.begin();
         j != frameBuffer.end();
         ++j)
    {
        ChannelList::ConstIterator i = channels.find (j.name());

        if (i == channels.end())
            continue;

        if (i.channel().xSampling != j.slice().xSampling ||
            i.channel().ySampling != j.slice().ySampling)
            THROW (Iex::ArgExc, "X and/or y subsampling factors "
                "of \"" << i.name() << "\" channel "
                "of input file \"" << fileName() << "\" are "
                "not compatible with the frame buffer's "
                "subsampling factors.");
    }

    //
    // Initialize the slice table for readPixels().
    //

    vector<TInSliceInfo> slices;
    ChannelList::ConstIterator i = channels.begin();

    for (FrameBuffer::ConstIterator j = frameBuffer.begin();
         j != frameBuffer.end();
         ++j)
    {
        while (i != channels.end() && strcmp (i.name(), j.name()) < 0)
        {
            //
            // Channel i is present in the file but not
            // in the frame buffer; data for channel i
            // will be skipped during readPixels().
            //

            slices.push_back (TInSliceInfo (i.channel().type,
                        i.channel().type,
                        0,      // base
                        0,      // xStride
                        0,      // yStride
                        false,  // fill
                        true,   // skip
                        0.0));  // fillValue
            ++i;
        }

        bool fill = false;

        if (i == channels.end() || strcmp (i.name(), j.name()) > 0)
        {
            //
            // Channel i is present in the frame buffer, but not in the file.
            // In the frame buffer, slice j will be filled with a default value.
            //

            fill = true;
        }

        slices.push_back (TInSliceInfo (j.slice().type,
                                        fill? j.slice().type: i.channel().type,
                                        j.slice().base,
                                        j.slice().xStride,
                                        j.slice().yStride,
                                        fill,
                                        false, // skip
                                        j.slice().fillValue,
                                        (j.slice().xTileCoords)? 1: 0,
                                        (j.slice().yTileCoords)? 1: 0));

        if (i != channels.end() && !fill)
            ++i;
    }

    while (i != channels.end())
    {
    //
    // Channel i is present in the file but not
    // in the frame buffer; data for channel i
    // will be skipped during readPixels().
    //

    slices.push_back (TInSliceInfo (i.channel().type,
                    i.channel().type,
                    0, // base
                    0, // xStride
                    0, // yStride
                    false,  // fill
                    true, // skip
                    0.0)); // fillValue
    ++i;
    }

    //
    // Store the new frame buffer.
    //

    _data->frameBuffer = frameBuffer;
    _data->slices = slices;
}


const FrameBuffer &
TiledInputFile::frameBuffer () const
{
    Lock lock (*_data);
    return _data->frameBuffer;
}


bool
TiledInputFile::isComplete () const
{
    return _data->fileIsComplete;
}


void
TiledInputFile::readTiles (int dx1, int dx2, int dy1, int dy2, int lx, int ly)
{
    //
    // Read a range of tiles from the file into the framebuffer
    //

    try
    {
        Lock lock (*_data);

        if (_data->slices.size() == 0)
            throw Iex::ArgExc ("No frame buffer specified "
                   "as pixel data destination.");

        //
        // Determine the first and last tile coordinates in both dimensions.
        // We always attempt to read the range of tiles in the order that
        // they are stored in the file.
        //

        if (dx1 > dx2)
            std::swap (dx1, dx2);

        if (dy1 > dy2)
            std::swap (dy1, dy2);

        int dyStart = dy1;
    int dyStop  = dy2 + 1;
    int dY      = 1;

        if (_data->lineOrder == DECREASING_Y)
        {
            dyStart = dy2;
            dyStop  = dy1 - 1;
            dY      = -1;
        }

        //
        // Create a task group for all tile buffer tasks.  When the
    // task group goes out of scope, the destructor waits until
    // all tasks are complete.
        //

        {
            TaskGroup taskGroup;
            int tileNumber = 0;

            for (int dy = dyStart; dy != dyStop; dy += dY)
            {
                for (int dx = dx1; dx <= dx2; dx++)
                {
                    if (!isValidTile (dx, dy, lx, ly))
                        THROW (Iex::ArgExc,
                   "Tile (" << dx << ", " << dy << ", " <<
                   lx << "," << ly << ") is not a valid tile.");

                    ThreadPool::addGlobalTask (newTileBufferTask (&taskGroup,
                                                                  _data,
                                                                  tileNumber++,
                                                                  dx, dy,
                                                                  lx, ly));
                }
            }

        //
            // finish all tasks
        //
        }

    //
    // Exeption handling:
    //
    // TileBufferTask::execute() may have encountered exceptions, but
    // those exceptions occurred in another thread, not in the thread
    // that is executing this call to TiledInputFile::readTiles().
    // TileBufferTask::execute() has caught all exceptions and stored
    // the exceptions' what() strings in the tile buffers.
    // Now we check if any tile buffer contains a stored exception; if
    // this is the case then we re-throw the exception in this thread.
    // (It is possible that multiple tile buffers contain stored
    // exceptions.  We re-throw the first exception we find and
    // ignore all others.)
    //

    const string *exception = 0;

        for (int i = 0; i < _data->tileBuffers.size(); ++i)
    {
            TileBuffer *tileBuffer = _data->tileBuffers[i];

        if (tileBuffer->hasException && !exception)
        exception = &tileBuffer->exception;

        tileBuffer->hasException = false;
    }

    if (exception)
        throw Iex::IoExc (*exception);
    }
    catch (Iex::BaseExc &e)
    {
        REPLACE_EXC (e, "Error reading pixel data from image "
                        "file \"" << fileName() << "\". " << e);
        throw;
    }
}


void
TiledInputFile::readTiles (int dx1, int dx2, int dy1, int dy2, int l)
{
    readTiles (dx1, dx2, dy1, dy2, l, l);
}


void
TiledInputFile::readTile (int dx, int dy, int lx, int ly)
{
    readTiles (dx, dx, dy, dy, lx, ly);
}


void
TiledInputFile::readTile (int dx, int dy, int l)
{
    readTile (dx, dy, l, l);
}


void
TiledInputFile::rawTileData (int &dx, int &dy,
                 int &lx, int &ly,
                             const char *&pixelData,
                 int &pixelDataSize)
{
    try
    {
        Lock lock (*_data);

        if (!isValidTile (dx, dy, lx, ly))
            throw Iex::ArgExc ("Tried to read a tile outside "
                   "the image file's data window.");

