Line data    Source code

       1              : /*
       2              :   This file is part of TALER
       3              :   Copyright (C) 2020-2026 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 src/backend/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              : #include <taler-merchant-httpd_qr.h>
      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            4 : TMH_create_qrcode (const char *uri)
      34              : {
      35              :   QRinput *qri;
      36              :   QRcode *qrc;
      37            4 :   struct GNUNET_Buffer buf = { 0 };
      38              : 
      39            4 :   qri = QRinput_new2 (0,
      40              :                       QR_ECLEVEL_H);
      41            4 :   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            4 :   if ( (0 !=
      51            4 :         QRinput_append (qri,
      52              :                         QR_MODE_AN,
      53            4 :                         strlen (uri),
      54            4 :                         (unsigned char *) uri)) &&
      55              :        (0 !=
      56            4 :         QRinput_append (qri,
      57              :                         QR_MODE_8,
      58            4 :                         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            4 :   qrc = QRcode_encodeInput (qri);
      67            4 :   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            4 :   QRinput_free (qri);
      75            4 :   GNUNET_buffer_write_fstr (&buf,
      76              :                             "<svg width='100%%' height='100%%' viewBox='0 0 %u %u' "
      77              :                             "version='1.1' xmlns='http://www.w3.org/2000/svg' "
      78              :                             "aria-hidden='true' focusable='false' "
      79              :                             "style='shape-rendering: crispedges;'>\n",
      80              :                             qrc->width,
      81              :                             qrc->width);
      82          184 :   for (unsigned int y = 0; y<(unsigned int) qrc->width; y++)
      83              :   {
      84         8344 :     for (unsigned int x = 0; x<(unsigned int) qrc->width; x++)
      85              :     {
      86         8164 :       unsigned int off = x + y * (unsigned int) qrc->width;
      87         8164 :       if (0 == (qrc->data[off] & 1))
      88         4007 :         continue;
      89         4157 :       GNUNET_buffer_write_fstr (&buf,
      90              :                                 " <rect x=%u y=%u width=1 height=1 />\n",
      91              :                                 x,
      92              :                                 y);
      93              :     }
      94              :   }
      95            4 :   GNUNET_buffer_write_str (&buf,
      96              :                            "</svg>");
      97            4 :   QRcode_free (qrc);
      98            4 :   return GNUNET_buffer_reap_str (&buf);
      99              : }