QGIS API Documentation 3.99.0-Master (d270888f95f)
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QgsRuleBasedRenderer::Rule Class Reference

Represents an individual rule for a rule-based renderer. More...

#include <qgsrulebasedrenderer.h>

Public Types

enum  RenderResult { Filtered = 0 , Inactive , Rendered }
 The result of rendering a rule. More...

Public Member Functions

 Rule (const Rule &rh)=delete
 Rule (QgsSymbol *symbol, int maximumScale=0, int minimumScale=0, const QString &filterExp=QString(), const QString &label=QString(), const QString &description=QString(), bool elseRule=false)
 Constructor takes ownership of the symbol.
 ~Rule ()
bool accept (QgsStyleEntityVisitorInterface *visitor) const
 Accepts the specified symbology visitor, causing it to visit all child rules associated with the rule.
bool active () const
 Returns if this rule is active.
void appendChild (QgsRuleBasedRenderer::Rule *rule)
 add child rule, take ownership, sets this as parent
const QgsRuleBasedRenderer::RuleListchildren () const
 Returns all children rules of this rule.
QgsRuleBasedRenderer::Ruleclone () const
 clone this rule, return new instance
QSet< int > collectZLevels ()
 Gets all used z-levels from this rule and children.
bool dependsOnScale () const
QgsRuleBasedRenderer::RuleList descendants () const
 Returns all children, grand-children, grand-grand-children, grand-gra... you get it.
QString description () const
 A human readable description for this rule.
QString dump (int indent=0) const
 Dump for debug purpose.
QgsExpressionfilter () const
 A filter that will check if this rule applies.
QString filterExpression () const
 A filter that will check if this rule applies.
QgsRuleBasedRenderer::RulefindRuleByKey (const QString &key)
 Try to find a rule given its unique key.
bool hasActiveChildren () const
 Returns true if the rule has any active children.
void insertChild (int i, QgsRuleBasedRenderer::Rule *rule)
 add child rule, take ownership, sets this as parent
bool isElse () const
 Check if this rule is an ELSE rule.
bool isFilterOK (const QgsFeature &f, QgsRenderContext *context=nullptr) const
 Check if a given feature shall be rendered by this rule.
bool isScaleOK (double scale) const
 Check if this rule applies for a given scale.
QString label () const
QSet< QString > legendKeysForFeature (const QgsFeature &feature, QgsRenderContext *context=nullptr)
 Returns which legend keys match the feature.
QgsLegendSymbolList legendSymbolItems (int currentLevel=-1) const
double maximumScale () const
 Returns the maximum map scale (i.e.
double minimumScale () const
 Returns the minimum map scale (i.e.
bool needsGeometry () const
 Returns true if this rule or one of its children needs the geometry to be applied.
Ruleoperator= (const Rule &rh)=delete
QgsRuleBasedRenderer::Ruleparent ()
 The parent rule.
void removeChild (QgsRuleBasedRenderer::Rule *rule)
 delete child rule
void removeChildAt (int i)
 delete child rule
QgsRuleBasedRenderer::Rule::RenderResult renderFeature (QgsRuleBasedRenderer::FeatureToRender &featToRender, QgsRenderContext &context, QgsRuleBasedRenderer::RenderQueue &renderQueue)
 Render a given feature, will recursively call subclasses and only render if the constraints apply.
QString ruleKey () const
 Unique rule identifier (for identification of rule within renderer).
QgsRuleBasedRenderer::RuleList rulesForFeature (const QgsFeature &feature, QgsRenderContext *context=nullptr, bool onlyActive=true)
 Returns the list of rules used to render the feature in a specific context.
QDomElement save (QDomDocument &doc, QgsSymbolMap &symbolMap) const
void setActive (bool state)
 Sets if this rule is active.
void setDescription (const QString &description)
 Set a human readable description for this rule.
void setFilterExpression (const QString &filterExp)
 Set the expression used to check if a given feature shall be rendered with this rule.
void setIsElse (bool iselse)
 Sets if this rule is an ELSE rule.
void setLabel (const QString &label)
void setMaximumScale (double scale)
 Sets the maximum map scale (i.e.
void setMinimumScale (double scale)
 Sets the minimum map scale (i.e.
void setNormZLevels (const QMap< int, int > &zLevelsToNormLevels)
 assign normalized z-levels [0..N-1] for this rule's symbol for quick access during rendering
void setRuleKey (const QString &key)
 Override the assigned rule key (should be used just internally by rule-based renderer).
void setSymbol (QgsSymbol *sym)
 Sets a new symbol (or nullptr). Deletes old symbol.
bool startRender (QgsRenderContext &context, const QgsFields &fields, QString &filter)
 prepare the rule for rendering and its children (build active children array)
void stopRender (QgsRenderContext &context)
 Stop a rendering process.
QgsSymbolsymbol ()
QgsSymbolList symbols (const QgsRenderContext &context=QgsRenderContext()) const
 Returns a list of the symbols used by this rule and all children of this rule.
QgsSymbolList symbolsForFeature (const QgsFeature &feature, QgsRenderContext *context=nullptr)
 tell which symbols will be used to render the feature
QgsRuleBasedRenderer::RuletakeChild (QgsRuleBasedRenderer::Rule *rule)
 take child rule out, set parent as nullptr
QgsRuleBasedRenderer::RuletakeChildAt (int i)
 take child rule out, set parent as nullptr
bool toSld (QDomDocument &doc, QDomElement &element, QgsSldExportContext &context) const
 Saves the rule to SLD.
Q_DECL_DEPRECATED void toSld (QDomDocument &doc, QDomElement &element, QVariantMap props) const
 Saves the symbol layer as SLD.
QSet< QString > usedAttributes (const QgsRenderContext &context) const
 Returns the attributes used to evaluate the expression of this rule.
bool willRenderFeature (const QgsFeature &feature, QgsRenderContext *context=nullptr)
 only tell whether a feature will be rendered without actually rendering it

Static Public Member Functions

static QgsRuleBasedRenderer::Rulecreate (QDomElement &ruleElem, QgsSymbolMap &symbolMap, bool reuseId=true, const QgsReadWriteContext &context=QgsReadWriteContext())
 Create a rule from an XML definition.
static QgsRuleBasedRenderer::RulecreateFromSld (QDomElement &element, Qgis::GeometryType geomType)
 Create a rule from the SLD provided in element and for the specified geometry type.

