Line data    Source code

       1             : /*
       2             :   This file is part of TALER
       3             :   Copyright (C) 2020 Taler Systems SA
       4             : 
       5             :   TALER is free software; you can redistribute it and/or modify it under the
       6             :   terms of the GNU General Public License as published by the Free Software
       7             :   Foundation; either version 3, or (at your option) any later version.
       8             : 
       9             :   TALER is distributed in the hope that it will be useful, but WITHOUT ANY
      10             :   WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
      11             :   A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
      12             : 
      13             :   You should have received a copy of the GNU General Public License along with
      14             :   TALER; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
      15             : */
      16             : /**
      17             :  * @file taler-merchant-httpd_qr.c
      18             :  * @brief logic to create QR codes in HTML
      19             :  * @author Christian Grothoff
      20             :  */
      21             : #include "platform.h"
      22             : #include <gnunet/gnunet_util_lib.h>
      23             : #include <qrencode.h>
      24             : 
      25             : 
      26             : /**
      27             :  * Create the HTML for a QR code for a URI.
      28             :  *
      29             :  * @param uri input string to encode
      30             :  * @return NULL on error, encoded URI otherwise
      31             :  */
      32             : char *
      33           0 : TMH_create_qrcode (const char *uri)
      34             : {
      35             :   QRinput *qri;
      36             :   QRcode *qrc;
      37           0 :   struct GNUNET_Buffer buf = { 0 };
      38             : 
      39           0 :   qri = QRinput_new2 (0,
      40             :                       QR_ECLEVEL_M);
      41           0 :   if (NULL == qri)
      42             :   {
      43           0 :     GNUNET_log_strerror (GNUNET_ERROR_TYPE_WARNING,
      44             :                          "QRinput_new2");
      45           0 :     return NULL;
      46             :   }
      47             :   /* first try encoding as uppercase-only alpha-numerical
      48             :      QR code (much smaller encoding); if that fails, also
      49             :      try using binary encoding */
      50           0 :   if ( (0 !=
      51           0 :         QRinput_append (qri,
      52             :                         QR_MODE_AN,
      53           0 :                         strlen (uri),
      54           0 :                         (unsigned char *) uri)) &&
      55             :        (0 !=
      56           0 :         QRinput_append (qri,
      57             :                         QR_MODE_8,
      58           0 :                         strlen (uri),
      59             :                         (unsigned char *) uri)) )
      60             :   {
      61           0 :     GNUNET_log_strerror (GNUNET_ERROR_TYPE_WARNING,
      62             :                          "QRinput_append");
      63           0 :     QRinput_free (qri);
      64           0 :     return NULL;
      65             :   }
      66           0 :   qrc = QRcode_encodeInput (qri);
      67           0 :   if (NULL == qrc)
      68             :   {
      69           0 :     GNUNET_log_strerror (GNUNET_ERROR_TYPE_WARNING,
      70             :                          "QRcode_encodeInput");
      71           0 :     QRinput_free (qri);
      72           0 :     return NULL;
      73             :   }
      74           0 :   QRinput_free (qri);
      75           0 :   GNUNET_buffer_write_fstr (&buf,
      76             :                             "<svg width='100mm' height='100mm' viewBox='0 0 %u %u' "
      77             :                             "version='1.1' xmlns='http://www.w3.org/2000/svg' "
      78             :                             "style='shape-rendering: crispedges;'>\n",
      79             :                             qrc->width,
      80             :                             qrc->width);
      81           0 :   for (unsigned int y = 0; y<(unsigned int) qrc->width; y++)
      82             :   {
      83           0 :     for (unsigned int x = 0; x<(unsigned int) qrc->width; x++)
      84             :     {
      85           0 :       unsigned int off = x + y * (unsigned int) qrc->width;
      86           0 :       if (0 == (qrc->data[off] & 1))
      87           0 :         continue;
      88           0 :       GNUNET_buffer_write_fstr (&buf,
      89             :                                 " <rect x=%u y=%u width=1 height=1 />\n",
      90             :                                 x,
      91             :                                 y);
      92             :     }
      93             :   }
      94           0 :   GNUNET_buffer_write_str (&buf,
      95             :                            "</svg>");
      96           0 :   QRcode_free (qrc);
      97           0 :   return GNUNET_buffer_reap_str (&buf);
      98             : }