jpgsrc.cpp

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// $Id: jpgsrc.cpp 1282 2006-06-09 09:46:49Z alex $
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 */
// 


#include "camtypes.h"
//#include "ccfile.h" - in camtypes.h [AUTOMATICALLY REMOVED]

#include "jpglib_namespace.h"
#include "jpgermgr.h"
//#include "errors.h" - in camtypes.h [AUTOMATICALLY REMOVED]
//#include "andy.h"         // for _R(IDE_FILEREADERROR)

#include "jpgsrc.h"

// Place any IMPLEMENT type statements here
//CC_IMPLEMENT_MEMDUMP(CCWobJob, CC_CLASS_MEMDUMP)


// We want better memory tracking
#define new CAM_DEBUG_NEW


// Functions follow



/********************************************************************************************

>   JPEGDataSource::JPEGDataSource(CCFile* pInputFile)

    Author:     Colin_Barfoot (Xara Group Ltd) <camelotdev@xara.com>
    Created:    08/08/96
    Inputs:     pFile : a pointer to a CCFile providing the source for a JPEG filter
    Purpose:    Default consturctor for a JPEGDataSource.
                This constructor sets up the callback functions to be used when the IJG
                library requires more data to be read from the source given as the argument
                to this constructor.

********************************************************************************************/
JPEGDataSource::JPEGDataSource(CCFile* pInputFile) : m_pInputFile(pInputFile)
{
    m_bStartOfFile  = FALSE;    // Provide safe defaults
    m_pBuffer       = NULL;

    // Override default "methods"
    init_source         = InitSource;
    fill_input_buffer   = FillInputBuffer;
    skip_input_data     = SkipInputData;
    /*
    * An additional method that can be provided by data source modules is the
    * resync_to_restart method for error recovery in the presence of RST markers.
    * For the moment, this source module just uses the default resync method
    * provided by the JPEG library.  That method assumes that no backtracking
    * is possible.
    */
    resync_to_restart   = libJPEG::jpeg_resync_to_restart;
    term_source         = TerminateSource;

    // Initialize base class!!
    bytes_in_buffer     = 0;        // forces fill_input_buffer on first read
    next_input_byte     = NULL;     // until buffer loaded
}


/********************************************************************************************

>   boolean JPEGDataSource::InitBuffer(j_decompress_ptr cinfo)

    Author:     Colin_Barfoot (Xara Group Ltd) <camelotdev@xara.com>
    Created:    08/08/96
    Inputs:     cinfo : a pointer to a CCFile providing the source for a JPEG filter
    Purpose:    Initializes the buffer to be used by the m_pFile object.
    Notes:      Uses the IJG library for memory allocation

********************************************************************************************/
libJPEG::boolean    JPEGDataSource::InitBuffer(libJPEG::j_decompress_ptr cinfo)
{
    using namespace libJPEG;

    m_pBuffer = (JOCTET *) (*cinfo->mem->alloc_small) 
                    ((j_common_ptr) cinfo, JPOOL_PERMANENT, INPUT_BUF_SIZE * sizeof(JOCTET));
    return (m_pBuffer != NULL);
}


/********************************************************************************************

>   void JPEGDataSource::InitSource(j_decompress_ptr cinfo)

    Author:     Colin_Barfoot (Xara Group Ltd) <camelotdev@xara.com>
    Created:    08/08/96
    Inputs:     cinfo : a pointer to a j_decompress_ptr provided by the IJG routines
    Purpose:    Initialize source --- called by jpeg_read_header before any data is actually
                read.

    Notes:      We reset the empty-input-file flag for each image, but we don't clear the
                input buffer. This is correct behavior for reading a series of images from
                one source.

********************************************************************************************/
void JPEGDataSource::InitSource(libJPEG::j_decompress_ptr cinfo)
{
    JPEGDataSource* pThis = (JPEGDataSource*)cinfo->src;

    pThis->m_bStartOfFile = TRUE;
}



/********************************************************************************************

>   boolean JPEGDataSource::FillInputBuffer (j_decompress_ptr cinfo)

    Author:     Colin_Barfoot (Xara Group Ltd) <camelotdev@xara.com>
    Created:    08/08/96
    Inputs:     cinfo : a pointer to a j_decompress_ptr provided by the IJG routines
    Purpose:    Overrides the standard implementation using stdio with a CCFile version.

    Notes:      The following extract from the IJG library explains its purpose:

                Fill the input buffer --- called whenever buffer is emptied.

                In typical applications, this should read fresh data into the buffer
                (ignoring the current state of next_input_byte & bytes_in_buffer),
                reset the pointer & count to the start of the buffer, and return TRUE
                indicating that the buffer has been reloaded.  It is not necessary to
                fill the buffer entirely, only to obtain at least one more byte.

                There is no such thing as an EOF return.  If the end of the file has been
                reached, the routine has a choice of ERREXIT() or inserting fake data into
                the buffer.  In most cases, generating a warning message and inserting a
                fake EOI marker is the best course of action --- this will allow the
                decompressor to output however much of the image is there.  However,
                the resulting error message is misleading if the real problem is an empty
                input file, so we handle that case specially.

