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129 lines
4.9 KiB
Python
129 lines
4.9 KiB
Python
# -*- coding: utf-8 -*-
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"""
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***************************************************************************
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user.py
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---------------------
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Date : January 2015
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Copyright : (C) 2015 by Nathan Woodrow
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Email : woodrow dot nathan at gmail dot com
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***************************************************************************
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* *
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* This program is free software; you can redistribute it and/or modify *
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* it under the terms of the GNU General Public License as published by *
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* the Free Software Foundation; either version 2 of the License, or *
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* (at your option) any later version. *
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* *
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***************************************************************************
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"""
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__author__ = 'Nathan Woodrow'
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__date__ = 'January 2015'
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__copyright__ = '(C) 2015, Nathan Woodrow'
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# This will get replaced with a git SHA1 when you do a git archive
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__revision__ = '$Format:%H$'
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import os
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import sys
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import glob
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import traceback
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from qgis.PyQt.QtCore import QCoreApplication
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from qgis.core import Qgis, QgsApplication, QgsMessageLog
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def load_user_expressions(path):
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"""
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Load all user expressions from the given paths
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"""
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#Loop all py files and import them
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modules = glob.glob(path + "/*.py")
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names = [os.path.basename(f)[:-3] for f in modules]
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for name in names:
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if name == "__init__":
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continue
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# As user expression functions should be registered with qgsfunction
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# just importing the file is enough to get it to load the functions into QGIS
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try:
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__import__("expressions.{0}".format(name), locals(), globals())
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except:
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error = traceback.format_exc()
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msgtitle = QCoreApplication.translate("UserExpressions", "User expressions")
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msg = QCoreApplication.translate("UserExpressions", "The user expression {0} is not valid").format(name)
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QgsMessageLog.logMessage(msg + "\n" + error, msgtitle, Qgis.Warning)
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userpythonhome = os.path.join(QgsApplication.qgisSettingsDirPath(), "python")
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expressionspath = os.path.join(userpythonhome, "expressions")
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sys.path.append(userpythonhome)
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if not os.path.exists(expressionspath):
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os.makedirs(expressionspath)
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initfile = os.path.join(expressionspath, "__init__.py")
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if not os.path.exists(initfile):
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open(initfile, "w").close()
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template = """\"\"\"
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Define a new function using the @qgsfunction decorator.
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The function accept the following parameters
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:param [any]: Define any parameters you want to pass to your function before
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the following arguments.
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:param feature: The current feature
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:param parent: The QgsExpression object
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:param context: If there is an argument called ``context`` found at the last
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position, this variable will contain a ``QgsExpressionContext``
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object, that gives access to various additional information like
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expression variables. E.g. ``context.variable('layer_id')``
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:returns: The result of the expression.
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The @qgsfunction decorator accepts the following arguments:
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:param args: Defines the number of arguments. With ``args='auto'`` the number of
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arguments will automatically be extracted from the signature.
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With ``args=-1``, any number of arguments are accepted.
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:param group: The name of the group under which this expression function will
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be listed.
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:param handlesnull: Set this to True if your function has custom handling for NULL values.
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If False, the result will always be NULL as soon as any parameter is NULL.
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Defaults to False.
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:param usesgeometry: Set this to False if your function does not access
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feature.geometry(). Defaults to True.
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:param referenced_columns: An array of attribute names that are required to run
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this function. Defaults to
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[QgsFeatureRequest.ALL_ATTRIBUTES].
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\"\"\"
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from qgis.core import *
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from qgis.gui import *
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@qgsfunction(args='auto', group='Custom')
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def my_sum(value1, value2, feature, parent):
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\"\"\"
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Calculates the sum of the two parameters value1 and value2.
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<h2>Example usage:</h2>
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<ul>
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<li>my_sum(5, 8) -> 13</li>
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<li>my_sum(\"field1\", \"field2\") -> 42</li>
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</ul>
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\"\"\"
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return value1 + value2
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"""
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try:
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import expressions
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expressions.load = load_user_expressions
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expressions.load(expressionspath)
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expressions.template = template
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except ImportError:
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# We get a import error and crash for some reason even if we make the expressions package
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# TODO Fix the crash on first load with no expressions folder
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# But for now it's not the end of the world if it doesn't load the first time
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pass
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