QGIS/python/plugins/processing/algs/ftools/ExtentFromLayer.py

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

"""
***************************************************************************
    ExtentFromLayer.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__ = '$Format:%H$'

from PyQt4.QtCore import *
from qgis.core import *
from processing.core.GeoAlgorithm import GeoAlgorithm
from processing.tools import dataobjects, vector
from processing.parameters.ParameterVector import ParameterVector
from processing.parameters.ParameterBoolean import ParameterBoolean
from processing.outputs.OutputVector import OutputVector

class ExtentFromLayer(GeoAlgorithm):

    INPUT_LAYER = "INPUT_LAYER"
    BY_FEATURE = "BY_FEATURE"

    OUTPUT = "OUTPUT"

    #===========================================================================
    # def getIcon(self):
    #    return QtGui.QIcon(os.path.dirname(__file__) + "/icons/layer_extent.png")
    #===========================================================================

    def defineCharacteristics(self):
        self.name = "Polygon from layer extent"
        self.group = "Vector general tools"

        self.addParameter(ParameterVector(self.INPUT_LAYER, "Input layer", [ParameterVector.VECTOR_TYPE_ANY]))
        self.addParameter(ParameterBoolean(self.BY_FEATURE, "Calculate extent for each feature separately", False))

        self.addOutput(OutputVector(self.OUTPUT, "Output layer"))

    def processAlgorithm(self, progress):
        layer = dataobjects.getObjectFromUri(self.getParameterValue(self.INPUT_LAYER))
        byFeature = self.getParameterValue(self.BY_FEATURE)

        fields = [ QgsField("MINX", QVariant.Double),
                   QgsField("MINY", QVariant.Double),
                   QgsField("MAXX", QVariant.Double),
                   QgsField("MAXY", QVariant.Double),
                   QgsField("CNTX", QVariant.Double),
                   QgsField("CNTY", QVariant.Double),
                   QgsField("AREA", QVariant.Double),
                   QgsField("PERIM", QVariant.Double),
                   QgsField("HEIGHT", QVariant.Double),
                   QgsField("WIDTH", QVariant.Double)
                 ]

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

        if byFeature:
            self.featureExtent(layer, writer, progress)
        else:
            self.layerExtent(layer, writer, progress)

        del writer

    def layerExtent(self, layer, writer, progress):
        rect = layer.extent()
        minx = rect.xMinimum()
        miny = rect.yMinimum()
        maxx = rect.xMaximum()
        maxy = rect.yMaximum()
        height = rect.height()
        width = rect.width()
        cntx = minx + (width / 2.0)
        cnty = miny + (height / 2.0)
        area = width * height
        perim = (2 * width) + (2 * height)

        rect = [QgsPoint(minx, miny),
                QgsPoint(minx, maxy),
                QgsPoint(maxx, maxy),
                QgsPoint(maxx, miny),
                QgsPoint(minx, miny)
               ]
        geometry = QgsGeometry().fromPolygon([rect])
        feat = QgsFeature()
        feat.setGeometry(geometry)
        attrs = [minx,miny,maxx,maxy,cntx,cnty,area,perim,height,width]
        feat.setAttributes(attrs)
        writer.addFeature(feat)

    def featureExtent(self, layer, writer, progress):
        current = 0
        features = vector.features(layer)
        total = 100.0 / float(len(features))
        feat = QgsFeature()
        for f in features:
            rect = f.geometry().boundingBox()
            minx = rect.xMinimum()
            miny = rect.yMinimum()
            maxx = rect.xMaximum()
            maxy = rect.yMaximum()
            height = rect.height()
            width = rect.width()
            cntx = minx + (width / 2.0)
            cnty = miny + (height / 2.0)
            area = width * height
            perim = (2 * width) + (2 * height)
            rect = [QgsPoint(minx, miny),
                    QgsPoint(minx, maxy),
                    QgsPoint(maxx, maxy),
                    QgsPoint(maxx, miny),
                    QgsPoint(minx, miny)
                   ]

            geometry = QgsGeometry().fromPolygon([rect])
            feat.setGeometry(geometry)
            attrs = [minx,miny,maxx,maxy,cntx,cnty,area,perim,height,width]
            feat.setAttributes(attrs)

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