def fetch_wmts_tiles(bounding_box: Polygon,
url=DEFAULT_URL,
layer=DEFAULT_LAYER,
zoom_from=DEFAULT_ZOOM_FROM,
zoom_to=DEFAULT_ZOOM_TO):
# initialize wmts connection
logger.info("fetch layer {} from {} (z: {} to {})".format(
layer, url, zoom_from, zoom_to))
tile_server = wmts.WebMapTileService(url)
# calculate possible extent
if tile_server.contents[layer]:
long1, lat1, long2, lat2 = tile_server.contents[layer].boundingBoxWGS84
p1 = webmercator.Point(latitude=lat1, longitude=long1)
p2 = webmercator.Point(latitude=lat2, longitude=long2)
server_box = Polygon(
((p1.meter_x, p1.meter_y), (p1.meter_x, p2.meter_y),
(p2.meter_x, p2.meter_y), (p2.meter_x, p1.meter_y), (p1.meter_x,
p1.meter_y)))
unified_bb = server_box
if bounding_box is not None:
unified_bb = server_box.intersection(bounding_box)
min_x, min_y = unified_bb.centroid
max_x, max_y = min_x, min_y
for x, y in unified_bb.coords[
0]: # first of multiple geometries hold the bb
if x < min_x:
min_x = x
if x > max_x:
max_x = x
if y < min_y:
min_y = y
if y > max_y:
max_y = y
# get all tiles in the available extent and zoomlevel
for zoom in range(zoom_from,
zoom_to): # FIXME: fixed values -> configurable
p_from = webmercator.Point(meter_x=min_x,
meter_y=min_y,
zoom_level=zoom)
p_to = webmercator.Point(meter_x=max_x,
meter_y=max_y,
zoom_level=zoom)
logger.info(
"getting all tiles with z {} for ({}, {}), ({}, {})".format(
zoom, p_from.tile_x, p_from.tile_y, p_to.tile_x,
p_to.tile_y))
for y in range(p_to.tile_y, p_from.tile_y + 1):
for x in range(p_from.tile_x, p_to.tile_x + 1):
retry = True
while retry:
try:
fetch_wmts_tile(tile_server, layer, x, y, zoom)
retry = False
except Exception as e:
logger.warning(
"Got exception {} - need to repeat".format(e))
else:
pass # TODO: error
def map_tile(request, layer_slug, boundary_slug, tile_zoom, tile_x, tile_y, format):
if not has_imaging_library: raise Http404("Cairo is not available.")
layer = get_object_or_404(MapLayer, slug=layer_slug)
# Load basic parameters.
try:
size = int(request.GET.get('size', '256' if format not in ('json', 'jsonp') else '64'))
if size not in (64, 128, 256, 512, 1024): raise ValueError()
srs = int(request.GET.get('srs', '3857'))
except ValueError:
raise Http404("Invalid parameter.")
db_srs, out_srs = get_srs(srs)
# Get the bounding box for the tile, in the SRS of the output.
try:
tile_x = int(tile_x)
tile_y = int(tile_y)
tile_zoom = int(tile_zoom)
except ValueError:
raise Http404("Invalid parameter.")
# Guess the world size. We need to know the size of the world in
# order to locate the bounding box of any viewport at zoom levels
# greater than zero.
if "radius" not in request.GET:
p = Point( (-90.0, 0.0), srid=db_srs.srid )
p.transform(out_srs)
world_left = p[0]*2
world_top = -world_left
world_size = -p[0] * 4.0
else:
p = Point((0,0), srid=out_srs.srid )
p.transform(db_srs)
p1 = Point([p[0] + 1.0, p[1] + 1.0], srid=db_srs.srid)
p.transform(out_srs)
p1.transform(out_srs)
world_size = math.sqrt(abs(p1[0]-p[0])*abs(p1[1]-p[1])) * float(request.GET.get('radius', '50'))
world_left = p[0] - world_size/2.0
world_top = p[1] + world_size/2.0
tile_world_size = world_size / math.pow(2.0, tile_zoom)
p1 = Point( (world_left + tile_world_size*tile_x, world_top - tile_world_size*tile_y) )
p2 = Point( (world_left + tile_world_size*(tile_x+1), world_top - tile_world_size*(tile_y+1)) )
bbox = Polygon( ((p1[0], p1[1]),(p2[0], p1[1]),(p2[0], p2[1]),(p1[0], p2[1]),(p1[0], p1[1])), srid=out_srs.srid )
