Issue #16: support GPX.

Author: enzet

README.md

@@ -210,6 +210,10 @@ will download OSM data to `cache/2.284,48.860,2.290,48.865.osm` and render an SV
 | <span style="white-space: nowrap;">`-z`</span>, <span style="white-space: nowrap;">`--zoom`</span> `<float>` | OSM zoom level, default value: 18.0 |
 | <span style="white-space: nowrap;">`-c`</span>, <span style="white-space: nowrap;">`--coordinates`</span> `<latitude>,<longitude>` | coordinates of any location within the tile |
 | <span style="white-space: nowrap;">`-s`</span>, <span style="white-space: nowrap;">`--size`</span> `<width>,<height>` | resulting image size |
+| <span style="white-space: nowrap;">`--gpx`</span> `<path>` | path to a GPX file to draw as a track overlay |
+| <span style="white-space: nowrap;">`--track-color`</span> `<color>` | track stroke color (default: #FF0000), default value: `#FF0000` |
+| <span style="white-space: nowrap;">`--track-width`</span> `<float>` | track stroke width in pixels (default: 3.0), default value: 3.0 |
+| <span style="white-space: nowrap;">`--track-opacity`</span> `<float>` | track stroke opacity (default: 0.8), default value: 0.8 |
 
 plus [map configuration options](#map-options)
 
@@ -223,6 +227,27 @@ Second, the OSM API only returns data that falls within the requested bounding b
 
 You can skip the download entirely by passing your own OSM or Overpass JSON file with the `--input` option. The Overpass step can be disabled with the `--no-overpass` flag. When disabled, Map Machine will attempt to reconstruct water polygons from the partial data by completing boundaries along the bounding box edges.
 
+### GPX track overlay
+
+The `render` command can draw GPX tracks on top of the map. When a GPX file is provided with `--gpx`, Map Machine parses the track, computes a bounding box around it (with a small padding), downloads the corresponding OSM data, and renders the track as a colored line on top of the map.
+
+```shell
+map-machine render --gpx track.gpx
+```
+
+You can also combine `--gpx` with an explicit bounding box or other render options:
+
+```shell
+map-machine render --gpx track.gpx \
+    --track-color "#0000FF" --track-width 5 --track-opacity 0.6
+```
+
+Track style options:
+
+  * `--track-color`: stroke color (default: `#FF0000`),
+  * `--track-width`: stroke width in pixels (default: 3.0),
+  * `--track-opacity`: stroke opacity (default: 0.8).
+
 ## Tile generation
 
 Command `tile` is used to generate PNG tiles for [slippy maps](https://wiki.openstreetmap.org/wiki/Slippy_Map). To use them, run [Map Machine tile server](#tile-server).

doc/moi/readme.moi

@@ -328,6 +328,29 @@ with the \c {--input} option. The Overpass step can be disabled with the
 water polygons from the partial data by completing boundaries along the bounding
 box edges.
 
+\3 {GPX track overlay} {gpx-track-overlay}
+
+The \c {render} command can draw GPX tracks on top of the map. When a GPX file
+is provided with \c {--gpx}, Map Machine parses the track, computes a bounding
+box around it (with a small padding), downloads the corresponding OSM data, and
+renders the track as a colored line on top of the map.
+
+\code {shell} {map-machine render --gpx track.gpx}
+
+You can also combine \c {--gpx} with an explicit bounding box or other render
+options:
+
+\code {shell} {
+map-machine render --gpx track.gpx \\
+    --track-color "#0000FF" --track-width 5 --track-opacity 0.6
+}
+
+Track style options:
+\list
+    {\c {--track-color}: stroke color (default: \c {#FF0000}),}
+    {\c {--track-width}: stroke width in pixels (default: 3.0),}
+    {\c {--track-opacity}: stroke opacity (default: 0.8).}
+
 \2 {Tile generation} {tile-generation}
 
