QGIS API Documentation  3.13.0-Master (9729a43df7)
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 <QString>
24 #include <QVariantMap>
25 
27 class QgsProject;
28 class QgsLayout;
29 class QgsSymbol;
30 class QgsLayoutAtlas;
31 class QgsLayoutItem;
33 class QgsProcessingModelAlgorithm;
36 
45 class CORE_EXPORT QgsExpressionContextUtils
46 {
47  public:
48 
54  static QgsExpressionContextScope *globalScope() SIP_FACTORY;
55 
62  static QgsExpressionContextScope *formScope( const QgsFeature &formFeature = QgsFeature( ), const QString &formMode = QString() ) SIP_FACTORY;
63 
70  static QgsExpressionContextScope *parentFormScope( const QgsFeature &formFeature = QgsFeature( ), const QString &formMode = QString() ) SIP_FACTORY;
71 
81  static void setGlobalVariable( const QString &name, const QVariant &value );
82 
91  static void setGlobalVariables( const QVariantMap &variables );
92 
100  static void removeGlobalVariable( const QString &name );
101 
108  static QgsExpressionContextScope *projectScope( const QgsProject *project ) SIP_FACTORY;
109 
120  static void setProjectVariable( QgsProject *project, const QString &name, const QVariant &value );
121 
131  static void setProjectVariables( QgsProject *project, const QVariantMap &variables );
132 
141  static void removeProjectVariable( QgsProject *project, const QString &name );
142 
147  static QgsExpressionContextScope *layerScope( const QgsMapLayer *layer ) SIP_FACTORY;
148 
153  static QList<QgsExpressionContextScope *> globalProjectLayerScopes( const QgsMapLayer *layer ) SIP_FACTORY;
154 
164  static void setLayerVariable( QgsMapLayer *layer, const QString &name, const QVariant &value );
165 
174  static void setLayerVariables( QgsMapLayer *layer, const QVariantMap &variables );
175 
180  static QgsExpressionContextScope *mapSettingsScope( const QgsMapSettings &mapSettings ) SIP_FACTORY;
181 
188  static QgsExpressionContextScope *mapToolCaptureScope( const QList<QgsPointLocator::Match> &matches ) SIP_FACTORY;
189 
196  static QgsExpressionContextScope *updateSymbolScope( const QgsSymbol *symbol, QgsExpressionContextScope *symbolScope = nullptr );
197 
203  static QgsExpressionContextScope *layoutScope( const QgsLayout *layout ) SIP_FACTORY;
204 
215  static void setLayoutVariable( QgsLayout *layout, const QString &name, const QVariant &value );
216 
226  static void setLayoutVariables( QgsLayout *layout, const QVariantMap &variables );
227 
233  static QgsExpressionContextScope *atlasScope( const QgsLayoutAtlas *atlas ) SIP_FACTORY;
234 
242  static QgsExpressionContextScope *layoutItemScope( const QgsLayoutItem *item ) SIP_FACTORY;
243 
252  static void setLayoutItemVariable( QgsLayoutItem *item, const QString &name, const QVariant &value );
253 
261  static void setLayoutItemVariables( QgsLayoutItem *item, const QVariantMap &variables );
262 
269  static QgsExpressionContextScope *multiFrameScope( const QgsLayoutMultiFrame *frame ) SIP_FACTORY;
270 
279  static void setLayoutMultiFrameVariable( QgsLayoutMultiFrame *frame, const QString &name, const QVariant &value );
280 
288  static void setLayoutMultiFrameVariables( QgsLayoutMultiFrame *frame, const QVariantMap &variables );
289 
295  static QgsExpressionContext createFeatureBasedContext( const QgsFeature &feature, const QgsFields &fields );
296 
303  static QgsExpressionContextScope *processingAlgorithmScope( const QgsProcessingAlgorithm *algorithm, const QVariantMap &parameters, QgsProcessingContext &context ) SIP_FACTORY;
304 
311  static QgsExpressionContextScope *processingModelAlgorithmScope( const QgsProcessingModelAlgorithm *model, const QVariantMap &parameters, QgsProcessingContext &context ) SIP_FACTORY;
312 
317  static QgsExpressionContextScope *notificationScope( const QString &message = QString() ) SIP_FACTORY;
318 
322  static void registerContextFunctions();
323 
324  private:
325 
326  class GetLayerVisibility : public QgsScopedExpressionFunction
327  {
328  public:
329  GetLayerVisibility( const QList<QgsMapLayer *> &layers, double scale = 0 );
330  QVariant func( const QVariantList &values, const QgsExpressionContext *, QgsExpression *, const QgsExpressionNodeFunction * ) override;
331  QgsScopedExpressionFunction *clone() const override;
332 
333  private:
334  GetLayerVisibility();
335 
336  QList< QPointer< QgsMapLayer > > mLayers;
337  QMap< QPointer< QgsMapLayer >, QPair< double, double > > mScaleBasedVisibilityDetails;
338  double mScale = 0.0;
339 
340  };
341 
342  friend class QgsLayoutItemMap; // needs access to GetLayerVisibility
343 
344 };
345 
346 #ifndef SIP_RUN
347 
355 {
356  public:
357 
367  : mContext( context )
368  {
369  mContext.appendScope( scope );
370  }
371 
373  {
374  delete mContext.popScope();
375  }
376 
377  private:
378  QgsExpressionContext &mContext;
379 };
380 #endif
381 
382 #endif // QGSEXPRESSIONCONTEXTUTILS_H
Class for parsing and evaluation of expressions (formerly called "search strings").
Base class for all map layer types.
Definition: qgsmaplayer.h:81
Base class for graphical items within a QgsLayout.
Abstract base class for all rendered symbols.
Definition: qgssymbol.h:63
Container of fields for a vector layer.
Definition: qgsfields.h:42
The feature class encapsulates a single feature including its id, geometry and a list of field/values...
Definition: qgsfeature.h:55
Abstract base class for processing algorithms.
Abstract base class for layout items with the ability to distribute the content to several frames (Qg...
The QgsMapSettings class contains configuration for rendering of the map.
Layout graphical items for displaying a map.
Expression contexts are used to encapsulate the parameters around which a QgsExpression should be eva...
Class used to render QgsLayout as an atlas, by iterating over the features from an associated vector ...
Encapsulates a QGIS project, including sets of map layers and their styles, layouts, annotations, canvases, etc.
Definition: qgsproject.h:92
#define SIP_FACTORY
Definition: qgis_sip.h:76
Single scope for storing variables and functions for use within a QgsExpressionContext.
An expression node for expression functions.
Base class for layouts, which can contain items such as maps, labels, scalebars, etc.
Definition: qgslayout.h:49
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
Contains utilities for working with QgsExpressionContext objects, including methods for creating scop...
QgsExpressionContextScopePopper(QgsExpressionContext &context, QgsExpressionContextScope *scope)
Constructor for QgsExpressionContextScopePopper.
Contains information about the context in which a processing algorithm is executed.
RAII class to pop scope from an expression context on destruction.
Expression function for use within a QgsExpressionContextScope.