Portable version of `django.contrib.gis.geos.geometry.GEOSGeometryBase.buffer_with_style()`

geos_buffer_with_style.py

'''
https://code.djangoproject.com/ticket/28960

For Python 2.x you need to delete the annotations and related imports.
'''

from ctypes import c_double, c_int

from django.contrib.gis.geos.libgeos import GEOM_PTR
from django.contrib.gis.geos.prototypes.topology import Topology
from django.contrib.gis.geos.geometry import GEOSGeometry


# https://github.com/OSGeo/geos/blob/master/capi/geos_c.h.in#L1442
# > extern GEOSGeometry GEOS_DLL *GEOSBufferWithStyle(const GEOSGeometry* g,
# > double width, int quadsegs, int endCapStyle, int joinStyle,
# > double mitreLimit);
geos_bufferwithstyle = Topology(
    'GEOSBufferWithStyle',
    argtypes=[GEOM_PTR, c_double, c_int, c_int, c_int, c_double],
)


# https://github.com/OSGeo/geos/blob/master/include/geos/operation/buffer/BufferParameters.h#L57
BUFFER_CAP_ROUND = 1
BUFFER_CAP_FLAT = 2
BUFFER_CAP_SQUARE = 3

BUFFER_JOIN_ROUND = 1
BUFFER_JOIN_MITRE = 2
BUFFER_JOIN_BEVEL = 3


def buffer_with_style(
    geometry: GEOSGeometry,
    width: float,
    quadsegs: int = 8,
    end_cap_style: int = BUFFER_CAP_ROUND,
    join_style: int = BUFFER_JOIN_ROUND,
    mitre_limit: float = 5.0,
) -> GEOSGeometry:
    """
    Advanced version of the `geometry.buffer()`. Does the same, but allows to
    customize the styles of the final value.

    End cap style can be round (1), flat (2) or square (3). Default is round.
    Join style can be round (1), mitre (2) or bevel (3). Default is round.
    Mitre ratio limit only affects mitered join style. Default is 5.0.

    More about styles: http://www.postgis.net/docs/ST_Buffer.html
    """
    return geometry._topology(geos_bufferwithstyle(
        geometry.ptr, width, quadsegs, end_cap_style, join_style, mitre_limit,
    ))


# ========================================================================== #
# ==== DEMO ================================================================ #
# ========================================================================== #
# Delete it before use in production
if __name__ == '__main__':
    from django.contrib.gis.geos import LineString

    from geos_buffer_with_style import buffer_with_style, BUFFER_CAP_FLAT, BUFFER_JOIN_MITRE

    line = LineString((5, 5), (8, 16))
    rectangle = buffer_with_style(line, 1.5, end_cap_flat=BUFFER_CAP_FLAT, join_style=BUFFER_JOIN_MITRE)