                In applications that need to be able to suspend compression due to input
                not being available yet, a FALSE return indicates that no more data can be
                obtained right now, but more may be forthcoming later.  In this situation,
                the decompressor will return to its caller (with an indication of the
                number of scanlines it has read, if any).  The application should resume
                decompression after it has loaded more data into the input buffer.  Note
                that there are substantial restrictions on the use of suspension --- see
                the documentation.

                When suspending, the decompressor will back up to a convenient restart point
                (typically the start of the current MCU). next_input_byte & bytes_in_buffer
                indicate where the restart point will be if the current call returns FALSE.
                Data beyond this point must be rescanned after resumption, so move it to
                the front of the buffer rather than discarding it.

********************************************************************************************/
libJPEG::boolean JPEGDataSource::FillInputBuffer (libJPEG::j_decompress_ptr cinfo)
{
    JPEGDataSource* pThis = (JPEGDataSource*)cinfo->src;
    CCFile* pFile = pThis->m_pInputFile;

    if (pFile->bad())
    {
        JPEGErrorManager* pError = (JPEGErrorManager*)cinfo->err;
        pError->ThrowError(_R(IDE_FILEREADERROR));
    }

    size_t start = pFile->tellIn();
    pFile->read(pThis->m_pBuffer, INPUT_BUF_SIZE);
    size_t nbytes = pFile->tellIn() - start;
    if (nbytes < INPUT_BUF_SIZE)
    {
        // For some reason trying to read too many bytes from a CCFile sets the stream bad
        // so don't let it stick some absurd message up
        Error::ClearError();
        // & clear any eof signal
        pFile->SetGoodState();
    }
    if (nbytes <= 0)
    {
        if (pThis->m_bStartOfFile)  // Treat empty input file as fatal error
        {
            using namespace libJPEG;
            ERREXIT(cinfo, JERR_INPUT_EMPTY);
        }
        
        using namespace libJPEG;
        WARNMS(cinfo, JWRN_JPEG_EOF);
        // Insert a fake EOI marker
        pThis->m_pBuffer[0] = (JOCTET) 0xFF;
        pThis->m_pBuffer[1] = (JOCTET) JPEG_EOI;
        nbytes = 2;
    }

    pThis->next_input_byte = pThis->m_pBuffer;
    pThis->bytes_in_buffer = nbytes;
    pThis->m_bStartOfFile = FALSE;

    return TRUE;
}


/********************************************************************************************

>   void JPEGDataSource::SkipInputData(j_decompress_ptr cinfo, INT32 num_bytes)

    Author:     Colin_Barfoot (Xara Group Ltd) <camelotdev@xara.com>
    Created:    08/08/96
    Inputs:     cinfo : a pointer to a j_decompress_ptr provided by the IJG routines
    Purpose:    Overrides the standard implementation using stdio with a CCFile version.
                Skip data --- used to skip over a potentially large amount of
                uninteresting data (such as an APPn marker).

                Writers of suspendable-input applications must note that skip_input_data
                is not granted the right to give a suspension return.  If the skip extends
                beyond the data currently in the buffer, the buffer can be marked empty so
                that the next read will cause a fill_input_buffer call that can suspend.
                Arranging for additional bytes to be discarded before reloading the input
                buffer is the application writer's problem.

********************************************************************************************/
void JPEGDataSource::SkipInputData(libJPEG::j_decompress_ptr cinfo, long /*TYPENOTE: Correct*/ num_bytes)
{
    JPEGDataSource* pThis = (JPEGDataSource*)cinfo->src;
  /* Just a dumb implementation for now.  Could use fseek() except
   * it doesn't work on pipes.  Not clear that being smart is worth
   * any trouble anyway --- large skips are infrequent.
   */
    if (num_bytes > 0)
    {
        while (num_bytes > (INT32) pThis->bytes_in_buffer)
        {
            num_bytes -= (INT32) pThis->bytes_in_buffer;
            (void)FillInputBuffer(cinfo);
            /* note we assume that fill_input_buffer will never return FALSE,
            * so suspension need not be handled.
            */
        }
        pThis->next_input_byte += (size_t) num_bytes;
        pThis->bytes_in_buffer -= (size_t) num_bytes;
    }
}



/********************************************************************************************

>   void JPEGDataSource::SkipInputData(j_decompress_ptr cinfo, INT32 num_bytes)

    Author:     Colin_Barfoot (Xara Group Ltd) <camelotdev@xara.com>
    Created:    08/08/96
    Inputs:     cinfo : a pointer to a j_decompress_ptr provided by the IJG routines
    Purpose:    Overrides the standard implementation using stdio with a CCFile version.
                The following extract from the IJG library explains its purpose:
                Terminate source --- called by jpeg_finish_decompress
                after all data has been read.  Often a no-op.

                NB: *not* called by jpeg_abort or jpeg_destroy; surrounding
                application must deal with any cleanup that should happen even
                for error exit.

********************************************************************************************/
void JPEGDataSource::TerminateSource(libJPEG::j_decompress_ptr cinfo)
{
//  JPEGDataSource* pThis = (JPEGDataSource*)cinfo->src;
  /* no work necessary here */
}

---