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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 : }