QGIS/python/plugins/processing/algs/qgis/VoronoiPolygons.py

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

"""
***************************************************************************
    VoronoiPolygons.py
    ---------------------
    Date                 : August 2012
    Copyright            : (C) 2012 by Victor Olaya
    Email                : volayaf at gmail dot com
***************************************************************************
*                                                                         *
*   This program 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.                                   *
*                                                                         *
***************************************************************************
"""

__author__ = 'Victor Olaya'
__date__ = 'August 2012'
__copyright__ = '(C) 2012, Victor Olaya'

# This will get replaced with a git SHA1 when you do a git archive

__revision__ = '$Format:%H$'

import os

from qgis.PyQt.QtGui import QIcon

from qgis.core import QGis, QgsFeatureRequest, QgsFeature, QgsGeometry, QgsPoint

from processing.core.GeoAlgorithm import GeoAlgorithm
from processing.core.GeoAlgorithmExecutionException import GeoAlgorithmExecutionException
from processing.core.parameters import ParameterVector
from processing.core.parameters import ParameterNumber
from processing.core.outputs import OutputVector
from processing.tools import dataobjects, vector

from . import voronoi

pluginPath = os.path.split(os.path.split(os.path.dirname(__file__))[0])[0]


class VoronoiPolygons(GeoAlgorithm):

    INPUT = 'INPUT'
    BUFFER = 'BUFFER'
    OUTPUT = 'OUTPUT'

    def getIcon(self):
        return QIcon(os.path.join(pluginPath, 'images', 'ftools', 'voronoi.png'))

    def defineCharacteristics(self):
        self.name, self.i18n_name = self.trAlgorithm('Voronoi polygons')
        self.group, self.i18n_group = self.trAlgorithm('Vector geometry tools')

        self.addParameter(ParameterVector(self.INPUT,
                                          self.tr('Input layer'), [ParameterVector.VECTOR_TYPE_POINT]))
        self.addParameter(ParameterNumber(self.BUFFER,
                                          self.tr('Buffer region'), 0.0, 100.0, 0.0))

        self.addOutput(OutputVector(self.OUTPUT, self.tr('Voronoi polygons')))

    def processAlgorithm(self, progress):
        layer = dataobjects.getObjectFromUri(self.getParameterValue(self.INPUT))

        buf = self.getParameterValue(self.BUFFER)

        writer = self.getOutputFromName(self.OUTPUT).getVectorWriter(
            layer.pendingFields().toList(), QGis.WKBPolygon, layer.crs())

        outFeat = QgsFeature()
        extent = layer.extent()
        extraX = extent.height() * (buf / 100.0)
        extraY = extent.width() * (buf / 100.0)
        height = extent.height()
        width = extent.width()
        c = voronoi.Context()
        pts = []
        ptDict = {}
        ptNdx = -1

        features = vector.features(layer)
        total = 100.0 / len(features)
        for current, inFeat in enumerate(features):
            geom = QgsGeometry(inFeat.geometry())
            point = geom.asPoint()
            x = point.x() - extent.xMinimum()
            y = point.y() - extent.yMinimum()
            pts.append((x, y))
            ptNdx += 1
            ptDict[ptNdx] = inFeat.id()
            progress.setPercentage(int(current * total))

        if len(pts) < 3:
            raise GeoAlgorithmExecutionException(
                self.tr('Input file should contain at least 3 points. Choose '
                        'another file and try again.'))

        uniqueSet = set(item for item in pts)
        ids = [pts.index(item) for item in uniqueSet]
        sl = voronoi.SiteList([voronoi.Site(i[0], i[1], sitenum=j) for (j,
                                                                        i) in enumerate(uniqueSet)])
        voronoi.voronoi(sl, c)
        inFeat = QgsFeature()

        current = 0
        total = 100.0 / len(c.polygons)

        for (site, edges) in c.polygons.iteritems():
            request = QgsFeatureRequest().setFilterFid(ptDict[ids[site]])
            inFeat = layer.getFeatures(request).next()
            lines = self.clip_voronoi(edges, c, width, height, extent, extraX, extraY)

            geom = QgsGeometry.fromMultiPoint(lines)
            geom = QgsGeometry(geom.convexHull())
            outFeat.setGeometry(geom)
            outFeat.setAttributes(inFeat.attributes())
            writer.addFeature(outFeat)

            current += 1
            progress.setPercentage(int(current * total))

        del writer

    def clip_voronoi(self, edges, c, width, height, extent, exX, exY):
        """Clip voronoi function based on code written for Inkscape.
        Copyright (C) 2010 Alvin Penner, penner@vaxxine.com
        """

