tile.py

#-*- coding: utf-8 -*-

#******************************************************************************
#
# QTiles
# ---------------------------------------------------------
# Generates tiles from QGIS project
#
# Copyright (C) 2012-2014 NextGIS (info@nextgis.org)
#
# This source is free software; you can redistribute it and/or modify it under
# the terms of the GNU General Public License as published by the Free
# Software Foundation, either version 2 of the License, or (at your option)
# any later version.
#
# This code is distributed in the hope that it will be useful, but WITHOUT ANY
# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
# FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
# details.
#
# A copy of the GNU General Public License is available on the World Wide Web
# at <http://www.gnu.org/licenses/>. You can also obtain it by writing
# to the Free Software Foundation, 51 Franklin Street, Suite 500 Boston,
# MA 02110-1335 USA.
#
#******************************************************************************

import math

from qgis.core import *

class Tile:
    def __init__(self, x=0, y=0, z=0, tms=1, meta=1):
        self.x = x
        self.y = y
        self.z = z
        self.tms = tms
        if 2**self.z < meta:
            self.meta = 2**z
        else:
            self.meta = meta

    def toPoint(self):
        n = math.pow(2, self.z)
        longitude = float(self.x) / n * 360.0 - 180.0
        latitude = self.tms * math.degrees(math.atan(math.sinh(math.pi * (1.0 - 2.0 * float(self.y) / n))))
        return QgsPointXY(longitude, latitude)

    def toRectangle(self):
        return QgsRectangle(self.toPoint(), Tile(self.x + self.meta, self.y + self.meta, self.z, self.tms, 1).toPoint())

    def toRectangleBuffered(self):
        UL = Tile(self.x - 1, self.y - 1, self.z, self.tms, 1).toPoint()
        LR = Tile(self.x + self.meta + 1, self.y + self.meta + 1, self.z, self.tms, 1).toPoint()
        return QgsRectangle(UL, LR)