JpegDef.hpp

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#ifndef JPEGDEF_HPP_
#define JPEGDEF_HPP_

extern "C" {
#include <stdio.h>
#include <jpeglib.h>
#include <setjmp.h>
/* this is not a core library module, so it doesn't define JPEG_INTERNALS */
#include "jerror.h"
}

#ifndef HAVE_STDLIB_H                           /* <stdlib.h> should declare malloc(),free() */
extern void * malloc JPP((size_t size));
extern void free JPP((void *ptr));
#endif


/*
 * In ANSI C, and indeed any rational implementation, size_t is also the
 * type returned by sizeof().  However, it seems there are some irrational
 * implementations out there, in which sizeof() returns an int even though
 * size_t is defined as long or unsigned long.  To ensure consistent results
 * we always use this SIZEOF() macro in place of using sizeof() directly.
 */
#define SIZEOF(object)          ((size_t) sizeof(object))
/*
 * The modules that use fread() and fwrite() always invoke them through
 * these macros.  On some systems you may need to twiddle the argument casts.
 * CAUTION: argument order is different from underlying functions!
 */
#define JFREAD(file,buf,sizeofbuf)  \
                                ((size_t) fread((void *) (buf), (size_t) 1, (size_t) (sizeofbuf), (file)))
#define JFWRITE(file,buf,sizeofbuf)  \
                                ((size_t) fwrite((const void *) (buf), (size_t) 1, (size_t) (sizeofbuf), (file)))





typedef struct  {
                struct jpeg_error_mgr pub;      /* "public" fields */
                jmp_buf setjmp_buffer;          /* for return to caller */
} my_error_mgr;

typedef my_error_mgr * my_error_ptr;


inline
void my_error_exit(j_common_ptr cinfo)
{
                /* cinfo->err really points to a my_error_mgr struct, so coerce pointer */
                my_error_ptr myerr = (my_error_ptr) cinfo->err;

                /* Always display the message. */
                /* We could postpone this until after returning, if we chose. */
                //(*cinfo->err->output_message) (cinfo);

                /* Return control to the setjmp point */
                longjmp(myerr->setjmp_buffer, 1);
}

typedef struct jpeg_decompress_struct my_jpeg_decompress_struct;
typedef struct jpeg_compress_struct my_jpeg_compress_struct;




typedef struct {
                struct jpeg_destination_mgr pub; /* public fields */
                FILE * outfile;                 /* target stream */
                JOCTET * buffer;                                /* start of buffer */
} slip_destination_mgr;

typedef slip_destination_mgr * slip_dest_ptr;

#define OUTPUT_BUF_SIZE  4096   /* choose an efficiently fwrite'able size */

METHODDEF(void)
slip_init_destination (j_compress_ptr cinfo)
{
                slip_dest_ptr dest = (slip_dest_ptr) cinfo->dest;

                /* Allocate the output buffer --- it will be released when done with image */
                dest->buffer = (JOCTET *)
                                                                  (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
                                                                                                  OUTPUT_BUF_SIZE * SIZEOF(JOCTET));

                dest->pub.next_output_byte = dest->buffer;
                dest->pub.free_in_buffer = OUTPUT_BUF_SIZE;
}

METHODDEF(boolean)
slip_empty_output_buffer (j_compress_ptr cinfo)
{
                slip_dest_ptr dest = (slip_dest_ptr) cinfo->dest;

                if (JFWRITE(dest->outfile, dest->buffer, OUTPUT_BUF_SIZE) !=
                                                (size_t) OUTPUT_BUF_SIZE)
                                ERREXIT(cinfo, JERR_FILE_WRITE);

                dest->pub.next_output_byte = dest->buffer;
                dest->pub.free_in_buffer = OUTPUT_BUF_SIZE;

                return TRUE;
}

/*
 * Terminate destination --- called by jpeg_finish_compress
 * after all data has been written.  Usually needs to flush buffer.
 *
 * NB: *not* called by jpeg_abort or jpeg_destroy; surrounding
 * application must deal with any cleanup that should happen even
 * for error exit.
 */

METHODDEF(void)
slip_term_destination (j_compress_ptr cinfo)
{
                slip_dest_ptr dest = (slip_dest_ptr) cinfo->dest;
                size_t datacount = OUTPUT_BUF_SIZE - dest->pub.free_in_buffer;

                /* Write any data remaining in the buffer */
                if (datacount > 0) {
                                if (JFWRITE(dest->outfile, dest->buffer, datacount) != datacount)
                                                ERREXIT(cinfo, JERR_FILE_WRITE);
                }
                fflush(dest->outfile);
                /* Make sure we wrote the output file OK */
                if (ferror(dest->outfile))
                                ERREXIT(cinfo, JERR_FILE_WRITE);
}


GLOBAL(void)
slip_jpeg_stdio_dest (j_compress_ptr cinfo, FILE * outfile)
{
                slip_dest_ptr dest;

