QGIS API Documentation 3.27.0-Master (95e00c50d2)
qgsrulebasedlabeling.cpp
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1/***************************************************************************
2 qgsrulebasedlabeling.cpp
3 ---------------------
4 begin : September 2015
5 copyright : (C) 2015 by Martin Dobias
6 email : wonder dot sk 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 ***************************************************************************/
16#include "qgssymbollayerutils.h"
18
20 : QgsVectorLayerLabelProvider( layer, QString(), withFeatureLoop, nullptr )
21{
22 mRules.reset( rules.clone() );
23 mRules->rootRule()->createSubProviders( layer, mSubProviders, this );
24}
25
26QgsVectorLayerLabelProvider *QgsRuleBasedLabelProvider::createProvider( QgsVectorLayer *layer, const QString &providerId, bool withFeatureLoop, const QgsPalLayerSettings *settings )
27{
28 return new QgsVectorLayerLabelProvider( layer, providerId, withFeatureLoop, settings );
29}
30
31bool QgsRuleBasedLabelProvider::prepare( QgsRenderContext &context, QSet<QString> &attributeNames )
32{
33 for ( QgsVectorLayerLabelProvider *provider : std::as_const( mSubProviders ) )
34 provider->setEngine( mEngine );
35
36 // populate sub-providers
37 mRules->rootRule()->prepare( context, attributeNames, mSubProviders );
38 return true;
39}
40
41QList<QgsLabelFeature *> QgsRuleBasedLabelProvider::registerFeature( const QgsFeature &feature, QgsRenderContext &context, const QgsGeometry &obstacleGeometry, const QgsSymbol *symbol )
42{
43 // will register the feature to relevant sub-providers
44 return std::get< 1 >( mRules->rootRule()->registerFeature( feature, context, mSubProviders, obstacleGeometry, symbol ) );
45}
46
47QList<QgsAbstractLabelProvider *> QgsRuleBasedLabelProvider::subProviders()
48{
49 QList<QgsAbstractLabelProvider *> lst;
50 for ( QgsVectorLayerLabelProvider *subprovider : std::as_const( mSubProviders ) )
51 lst << subprovider;
52 return lst;
53}
54
55
57
58QgsRuleBasedLabeling::Rule::Rule( QgsPalLayerSettings *settings, double scaleMinDenom, double scaleMaxDenom, const QString &filterExp, const QString &description, bool elseRule )
59 : mSettings( settings )
60 , mMaximumScale( scaleMinDenom )
61 , mMinimumScale( scaleMaxDenom )
62 , mFilterExp( filterExp )
63 , mDescription( description )
64 , mElseRule( elseRule )
65{
66 if ( mElseRule )
67 mFilterExp = QStringLiteral( "ELSE" );
68
69 initFilter();
70}
71
73{
74 qDeleteAll( mChildren );
75 // do NOT delete parent
76}
77
79{
80 if ( mSettings.get() == settings )
81 return;
82
83 mSettings.reset( settings );
84}
85
87{
88 RuleList l;
89 for ( Rule *c : mChildren )
90 {
91 l += c;
92 l += c->descendants();
93 }
94 return l;
95}
96
97void QgsRuleBasedLabeling::Rule::initFilter()
98{
99 if ( mFilterExp.trimmed().compare( QLatin1String( "ELSE" ), Qt::CaseInsensitive ) == 0 )
100 {
101 mElseRule = true;
102 mFilter.reset( );
103 }
104 else if ( mFilterExp.trimmed().isEmpty() )
105 {
106 mElseRule = false;
107 mFilter.reset();
108 }
109 else
110 {
111 mElseRule = false;
112 mFilter = std::make_unique< QgsExpression >( mFilterExp );
113 }
114}
115
116void QgsRuleBasedLabeling::Rule::updateElseRules()
117{
118 mElseRules.clear();
