QGIS API Documentation  3.37.0-Master (a5b4d9743e8)
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"
22 #include "qgsexpressioncontext.h"
23 #include "qgsmeshdataprovider.h"
24 
25 #include <QString>
26 #include <QVariantMap>
27 
29 class QgsProject;
30 class QgsLayout;
31 class QgsSymbol;
32 class QgsLayoutAtlas;
33 class QgsLayoutItem;
34 class QgsMapSettings;
36 class QgsProcessingModelAlgorithm;
39 
47 class CORE_EXPORT QgsExpressionContextUtils
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
356 class 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: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: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.
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.
virtual QgsScopedExpressionFunction * clone() const =0
Returns a clone of 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.