"""
Raw tile handling.
"""
from pngtile.application import BaseApplication
from werkzeug import Request, Response, exceptions
import pypngtile
## Coordinates
# width of a tile
TILE_WIDTH = 256
TILE_HEIGHT = 256
# max. output resolution to allow
MAX_PIXELS = 1920 * 1200
def scale (val, zoom):
"""
Scale dimension by zoom factor
zl > 0 -> bigger
zl < 0 -> smaller
"""
if zoom > 0:
return val << zoom
elif zoom < 0:
return val >> -zoom
else:
return val
def scale_center (val, dim, zoom):
"""
Scale value about center by zoom.
"""
return scale(val - dim / 2, zoom)
class TileApplication (BaseApplication):
def __init__ (self, **opts):
BaseApplication.__init__(self, **opts)
def render_region (self, request, image):
"""
Handle request for an image region
"""
width = int(request.args['w'])
height = int(request.args['h'])
x = int(request.args['x'])
y = int(request.args['y'])
zoom = int(request.args.get('zoom', "0"))
# safely limit
if width * height > MAX_PIXELS:
raise exceptions.BadRequest("Image size: %d * %d > %d" % (width, height, MAX_PIXELS))
x = scale(x, zoom)
y = scale(y, zoom)
try:
return image.tile_mem(width, height, x, y, zoom)
except pypngtile.Error as error:
raise exceptions.BadRequest(str(error))
def render_tile (self, request, image):
"""
Handle request for image tile
"""
width = TILE_WIDTH
height = TILE_HEIGHT
row = int(request.args['row'])
col = int(request.args['col'])
zoom = int(request.args.get('zoom', "0"))
x = scale(row * width, zoom)
y = scale(col * height, zoom)
try:
return image.tile_mem(width, height, x, y, zoom)
except pypngtile.Error as error:
raise exceptions.BadRequest(str(error))
def handle (self, request):
"""
Handle request for an image
"""
try:
image, name = self.get_image(request.path)
except pypngtile.Error as error:
raise exceptions.BadRequest(str(error))
if 'w' in request.args and 'h' in request.args and 'x' in request.args and 'y' in request.args:
png = self.render_region(request, image)
elif 'row' in request.args and 'col' in request.args:
png = self.render_tile(request, image)
else:
raise exceptions.BadRequest("Unknown args")
return Response(png, content_type='image/png')