119 for ( Rule *rule : std::as_const( mChildren ) )
120 {
121 if ( rule->isElse() )
122 mElseRules << rule;
123 }
124}
125
127{
128 if ( mSettings && mSettings->format().containsAdvancedEffects() )
129 return true;
130
131 for ( Rule *rule : std::as_const( mChildren ) )
132 {
133 if ( rule->requiresAdvancedEffects() )
134 return true;
135 }
136
137 return false;
138}
139
141{
142 // NOTE: if visitEnter returns false it means "don't visit the rule", not "abort all further visitations"
144 return true;
145
146 if ( mSettings )
147 {
148 QgsStyleLabelSettingsEntity entity( *mSettings );
149 if ( !visitor->visit( QgsStyleEntityVisitorInterface::StyleLeaf( &entity ) ) )
150 return false;
151 }
152
153 if ( !mChildren.empty() )
154 {
155 for ( const Rule *rule : mChildren )
156 {
157 if ( !rule->accept( visitor ) )
158 return false;
159 }
160 }
161
162 if ( mParent && !visitor->visitExit( QgsStyleEntityVisitorInterface::Node( QgsStyleEntityVisitorInterface::NodeType::SymbolRule, mRuleKey, mDescription ) ) )
163 return false;
164
165 return true;
166}
167
168void QgsRuleBasedLabeling::Rule::subProviderIds( QStringList &list ) const
169{
170 for ( const Rule *rule : std::as_const( mChildren ) )
171 {
172 if ( rule->settings() )
173 list << rule->ruleKey();
174
175 rule->subProviderIds( list );
176 }
177}
178
179
181{
182 mChildren.append( rule );
183 rule->mParent = this;
184 updateElseRules();
185}
186
188{
189 mChildren.insert( i, rule );
190 rule->mParent = this;
191 updateElseRules();
192}
193
195{
196 delete mChildren.at( i );
197 mChildren.removeAt( i );
198 updateElseRules();
199}
200
202{
203 // we could use a hash / map for search if this will be slow...
204
205 if ( key == mRuleKey )
206 return this;
207
208 for ( Rule *rule : mChildren )
209 {
210 const Rule *r = rule->findRuleByKey( key );
211 if ( r )
212 return r;
213 }
214 return nullptr;
215}
216
218{
219 if ( key == mRuleKey )
220 return this;
221
222 for ( Rule *rule : std::as_const( mChildren ) )
223 {
224 Rule *r = rule->findRuleByKey( key );
225 if ( r )
226 return r;
227 }
228 return nullptr;
229}
230
232{
233 QgsPalLayerSettings *s = mSettings.get() ? new QgsPalLayerSettings( *mSettings ) : nullptr;
234 Rule *newrule = new Rule( s, mMaximumScale, mMinimumScale, mFilterExp, mDescription );
235 newrule->setActive( mIsActive );
236 // clone children
237 for ( Rule *rule : mChildren )
238 newrule->appendChild( rule->clone() );
239 return newrule;
240}
241
243{
244 QgsPalLayerSettings *settings = nullptr;
245 QDomElement settingsElem = ruleElem.firstChildElement( QStringLiteral( "settings" ) );
246 if ( !settingsElem.isNull() )
247 {
249 settings->readXml( settingsElem, context );
250 }
251
252 QString filterExp = ruleElem.attribute( QStringLiteral( "filter" ) );
253 QString description = ruleElem.attribute( QStringLiteral( "description" ) );
254 int scaleMinDenom = ruleElem.attribute( QStringLiteral( "scalemindenom" ), QStringLiteral( "0" ) ).toInt();
255 int scaleMaxDenom = ruleElem.attribute( QStringLiteral( "scalemaxdenom" ), QStringLiteral( "0" ) ).toInt();
256 QString ruleKey = ruleElem.attribute( QStringLiteral( "key" ) );
257 Rule *rule = new Rule( settings, scaleMinDenom, scaleMaxDenom, filterExp, description );
