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// SPDX-License-Identifier: GPL-2.0
#include "core/parse-gpx.h"
#include "core/dive.h"
// TODO: instead of manually parsing the XML, we should consider using
// one of the two XML frameworks that we already use elsewhere in
// the code
// Read text from the present position in the file until
// the first 'delim' character is encountered.
static int getSubstring(QFile *file, QString *bufptr, char delim)
{
char c;
bufptr->clear();
do {
if (file->read(&c, 1) <= 0) // EOF
return 1;
if (c == delim) break;
bufptr->append(QChar(c));
} while (c != delim);
return 0;
}
// Find the next occurence of a specified target GPX element in the file,
// characerised by a "<xxx " or "<xxx>" character sequence.
// 'target' specifies the name of the element searched for.
// termc is the ending character of the element name search = '>' or ' '.
static int findXmlElement(QFile *fileptr, QString target, QString *bufptr, char termc)
{
bool match = false;
char c;
char skipdelim = (termc == ' ') ? '>' : ' ';
do { // Skip input until first start new of element (<) is encountered:
if (getSubstring(fileptr, bufptr, '<'))
return 1; // EOF
bufptr->clear();
do { // Read name of following element and store it in buf
if (fileptr->read(&c, 1) <= 0) // EOF encountered
return 1;
if ((c == '>') || (c == ' ')) // found a valid delimiter
break;
bufptr->append(QChar(c));
} while ((c != '>') && (c != ' '));
if (*bufptr == "/trk") // End of GPS track found: return EOF
return 1;
if (c == skipdelim)
continue; // if inappropriate delimiter was found, redo from start
if (*bufptr == target) // Compare xml element name from gpx file with the
match = true; // the target element searched for.
} while (match == false);
return 0;
}
// Find the coordinates at the time specified in coords.start_dive
// by searching the gpx file "fileName". Here is a typical trkpt element in GPX:
// <trkpt lat="-26.84" lon="32.88"><ele>-53.7</ele><time>2017-08-06T04:56:42Z</time></trkpt>
int getCoordsFromGPXFile(struct dive_coords *coords, QString fileName)
{
struct tm tm1;
time_t when = 0;
double lon, lat;
int line = 0;
int64_t time_offset = coords->settingsDiff_offset + coords->timeZone_offset;
time_t divetime;
bool first_line = true;
bool found = false;
divetime = coords->start_dive;
QString buf;
QFile gpxFile;
gpxFile.setFileName(fileName);
if (!gpxFile.open(QIODevice::ReadOnly | QIODevice::Text)) {
QByteArray local8bitBAString1 = fileName.toLocal8Bit();
char *fname = local8bitBAString1.data(); // convert QString to a C string fileName
fprintf(stderr, "GPS file open error: file name = %s\n", fname);
return 1;
}
#ifdef GPSDEBUG
struct tm time; // decode the time of start of dive:
utc_mkdate(divetime, &time);
int dyr,dmon,dday,dhr,dmin;
dyr = time.tm_year;
dmon = time.tm_mon;
dday = time.tm_mday;
dhr = time.tm_hour;
dmin = time.tm_min;
#endif
do {
line++; // this is the sequence number of the trkpt xml element processed
// Find next trkpt xml element (This function also detects </trk> that signals EOF):
if (findXmlElement(&gpxFile, QString("trkpt"), &buf, ' ')) // This is the normal exit point
break; // for this routine
// == Get coordinates: ==
if (getSubstring(&gpxFile, &buf, '"')) // read up to the end of the "lat=" label
break; // on EOF
if (buf != "lat=") {
fprintf(stderr, "GPX parse error: cannot find latitude (trkpt #%d)\n", line);
return 1;
}
if (getSubstring(&gpxFile, &buf, '"')) // read up to the end of the latitude value
break; // on EOF
lat = buf.toDouble(); // Convert lat to decimal
if (getSubstring(&gpxFile, &buf, ' ')) // Read past space char
break; // on EOF
if (getSubstring(&gpxFile, &buf, '"')) // Read up to end of "lon=" label
break; // on EOF
if (buf != "lon=") {
fprintf(stderr, "GPX parse error: cannot find longitude (trkpt #%d)\n", line);
return 1;
}
if (getSubstring(&gpxFile, &buf, '"')) // get string with longitude
break; // on EOF
lon = buf.toDouble(); // Convert longitude to decimal
// == get time: ==
if (findXmlElement(&gpxFile, QString("time"), &buf, '>')) // Find the <time> element
break; // on EOF
if (getSubstring(&gpxFile, &buf, '<')) // Read the string containing date/time
break; // on EOF
bool ok;
tm1.tm_year = buf.left(4).toInt(&ok, 10); // Extract the different substrings:
tm1.tm_mon = buf.mid(5,2).toInt(&ok,10) - 1;
tm1.tm_mday = buf.mid(8,2).toInt(&ok,10);
tm1.tm_hour = buf.mid(11,2).toInt(&ok,10);
tm1.tm_min = buf.mid(14,2).toInt(&ok,10);
tm1.tm_sec = buf.mid(17,2).toInt(&ok,10);
when = utc_mktime(&tm1) + time_offset;
if (first_line) {
first_line = false;
coords->start_track = when; // Local time of start of GPS track
}
if ((when > divetime && found == false)) { // This GPS local time corresponds to the start time of the dive
coords->lon = lon; // save the coordinates
coords->lat = lat;
found = true;
}
#ifdef GPSDEBUG
utc_mkdate(when, &time); // print time and coordinates of each of the trkpt elements of the GPX file
fprintf(stderr, " %02d: lat=%f lon=%f timestamp=%ld (%ld) %02d/%02d/%02d %02d:%02d dt=%ld %02d/%02d/%02d %02d:%02d\n", line, lat,
lon, when, time_offset, time.tm_year, time.tm_mon+1, time.tm_mday, time.tm_hour, time.tm_min, divetime, dyr, dmon+1, dday,dhr, dmin );
#endif
} while (true); // This loop executes until EOF causes a break out of the loop
coords->end_track = when; // This is the local time of the end of the GPS track
gpxFile.close();
return 0;
}
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