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fdfe0cee23
This allows nice and simple, elegant construction of checks for
Python.
To use, Python based checks should use the decorator syntax:
from qgis.core import check
@check.register(type=QgsAbstractValidityCheck.TypeLayoutCheck)
def my_layout_check(context, feedback):
results = ...
return results
Or, a more complete example. This one throws a warning when attempting
to export a layout with a map item set to the Web Mercator projection:
@check.register(type=QgsAbstractValidityCheck.TypeLayoutCheck)
def layout_map_crs_choice_check(context, feedback):
layout = context.layout
results = []
for i in layout.items():
if isinstance(i, QgsLayoutItemMap) and i.crs().authid() == 'EPSG:3857':
res = QgsValidityCheckResult()
res.type = QgsValidityCheckResult.Warning
res.title='Map projection is misleading'
res.detailedDescription='The projection for the map item {} is set to <i>Web Mercator (EPSG:3857)</i> which misrepresents areas and shapes. Consider using an appropriate local projection instead.'.format(i.displayName())
results.append(res)
return results
96 lines
3.0 KiB
Python
96 lines
3.0 KiB
Python
# -*- coding: utf-8 -*-
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"""
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***************************************************************************
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validitycheck.py
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---------------------
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Date : January 2019
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Copyright : (C) 2019 by Nyall Dawson
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Email : nyall dot dawson 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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from qgis._core import (
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QgsAbstractValidityCheck,
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QgsApplication)
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class CheckFactory:
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"""
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Constructs QgsAbstractValidityChecks using a decorator.
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To use, Python based checks should use the decorator syntax:
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.. highlight:: python
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.. code-block:: python
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@check.register(type=QgsAbstractValidityCheck.TypeLayoutCheck)
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def my_layout_check(context, feedback):
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results = ...
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return results
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"""
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def __init__(self):
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# unfortunately /Transfer/ annotation isn't working correct on validityCheckRegistry().addCheck(),
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# so we manually need to store a reference to all checks we register
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self.checks = []
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def register(self, type, *args, **kwargs):
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"""
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Implements a decorator for registering Python based checks.
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:param type: check type, e.g. QgsAbstractValidityCheck.TypeLayoutCheck
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"""
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def dec(f):
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check = CheckWrapper(check_type=type, check_func=f)
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self.checks.append(check)
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QgsApplication.validityCheckRegistry().addCheck(check)
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return dec
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class CheckWrapper(QgsAbstractValidityCheck):
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"""
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Wrapper object used to create new validity checks from @check.
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"""
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def __init__(self, check_type, check_func):
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"""
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Initializer for CheckWrapper.
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:param check_type: check type, e.g. QgsAbstractValidityCheck.TypeLayoutCheck
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:param check_func: test function, should return a list of QgsValidityCheckResult results
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"""
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super().__init__()
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self._check_type = check_type
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self._results = []
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self._check_func = check_func
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def create(self):
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return CheckWrapper(check_type=self._check_type, check_func=self._check_func)
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def id(self):
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return self._check_func.__name__
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def checkType(self):
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return self._check_type
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def prepareCheck(self, context, feedback):
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self._results = self._check_func(context, feedback)
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if self._results is None:
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self._results = []
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return True
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def runCheck(self, context, feedback):
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return self._results
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check = CheckFactory()
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