258
259 if ( !ruleKey.isEmpty() )
260 rule->mRuleKey = ruleKey;
261
262 rule->setActive( ruleElem.attribute( QStringLiteral( "active" ), QStringLiteral( "1" ) ).toInt() );
263
264 QDomElement childRuleElem = ruleElem.firstChildElement( QStringLiteral( "rule" ) );
265 while ( !childRuleElem.isNull() )
266 {
267 Rule *childRule = create( childRuleElem, context );
268 if ( childRule )
269 {
270 rule->appendChild( childRule );
271 }
272 else
273 {
274 //QgsDebugMsg( QStringLiteral( "failed to init a child rule!" ) );
275 }
276 childRuleElem = childRuleElem.nextSiblingElement( QStringLiteral( "rule" ) );
277 }
278
279 return rule;
280}
281
282QDomElement QgsRuleBasedLabeling::Rule::save( QDomDocument &doc, const QgsReadWriteContext &context ) const
283{
284 QDomElement ruleElem = doc.createElement( QStringLiteral( "rule" ) );
285
286 if ( mSettings )
287 {
288 ruleElem.appendChild( mSettings->writeXml( doc, context ) );
289 }
290 if ( !mFilterExp.isEmpty() )
291 ruleElem.setAttribute( QStringLiteral( "filter" ), mFilterExp );
292 if ( !qgsDoubleNear( mMaximumScale, 0 ) )
293 ruleElem.setAttribute( QStringLiteral( "scalemindenom" ), mMaximumScale );
294 if ( !qgsDoubleNear( mMinimumScale, 0 ) )
295 ruleElem.setAttribute( QStringLiteral( "scalemaxdenom" ), mMinimumScale );
296 if ( !mDescription.isEmpty() )
297 ruleElem.setAttribute( QStringLiteral( "description" ), mDescription );
298 if ( !mIsActive )
299 ruleElem.setAttribute( QStringLiteral( "active" ), 0 );
300 ruleElem.setAttribute( QStringLiteral( "key" ), mRuleKey );
301
302 for ( RuleList::const_iterator it = mChildren.constBegin(); it != mChildren.constEnd(); ++it )
303 {
304 Rule *rule = *it;
305 ruleElem.appendChild( rule->save( doc, context ) );
306 }
307 return ruleElem;
308}
309
311{
312 if ( mSettings )
313 {
314 // add provider!
315 QgsVectorLayerLabelProvider *p = provider->createProvider( layer, mRuleKey, false, mSettings.get() );
316 delete subProviders.value( this, nullptr );
317 subProviders[this] = p;
318 }
319
320 // call recursively
321 for ( Rule *rule : std::as_const( mChildren ) )
322 {
323 rule->createSubProviders( layer, subProviders, provider );
324 }
325}
326
328{
329 if ( mSettings )
330 {
332 if ( !p->prepare( context, attributeNames ) )
333 {
334 subProviders.remove( this );
335 delete p;
336 }
337 }
338
339 if ( mFilter )
340 {
341 attributeNames.unite( mFilter->referencedColumns() );
342 mFilter->prepare( &context.expressionContext() );
343 }
344
345 // call recursively
346 for ( Rule *rule : std::as_const( mChildren ) )
347 {
348 rule->prepare( context, attributeNames, subProviders );
349 }
350}
351
352std::tuple< QgsRuleBasedLabeling::Rule::RegisterResult, QList< QgsLabelFeature * > > QgsRuleBasedLabeling::Rule::registerFeature( const QgsFeature &feature, QgsRenderContext &context, QgsRuleBasedLabeling::RuleToProviderMap &subProviders, const QgsGeometry &obstacleGeometry, const QgsSymbol *symbol )
353{
354 QList< QgsLabelFeature * > labels;
355 if ( !isFilterOK( feature, context )
356 || !isScaleOK( context.rendererScale() ) )
357 {
358 return { Filtered, labels };
359 }
360
361 bool registered = false;
362
363 // do we have active subprovider for the rule?