# A function to convert world coordinates in the output SRS into
# pixel coordinates.
blon1, blat1, blon2, blat2 = bbox.extent
bx = float(size)/(blon2-blon1)
by = float(size)/(blat2-blat1)
def viewport(coord):
# Convert the world coordinates to image coordinates according to the bounding box
# (in output SRS).
return float(coord[0] - blon1)*bx, (size-1) - float(coord[1] - blat1)*by
# Convert the bounding box to the database SRS.
db_bbox = bbox.transform(db_srs, clone=True)
# What is the width of a pixel in the database SRS? If it is smaller than
# SIMPLE_SHAPE_TOLERANCE, load the simplified geometry from the database.
shape_field = 'shape'
pixel_width = (db_bbox.extent[2]-db_bbox.extent[0]) / size / 2
if pixel_width > boundaries_settings.SIMPLE_SHAPE_TOLERANCE:
shape_field = 'simple_shape'
# Query for any boundaries that intersect the bounding box.
boundaries = Boundary.objects.filter(set=layer.boundaryset, shape__intersects=db_bbox)\
.values("id", "slug", "name", "label_point", shape_field)
if boundary_slug: boundaries = boundaries.filter(slug=boundary_slug)
boundary_id_map = dict( (b["id"], b) for b in boundaries )
if len(boundaries) == 0:
if format == "svg":
raise Http404("No boundaries here.")
elif format in ("png", "gif"):
# Send a 1x1 transparent image. Google is OK getting 404s for map tile images
# but OpenLayers isn't. Maybe cache the image?
im = cairo.ImageSurface(cairo.FORMAT_ARGB32, 1, 1)
ctx = cairo.Context(im)
buf = StringIO()
im.write_to_png(buf)
v = buf.getvalue()
if format == "gif": v = convert_png_to_gif(v)
r = HttpResponse(v, content_type='image/' + format)
r["Content-Length"] = len(v)
return r
elif format == "json":
# Send an empty "UTF-8 Grid"-like response.
return HttpResponse('{"error":"nothing-here"}', content_type="application/json")
elif format == "jsonp":
# Send an empty "UTF-8 Grid"-like response.
return HttpResponse(request.GET.get("callback", "callback") + '({"error":"nothing-here"})', content_type="text/javascript")
# Query for layer style information and then set it on the boundary objects.
styles = layer.boundaries.filter(boundary__in=boundary_id_map.keys())
for style in styles:
boundary_id_map[style.boundary_id]["style"] = style
# Create the image buffer.
if format in ('png', 'gif'):
im = cairo.ImageSurface(cairo.FORMAT_ARGB32, size, size)
elif format == 'svg':
buf = StringIO()
im = cairo.SVGSurface(buf, size, size)
elif format in ('json', 'jsonp'):
# This is going to be a "UTF-8 Grid"-like response, but we generate that
# info by first creating an actual image, with colors coded by index to
# represent which boundary covers which pixels.
im = cairo.ImageSurface(cairo.FORMAT_RGB24, size, size)
# Color helpers.
def get_rgba_component(c):
return c if isinstance(c, float) else c/255.0
def get_rgba_tuple(clr, alpha=.25):
# Colors are specified as tuples/lists with 3 (RGB) or 4 (RGBA)
# components. Components that are float values must be in the
# range 0-1, while all other values are in the range 0-255.
# Because .gif does not support partial transparency, alpha values
# are forced to 1.
return (get_rgba_component(clr[0]), get_rgba_component(clr[1]), get_rgba_component(clr[2]),
get_rgba_component(clr[3]) if len(clr) == 4 and format != 'gif' else (alpha if format != 'gif' else 1.0))
# Create the drawing surface.
ctx = cairo.Context(im)
ctx.select_font_face(maps_settings.MAP_LABEL_FONT, cairo.FONT_SLANT_NORMAL, cairo.FONT_WEIGHT_NORMAL)
if format in ('json', 'jsonp'):
# For the UTF-8 Grid response, turn off anti-aliasing since the color we draw to each pixel
# is a code for what is there.
ctx.set_antialias(cairo.ANTIALIAS_NONE)
def max_extent(shape):
a, b, c, d = shape.extent
return max(c-a, d-b)
# Transform the boundaries to output coordinates.
draw_shapes = []
for bdry in boundaries:
if not "style" in bdry: continue # Boundary had no corresponding MapLayerBoundary
shape = bdry[shape_field]
# Simplify to the detail that could be visible in the output. Although
# simplification may be a little expensive, drawing a more complex
# polygon is even worse.
try:
shape = shape.simplify(pixel_width, preserve_topology=True)