 Command \c {tile} is used to generate PNG tiles for

map_machine/gpx.py

@@ -0,0 +1,77 @@
+"""GPX file loading and bounding box computation."""
+
+from __future__ import annotations
+
+import logging
+from typing import TYPE_CHECKING
+
+import gpxpy
+import gpxpy.gpx
+
+from map_machine.geometry.bounding_box import (
+    LATITUDE_MAX_DIFFERENCE,
+    LONGITUDE_MAX_DIFFERENCE,
+    BoundingBox,
+)
+
+if TYPE_CHECKING:
+    from pathlib import Path
+
+__author__ = "Sergey Vartanov"
+__email__ = "me@enzet.ru"
+
+logger: logging.Logger = logging.getLogger(__name__)
+
+DEFAULT_PADDING: float = 0.005
+
+
+def load_gpx(path: Path) -> gpxpy.gpx.GPX:
+    """Parse a GPX file.
+
+    :param path: path to the GPX file
+    :return: parsed GPX data
+    """
+    with path.open(encoding="utf-8") as gpx_file:
+        return gpxpy.parse(gpx_file)
+
+
+def get_bounding_box(
+    gpx: gpxpy.gpx.GPX, padding: float = DEFAULT_PADDING
+) -> BoundingBox:
+    """Compute bounding box from GPX track points with padding.
+
+    :param gpx: parsed GPX data
+    :param padding: padding in degrees around the track
+    :return: bounding box covering all track points
+    :raises ValueError: if the GPX has no track points or the resulting
+        bounding box exceeds the size limit
+    """
+    bounds = gpx.get_bounds()
+    if (
+        bounds is None
+        or bounds.min_longitude is None
+        or bounds.min_latitude is None
+        or bounds.max_longitude is None
+        or bounds.max_latitude is None
+    ):
+        message = "GPX file contains no track points."
+        raise ValueError(message)
+
+    left: float = bounds.min_longitude - padding
+    bottom: float = bounds.min_latitude - padding
+    right: float = bounds.max_longitude + padding
+    top: float = bounds.max_latitude + padding
+
+    if (
+        right - left > LONGITUDE_MAX_DIFFERENCE
+        or top - bottom > LATITUDE_MAX_DIFFERENCE
+    ):
+        message = (
+            f"GPX track bounding box is too large "
+            f"({right - left:.3f}° × {top - bottom:.3f}°). "
+            f"Maximum allowed is "
+            f"{LONGITUDE_MAX_DIFFERENCE}° × {LATITUDE_MAX_DIFFERENCE}°."
+        )
+        raise ValueError(message)
+
+    return BoundingBox(left, bottom, right, top)

map_machine/mapper.py

@@ -26,6 +26,7 @@
     WaterRelationProcessor,
 )
 from map_machine.geometry.flinger import Flinger, MercatorFlinger
+from map_machine.geometry.vector import Polyline
 from map_machine.map_configuration import LabelMode, MapConfiguration
 from map_machine.osm.osm_getter import (
     NetworkError,
@@ -43,6 +44,9 @@
     import argparse
     from collections.abc import Iterable
 
+    import gpxpy.gpx
+    from gpxpy.gpx import GPX
+
     from map_machine.figure import StyledFigure
     from map_machine.geometry.vector import Segment
 
@@ -352,6 +356,18 @@ def render_map(arguments: argparse.Namespace) -> None:
     cache_path: Path = Path(arguments.cache)
     cache_path.mkdir(parents=True, exist_ok=True)
 
+    # Parse GPX file if provided.
+
+    gpx_data: GPX | None = None
+    if getattr(arguments, "gpx", None):
+        from map_machine.gpx import get_bounding_box, load_gpx  # noqa: PLC0415
+
+        gpx_path: Path = Path(arguments.gpx)
+        if not gpx_path.is_file():
+            fatal(f"No such file: `{gpx_path}`.")
+            sys.exit(1)
+        gpx_data = load_gpx(gpx_path)
+
     # Compute bounding box.
 
     bounding_box: BoundingBox | None = None
@@ -391,6 +407,9 @@ def render_map(arguments: argparse.Namespace) -> None:
                 coordinates, configuration.zoom_level, width, height
             )
 
+    elif gpx_data is not None:
+        bounding_box = get_bounding_box(gpx_data)
+
     # Determine files.
 
     input_file_names: list[Path]
@@ -407,7 +426,9 @@ def render_map(arguments: argparse.Namespace) -> None:
             logger.fatal(error.message)
             sys.exit(1)
     else:
-        fatal("Specify either --input, or --bounding-box, or --coordinates.")
+        fatal(
+            "Specify `--input`, `--bounding-box`, `--coordinates`, or `--gpx`."
+        )
 
     # Get OpenStreetMap data.
 
@@ -499,8 +520,67 @@ def render_map(arguments: argparse.Namespace) -> None:
     map_: Map = Map(flinger=flinger, svg=svg, configuration=configuration)
     map_.draw(constructor)
 
