start of proj4 support (part of GPS support)

src/c3nav/mapdata/api/map.py

@@ -9,6 +9,7 @@ from ninja import Router as APIRouter
 from pydantic import Field as APIField
 from pydantic import PositiveInt
 
+from c3nav import settings
 from c3nav.api.auth import auth_permission_responses, auth_responses, validate_responses
 from c3nav.api.exceptions import API404, APIPermissionDenied, APIRequestValidationFailed
 from c3nav.api.schema import BaseSchema
@@ -19,8 +20,9 @@ from c3nav.mapdata.models.locations import DynamicLocation, LocationRedirect, Po
 from c3nav.mapdata.schemas.filters import BySearchableFilter, RemoveGeometryFilter
 from c3nav.mapdata.schemas.model_base import AnyLocationID, AnyPositionID, CustomLocationID
 from c3nav.mapdata.schemas.models import (AnyPositionStatusSchema, FullListableLocationSchema, FullLocationSchema,
-                                          LocationDisplay, SlimListableLocationSchema, SlimLocationSchema,
+                                          LocationDisplay, ProjectionPipelineSchema, ProjectionSchema,
-                                          all_location_definitions, listable_location_definitions)
+                                          SlimListableLocationSchema, SlimLocationSchema, all_location_definitions,
+                                          listable_location_definitions)
 from c3nav.mapdata.schemas.responses import LocationGeometry, WithBoundsSchema
 from c3nav.mapdata.utils.locations import (get_location_by_id_for_request, get_location_by_slug_for_request,
                                            searchable_locations_for_request, visible_locations_for_request)
@@ -310,3 +312,20 @@ def set_position(request, position_id: AnyPositionID, update: UpdatePositionSche
     location.save()
 
     return location.serialize_position()
+
+
+@map_api_router.get('/projection/', summary='get proj4 string',
+                    description="get proj4 string for converting WGS84 coordinates to c3nva coordinates",
+                    response={200: Union[ProjectionSchema, ProjectionPipelineSchema], **auth_responses})
+def get_projection(request):
+    obj = {
+        "pipeline": settings.PROJECTION_TRANSFORMER_STRING
+    }
+    if True:
+        obj.update({
+            'proj4': settings.PROJECTION_PROJ4,
+            'zero_point': settings.PROJECTION_ZERO_POINT,
+            'rotation': settings.PROJECTION_ROTATION,
+            'rotation_matrix': settings.PROJECTION_ROTATION_MATRIX,
+        })
+    return obj

src/c3nav/mapdata/schemas/models.py

@@ -793,3 +793,46 @@ AnyPositionStatusSchema = Annotated[
     ],
     Discriminator("available"),
 ]
+
+
+class ProjectionPipelineSchema(BaseSchema):
+    pipeline: Union[
+        Annotated[NonEmptyStr, APIField(title='proj4 string')],
+        Annotated[None, APIField(title='null', description='projection not available')]
+    ] = APIField(
+        title='proj4 string',
+        description='proj4 string for converting WGS84 coordinates to c3nav coordinates if available',
+        example='+proj=utm +zone=33 +ellps=GRS80 +units=m +no_defs'
+    )
+
+class ProjectionSchema(ProjectionPipelineSchema):
+    proj4: NonEmptyStr = APIField(
+        title='proj4 string',
+        description='proj4 string for converting WGS84 coordinates to c3nav coordinates without offset and rotation',
+        example='+proj=utm +zone=33 +ellps=GRS80 +units=m +no_defs'
+    )
+    zero_point: tuple[float, float] = APIField(
+        title='zero point',
+        description='coordinates of the zero point of the c3nav coordinate system',
+        example=(0.0, 0.0),
+    )
+    rotation: float = APIField(
+        title='rotation',
+        description='rotational offset of the c3nav coordinate system',
+        example=0.0,
+    )
+    rotation_matrix: Optional[tuple[
+        float, float, float, float,
+        float, float, float, float,
+        float, float, float, float,
+        float, float, float, float,
+    ]] = APIField(
+        title='rotation matrix',
+        description='rotation matrix for rotational offset of the c3nav coordinate system',
+        example=[
+            1, 0, 0, 0,
+            0, 1, 0, 0,
+            0, 0, 1, 0,
+            0, 0, 0, 1
+        ]
+    )

src/c3nav/settings.py

@@ -1,4 +1,5 @@
 # c3nav settings, mostly taken from the pretix project
+import math
 import os
 import re
 import string
@@ -12,6 +13,7 @@ from django.core.exceptions import ImproperlyConfigured
 from django.utils.crypto import get_random_string
 from django.utils.dateparse import parse_duration
 from django.utils.translation import gettext_lazy as _
+from pyproj import Proj, Transformer
 
 from c3nav import __version__ as c3nav_version
 from c3nav.utils.config import C3navConfigParser
@@ -606,6 +608,68 @@ BASE_THEME = {
 
 WIFI_SSIDS = [n for n in config.get('c3nav', 'wifi_ssids', fallback='').split(',') if n]
 
