QGIS API Documentation 3.37.0-Master (684a802617f)
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qgsexpressioncontextutils.h
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1/***************************************************************************
2 qgsexpressioncontextutils.h
3 ---------------------------
4 Date : April 2015
5 Copyright : (C) 2015 by Nyall Dawson
6 Email : nyall dot dawson at gmail dot com
7 ***************************************************************************
8 * *
9 * This program is free software; you can redistribute it and/or modify *
10 * it under the terms of the GNU General Public License as published by *
11 * the Free Software Foundation; either version 2 of the License, or *
12 * (at your option) any later version. *
13 * *
14 ***************************************************************************/
15#ifndef QGSEXPRESSIONCONTEXTUTILS_H
16#define QGSEXPRESSIONCONTEXTUTILS_H
17
18#include "qgis_core.h"
19#include "qgis_sip.h"
20#include "qgsfeature.h"
21#include "qgspointlocator.h"
23#include "qgsmeshdataprovider.h"
24
25#include <QString>
26#include <QVariantMap>
27
29class QgsProject;
30class QgsLayout;
31class QgsSymbol;
32class QgsLayoutAtlas;
33class QgsLayoutItem;
34class QgsMapSettings;
36class QgsProcessingModelAlgorithm;
39
48{
49 public:
50
56 static QgsExpressionContextScope *globalScope() SIP_FACTORY;
57
64 static QgsExpressionContextScope *formScope( const QgsFeature &formFeature = QgsFeature( ), const QString &formMode = QString() ) SIP_FACTORY;
65
72 static QgsExpressionContextScope *parentFormScope( const QgsFeature &formFeature = QgsFeature( ), const QString &formMode = QString() ) SIP_FACTORY;
73
83 static void setGlobalVariable( const QString &name, const QVariant &value );
84
93 static void setGlobalVariables( const QVariantMap &variables );
94
102 static void removeGlobalVariable( const QString &name );
103
110 static QgsExpressionContextScope *projectScope( const QgsProject *project ) SIP_FACTORY;
111
122 static void setProjectVariable( QgsProject *project, const QString &name, const QVariant &value );
123
133 static void setProjectVariables( QgsProject *project, const QVariantMap &variables );
134
143 static void removeProjectVariable( QgsProject *project, const QString &name );
144
149 static QgsExpressionContextScope *layerScope( const QgsMapLayer *layer ) SIP_FACTORY;
150
154 static QList<QgsExpressionContextScope *> globalProjectLayerScopes( const QgsMapLayer *layer ) SIP_FACTORY;
155
165 static void setLayerVariable( QgsMapLayer *layer, const QString &name, const QVariant &value );
166
175 static void setLayerVariables( QgsMapLayer *layer, const QVariantMap &variables );
176
181 static QgsExpressionContextScope *mapSettingsScope( const QgsMapSettings &mapSettings ) SIP_FACTORY;
182
188 static QgsExpressionContextScope *mapToolCaptureScope( const QList<QgsPointLocator::Match> &matches ) SIP_FACTORY;
189
197 static QgsExpressionContextScope *mapLayerPositionScope( const QgsPointXY &position ) SIP_FACTORY;
198
204 static QgsExpressionContextScope *updateSymbolScope( const QgsSymbol *symbol, QgsExpressionContextScope *symbolScope = nullptr );
205
210 static QgsExpressionContextScope *layoutScope( const QgsLayout *layout ) SIP_FACTORY;
211
221 static void setLayoutVariable( QgsLayout *layout, const QString &name, const QVariant &value );
222
231 static void setLayoutVariables( QgsLayout *layout, const QVariantMap &variables );
232
238 static QgsExpressionContextScope *atlasScope( const QgsLayoutAtlas *atlas ) SIP_FACTORY;
239
246 static QgsExpressionContextScope *layoutItemScope( const QgsLayoutItem *item ) SIP_FACTORY;
247
255 static void setLayoutItemVariable( QgsLayoutItem *item, const QString &name, const QVariant &value );
256
263 static void setLayoutItemVariables( QgsLayoutItem *item, const QVariantMap &variables );
264
271 static QgsExpressionContextScope *multiFrameScope( const QgsLayoutMultiFrame *frame ) SIP_FACTORY;
272
281 static void setLayoutMultiFrameVariable( QgsLayoutMultiFrame *frame, const QString &name, const QVariant &value );
282
290 static void setLayoutMultiFrameVariables( QgsLayoutMultiFrame *frame, const QVariantMap &variables );
291
297 static QgsExpressionContext createFeatureBasedContext( const QgsFeature &feature, const QgsFields &fields );
298
305 static QgsExpressionContextScope *processingAlgorithmScope( const QgsProcessingAlgorithm *algorithm, const QVariantMap &parameters, QgsProcessingContext &context ) SIP_FACTORY;
306
313 static QgsExpressionContextScope *processingModelAlgorithmScope( const QgsProcessingModelAlgorithm *model, const QVariantMap &parameters, QgsProcessingContext &context ) SIP_FACTORY;
314
319 static QgsExpressionContextScope *notificationScope( const QString &message = QString() ) SIP_FACTORY;
320
324 static void registerContextFunctions();
325
331
332 private:
333
334 class GetLayerVisibility : public QgsScopedExpressionFunction
335 {
336 public:
337 GetLayerVisibility( const QList<QgsMapLayer *> &layers, double scale = 0 );
338 QVariant func( const QVariantList &values, const QgsExpressionContext *, QgsExpression *, const QgsExpressionNodeFunction * ) override;
