QGIS API Documentation 3.29.0-Master (19d7edcfed)
qgsexpressioncontextutils.h
Go to the documentation of this file.
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#include <QString>
25#include <QVariantMap>
26
28class QgsProject;
29class QgsLayout;
30class QgsSymbol;
31class QgsLayoutAtlas;
32class QgsLayoutItem;
34class QgsProcessingModelAlgorithm;
37
47{
48 public:
49
55 static QgsExpressionContextScope *globalScope() SIP_FACTORY;
56
63 static QgsExpressionContextScope *formScope( const QgsFeature &formFeature = QgsFeature( ), const QString &formMode = QString() ) SIP_FACTORY;
64
71 static QgsExpressionContextScope *parentFormScope( const QgsFeature &formFeature = QgsFeature( ), const QString &formMode = QString() ) SIP_FACTORY;
72
82 static void setGlobalVariable( const QString &name, const QVariant &value );
83
92 static void setGlobalVariables( const QVariantMap &variables );
93
101 static void removeGlobalVariable( const QString &name );
102
109 static QgsExpressionContextScope *projectScope( const QgsProject *project ) SIP_FACTORY;
110
121 static void setProjectVariable( QgsProject *project, const QString &name, const QVariant &value );
122
132 static void setProjectVariables( QgsProject *project, const QVariantMap &variables );
133
142 static void removeProjectVariable( QgsProject *project, const QString &name );
143
148 static QgsExpressionContextScope *layerScope( const QgsMapLayer *layer ) SIP_FACTORY;
149
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
189 static QgsExpressionContextScope *mapToolCaptureScope( const QList<QgsPointLocator::Match> &matches ) SIP_FACTORY;
190
198 static QgsExpressionContextScope *mapLayerPositionScope( const QgsPointXY &position ) SIP_FACTORY;
199
206 static QgsExpressionContextScope *updateSymbolScope( const QgsSymbol *symbol, QgsExpressionContextScope *symbolScope = nullptr );
207
213 static QgsExpressionContextScope *layoutScope( const QgsLayout *layout ) SIP_FACTORY;
214
225 static void setLayoutVariable( QgsLayout *layout, const QString &name, const QVariant &value );
226
236 static void setLayoutVariables( QgsLayout *layout, const QVariantMap &variables );
237
243 static QgsExpressionContextScope *atlasScope( const QgsLayoutAtlas *atlas ) SIP_FACTORY;
244
252 static QgsExpressionContextScope *layoutItemScope( const QgsLayoutItem *item ) SIP_FACTORY;
253
262 static void setLayoutItemVariable( QgsLayoutItem *item, const QString &name, const QVariant &value );
263
271 static void setLayoutItemVariables( QgsLayoutItem *item, const QVariantMap &variables );
272
279 static QgsExpressionContextScope *multiFrameScope( const QgsLayoutMultiFrame *frame ) SIP_FACTORY;
280
289 static void setLayoutMultiFrameVariable( QgsLayoutMultiFrame *frame, const QString &name, const QVariant &value );
290
298 static void setLayoutMultiFrameVariables( QgsLayoutMultiFrame *frame, const QVariantMap &variables );
299
305 static QgsExpressionContext createFeatureBasedContext( const QgsFeature &feature, const QgsFields &fields );
306
313 static QgsExpressionContextScope *processingAlgorithmScope( const QgsProcessingAlgorithm *algorithm, const QVariantMap &parameters, QgsProcessingContext &context ) SIP_FACTORY;
314
321 static QgsExpressionContextScope *processingModelAlgorithmScope( const QgsProcessingModelAlgorithm *model, const QVariantMap &parameters, QgsProcessingContext &context ) SIP_FACTORY;
322
327 static QgsExpressionContextScope *notificationScope( const QString &message = QString() ) SIP_FACTORY;
328
332 static void registerContextFunctions();
333
339
340 private:
341
342 class GetLayerVisibility : public QgsScopedExpressionFunction
343 {
344 public:
345 GetLayerVisibility( const QList<QgsMapLayer *> &layers, double scale = 0 );
346 QVariant func( const QVariantList &values, const QgsExpressionContext *, QgsExpression *, const QgsExpressionNodeFunction * ) override;
347 QgsScopedExpressionFunction *clone() const override;
348
349 private:
350 GetLayerVisibility();
351
352 QList< QPointer< QgsMapLayer > > mLayers;
353 QMap< QPointer< QgsMapLayer >, QPair< double, double > > mScaleBasedVisibilityDetails;
354 double mScale = 0.0;
355
356 };
357
358 friend class QgsLayoutItemMap; // needs access to GetLayerVisibility
359
360};
361
363#ifndef SIP_RUN
364class LoadLayerFunction : public QgsScopedExpressionFunction
365{
366 public:
367 LoadLayerFunction()
368 : QgsScopedExpressionFunction( QStringLiteral( "load_layer" ), QgsExpressionFunction::ParameterList() << QgsExpressionFunction::Parameter( QStringLiteral( "uri" ) ) << QgsExpressionFunction::Parameter( QStringLiteral( "provider" ) ), QStringLiteral( "Map Layers" ) )
369 {}
370
371 QVariant func( const QVariantList &, const QgsExpressionContext *, QgsExpression *parent, const QgsExpressionNodeFunction * ) override;
372 bool isStatic( const QgsExpressionNodeFunction *node, QgsExpression *parent, const QgsExpressionContext *context ) const override;
373
374 QgsScopedExpressionFunction *clone() const override;
375
376};
377#endif
379
380#ifndef SIP_RUN
381
389{
390 public:
391
401 : mContext( context )
402 {
403 mContext.appendScope( scope );
404 }
405
407 {
408 delete mContext.popScope();
409 }
410
411 private:
412 QgsExpressionContext &mContext;
413};
414#endif
415
416#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:56
Container of fields for a vector layer.
Definition: qgsfields.h:45
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:51
Base class for all map layer types.
Definition: qgsmaplayer.h:73
The QgsMapSettings class contains configuration for rendering of the map.
A class to represent a 2D point.
Definition: qgspointxy.h:59
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:105
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:93
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.