364 if ( subProviders.contains( this ) && mIsActive )
365 {
366 labels.append( subProviders[this]->registerFeature( feature, context, obstacleGeometry, symbol ) );
367 registered = true;
368 }
369
370 bool matchedAChild = false;
371
372 // call recursively
373 for ( Rule *rule : std::as_const( mChildren ) )
374 {
375 // Don't process else rules yet
376 if ( !rule->isElse() )
377 {
378 RegisterResult res;
379 QList< QgsLabelFeature * > added;
380 std::tie( res, added ) = rule->registerFeature( feature, context, subProviders, obstacleGeometry );
381 labels.append( added );
382 // consider inactive items as "matched" so the else rule will ignore them
383 matchedAChild |= ( res == Registered || res == Inactive );
384 registered |= matchedAChild;
385 }
386 }
387
388 // If none of the rules passed then we jump into the else rules and process them.
389 if ( !matchedAChild )
390 {
391 for ( Rule *rule : std::as_const( mElseRules ) )
392 {
393 RegisterResult res;
394 QList< QgsLabelFeature * > added;
395 std::tie( res, added ) = rule->registerFeature( feature, context, subProviders, obstacleGeometry, symbol ) ;
396 matchedAChild |= ( res == Registered || res == Inactive );
397 registered |= res != Filtered;
398 labels.append( added );
399 }
400 }
401
402 if ( !mIsActive || ( matchedAChild && !registered ) )
403 return { Inactive, labels };
404 else if ( registered )
405 return { Registered, labels };
406 else
407 return { Filtered, labels };
408}
409
410bool QgsRuleBasedLabeling::Rule::isFilterOK( const QgsFeature &f, QgsRenderContext &context ) const
411{
412 if ( ! mFilter || mElseRule )
413 return true;
414
415 context.expressionContext().setFeature( f );
416 QVariant res = mFilter->evaluate( &context.expressionContext() );
417 return res.toBool();
418}
419
420bool QgsRuleBasedLabeling::Rule::isScaleOK( double scale ) const
421{
422 if ( qgsDoubleNear( scale, 0.0 ) ) // so that we can count features in classes without scale context
423 return true;
424 if ( qgsDoubleNear( mMaximumScale, 0.0 ) && qgsDoubleNear( mMinimumScale, 0.0 ) )
425 return true;
426 if ( !qgsDoubleNear( mMaximumScale, 0.0 ) && mMaximumScale > scale )
427 return false;
428 if ( !qgsDoubleNear( mMinimumScale, 0.0 ) && mMinimumScale < scale )
429 return false;
430 return true;
431}
432
434
436 : mRootRule( root )
437{
438}
439
441{
442 Rule *rootRule = mRootRule->clone();
443
444 // normally with clone() the individual rules get new keys (UUID), but here we want to keep
445 // the tree of rules intact, so that other components that may use the rule keys work nicely (e.g. map themes)
446 rootRule->setRuleKey( mRootRule->ruleKey() );
447 RuleList origDescendants = mRootRule->descendants();
448 RuleList clonedDescendants = rootRule->descendants();
449 Q_ASSERT( origDescendants.count() == clonedDescendants.count() );
450 for ( int i = 0; i < origDescendants.count(); ++i )
451 clonedDescendants[i]->setRuleKey( origDescendants[i]->ruleKey() );
452
453 return new QgsRuleBasedLabeling( rootRule );
454}
455
457{
458}
459
461{
462 return mRootRule.get();
463}
464
466{
467 return mRootRule.get();
468}
469
470
471QgsRuleBasedLabeling *QgsRuleBasedLabeling::create( const QDomElement &element, const QgsReadWriteContext &context )
472{
473 QDomElement rulesElem = element.firstChildElement( QStringLiteral( "rules" ) );
474