                /* The destination object is made permanent so that multiple JPEG images
                 * can be written to the same file without re-executing jpeg_stdio_dest.
                 * This makes it dangerous to use this manager and a different destination
                 * manager serially with the same JPEG object, because their private object
                 * sizes may be different.  Caveat programmer.
                 */
                if (cinfo->dest == 0) {         /* first time for this JPEG object? */
                                cinfo->dest = (struct jpeg_destination_mgr *)
                                                                  (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
                                                                                                  SIZEOF(slip_destination_mgr));
                }

                dest = (slip_dest_ptr) cinfo->dest;
                dest->pub.init_destination = slip_init_destination;
                dest->pub.empty_output_buffer = slip_empty_output_buffer;
                dest->pub.term_destination = slip_term_destination;
                dest->outfile = outfile;
}





/* Expanded data source object for stdio input */

typedef struct {
                struct jpeg_source_mgr pub;     /* public fields */

                FILE * infile;                  /* source stream */
                JOCTET * buffer;                                /* start of buffer */
                boolean start_of_file;          /* have we gotten any data yet? */
} slip_source_mgr;

typedef slip_source_mgr * slip_src_ptr;

#define INPUT_BUF_SIZE  4096    /* choose an efficiently fread'able size */


/*
 * Initialize source --- called by jpeg_read_header
 * before any data is actually read.
 */

METHODDEF(void)
slip_init_source (j_decompress_ptr cinfo)
{
                slip_src_ptr src = (slip_src_ptr) cinfo->src;

                /* 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.
                 */
                src->start_of_file = TRUE;
}

/*
 * 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.
 */

METHODDEF(boolean)
slip_fill_input_buffer (j_decompress_ptr cinfo)
{
                slip_src_ptr src = (slip_src_ptr) cinfo->src;
                size_t nbytes;

                nbytes = JFREAD(src->infile, src->buffer, INPUT_BUF_SIZE);

                if (nbytes <= 0) {
                                if (src->start_of_file)         /* Treat empty input file as fatal error */
                                                ERREXIT(cinfo, JERR_INPUT_EMPTY);
                                WARNMS(cinfo, JWRN_JPEG_EOF);
                                /* Insert a fake EOI marker */
                                src->buffer[0] = (JOCTET) 0xFF;
                                src->buffer[1] = (JOCTET) JPEG_EOI;
                                nbytes = 2;
                }

                src->pub.next_input_byte = src->buffer;
                src->pub.bytes_in_buffer = nbytes;
                src->start_of_file = FALSE;

                return TRUE;
}

/*
 * 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.
 */

METHODDEF(void)
slip_skip_input_data (j_decompress_ptr cinfo, long num_bytes)
{
                struct jpeg_source_mgr * src = 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 > (long) src->bytes_in_buffer) {
                                                num_bytes -= (long) src->bytes_in_buffer;
                                                (void) (*src->fill_input_buffer) (cinfo);
                                                /* note we assume that fill_input_buffer will never return FALSE,
                                                 * so suspension need not be handled.
                                                 */
                                }
                                src->next_input_byte += (size_t) num_bytes;
                                src->bytes_in_buffer -= (size_t) num_bytes;
                }
}


/*
 * 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.
 */


/*
 * 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.
 */

METHODDEF(void)
slip_term_source (j_decompress_ptr cinfo)
{
                /* no work necessary here */
}


/*
 * Prepare for input from a stdio stream.
 * The caller must have already opened the stream, and is responsible
 * for closing it after finishing decompression.
 */

GLOBAL(void)
slip_jpeg_stdio_src (j_decompress_ptr cinfo, FILE * infile)
{
                slip_src_ptr src;

                /* The source object and input buffer are made permanent so that a series
                 * of JPEG images can be read from the same file by calling jpeg_stdio_src
                 * only before the first one.  (If we discarded the buffer at the end of
                 * one image, we'd likely lose the start of the next one.)
                 * This makes it unsafe to use this manager and a different source
                 * manager serially with the same JPEG object.  Caveat programmer.
                 */
                if (cinfo->src == 0) {          /* first time for this JPEG object? */
                                cinfo->src = (struct jpeg_source_mgr *)
                                  (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
                                                                  SIZEOF(slip_source_mgr));
                                src = (slip_src_ptr) cinfo->src;
                                src->buffer = (JOCTET *)
                                  (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
                                                                  INPUT_BUF_SIZE * SIZEOF(JOCTET));
                }

                src = (slip_src_ptr) cinfo->src;
                src->pub.init_source = slip_init_source;
                src->pub.fill_input_buffer = slip_fill_input_buffer;
                src->pub.skip_input_data = slip_skip_input_data;
                src->pub.resync_to_restart = jpeg_resync_to_restart; /* use default method */
                src->pub.term_source = slip_term_source;
                src->infile = infile;
                src->pub.bytes_in_buffer = 0; /* forces fill_input_buffer on first read */
                src->pub.next_input_byte = 0; /* until buffer loaded */
}

#endif /* JPEGDEF_HPP_ */