343 lines
12 KiB
Python
Executable File
343 lines
12 KiB
Python
Executable File
#!/usr/bin/python3
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# Copyright (c) 2012-2014 Tobias Leupold <tobias.leupold@web.de>
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#
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# gpx2svg - Convert GPX formatted geodata to Scalable Vector Graphics (SVG)
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#
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# This program is free software; you can redistribute it and/or modify it
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# under the terms of the GNU General Public License as published by the Free
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# Software Foundation in version 2 of the License.
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#
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# This program is distributed in the hope that it will be useful, but
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# WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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# or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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# for more details.
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#
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# You should have received a copy of the GNU General Public License along
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# with this program; if not, write to the Free Software Foundation, Inc.,
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# 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
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__version__ = 'svn' #'0.1.2'
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import argparse
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import sys
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import math
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from xml.dom.minidom import parse as parseXml
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def parseGpx(gpxFile):
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"""Get the latitude and longitude data of all track segments in a GPX file"""
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# Get the XML information
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try:
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gpx = parseXml(gpxFile)
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except IOError as error:
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print('Error while reading file: %s. Terminating.' % error, file = sys.stderr)
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sys.exit(1)
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except:
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print('Error while parsing XML data:', file = sys.stderr)
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print(sys.exc_info(), file = sys.stderr)
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print('Terminating.', file = sys.stderr)
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sys.exit(1)
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# Iterate over all tracks, track segments and points
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gpsData = []
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for track in gpx.getElementsByTagName('trk'):
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for trackseg in track.getElementsByTagName('trkseg'):
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trackSegData = []
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for point in trackseg.getElementsByTagName('trkpt'):
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trackSegData.append(
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(float(point.attributes['lon'].value), float(point.attributes['lat'].value))
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)
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# Leave out empty segments
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if(trackSegData != []):
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gpsData.append(trackSegData)
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return gpsData
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def calcProjection(gpsData):
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"""Calculate a plane projection for a GPS dataset"""
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projectedData = []
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for segment in gpsData:
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projectedSegment = []
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for coord in segment:
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# At the moment, we only have the Mercator projection
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projectedSegment.append(mercatorProjection(coord))
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projectedData.append(projectedSegment)
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return(projectedData)
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def mercatorProjection(coord):
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"""Calculate the Mercator projection of a coordinate pair"""
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# Assuming we're on earth, we have (according to GRS 80):
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r = 6378137.0
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# As long as meridian = 0 and can't be changed, we don't need:
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# meridian = meridian * math.pi / 180.0
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# x = r * ((coord[0] * math.pi / 180.0) - meridian)
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# Instead, we use this simplified version:
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x = r * coord[0] * math.pi / 180.0
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y = r * math.log(math.tan((math.pi / 4.0) + ((coord[1] * math.pi / 180.0) / 2.0)))
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return((x, y))
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def moveProjectedData(gpsData):
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"""Move a dataset to 0,0 and return it with the resulting width and height"""
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# Find the minimum and maximum x and y coordinates
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minX = maxX = gpsData[0][0][0]
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minY = maxY = gpsData[0][0][1]
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for segment in gpsData:
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for coord in segment:
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if coord[0] < minX:
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minX = coord[0]
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if coord[0] > maxX:
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maxX = coord[0]
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if coord[1] < minY:
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minY = coord[1]
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if coord[1] > maxY:
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maxY = coord[1]
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# Move the GPS data to 0,0
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movedGpsData = []
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for segment in gpsData:
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movedSegment = []
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for coord in segment:
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movedSegment.append((coord[0] - minX, coord[1] - minY))
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movedGpsData.append(movedSegment)
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# Return the moved data and it's width and height
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return(movedGpsData, maxX - minX, maxY - minY)
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def searchCircularSegments(gpsData):
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"""Splits a GPS dataset to tracks that are circular and other tracks"""