475 Rule *root = Rule::create( rulesElem, context );
476 if ( !root )
477 return nullptr;
478
480 return rl;
481}
482
484{
485 return QStringLiteral( "rule-based" );
486}
487
488QDomElement QgsRuleBasedLabeling::save( QDomDocument &doc, const QgsReadWriteContext &context ) const
489{
490 QDomElement elem = doc.createElement( QStringLiteral( "labeling" ) );
491 elem.setAttribute( QStringLiteral( "type" ), QStringLiteral( "rule-based" ) );
492
493 QDomElement rulesElem = mRootRule->save( doc, context );
494 rulesElem.setTagName( QStringLiteral( "rules" ) ); // instead of just "rule"
495 elem.appendChild( rulesElem );
496
497 return elem;
498}
499
501{
502 return new QgsRuleBasedLabelProvider( *this, layer, false );
503}
504
506{
507 QStringList lst;
508 mRootRule->subProviderIds( lst );
509 return lst;
510}
511
512QgsPalLayerSettings QgsRuleBasedLabeling::settings( const QString &providerId ) const
513{
514 const Rule *rule = mRootRule->findRuleByKey( providerId );
515 if ( rule && rule->settings() )
516 return *rule->settings();
517
518 return QgsPalLayerSettings();
519}
520
522{
523 return mRootRule->accept( visitor );
524}
525
527{
528 return mRootRule->requiresAdvancedEffects();
529}
530
531void QgsRuleBasedLabeling::setSettings( QgsPalLayerSettings *settings, const QString &providerId )
532{
533 if ( settings )
534 {
535 Rule *rule = mRootRule->findRuleByKey( providerId );
536 if ( rule && rule->settings() )
537 rule->setSettings( settings );
538 }
539}
540
541void QgsRuleBasedLabeling::toSld( QDomNode &parent, const QVariantMap &props ) const
542{
543 if ( !mRootRule )
544 {
545 return;
546 }
547
548 const QgsRuleBasedLabeling::RuleList rules = mRootRule->children();
549 for ( Rule *rule : rules )
550 {
551 QgsPalLayerSettings *settings = rule->settings();
552
553 if ( settings && settings->drawLabels )
554 {
555 QDomDocument doc = parent.ownerDocument();
556
557 QDomElement ruleElement = doc.createElement( QStringLiteral( "se:Rule" ) );
558 parent.appendChild( ruleElement );
559
560 if ( !rule->filterExpression().isEmpty() )
561 {
562 QgsSymbolLayerUtils::createFunctionElement( doc, ruleElement, rule->filterExpression() );
563 }
564
565 // scale dependencies, the actual behavior is that the PAL settings min/max and
566 // the rule min/max get intersected
567 QVariantMap localProps = QVariantMap( props );
568 QgsSymbolLayerUtils::mergeScaleDependencies( rule->maximumScale(), rule->minimumScale(), localProps );
570 {
572 }
573 QgsSymbolLayerUtils::applyScaleDependency( doc, ruleElement, localProps );
574
576 }
577
578 }
579
580}
const QgsLabelingEngine * mEngine
Associated labeling engine.
QgsMapLayer * layer() const
Returns the associated layer, or nullptr if no layer is associated with the provider.
QString providerId() const
Returns provider ID - useful in case there is more than one label provider within a layer (e....
virtual void writeTextSymbolizer(QDomNode &parent, QgsPalLayerSettings &settings, const QVariantMap &props) const
Writes a TextSymbolizer element contents based on the provided labeling settings.
void setFeature(const QgsFeature &feature)
Convenience function for setting a feature for the context.
The feature class encapsulates a single feature including its unique ID, geometry and a list of field...
Definition: qgsfeature.h:56
A geometry is the spatial representation of a feature.
