def vector(tcLayer, bounds, levels, connection, data):
# http://www.gdal.org/ogr/classOGRDataSource.html#a6acc228db6513784a56ce12334a8c33
pad = pack('x')
tiles = {}
ogrBounds = polygon(bounds)
ds = ogr.Open("PG:%s"%connection.strip('"'))
if ds is None:
raise Exception("PGconnectdb failed: '%s'"%connection)
assert ds is not None
for sql in re.split('"\W*"', data):
layer = ds.ExecuteSQL("SELECT " + sql.strip('" '), ogrBounds)
if layer is not None:
layer.ResetReading()
for geometry in (f.GetGeometryRef() for f in layer):
minx, maxx, miny, maxy = geometry.GetEnvelope()
# dont generate all tile for the whole feature if it is larger than the requested bbox
logger.debug('feature bbox: ' + str(minx) + ' ' + str(miny) + ' ' + str(maxx) + ' ' + str(maxy))
nminx = max(min(minx,maxx),min(bounds[0],bounds[2]))
nminy = max(min(miny,maxy),min(bounds[1],bounds[3]))
nmaxx = min(max(minx,maxx),max(bounds[0],bounds[2]))
nmaxy = min(max(miny,maxy),max(bounds[1],bounds[3]))
logger.debug('final bbox: ' + str(nminx) + ' ' + str(nminy) + ' ' + str(nmaxx) + ' ' + str(nmaxy))
for x, y, z in grid(tcLayer, (nminx, nminy, nmaxx, nmaxy), levels, use_buffer=True):
tile = pack('3i', x, y, z)
if tile not in tiles:
metatile = MetaTile(tcLayer, x, y, z)
tminx, tminy, tmaxx, tmaxy = metatile.bounds()
shift = tcLayer.yshift(z) if hasattr(tcLayer, 'yshift') else 0.0
tminy -= shift
tmaxy -= shift
if geometry.Intersect(polygon((tminx, tminy, tmaxx, tmaxy))):
tiles[tile] = pad
yield (x, y, z)
ds.ReleaseResultSet(layer)
ds.Destroy()