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circularSegments = []
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straightSegments = []
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for segment in gpsData:
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if segment[0] == segment[len(segment) - 1]:
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circularSegments.append(segment)
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else:
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straightSegments.append(segment)
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return(circularSegments, straightSegments)
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def combineSegmentPairs(gpsData):
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"""Combine segment pairs to one bigger segment"""
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combinedData = []
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# Walk through the GPS data and search for segment pairs
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# that end with the starting point of another track
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while len(gpsData) > 0:
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# Get one segment from the source GPS data
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firstTrackData = gpsData.pop()
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foundMatch = False
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# Try to find a matching segment
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for i in range(len(gpsData)):
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if firstTrackData[len(firstTrackData) - 1] == gpsData[i][0]:
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# There is a matching segment, so break here
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foundMatch = True
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break
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if foundMatch == True:
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# We found a pair of segments with one shared point, so pop the data of the second
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# segment from the source GPS data and create a new segment containing all data, but
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# without the overlapping point
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firstTrackData.pop()
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combinedData.append(firstTrackData + gpsData[i])
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gpsData.pop(i)
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else:
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# No segment with a shared point was found, so just append the data to the output
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combinedData.append(firstTrackData)
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return(searchCircularSegments(combinedData))
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def combineSegments(gpsData):
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"""Combine all segments of a GPS dataset that can be combined"""
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# Search for circular segments. We can't combine them with any other segment.
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circularSegments, remainingSegments = searchCircularSegments(gpsData)
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# Search for segments that can be combined
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while True:
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# Look how many tracks we have now
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segmentsBefore = len(remainingSegments)
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# Search for segments that can be combined
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newCircularSegments, remainingSegments = combineSegmentPairs(remainingSegments)
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# Add newly found circular segments to processedSegments -- they can't be used anymore
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circularSegments = circularSegments + newCircularSegments
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if segmentsBefore == len(remainingSegments):
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# combineSegmentPairs() did not reduce the number of tracks anymore,
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# so we can't combine more tracks and can stop here
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break
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return(circularSegments + remainingSegments)
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def scaleCoords(coord, height, scale):
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"""Return a scaled pair of coordinates"""
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return(coord[0] * scale, (coord[1] * -1 + height) * scale)
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def createCoordString(segment, height, scale):
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"""Create the coordinate part of an SVG path string from a GPS data segment"""
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coordString = ''
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for coord in segment:
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x, y = scaleCoords(coord, height, scale)
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coordString = coordString + ' ' + str(x) + ',' + str(y)
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return coordString
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def createPathString(drawCommand):
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"""Return a complete path element for a draw command string"""
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return '<path d="' + drawCommand + '" style="fill:none;stroke:black" />\n'
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def writeSvgData(gpsData, width, height, maxPixels, dropSinglePoints, outfile):
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"""Output the SVG data -- quick 'n' dirty, without messing around with dom stuff ;-)"""
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# Calculate the scale factor we need to fit the requested maximal output size
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if width <= maxPixels and height <= maxPixels:
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scale = 1
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elif width > height:
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scale = maxPixels / width
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else:
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scale = maxPixels / height
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# Open the requested output file or map to /dev/stdout
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if outfile != '/dev/stdout':
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fp = open(outfile, 'w')
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else:
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fp = sys.stdout
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# Header data
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fp.write('<?xml version="1.0" encoding="UTF-8" standalone="no"?>\n')
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fp.write('<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN"\n "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">\n')
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fp.write(
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'<svg xmlns="http://www.w3.org/2000/svg" version="1.1" width="%spx" height="%spx">\n' % (
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width * scale, height * scale
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)
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)
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# Process all track segments and generate ids and path drawing commands for them
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# First, we split the data to circular and straight segments
