"""Draw a heatmap poster."""
# Copyright 2016-2019 Florian Pigorsch & Contributors. All rights reserved.
#
# Use of this source code is governed by a MIT-style
# license that can be found in the LICENSE file.
import argparse
import logging
import math
import svgwrite
import s2sphere as s2
from gpxtrackposter.exceptions import ParameterError
from gpxtrackposter.poster import Poster
from gpxtrackposter.tracks_drawer import TracksDrawer
from gpxtrackposter.xy import XY
from gpxtrackposter import utils
log = logging.getLogger(__name__)
class HeatmapDrawer(TracksDrawer):
"""Draw a heatmap Poster based on the tracks.
Attributes:
center: Center of the heatmap.
radius: Scale the heatmap so that a circle with radius (in KM) is visible.
Methods:
Create_args: Create arguments for heatmap.
fetch_args: Get arguments passed.
draw: Draw the heatmap based on the Poster's tracks.
"""
def __init__(self, the_poster: Poster):
super().__init__(the_poster)
self._center = None
self._radius = None
def create_args(self, args_parser: argparse.ArgumentParser):
group = args_parser.add_argument_group("Heatmap Type Options")
group.add_argument(
"--heatmap-center",
dest="heatmap_center",
metavar="LAT,LNG",
type=str,
help="Center of the heatmap (default: automatic).",
)
group.add_argument(
"--heatmap-radius",
dest="heatmap_radius",
metavar="RADIUS_KM",
type=float,
help="Scale the heatmap such that at least a circle with radius=RADIUS_KM is visible "
"(default: automatic).",
)
def fetch_args(self, args: argparse.Namespace):
"""Get arguments that were passed, and also perform basic validation on them.
For example, make sure the center is an actual lat, lng , and make sure the radius is a
positive number. Also, if radius is passed, then center must also be passed.
Raises:
ParameterError: Center was not a valid lat, lng coordinate, or radius was not positive.
"""
self._center = None
if args.heatmap_center:
latlng_str = args.heatmap_center.split(",")
if len(latlng_str) != 2:
raise ParameterError(f"Not a valid LAT,LNG pair: {args.heatmap_center}")
try:
lat = float(latlng_str[0].strip())
lng = float(latlng_str[1].strip())
except ValueError as e:
raise ParameterError(
f"Not a valid LAT,LNG pair: {args.heatmap_center}"
) from e
if not (-90 <= lat <= 90) or not (-180 <= lng <= 180):
raise ParameterError(f"Not a valid LAT,LNG pair: {args.heatmap_center}")
self._center = s2.LatLng.from_degrees(lat, lng)
if args.heatmap_radius:
if args.heatmap_radius <= 0:
raise ParameterError(
f"Not a valid radius: {args.heatmap_radius} (must be > 0)"
)
if not args.heatmap_center:
raise ParameterError("--heatmap-radius needs --heatmap-center")
self._radius = args.heatmap_radius
def _determine_bbox(self) -> s2.LatLngRect:
if self._center:
log.info(f"Forcing heatmap center to {self._center}")
dlat, dlng = 0, 0
if self._radius:
er = 6378.1
quarter = er * math.pi / 2
dlat = 90 * self._radius / quarter
scale = 1 / math.cos(self._center.lat().radians)
dlng = scale * 90 * self._radius / quarter
else:
for tr in self.poster.tracks:
for line in tr.polylines:
for latlng in line:
d = abs(self._center.lat().degrees - latlng.lat().degrees)
dlat = max(dlat, d)
d = abs(self._center.lng().degrees - latlng.lng().degrees)
while d > 360:
d -= 360
if d > 180:
d = 360 - d
dlng = max(dlng, d)
return s2.LatLngRect.from_center_size(
self._center, s2.LatLng.from_degrees(2 * dlat, 2 * dlng)
)
tracks_bbox = s2.LatLngRect()
for tr in self.poster.tracks:
tracks_bbox = tracks_bbox.union(tr.bbox())
return tracks_bbox
def draw(self, dr: svgwrite.Drawing, size: XY, offset: XY):
"""Draw the heatmap based on tracks."""
bbox = self._determine_bbox()
for tr in self.poster.tracks:
color = self.color(self.poster.length_range, tr.length, tr.special)
for line in utils.project(bbox, size, offset, tr.polylines):
for opacity, width in [(0.1, 5.0), (0.2, 2.0), (1.0, 0.3)]:
dr.add(
dr.polyline(
points=line,
stroke=color,
stroke_opacity=opacity,
fill="none",
stroke_width=width,
stroke_linejoin="round",
stroke_linecap="round",
)
)