        def clip_line(x1, y1, x2, y2, w, h, x, y):
            if x1 < 0 - x and x2 < 0 - x:
                return [0, 0, 0, 0]
            if x1 > w + x and x2 > w + x:
                return [0, 0, 0, 0]
            if x1 < 0 - x:
                y1 = (y1 * x2 - y2 * x1) / (x2 - x1)
                x1 = 0 - x
            if x2 < 0 - x:
                y2 = (y1 * x2 - y2 * x1) / (x2 - x1)
                x2 = 0 - x
            if x1 > w + x:
                y1 = y1 + (w + x - x1) * (y2 - y1) / (x2 - x1)
                x1 = w + x
            if x2 > w + x:
                y2 = y1 + (w + x - x1) * (y2 - y1) / (x2 - x1)
                x2 = w + x
            if y1 < 0 - y and y2 < 0 - y:
                return [0, 0, 0, 0]
            if y1 > h + y and y2 > h + y:
                return [0, 0, 0, 0]
            if x1 == x2 and y1 == y2:
                return [0, 0, 0, 0]
            if y1 < 0 - y:
                x1 = (x1 * y2 - x2 * y1) / (y2 - y1)
                y1 = 0 - y
            if y2 < 0 - y:
                x2 = (x1 * y2 - x2 * y1) / (y2 - y1)
                y2 = 0 - y
            if y1 > h + y:
                x1 = x1 + (h + y - y1) * (x2 - x1) / (y2 - y1)
                y1 = h + y
            if y2 > h + y:
                x2 = x1 + (h + y - y1) * (x2 - x1) / (y2 - y1)
                y2 = h + y
            return [x1, y1, x2, y2]

        lines = []
        hasXMin = False
        hasYMin = False
        hasXMax = False
        hasYMax = False
        for edge in edges:
            if edge[1] >= 0 and edge[2] >= 0:
                # Two vertices
                [x1, y1, x2, y2] = clip_line(
                    c.vertices[edge[1]][0],
                    c.vertices[edge[1]][1],
                    c.vertices[edge[2]][0],
                    c.vertices[edge[2]][1],
                    width,
                    height,
                    exX,
                    exY,
                )
            elif edge[1] >= 0:
                # Only one vertex
                if c.lines[edge[0]][1] == 0:
                    # Vertical line
                    xtemp = c.lines[edge[0]][2] / c.lines[edge[0]][0]
                    if c.vertices[edge[1]][1] > (height + exY) / 2:
                        ytemp = height + exY
                    else:
                        ytemp = 0 - exX
                else:
                    xtemp = width + exX
                    ytemp = (c.lines[edge[0]][2] - (width + exX)
                             * c.lines[edge[0]][0]) / c.lines[edge[0]][1]
                [x1, y1, x2, y2] = clip_line(
                    c.vertices[edge[1]][0],
                    c.vertices[edge[1]][1],
                    xtemp,
                    ytemp,
                    width,
                    height,
                    exX,
                    exY,
                )
            elif edge[2] >= 0:
                # Only one vertex
                if c.lines[edge[0]][1] == 0:
                    # Vertical line
                    xtemp = c.lines[edge[0]][2] / c.lines[edge[0]][0]
                    if c.vertices[edge[2]][1] > (height + exY) / 2:
                        ytemp = height + exY
                    else:
                        ytemp = 0.0 - exY
                else:
                    xtemp = 0.0 - exX
                    ytemp = c.lines[edge[0]][2] / c.lines[edge[0]][1]
                [x1, y1, x2, y2] = clip_line(
                    xtemp,
                    ytemp,
                    c.vertices[edge[2]][0],
                    c.vertices[edge[2]][1],
                    width,
                    height,
                    exX,
                    exY,
                )
            if x1 or x2 or y1 or y2:
                lines.append(QgsPoint(x1 + extent.xMinimum(), y1
                                      + extent.yMinimum()))
                lines.append(QgsPoint(x2 + extent.xMinimum(), y2
                                      + extent.yMinimum()))
                if 0 - exX in (x1, x2):
                    hasXMin = True
                if 0 - exY in (y1, y2):
                    hasYMin = True
                if height + exY in (y1, y2):
                    hasYMax = True
                if width + exX in (x1, x2):
                    hasXMax = True
        if hasXMin:
            if hasYMax:
                lines.append(QgsPoint(extent.xMinimum() - exX, height
                                      + extent.yMinimum() + exY))
            if hasYMin:
                lines.append(QgsPoint(extent.xMinimum() - exX,
                                      extent.yMinimum() - exY))
        if hasXMax:
            if hasYMax:
                lines.append(QgsPoint(width + extent.xMinimum() + exX, height
                                      + extent.yMinimum() + exY))
            if hasYMin:
                lines.append(QgsPoint(width + extent.xMinimum() + exX,
                                      extent.yMinimum() - exY))
        return lines