Definition: qgsgeometry.h:164
Contains settings for how a map layer will be labeled.
bool drawLabels
Whether to draw labels for this layer.
double minimumScale
The minimum map scale (i.e.
void readXml(const QDomElement &elem, const QgsReadWriteContext &context)
Read settings from a DOM element.
bool scaleVisibility
Set to true to limit label visibility to a range of scales.
double maximumScale
The maximum map scale (i.e.
The class is used as a container of context for various read/write operations on other objects.
Contains information about the context of a rendering operation.
double rendererScale() const
Returns the renderer map scale.
QgsExpressionContext & expressionContext()
Gets the expression context.
Label provider for rule based labeling.
bool prepare(QgsRenderContext &context, QSet< QString > &attributeNames) override
Prepare for registration of features.
std::unique_ptr< QgsRuleBasedLabeling > mRules
owned copy
QList< QgsLabelFeature * > registerFeature(const QgsFeature &feature, QgsRenderContext &context, const QgsGeometry &obstacleGeometry=QgsGeometry(), const QgsSymbol *symbol=nullptr) override
Register a feature for labeling as one or more QgsLabelFeature objects stored into mLabels.
QgsRuleBasedLabelProvider(const QgsRuleBasedLabeling &rules, QgsVectorLayer *layer, bool withFeatureLoop=true)
QgsRuleBasedLabeling::RuleToProviderMap mSubProviders
label providers are owned by labeling engine
virtual QgsVectorLayerLabelProvider * createProvider(QgsVectorLayer *layer, const QString &providerId, bool withFeatureLoop, const QgsPalLayerSettings *settings)
create a label provider
QList< QgsAbstractLabelProvider * > subProviders() override
Returns subproviders.
A child rule for QgsRuleBasedLabeling.
void setRuleKey(const QString &key)
Override the assigned rule key (should be used just internally by rule-based labeling)
QgsRuleBasedLabeling::Rule * clone() const
clone this rule, return new instance
void prepare(QgsRenderContext &context, QSet< QString > &attributeNames, RuleToProviderMap &subProviders)
call prepare() on sub-providers and populate attributeNames
std::tuple< RegisterResult, QList< QgsLabelFeature * > > registerFeature(const QgsFeature &feature, QgsRenderContext &context, RuleToProviderMap &subProviders, const QgsGeometry &obstacleGeometry=QgsGeometry(), const QgsSymbol *symbol=nullptr)
Register individual features.
QgsPalLayerSettings * settings() const
Returns the labeling settings.
RegisterResult
The result of registering a rule.
bool accept(QgsStyleEntityVisitorInterface *visitor) const
Accepts the specified symbology visitor, causing it to visit all child rules associated with the rule...
static QgsRuleBasedLabeling::Rule * create(const QDomElement &ruleElem, const QgsReadWriteContext &context)
Create a rule from an XML definition.
void subProviderIds(QStringList &list) const
append rule keys of descendants that contain valid settings (i.e.
bool requiresAdvancedEffects() const
Returns true if this rule or any of its children requires advanced composition effects to render.
void removeChildAt(int i)
delete child rule
void setActive(bool state)
Sets if this rule is active.
QDomElement save(QDomDocument &doc, const QgsReadWriteContext &context) const
store labeling info to XML element
void setSettings(QgsPalLayerSettings *settings)
Sets new settings (or nullptr). Deletes old settings if any.
QgsRuleBasedLabeling::RuleList descendants() const
Returns all children, grand-children, grand-grand-children, grand-gra... you get it.
void createSubProviders(QgsVectorLayer *layer, RuleToProviderMap &subProviders, QgsRuleBasedLabelProvider *provider)
add providers
Rule(QgsPalLayerSettings *settings, double maximumScale=0, double minimumScale=0, const QString &filterExp=QString(), const QString &description=QString(), bool elseRule=false)
takes ownership of settings, settings may be nullptr
void insertChild(int i, QgsRuleBasedLabeling::Rule *rule)
add child rule, take ownership, sets this as parent
const QgsRuleBasedLabeling::Rule * findRuleByKey(const QString &key) const
Try to find a rule given its unique key.
void appendChild(QgsRuleBasedLabeling::Rule *rule)
add child rule, take ownership, sets this as parent
Rule based labeling for a vector layer.
