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

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# -*- 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'
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# This will get replaced with a git SHA1 when you do a git archive
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__revision__ = '$Format:%H$'
from PyQt4.QtCore import QVariant
from qgis.core import QGis, QgsField, QgsPoint, QgsGeometry, QgsFeature
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from processing.core.GeoAlgorithm import GeoAlgorithm
from processing.core.parameters import ParameterVector
from processing.core.parameters import ParameterBoolean
from processing.core.outputs import OutputVector
from processing.tools import dataobjects, vector
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class ExtentFromLayer(GeoAlgorithm):
INPUT_LAYER = 'INPUT_LAYER'
BY_FEATURE = 'BY_FEATURE'
OUTPUT = 'OUTPUT'
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def defineCharacteristics(self):
self.name = 'Polygon from layer extent'
self.group = 'Vector general tools'
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self.addParameter(ParameterVector(self.INPUT_LAYER,
self.tr('Input layer'), [ParameterVector.VECTOR_TYPE_ANY]))
self.addParameter(ParameterBoolean(self.BY_FEATURE,
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self.tr('Calculate extent for each feature separately'), False))
self.addOutput(OutputVector(self.OUTPUT, self.tr('Extent')))
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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:
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self.featureExtent(layer, writer, progress)
else:
self.layerExtent(layer, writer, progress)
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del writer
def layerExtent(self, layer, writer, progress):
rect = layer.extent()
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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
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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])
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feat = QgsFeature()
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feat.setGeometry(geometry)
attrs = [
minx,
miny,
maxx,
maxy,
cntx,
cnty,
area,
perim,
height,
width,
]
feat.setAttributes(attrs)
writer.addFeature(feat)
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def featureExtent(self, layer, writer, progress):
current = 0
features = vector.features(layer)
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total = 100.0 / float(len(features))
feat = QgsFeature()
for f in features:
rect = f.geometry().boundingBox()
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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
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area = width * height
perim = 2 * width + 2 * height
rect = [QgsPoint(minx, miny), QgsPoint(minx, maxy), QgsPoint(maxx,
maxy), QgsPoint(maxx, miny), QgsPoint(minx, miny)]
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geometry = QgsGeometry().fromPolygon([rect])
feat.setGeometry(geometry)
attrs = [
minx,
miny,
maxx,
maxy,
cntx,
cnty,
area,
perim,
height,
width,
]
feat.setAttributes(attrs)
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writer.addFeature(feat)
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current += 1
progress.setPercentage(int(current * total))