qr_finder.c

00001 #include <config.h>
00002 #include <assert.h>
00003 
00004 #include <zbar.h>
00005 #include "decoder.h"
00006 
00007 #ifdef DEBUG_QR_FINDER
00008 # define DEBUG_LEVEL (DEBUG_QR_FINDER)
00009 #endif
00010 #include "zbar_debug.h"
00011 
00012 /* at this point lengths are all decode unit offsets from the decode edge
00013  * NB owned by finder
00014  */
00015 qr_finder_line *_zbar_decoder_get_qr_finder_line (zbar_decoder_t *dcode)
00016 {
00017     return(&dcode->qrf.line);
00018 }
00019 
00020 zbar_symbol_type_t _zbar_find_qr (zbar_decoder_t *dcode)
00021 {
00022     qr_finder_t *qrf = &dcode->qrf;
00023 
00024     /* update latest finder pattern width */
00025     qrf->s5 -= get_width(dcode, 6);
00026     qrf->s5 += get_width(dcode, 1);
00027     unsigned s = qrf->s5;
00028 
00029     if(get_color(dcode) != ZBAR_SPACE || s < 7)
00030         return(0);
00031 
00032     dprintf(2, "    qrf: s=%d", s);
00033 
00034     int ei = decode_e(pair_width(dcode, 1), s, 7);
00035     dprintf(2, " %d", ei);
00036     if(ei)
00037         goto invalid;
00038 
00039     ei = decode_e(pair_width(dcode, 2), s, 7);
00040     dprintf(2, "%d", ei);
00041     if(ei != 2)
00042         goto invalid;
00043 
00044     ei = decode_e(pair_width(dcode, 3), s, 7);
00045     dprintf(2, "%d", ei);
00046     if(ei != 2)
00047         goto invalid;
00048 
00049     ei = decode_e(pair_width(dcode, 4), s, 7);
00050     dprintf(2, "%d", ei);
00051     if(ei)
00052         goto invalid;
00053 
00054     /* valid QR finder symbol
00055      * mark positions needed by decoder
00056      */
00057     unsigned qz = get_width(dcode, 0);
00058     unsigned w = get_width(dcode, 1);
00059     qrf->line.eoffs = qz + (w + 1) / 2;
00060     qrf->line.len = qz + w + get_width(dcode, 2);
00061     qrf->line.pos[0] = qrf->line.len + get_width(dcode, 3);
00062     qrf->line.pos[1] = qrf->line.pos[0];
00063     w = get_width(dcode, 5);
00064     qrf->line.boffs = qrf->line.pos[0] + get_width(dcode, 4) + (w + 1) / 2;
00065 
00066     dprintf(2, " boff=%d pos=%d len=%d eoff=%d [valid]\n",
00067             qrf->line.boffs, qrf->line.pos[0], qrf->line.len,
00068             qrf->line.eoffs);
00069 
00070     return(ZBAR_QRCODE);
00071 
00072 invalid:
00073     dprintf(2, " [invalid]\n");
00074     return(0);
00075 }
00076