From ff18de053f338d0f100e7994db6ef5a2cac6280a Mon Sep 17 00:00:00 2001
From: willemferguson <willemferguson@zoology.up.ac.za>
Date: Sat, 25 Jan 2020 10:06:54 +0200
Subject: Parse GPX dive coordinates: Qt XML framework

This replaces the C-code XML parsing with a Qt infrastructure.
QXmlStreamReader is used to parse the GPX file.

It also takes into account comments by @neolit123

Signed-off-by: willemferguson <willemferguson@zoology.up.ac.za>
---
 core/parse-gpx.cpp | 155 +++++++++++++++++------------------------------------
 1 file changed, 48 insertions(+), 107 deletions(-)

(limited to 'core')

diff --git a/core/parse-gpx.cpp b/core/parse-gpx.cpp
index 16d2a17a2..d00e59d4d 100644
--- a/core/parse-gpx.cpp
+++ b/core/parse-gpx.cpp
@@ -1,55 +1,7 @@
 // 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;
-}
+#include <QXmlStreamReader>
 
 // 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:
@@ -57,15 +9,15 @@ static int findXmlElement(QFile *fileptr, QString target, QString *bufptr, char
 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 trkpt_time = 0;
 	time_t divetime;
+	int64_t time_offset = coords->settingsDiff_offset + coords->timeZone_offset;
+	double lon = 0, lat = 0;
+	int line = 0;
 	bool first_line = true;
 	bool found = false;
+	bool trkpt_found = false;
 	divetime = coords->start_dive;
-	QString buf;
 	QFile gpxFile;
 	gpxFile.setFileName(fileName);
 	if (!gpxFile.open(QIODevice::ReadOnly | QIODevice::Text)) {
@@ -86,61 +38,50 @@ int getCoordsFromGPXFile(struct dive_coords *coords, QString fileName)
 	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;
-		}
+	QXmlStreamReader gpxReader(&gpxFile);
+	while (!gpxReader.atEnd()) {
+		gpxReader.readNext();
+		if (gpxReader.isStartElement()) {
+			if (gpxReader.name() == "trkpt") {
+				trkpt_found = true;
+				line++;
+				foreach (const QXmlStreamAttribute &attr, gpxReader.attributes()) {
+					if (attr.name().toString() == QLatin1String("lat"))
+						lat = attr.value().toString().toDouble();
+					else if (attr.name().toString() == QLatin1String("lon"))
+						lon = attr.value().toString().toDouble();
+				}
+			}
+			if (gpxReader.name() == "time" && trkpt_found) {  // Ignore the <time> element in the GPX file header
+				QString dateTimeString = gpxReader.readElementText();
+				bool ok;
+				tm1.tm_year = dateTimeString.left(4).toInt(&ok, 10);  // Extract the date/time components:
+				tm1.tm_mon  = dateTimeString.mid(5,2).toInt(&ok,10) - 1;
+				tm1.tm_mday = dateTimeString.mid(8,2).toInt(&ok,10);
+				tm1.tm_hour = dateTimeString.mid(11,2).toInt(&ok,10);
+				tm1.tm_min  = dateTimeString.mid(14,2).toInt(&ok,10);
+				tm1.tm_sec  = dateTimeString.mid(17,2).toInt(&ok,10);
+				trkpt_time = utc_mktime(&tm1) + time_offset;
+				if (first_line) {
+					first_line = false;
+					coords->start_track = trkpt_time;   // Local time of start of GPS track
+				}
+				if (trkpt_time >= 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 );
+				utc_mkdate(trkpt_time, &time); // print coordinates and time of each trkpt element of the GPX file as well as dive start time
+				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, trkpt_time, 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
+
+			}
+		}
+	} // while !at.End() // This loop executes until EOF causes a break out of the loop
+	coords->end_track = trkpt_time;  // This is the local time of the end of the GPS track
 	gpxFile.close();
 	return 0;
 }
-- 
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