QList< QgsRuleBasedLabeling::Rule * > RuleList
std::unique_ptr< Rule > mRootRule
void toSld(QDomNode &parent, const QVariantMap &props) const override
Writes the SE 1.1 TextSymbolizer element based on the current layer labeling settings.
QStringList subProviders() const override
Gets list of sub-providers within the layer's labeling.
QgsRuleBasedLabeling(QgsRuleBasedLabeling::Rule *root)
Constructs the labeling from given tree of rules (takes ownership)
QgsVectorLayerLabelProvider * provider(QgsVectorLayer *layer) const override
static QgsRuleBasedLabeling * create(const QDomElement &element, const QgsReadWriteContext &context)
Create the instance from a DOM element with saved configuration.
void setSettings(QgsPalLayerSettings *settings, const QString &providerId=QString()) override
Set pal settings for a specific provider (takes ownership).
QgsPalLayerSettings settings(const QString &providerId=QString()) const override
Gets associated label settings.
QMap< QgsRuleBasedLabeling::Rule *, QgsVectorLayerLabelProvider * > RuleToProviderMap
QString type() const override
Unique type string of the labeling configuration implementation.
QgsRuleBasedLabeling * clone() const override
Returns a new copy of the object.
QgsRuleBasedLabeling::Rule * rootRule()
bool accept(QgsStyleEntityVisitorInterface *visitor) const override
Accepts the specified symbology visitor, causing it to visit all symbols associated with the labeling...
QDomElement save(QDomDocument &doc, const QgsReadWriteContext &context) const override
Returns labeling configuration as XML element.
bool requiresAdvancedEffects() const override
Returns true if drawing labels requires advanced effects like composition modes, which could prevent ...
An interface for classes which can visit style entity (e.g.
@ SymbolRule
Rule based symbology or label child rule.
virtual bool visitExit(const QgsStyleEntityVisitorInterface::Node &node)
Called when the visitor stops visiting a node.
virtual bool visitEnter(const QgsStyleEntityVisitorInterface::Node &node)
Called when the visitor starts visiting a node.
virtual bool visit(const QgsStyleEntityVisitorInterface::StyleLeaf &entity)
Called when the visitor will visit a style entity.
A label settings entity for QgsStyle databases.
Definition: qgsstyle.h:1435
static void applyScaleDependency(QDomDocument &doc, QDomElement &ruleElem, QVariantMap &props)
Checks if the properties contain scaleMinDenom and scaleMaxDenom, if available, they are added into t...
static bool createFunctionElement(QDomDocument &doc, QDomElement &element, const QString &function)
static void mergeScaleDependencies(double mScaleMinDenom, double mScaleMaxDenom, QVariantMap &props)
Merges the local scale limits, if any, with the ones already in the map, if any.
Abstract base class for all rendered symbols.
Definition: qgssymbol.h:93
The QgsVectorLayerLabelProvider class implements a label provider for vector layers.
virtual bool prepare(QgsRenderContext &context, QSet< QString > &attributeNames)
Prepare for registration of features.
QgsVectorLayerLabelProvider(QgsVectorLayer *layer, const QString &providerId, bool withFeatureLoop, const QgsPalLayerSettings *settings, const QString &layerName=QString())
Convenience constructor to initialize the provider from given vector layer.
const QgsPalLayerSettings & settings() const
Returns the layer's settings.
Represents a vector layer which manages a vector based data sets.
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 c
bool qgsDoubleNear(double a, double b, double epsilon=4 *std::numeric_limits< double >::epsilon())
Compare two doubles (but allow some difference)
Definition: qgis.h:2527
Contains information relating to a node (i.e.
Contains information relating to the style entity currently being visited.