339 QgsScopedExpressionFunction *clone() const override;
340
341 private:
342 GetLayerVisibility();
343
344 QList< QPointer< QgsMapLayer > > mLayers;
345 QMap< QPointer< QgsMapLayer >, QPair< double, double > > mScaleBasedVisibilityDetails;
346 double mScale = 0.0;
347
348 };
349
350 friend class QgsLayoutItemMap; // needs access to GetLayerVisibility
351
352};
353
355#ifndef SIP_RUN
356class LoadLayerFunction : public QgsScopedExpressionFunction
357{
358 public:
359 LoadLayerFunction()
360 : QgsScopedExpressionFunction( QStringLiteral( "load_layer" ), QgsExpressionFunction::ParameterList() << QgsExpressionFunction::Parameter( QStringLiteral( "uri" ) ) << QgsExpressionFunction::Parameter( QStringLiteral( "provider" ) ), QStringLiteral( "Map Layers" ) )
361 {}
362
363 QVariant func( const QVariantList &, const QgsExpressionContext *, QgsExpression *parent, const QgsExpressionNodeFunction * ) override;
364 bool isStatic( const QgsExpressionNodeFunction *node, QgsExpression *parent, const QgsExpressionContext *context ) const override;
365
366 QgsScopedExpressionFunction *clone() const override;
367
368};
369#endif
371
372#ifndef SIP_RUN
373
381{
382 public:
383
393 : mContext( context )
394 {
395 mContext.appendScope( scope );
396 }
397
399 {
400 delete mContext.popScope();
401 }
402
403 private:
404 QgsExpressionContext &mContext;
405};
406#endif
407
408#endif // QGSEXPRESSIONCONTEXTUTILS_H
RAII class to pop scope from an expression context on destruction.
QgsExpressionContextScopePopper(QgsExpressionContext &context, QgsExpressionContextScope *scope)
Constructor for QgsExpressionContextScopePopper.
Single scope for storing variables and functions for use within a QgsExpressionContext.
Contains utilities for working with QgsExpressionContext objects, including methods for creating scop...
static QgsExpressionContextScope * meshExpressionScope(QgsMesh::ElementType elementType)
Creates a new scope which contains functions relating to mesh layer element elementType.
Expression contexts are used to encapsulate the parameters around which a QgsExpression should be eva...
QgsExpressionContextScope * popScope()
Removes the last scope from the expression context and return it.
void appendScope(QgsExpressionContextScope *scope)
Appends a scope to the end of the context.
A abstract base class for defining QgsExpression functions.
An expression node for expression functions.
Class for parsing and evaluation of expressions (formerly called "search strings").
The feature class encapsulates a single feature including its unique ID, geometry and a list of field...
Definition qgsfeature.h:58
Container of fields for a vector layer.
Definition qgsfields.h:46
Class used to render QgsLayout as an atlas, by iterating over the features from an associated vector ...
Layout graphical items for displaying a map.
Base class for graphical items within a QgsLayout.
Abstract base class for layout items with the ability to distribute the content to several frames (Qg...
Base class for layouts, which can contain items such as maps, labels, scalebars, etc.
Definition qgslayout.h:49
Base class for all map layer types.
Definition qgsmaplayer.h:75
The QgsMapSettings class contains configuration for rendering of the map.
A class to represent a 2D point.
Definition qgspointxy.h:60
Abstract base class for processing algorithms.
Contains information about the context in which a processing algorithm is executed.
Encapsulates a QGIS project, including sets of map layers and their styles, layouts,...
Definition qgsproject.h:107
Expression function for use within a QgsExpressionContextScope.
virtual QgsScopedExpressionFunction * clone() const =0
Returns a clone of the function.
bool isStatic(const QgsExpressionNodeFunction *node, QgsExpression *parent, const QgsExpressionContext *context) const override
Will be called during prepare to determine if the function is static.
QVariant func(const QVariantList &values, const QgsExpressionContext *context, QgsExpression *parent, const QgsExpressionNodeFunction *node) override=0
Returns result of evaluating the function.
Abstract base class for all rendered symbols.
Definition qgssymbol.h:94
As part of the API refactoring and improvements which landed in the Processing API was substantially reworked from the x version This was done in order to allow much of the underlying Processing framework to be ported into allowing algorithms to be written in pure substantial changes are required in order to port existing x Processing algorithms for QGIS x The most significant changes are outlined not GeoAlgorithm For algorithms which operate on features one by consider subclassing the QgsProcessingFeatureBasedAlgorithm class This class allows much of the boilerplate code for looping over features from a vector layer to be bypassed and instead requires implementation of a processFeature method Ensure that your algorithm(or algorithm 's parent class) implements the new pure virtual createInstance(self) call
#define SIP_FACTORY
Definition qgis_sip.h:76
ElementType
Defines type of mesh elements.