+    if gpx_data is not None:
+        draw_gpx_tracks(
+            svg,
+            gpx_data,
+            flinger,
+            color=getattr(arguments, "track_color", "#FF0000"),
+            width=getattr(arguments, "track_width", 3.0),
+            opacity=getattr(arguments, "track_opacity", 0.8),
+        )
+
     logger.info("Writing output SVG to `%s`...", arguments.output_file_name)
     with Path(arguments.output_file_name).open(
         "w", encoding="utf-8"
     ) as output_file:
         svg.write(output_file)
+
+
+def draw_gpx_tracks(
+    svg: svgwrite.Drawing,
+    gpx_data: gpxpy.gpx.GPX,
+    flinger: Flinger,
+    color: str,
+    width: float,
+    opacity: float,
+) -> None:
+    """Draw GPX tracks on top of the map.
+
+    :param svg: SVG drawing to add track paths to
+    :param gpx_data: parsed GPX data from gpxpy
+    :param flinger: coordinate transformer (lat/lon to pixels)
+    :param color: track stroke color
+    :param width: track stroke width in pixels
+    :param opacity: track stroke opacity
+    """
+    segment_count: int = 0
+
+    for track in gpx_data.tracks:
+        for segment in track.segments:
+            if len(segment.points) < 2:
+                continue
+
+            points: list[np.ndarray] = [
+                flinger.fling(np.array((point.latitude, point.longitude)))
+                for point in segment.points
+            ]
+            polyline: Polyline = Polyline(points)
+            path_commands: str | None = polyline.get_path()
+
+            if path_commands:
+                path: SVGPath = SVGPath(d=path_commands)
+                path.update(
+                    {
+                        "fill": "none",
+                        "stroke": color,
+                        "stroke-width": width,
+                        "stroke-opacity": opacity,
+                        "stroke-linecap": "round",
+                        "stroke-linejoin": "round",
+                    }
+                )
+                svg.add(path)
+                segment_count += 1
+
+    logger.info("Drew %d track segment(s).", segment_count)

map_machine/ui/cli.py

@@ -422,6 +422,31 @@ def add_render_arguments(parser: argparse.ArgumentParser) -> None:
         metavar="<width>,<height>",
         help="resulting image size",
     )
+    parser.add_argument(
+        "--gpx",
+        metavar="<path>",
+        help="path to a GPX file to draw as a track overlay",
+    )
+    parser.add_argument(
+        "--track-color",
+        metavar="<color>",
+        default="#FF0000",
+        help="track stroke color (default: #FF0000)",
+    )
+    parser.add_argument(
+        "--track-width",
+        metavar="<float>",
+        type=float,
+        default=3.0,
+        help="track stroke width in pixels (default: 3.0)",
+    )
+    parser.add_argument(
+        "--track-opacity",
+        metavar="<float>",
+        type=float,
+        default=0.8,
+        help="track stroke opacity (default: 0.8)",
+    )
 
 
 def add_mapcss_arguments(parser: argparse.ArgumentParser) -> None:

pyproject.toml

@@ -40,6 +40,7 @@ dynamic = ["version"]
 dependencies = [
     "CairoSVG~=2.5.0",
     "colour~=0.1.5",
+    "gpxpy>=1.6.0",
     "numpy~=1.26.0",
     "Pillow~=12.1.0",
     "portolan~=1.0.1",

tests/data/test_track.gpx

@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<gpx xmlns="http://www.topografix.com/GPX/1/1" version="1.1"
+     creator="map-machine-test">
+  <trk>
+    <name>Test Track</name>
+    <trkseg>
+      <trkpt lat="20.0002" lon="10.0002"/>
+      <trkpt lat="20.0004" lon="10.0004"/>
+      <trkpt lat="20.0006" lon="10.0006"/>
+      <trkpt lat="20.0008" lon="10.0008"/>
+    </trkseg>
+  </trk>
+</gpx>

tests/test_command_line.py

@@ -113,8 +113,8 @@ def test_wrong_render_arguments() -> None:
     """Test `render` command with wrong arguments."""
     error_run(
         ["render", "-z", "17"],
-        b"CRITICAL Specify either --input, or --bounding-box, or "
-        b"--coordinates.\n",
+        b"CRITICAL Specify `--input`, `--bounding-box`, `--coordinates`, "
+        b"or `--gpx`.\n",
     )