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circularSegments, straightSegments = searchCircularSegments(gpsData)
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realCircularSegments = []
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singlePoints = []
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for segment in circularSegments:
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# We can leave out the last point, because it's equal to the first one
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segment.pop()
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if len(segment) == 1:
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# It's a single point
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if dropSinglePoints == False:
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# We want to keep single points, so add it to singlePoints
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singlePoints.append(segment)
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else:
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realCircularSegments.append(segment)
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circularSegments = realCircularSegments
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# Draw single points if requested
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if len(singlePoints) > 0:
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fp.write('<g>\n')
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for segment in singlePoints:
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x, y = scaleCoords(segment[0], height, scale)
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fp.write('<circle cx="' + str(x) + '" cy="' + str(y) + '" r="0.5" style="stroke:none;fill:black"/>\n')
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fp.write('</g>\n')
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# Draw all circular segments
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if len(circularSegments) > 0:
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fp.write('<g>\n')
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for segment in circularSegments:
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fp.write(createPathString('M' + createCoordString(segment, height, scale) + ' Z'))
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fp.write('</g>\n')
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# Draw all un-closed paths
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if len(straightSegments) > 0:
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fp.write('<g>\n')
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for segment in straightSegments:
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d = 'M' + createCoordString(segment, height, scale)
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fp.write(createPathString('M' + createCoordString(segment, height, scale)))
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fp.write('</g>\n')
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# Close the XML
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fp.write('</svg>\n')
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# Close the file if necessary
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if fp != sys.stdout:
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fp.close()
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def main():
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# Setup the command line argument parser
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cmdArgParser = argparse.ArgumentParser(
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description = 'Convert GPX formatted geodata to Scalable Vector Graphics (SVG)',
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epilog = 'gpx2svg %s - http://nasauber.de/opensource/gpx2svg/' % __version__
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)
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cmdArgParser.add_argument(
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'-i', metavar = 'FILE', nargs = '?', type = str, default = '/dev/stdin',
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help = 'GPX input file (default: read from STDIN)'
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)
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cmdArgParser.add_argument(
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'-o', metavar = 'FILE', nargs = '?', type = str, default = '/dev/stdout',
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help = 'SVG output file (default: write to STDOUT)'
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)
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cmdArgParser.add_argument(
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'-m', metavar = 'PIXELS', nargs = '?', type = int, default = 3000,
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help = 'Maximum width or height of the SVG output in pixels (default: 3000)'
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)
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cmdArgParser.add_argument(
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'-d', action = 'store_true',
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help = 'Drop single points (default: draw a circle with 1px diameter)'
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)
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cmdArgParser.add_argument(
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'-r', action = 'store_true',
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help = (
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'"Raw" conversion: Create one SVG path per track segment, '
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'don\'t try to combine paths that end with the starting point of another path'
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)
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)
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# Get the given arguments
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cmdArgs = cmdArgParser.parse_args()
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# Map "-" to STDIN or STDOUT
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if cmdArgs.i == '-':
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cmdArgs.i = '/dev/stdin'
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if cmdArgs.o == '-':
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cmdArgs.o = '/dev/stdout'
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# Get the latitude and longitude data from the given GPX file or STDIN
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gpsData = parseGpx(cmdArgs.i)
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# Check if we actually _have_ data
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if gpsData == []:
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print('No data to convert. Terminating.', file = sys.stderr)
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sys.exit(1)
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# Try to combine all track segments that can be combined if not requested otherwise
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if not cmdArgs.r:
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gpsData = combineSegments(gpsData)
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# Calculate a plane projection for a GPS dataset
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# At the moment, we only have the Mercator projection
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gpsData = calcProjection(gpsData)
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# Move the projected data to the 0,0 origin of a cartesial coordinate system
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# and get the raw width and height of the resulting vector data
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gpsData, width, height = moveProjectedData(gpsData)
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# Write the resulting SVG data to the requested output file or STDOUT
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writeSvgData(gpsData, width, height, cmdArgs.m, cmdArgs.d, cmdArgs.o)
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if __name__ == '__main__':
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main()
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