winjpg.c

来自「MinGUI 可视化程序代码」· C语言 代码 · 共 300 行

 /******************************************************************************
*
* Copyright  2006 National ASIC Center, All right Reserved
*
* FILE NAME:      winjpg.c
* PROGRAMMER:     ming.c
* Date of Creation:   2006/08/8
*
* DESCRIPTION:
*
* NOTE:
*
* FUNCTIONS LIST:
* -----------------------------------------------------------------------------
*
* -----------------------------------------------------------------------------
*
* MODIFICATION HISTORY
*     LastModify  2006/10/30
******************************************************************************/
#include "mingui.h"
//---------------------------------------------------------------------------
#if(JPEG_SUPPORT==true)
//---------------------------------------------------------------------------
#include "jpeglib.h"
#include "jerror.h"

/* Expanded data source object for stdio input */
typedef struct {
  struct jpeg_source_mgr pub;        /* public fields */

  STREAM *stream;                /* source stream */
  BYTE * buffer;                /* start of buffer */
  BOOL start_of_file;        /* have we gotten any data yet? */
} my_source_mgr;

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

typedef my_source_mgr * my_src_ptr;
//---------------------------------------------------------------------------
/*
 * Initialize source --- called by jpeg_read_header
 * before any data is actually read.
 */

static void init_source (j_decompress_ptr cinfo)
{
  my_src_ptr src = (my_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.
 */

static BOOL fill_input_buffer (j_decompress_ptr cinfo)
{
  my_src_ptr src = (my_src_ptr) cinfo->src;
  size_t nbytes;

  nbytes = StreamRead ( src->buffer,INPUT_BUF_SIZE,(STREAM *)src->stream);

  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).
 */

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

static void 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.
 */

//---------------------------------------------------------------------------
void my_jpeg_data_src (j_decompress_ptr cinfo, STREAM *stream)
{
  my_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 == NULL)         /* first time for this JPEG object? */
  {  cinfo->src = (struct jpeg_source_mgr *)
      (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
                                  sizeof(my_source_mgr));
    src = (my_src_ptr) cinfo->src;
    src->buffer = (JOCTET *)
      (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
                                  INPUT_BUF_SIZE * sizeof(JOCTET));
  }

  src = (my_src_ptr) cinfo->src;
  src->pub.init_source = init_source;
  src->pub.fill_input_buffer = fill_input_buffer;
  src->pub.skip_input_data = skip_input_data;
  src->pub.resync_to_restart = jpeg_resync_to_restart; /* use default method */
  src->pub.term_source = term_source;
  src->stream=stream;
  src->pub.bytes_in_buffer = 0; /* forces fill_input_buffer on first read */
  src->pub.next_input_byte = NULL; /* until buffer loaded */

}

int  CM_DecodeJPG(TImageHead *imgHead, STREAM *stream)
{   int ret = 0;    /* image load error*/
    unsigned char magic[5];

    /* This struct contains the JPEG decompression parameters
     * and pointers to working space 
     * (which is allocated as needed by the JPEG library).
     */

    struct jpeg_decompress_struct cinfo;
    struct jpeg_error_mgr jerr;

    if(StreamRead(magic,2,stream)!=2) 
       return 0;        /* not JPEG image*/
    if (magic[0] != 0xFF || magic[1] != 0xD8)
        return 0;        /* not JPEG image*/
    StreamRead (magic, 4, stream);
    StreamRead (magic, 4, stream);
    magic [4] = '\0';
 
    if (strncmp((char *)magic, "JFIF", 4) != 0 && strncmp((char *)magic, "Exif", 4) != 0)
        return 0;        /* not JPEG image*/
   
    StreamSeek(stream, -10, SEEK_CUR);
  

    /* Step 1: allocate and initialize JPEG decompression object */

    /* We set up the normal JPEG error routines. */
    cinfo.err = jpeg_std_error (&jerr);

    /* Now we can initialize the JPEG decompression object. */
    jpeg_create_decompress (&cinfo);

    /* Step 2: specify data source */
     my_jpeg_data_src (&cinfo, stream);

    /* Step 3: read file parameters with jpeg_read_header() */
    jpeg_read_header (&cinfo, TRUE);

     /* Step 4: set parameters for decompression */
    cinfo.out_color_space = JCS_RGB;
    cinfo.quantize_colors = FALSE;


    #if (BITS_PER_PIXEL <= 8) 
	{  RGBQUAD rgbColor;
       int i;
      
	   cinfo.quantize_colors = TRUE;
    
       /* Get system palette */
       cinfo.actual_number_of_colors = 0x01 << BITS_PER_PIXEL;
    
	   /* Allocate jpeg colormap space */
        cinfo.colormap = (*cinfo.mem->alloc_sarray)((j_common_ptr) &cinfo, JPOOL_IMAGE,
                       (JDIMENSION)cinfo.actual_number_of_colors, (JDIMENSION)3);
        
		imgHead->transPal=(PIXEL *)GetMem(cinfo.actual_number_of_colors*sizeof(PIXEL));
		imgHead->palsize=cinfo.actual_number_of_colors;
        
		/* Set colormap from system palette */
        for(i = 0; i < cinfo.actual_number_of_colors; ++i)
        {  PixelMapToColor(i,&rgbColor);
           cinfo.colormap[0][i] = rgbColor.b;
           cinfo.colormap[1][i] = rgbColor.g;
           cinfo.colormap[2][i] = rgbColor.r;
		   imgHead->transPal[i]=i;
        }
    }
    #endif

    jpeg_calc_output_dimensions (&cinfo);

    ret = 0;//ERR_BMP_MEM;

    imgHead->bpp = cinfo.output_components * 8;
    
    imgHead->width = cinfo.output_width;
    imgHead->height = cinfo.output_height;

    imgHead->pitch = ( (imgHead->width*imgHead->bpp+31)>>3 ) & ~0x3;
    imgHead->compression=0;
    
    imgHead->bits = (BYTE *)GetMem(imgHead->pitch * imgHead->height);
    if (!imgHead->bits) goto err;

    /* Step 5: Start decompressor */
    jpeg_start_decompress (&cinfo);

    /* Step 6: while (scan lines remain to be read) */
    while (cinfo.output_scanline < cinfo.output_height)
	{   JSAMPROW rowptr[1];
        BYTE* bits;
        bits = imgHead->bits + cinfo.output_scanline * imgHead->pitch;
        rowptr[0] = (JSAMPROW)(bits);
        jpeg_read_scanlines (&cinfo, rowptr, 1);
    }
    ret = TRUE;

err:
    /* Step 7: Finish decompression */
    jpeg_finish_decompress (&cinfo);

    /* Step 8: Release JPEG decompression object */
    jpeg_destroy_decompress (&cinfo);

    /* May want to check to see whether any corrupt-data
     * warnings occurred (test whether jerr.pub.num_warnings is nonzero).
     */

    return ret;
}
//---------------------------------------------------------------------------
#else

  int  CM_DecodeJPG(TImageHead *imgHead, STREAM *stream)
  { return 0;
  }
//---------------------------------------------------------------------------
#endif