def load_ring_little(dat):
"""
LinearRing {
uint32 numPoints;
Point points[numPoints];
}
"""
npts = struct.unpack('<I', dat.read(4))[0]
xy = struct.unpack('<%dd' % (npts * 2), dat.read(npts * 2 * 8))
return [cg.Point(xy[i:i + 2]) for i in range(0, npts * 2, 2)]
def loads(s):
"""
WKBGeometry {
union {
WKBPoint point;
WKBLineString linestring;
WKBPolygon polygon;
WKBGeometryCollection collection;
WKBMultiPoint mpoint;
WKBMultiLineString mlinestring;
WKBMultiPolygon mpolygon;
}
};
"""
# To allow recursive calls, read only the bytes we need.
if hasattr(s, 'read'):
dat = s
else:
dat = StringIO(s)
endian = ENDIAN[dat.read(1)]
typ = struct.unpack('I', dat.read(4))[0]
if typ == 1:
"""
WKBPoint {
byte byteOrder;
uint32 wkbType; 1
Point point;
}
Point {
double x;
double y;
};
"""
x, y = struct.unpack(endian + 'dd', dat.read(16))
return cg.Point((x, y))
elif typ == 2:
"""
WKBLineString {
byte byteOrder;
uint32 wkbType; 2
uint32 numPoints;
Point points[numPoints];
}
"""
n = struct.unpack(endian + 'I', dat.read(4))[0]
xy = struct.unpack(endian + '%dd' % (n * 2), dat.read(n * 2 * 8))
return cg.Chain([cg.Point(xy[i:i + 2]) for i in range(0, n * 2, 2)])
elif typ == 3:
"""
WKBPolygon {
byte byteOrder;
uint32 wkbType; 3
uint32 numRings;
LinearRing rings[numRings];
}
WKBPolygon has exactly 1 outer ring and n holes.
multipart Polygons are NOT support by WKBPolygon.
"""
nrings = struct.unpack(endian + 'I', dat.read(4))[0]
load_ring = load_ring_little if endian == '<' else load_ring_big
rings = [load_ring(dat) for _ in range(nrings)]
return cg.Polygon(rings[0], rings[1:])
elif typ == 4:
"""
WKBMultiPoint {
byte byteOrder;
uint32 wkbType; 4
uint32 num_wkbPoints;
WKBPoint WKBPoints[num_wkbPoints];
}
"""
npts = struct.unpack(endian + 'I', dat.read(4))[0]
return [loads(dat) for _ in range(npts)]
elif typ == 5:
"""
WKBMultiLineString {
byte byteOrder;
uint32 wkbType; 5
uint32 num_wkbLineStrings;
WKBLineString WKBLineStrings[num_wkbLineStrings];
}
"""
nparts = struct.unpack(endian + 'I', dat.read(4))[0]
chains = [loads(dat) for _ in range(nparts)]
return cg.Chain(sum([c.parts for c in chains], []))
elif typ == 6:
"""
wkbMultiPolygon {
byte byteOrder;
uint32 wkbType; 6
uint32 num_wkbPolygons;
WKBPolygon wkbPolygons[num_wkbPolygons];
}
"""
npolys = struct.unpack(endian + 'I', dat.read(4))[0]
polys = [loads(dat) for _ in range(npolys)]
parts = sum([p.parts for p in polys], [])
holes = sum([p.holes for p in polys if p.holes[0]], [])
# MULTIPOLYGON EMPTY, isn't well supported by pysal shape types.
if not parts:
return None
return cg.Polygon(parts, holes)
elif typ == 7:
"""
WKBGeometryCollection {
byte byte_order;
uint32 wkbType; 7
uint32 num_wkbGeometries;
WKBGeometry wkbGeometries[num_wkbGeometries]
}
"""
ngeoms = struct.unpack(endian + 'I', dat.read(4))[0]
return [loads(dat) for _ in range(ngeoms)]
raise TypeError('Type (%d) is unknown or unsupported.' % typ)
def load_ring_big(dat):
npts = struct.unpack('>I', dat.read(4))[0]
xy = struct.unpack('>%dd' % (npts * 2), dat.read(npts * 2 * 8))
return [cg.Point(xy[i:i + 2]) for i in range(0, npts * 2, 2)]
def Point(self, geoStr):
coords = self.regExes['spaces'].split(geoStr.strip())
return cg.Point((coords[0], coords[1]))