+
+# Projection
+PROJECTION_PROJ4 = config.get('projection', 'proj4', fallback=None)
+PROJECTION_ZERO_POINT = config.get('projection', 'zero_point', fallback=None)
+PROJECTION_ZERO_POINT_IS_WGS84 = '°' in PROJECTION_ZERO_POINT if PROJECTION_ZERO_POINT else False
+PROJECTION_ROTATION = config.getfloat('projection', 'rotation', fallback=0.0)
+PROJECTION_ROTATION_MATRIX = config.get('projection', 'rotation_matrix', fallback=None)
+PROJECTION_TRANSFORMER: Optional[Transformer] = None
+PROJECTION_TRANSFORMER_STRING: Optional[str] = None
+
+if PROJECTION_PROJ4:
+    if '+units=m' not in PROJECTION_PROJ4:
+        PROJECTION_PROJ4 += ' +units=m'
+    PROJECTION_TRANSFORMER_STRING = re.sub(r'\s?\+no_defs', '', PROJECTION_PROJ4)
+
+    if (PROJECTION_ZERO_POINT or PROJECTION_ROTATION) and 'pipeline' not in PROJECTION_TRANSFORMER_STRING:
+        PROJECTION_TRANSFORMER_STRING = f'+proj=pipeline +step {PROJECTION_TRANSFORMER_STRING}'
+
+    if PROJECTION_ZERO_POINT:
+        PROJECTION_ZERO_POINT = tuple((float(i) for i in PROJECTION_ZERO_POINT.split(',')))
+        if len(PROJECTION_ZERO_POINT) != 2:
+            raise ImproperlyConfigured(f'invalid projection zero point "{PROJECTION_ZERO_POINT!r}"')
+        if PROJECTION_ZERO_POINT_IS_WGS84:
+            PROJECTION_ZERO_POINT = Proj.from_pipeline(PROJECTION_PROJ4).transform(PROJECTION_ZERO_POINT[0],
+                                                                                   PROJECTION_ZERO_POINT[1])
+        PROJECTION_TRANSFORMER_STRING += (f' +step +proj=affine +xoff=-{PROJECTION_ZERO_POINT[0]} '
+                                          f'+yoff=-{PROJECTION_ZERO_POINT[1]}')
+
+    if PROJECTION_ROTATION != 0:
+        PROJECTION_ROTATION_MATRIX = (
+            math.cos(math.radians(PROJECTION_ROTATION)), math.sin(math.radians(PROJECTION_ROTATION)), 0, 0,
+            -math.sin(math.radians(PROJECTION_ROTATION)), math.cos(math.radians(PROJECTION_ROTATION)), 0, 0,
+            0, 0, 1, 0,
+            0, 0, 0, 1
+        )
+    elif PROJECTION_ROTATION_MATRIX:
+        PROJECTION_ROTATION_MATRIX = tuple((float(i) for i in PROJECTION_ROTATION_MATRIX.split(',')))
+        if len(PROJECTION_ROTATION_MATRIX) != 16:
+            raise ImproperlyConfigured(f'invalid rotation matrix "{PROJECTION_ROTATION_MATRIX!r}"')
+
+    if PROJECTION_ROTATION_MATRIX:
+        PROJECTION_TRANSFORMER_STRING += (
+            f' +step +proj=affine '
+            f'+s11={PROJECTION_ROTATION_MATRIX[0]} +s12={PROJECTION_ROTATION_MATRIX[1]}'
+        )
+        if PROJECTION_ROTATION_MATRIX[2] != 0:
+            PROJECTION_TRANSFORMER_STRING += f' +s13={PROJECTION_ROTATION_MATRIX[2]}'
+        PROJECTION_TRANSFORMER_STRING += f' +s21={PROJECTION_ROTATION_MATRIX[4]} +s22={PROJECTION_ROTATION_MATRIX[5]}'
+        if PROJECTION_ROTATION_MATRIX[6] != 0:
+            PROJECTION_TRANSFORMER_STRING += ' +s23={PROJECTION_ROTATION_MATRIX[6]}'
+        if PROJECTION_ROTATION_MATRIX[8] != 0:
+            PROJECTION_TRANSFORMER_STRING += f' +s31={PROJECTION_ROTATION_MATRIX[8]}'
+        if PROJECTION_ROTATION_MATRIX[9] != 0:
+            PROJECTION_TRANSFORMER_STRING += f' +s32={PROJECTION_ROTATION_MATRIX[9]}'
+        if PROJECTION_ROTATION_MATRIX[10] != 1:
+            PROJECTION_TRANSFORMER_STRING += f' +s33={PROJECTION_ROTATION_MATRIX[10]}'
+        if PROJECTION_ROTATION_MATRIX[15] != 1:
+            PROJECTION_TRANSFORMER_STRING += f' +tscale={PROJECTION_ROTATION_MATRIX[15]}'
+
+    PROJECTION_TRANSFORMER_STRING += ' +no_defs'
+    PROJECTION_TRANSFORMER = Proj.from_pipeline(PROJECTION_TRANSFORMER_STRING)
+
 USER_REGISTRATION = config.getboolean('c3nav', 'user_registration', fallback=True)
 
 INTERNAL_IPS = ('127.0.0.1', '::1')

src/requirements/production.txt

@@ -20,3 +20,4 @@ django_libsass==0.9
 channels==4.0.0
 daphne==4.1.0
 pyzstd==0.15.9
+pyproj==3.6.1