        TileBuffer *tileBuffer = _data->getTileBuffer (0);

        readNextTileData (_data, dx, dy, lx, ly,
              tileBuffer->buffer,
                          pixelDataSize);

        pixelData = tileBuffer->buffer;
    }
    catch (Iex::BaseExc &e)
    {
        REPLACE_EXC (e, "Error reading pixel data from image "
            "file \"" << fileName() << "\". " << e);
        throw;
    }
}


unsigned int
TiledInputFile::tileXSize () const
{
    return _data->tileDesc.xSize;
}


unsigned int
TiledInputFile::tileYSize () const
{
    return _data->tileDesc.ySize;
}


LevelMode
TiledInputFile::levelMode () const
{
    return _data->tileDesc.mode;
}


LevelRoundingMode
TiledInputFile::levelRoundingMode () const
{
    return _data->tileDesc.roundingMode;
}


int
TiledInputFile::numLevels () const
{
    if (levelMode() == RIPMAP_LEVELS)
    THROW (Iex::LogicExc, "Error calling numLevels() on image "
                  "file \"" << fileName() << "\" "
                  "(numLevels() is not defined for files "
                  "with RIPMAP level mode).");

    return _data->numXLevels;
}


int
TiledInputFile::numXLevels () const
{
    return _data->numXLevels;
}


int
TiledInputFile::numYLevels () const
{
    return _data->numYLevels;
}


bool
TiledInputFile::isValidLevel (int lx, int ly) const
{
    if (lx < 0 || ly < 0)
    return false;

    if (levelMode() == MIPMAP_LEVELS && lx != ly)
    return false;

    if (lx >= numXLevels() || ly >= numYLevels())
    return false;

    return true;
}


int
TiledInputFile::levelWidth (int lx) const
{
    try
    {
        return levelSize (_data->minX, _data->maxX, lx,
              _data->tileDesc.roundingMode);
    }
    catch (Iex::BaseExc &e)
    {
    REPLACE_EXC (e, "Error calling levelWidth() on image "
            "file \"" << fileName() << "\". " << e);
    throw;
    }
}


int
TiledInputFile::levelHeight (int ly) const
{
    try
    {
        return levelSize (_data->minY, _data->maxY, ly,
                          _data->tileDesc.roundingMode);
    }
    catch (Iex::BaseExc &e)
    {
    REPLACE_EXC (e, "Error calling levelHeight() on image "
            "file \"" << fileName() << "\". " << e);
    throw;
    }
}


int
TiledInputFile::numXTiles (int lx) const
{
    if (lx < 0 || lx >= _data->numXLevels)
    {
        THROW (Iex::ArgExc, "Error calling numXTiles() on image "
                "file \"" << _data->is->fileName() << "\" "
                "(Argument is not in valid range).");

    }

    return _data->numXTiles[lx];
}


int
TiledInputFile::numYTiles (int ly) const
{
    if (ly < 0 || ly >= _data->numYLevels)
    {
        THROW (Iex::ArgExc, "Error calling numYTiles() on image "
                "file \"" << _data->is->fileName() << "\" "
                "(Argument is not in valid range).");
    }

    return _data->numYTiles[ly];
}


Box2i
TiledInputFile::dataWindowForLevel (int l) const
{
    return dataWindowForLevel (l, l);
}


Box2i
TiledInputFile::dataWindowForLevel (int lx, int ly) const
{
    try
    {
    return Imf::dataWindowForLevel (_data->tileDesc,
                        _data->minX, _data->maxX,
                        _data->minY, _data->maxY,
                        lx, ly);
    }
    catch (Iex::BaseExc &e)
    {
    REPLACE_EXC (e, "Error calling dataWindowForLevel() on image "
            "file \"" << fileName() << "\". " << e);
    throw;
    }
}


Box2i
TiledInputFile::dataWindowForTile (int dx, int dy, int l) const
{
    return dataWindowForTile (dx, dy, l, l);
}


Box2i
TiledInputFile::dataWindowForTile (int dx, int dy, int lx, int ly) const
{
    try
    {
    if (!isValidTile (dx, dy, lx, ly))
        throw Iex::ArgExc ("Arguments not in valid range.");

        return Imf::dataWindowForTile (_data->tileDesc,
                       _data->minX, _data->maxX,
                       _data->minY, _data->maxY,
                       dx, dy, lx, ly);
    }
    catch (Iex::BaseExc &e)
    {
    REPLACE_EXC (e, "Error calling dataWindowForTile() on image "
            "file \"" << fileName() << "\". " << e);
    throw;
    }
}


bool
TiledInputFile::isValidTile (int dx, int dy, int lx, int ly) const
{
    return ((lx < _data->numXLevels && lx >= 0) &&
            (ly < _data->numYLevels && ly >= 0) &&
            (dx < _data->numXTiles[lx] && dx >= 0) &&
            (dy < _data->numYTiles[ly] && dy >= 0));
}


} // namespace Imf