except: # GEOSException
pass # try drawing original
# Make sure the results are all MultiPolygons for consistency.
if shape.__class__.__name__ == 'Polygon':
shape = MultiPolygon((shape,), srid=db_srs.srid)
else:
# Be sure to override SRS (for Google, see above). This code may
# never execute?
shape = MultiPolygon(list(shape), srid=db_srs.srid)
# Is this shape too small to be visible?
ext_dim = max_extent(shape)
if ext_dim < pixel_width:
continue
# Convert the shape to the output SRS.
shape.transform(out_srs)
draw_shapes.append( (len(draw_shapes), bdry, shape, ext_dim) )
# Draw shading, for each linear ring of each polygon in the multipolygon.
for i, bdry, shape, ext_dim in draw_shapes:
if not bdry["style"].color and format not in ('json', 'jsonp'): continue
for polygon in shape:
for ring in polygon: # should just be one since no shape should have holes?
color = bdry["style"].color
if format in ('json', 'jsonp'):
# We're returning a "UTF-8 Grid" indicating which feature is at
# each pixel location on the grid. In order to compute the grid,
# we draw to an image surface with a distinct color for each feature.
# Then we convert the pixel data into the UTF-8 Grid format.
ctx.set_source_rgb(*[ (((i+1)/(256**exp)) % 256)/255.0 for exp in xrange(3) ])
elif isinstance(color, (tuple, list)):
# Specify a 3/4-tuple (or list) for a solid color.
ctx.set_source_rgba(*get_rgba_tuple(color))
elif isinstance(color, dict):
# Specify a dict of the form { "color1": (R,G,B), "color2": (R,G,B) } to
# create a solid fill of color1 plus smaller stripes of color2.
if color.get("color", None) != None:
ctx.set_source_rgba(*get_rgba_tuple(color["color"]))
elif color.get("color1", None) != None and color.get("color2", None) != None:
pat = cairo.LinearGradient(0.0, 0.0, size, size)
for x in xrange(0,size, 32): # divisor of the size so gradient ends at the end
pat.add_color_stop_rgba(*([float(x)/size] + list(get_rgba_tuple(color["color1"], alpha=.3))))
pat.add_color_stop_rgba(*([float(x+28)/size] + list(get_rgba_tuple(color["color1"], alpha=.3))))
pat.add_color_stop_rgba(*([float(x+28)/size] + list(get_rgba_tuple(color["color2"], alpha=.4))))
pat.add_color_stop_rgba(*([float(x+32)/size] + list(get_rgba_tuple(color["color2"], alpha=.4))))
ctx.set_source(pat)
else:
continue # skip fill
else:
continue # Unknown color data structure.
ctx.new_path()
for pt in ring.coords:
ctx.line_to(*viewport(pt))
ctx.fill()
# Draw outlines, for each linear ring of each polygon in the multipolygon.
for i, bdry, shape, ext_dim in draw_shapes:
if format in ('json', 'jsonp'): continue
if ext_dim < pixel_width * 3: continue # skip outlines if too small
color = bdry["style"].color
for polygon in shape:
for ring in polygon: # should just be one since no shape should have holes?
ctx.new_path()
for pt in ring.coords:
ctx.line_to(*viewport(pt))
if not isinstance(color, dict) or not "border" in color or not "width" in color["border"]:
if ext_dim < pixel_width * 60:
ctx.set_line_width(1)
else:
ctx.set_line_width(2.5)
else:
ctx.set_line_width(color["border"]["width"])
if not isinstance(color, dict) or not "border" in color or not "color" in color["border"]:
ctx.set_source_rgba(.3,.3,.3, .75) # grey, semi-transparent
else:
ctx.set_source_rgba(*get_rgba_tuple(color["border"]["color"], alpha=.75))
ctx.stroke_preserve()
# Draw labels.
for i, bdry, shape, ext_dim in draw_shapes:
if format in ('json', 'jsonp'): continue
if ext_dim < pixel_width * 20: continue
color = bdry["style"].color
if isinstance(color, dict) and "label" in color and color["label"] == None: continue
# Get the location of the label stored in the database, or fall back to
# GDAL routine point_on_surface to get a point quickly.
if bdry["style"].label_point:
# Override the SRS on the point (for Google, see above). Then transform
# it to world coordinates.
pt = Point(tuple(bdry["style"].label_point), srid=db_srs.srid)
pt.transform(out_srs)
elif bdry["label_point"]:
# Same transformation as above.
pt = Point(tuple(bdry["label_point"]), srid=db_srs.srid)
pt.transform(out_srs)
else:
# No label_point is specified so try to find one by using the
# point_on_surface to find a point that is in the shape and
# in the viewport's bounding box.
try:
pt = bbox.intersection(shape).point_on_surface
except:
# Don't know why this would fail. Bad geometry of some sort.
# But we really don't want to leave anything unlabeled so
# try the center of the bounding box.
pt = bbox.centroid
if not shape.contains(pt):
continue
# Transform to world coordinates and ensure it is within the bounding box.
if not bbox.contains(pt):
# If it's not in the bounding box and the shape occupies most of this
# bounding box, try moving the point to somewhere in the current tile.
try:
inters = bbox.intersection(shape)
if inters.area < bbox.area/3: continue
pt = inters.point_on_surface
except:
continue
pt = viewport(pt)
txt = bdry["name"]
if isinstance(bdry["style"].metadata, dict): txt = bdry["style"].metadata.get("label", txt)
if ext_dim > size * pixel_width:
ctx.set_font_size(18)
else:
ctx.set_font_size(12)
x_off, y_off, tw, th = ctx.text_extents(txt)[:4]
# Is it within the rough bounds of the shape and definitely the bounds of this tile?
if tw < ext_dim/pixel_width/5 and th < ext_dim/pixel_width/5 \
and pt[0]-x_off-tw/2-4 > 0 and pt[1]-th-4 > 0 and pt[0]-x_off+tw/2+7 < size and pt[1]+6 < size:
# Draw the background rectangle behind the text.
ctx.set_source_rgba(0,0,0,.55) # black, some transparency
ctx.new_path()
ctx.line_to(pt[0]-x_off-tw/2-4,pt[1]-th-4)
ctx.rel_line_to(tw+9, 0)
ctx.rel_line_to(0, +th+8)
ctx.rel_line_to(-tw-9, 0)
ctx.fill()
# Now a drop shadow (also is partially behind the first rectangle).
ctx.set_source_rgba(0,0,0,.3) # black, some transparency
ctx.new_path()
ctx.line_to(pt[0]-x_off-tw/2-4,pt[1]-th-4)
ctx.rel_line_to(tw+11, 0)
ctx.rel_line_to(0, +th+10)
ctx.rel_line_to(-tw-11, 0)
ctx.fill()
# Draw the text.
ctx.set_source_rgba(1,1,1,1) # white
ctx.move_to(pt[0]-x_off-tw/2,pt[1])
ctx.show_text(txt)
if format in ("png", "gif"):
# Convert the image buffer to raw bytes.
buf = StringIO()
im.write_to_png(buf)
v = buf.getvalue()
if format == "gif": v = convert_png_to_gif(v)
# Form the response.
r = HttpResponse(v, content_type='image/' + format)
r["Content-Length"] = len(v)
elif format == "svg":
im.finish()
v = buf.getvalue()
r = HttpResponse(v, content_type='image/svg+xml')
r["Content-Length"] = len(v)
elif format in ('json', 'jsonp'):
# Get the bytes, which are RGBA sequences.
buf1 = list(im.get_data())
# Convert the 4-byte sequences back into integers that refer back to
# the boundary list. Count the number of pixels for each shape.
shapeidx = []
shapecount = { }
for i in xrange(0, size*size):
b = ord(buf1[i*4+2])*(256**0) + ord(buf1[i*4+1])*(256**1) + ord(buf1[i*4+0])*(256**2)
shapeidx.append(b)
if b > 0: shapecount[b] = shapecount.get(b, 0) + 1
# Assign low unicode code points to the most frequently occuring pixel values,
# except always map zero to character 32.
shapecode1 = { }
shapecode2 = { }
for k, count in sorted(shapecount.items(), key = lambda kv : kv[1]):
b = len(shapecode1) + 32 + 1
if b >= 34: b += 1
if b >= 92: b += 1
shapecode1[k] = b
shapecode2[b] = draw_shapes[k-1]
buf = ''
if format == 'jsonp': buf += request.GET.get("callback", "callback") + "(\n"
buf += '{"grid":['
for row in xrange(size):
if row > 0: buf += ",\n "
buf += json.dumps(u"".join(unichr(shapecode1[k] if k != 0 else 32) for k in shapeidx[row*size:(row+1)*size]))
buf += "],\n"
buf += ' "keys":' + json.dumps([""] + [shapecode2[k][1]["slug"] for k in sorted(shapecode2)], separators=(',', ':')) + ",\n"
buf += ' "data":' + json.dumps(dict(
(shapecode2[k][1]["slug"], {
"name": shapecode2[k][1]["name"],
})
for k in sorted(shapecode2)), separators=(',', ':'))
buf += "}"
if format == 'jsonp': buf += ")"
if format == "json":
r = HttpResponse(buf, content_type='application/json')
else:
r = HttpResponse(buf, content_type='text/javascript')
return r