Protected Member Functions

void initFilter ()

Detailed Description

Represents an individual rule for a rule-based renderer.

A rule consists of a symbol, filter expression and range of scales. If filter is empty, it matches all features. If scale range has both values zero, it matches all scales. If one of the min/max scale denominators is zero, there is no lower/upper bound for scales. A rule matches if both filter and scale range match.

Definition at line 151 of file qgsrulebasedrenderer.h.

Member Enumeration Documentation

◆ RenderResult

The result of rendering a rule.

Enumerator
Filtered 

The rule does not apply.

Inactive 

The rule is inactive.

Rendered 

Something was rendered.

Definition at line 155 of file qgsrulebasedrenderer.h.

Constructor & Destructor Documentation

◆ Rule() [1/2]

QgsRuleBasedRenderer::Rule::Rule ( QgsSymbol * symbol,
int maximumScale = 0,
int minimumScale = 0,
const QString & filterExp = QString(),
const QString & label = QString(),
const QString & description = QString(),
bool elseRule = false )

Constructor takes ownership of the symbol.

Definition at line 45 of file qgsrulebasedrenderer.cpp.

◆ ~Rule()

QgsRuleBasedRenderer::Rule::~Rule ( )

Definition at line 61 of file qgsrulebasedrenderer.cpp.

◆ Rule() [2/2]

QgsRuleBasedRenderer::Rule::Rule ( const Rule & rh)
delete

Member Function Documentation

◆ accept()

bool QgsRuleBasedRenderer::Rule::accept ( QgsStyleEntityVisitorInterface * visitor) const

Accepts the specified symbology visitor, causing it to visit all child rules associated with the rule.

Returns true if the visitor should continue visiting other objects, or false if visiting should be canceled.

Since
QGIS 3.10

Definition at line 164 of file qgsrulebasedrenderer.cpp.

◆ active()

bool QgsRuleBasedRenderer::Rule::active ( ) const
inline

Returns if this rule is active.

Returns
true if the rule is active

Definition at line 259 of file qgsrulebasedrenderer.h.

◆ appendChild()

void QgsRuleBasedRenderer::Rule::appendChild ( QgsRuleBasedRenderer::Rule * rule)

add child rule, take ownership, sets this as parent

Definition at line 86 of file qgsrulebasedrenderer.cpp.

◆ children()

const QgsRuleBasedRenderer::RuleList & QgsRuleBasedRenderer::Rule::children ( ) const
inline

Returns all children rules of this rule.

Returns
A list of rules

Definition at line 414 of file qgsrulebasedrenderer.h.

◆ clone()

QgsRuleBasedRenderer::Rule * QgsRuleBasedRenderer::Rule::clone ( ) const

clone this rule, return new instance

Definition at line 315 of file qgsrulebasedrenderer.cpp.

◆ collectZLevels()

QSet< int > QgsRuleBasedRenderer::Rule::collectZLevels ( )

Gets all used z-levels from this rule and children.

Definition at line 555 of file qgsrulebasedrenderer.cpp.

◆ create()

QgsRuleBasedRenderer::Rule * QgsRuleBasedRenderer::Rule::create ( QDomElement & ruleElem,
QgsSymbolMap & symbolMap,
bool reuseId = true,
const QgsReadWriteContext & context = QgsReadWriteContext() )
static

Create a rule from an XML definition.

Parameters
ruleElemThe XML rule element
symbolMapSymbol map
reuseIdset to true to create an exact copy of the original symbol or false to create a new rule with the same parameters as the original but a new unique ruleKey(). (Since QGIS 3.30)
contextThe rendering context (Since QGIS 4.0)
Returns
A new rule

Definition at line 791 of file qgsrulebasedrenderer.cpp.

◆ createFromSld()

QgsRuleBasedRenderer::Rule * QgsRuleBasedRenderer::Rule::createFromSld ( QDomElement & element,
Qgis::GeometryType geomType )
static

Create a rule from the SLD provided in element and for the specified geometry type.

Definition at line 855 of file qgsrulebasedrenderer.cpp.

◆ dependsOnScale()

bool QgsRuleBasedRenderer::Rule::dependsOnScale ( ) const
inline

Definition at line 215 of file qgsrulebasedrenderer.h.

◆ descendants()

QgsRuleBasedRenderer::RuleList QgsRuleBasedRenderer::Rule::descendants ( ) const

Returns all children, grand-children, grand-grand-children, grand-gra... you get it.

Returns
A list of descendant rules

Definition at line 844 of file qgsrulebasedrenderer.cpp.

◆ description()

QString QgsRuleBasedRenderer::Rule::description ( ) const
inline

A human readable description for this rule.

Returns
Description

Definition at line 252 of file qgsrulebasedrenderer.h.

◆ dump()

QString QgsRuleBasedRenderer::Rule::dump ( int indent = 0) const

Dump for debug purpose.

Parameters
indentHow many characters to indent. Will increase by two with every of the recursive calls
Returns
A string representing this rule

Definition at line 193 of file qgsrulebasedrenderer.cpp.

◆ filter()

QgsExpression * QgsRuleBasedRenderer::Rule::filter ( ) const
inline

A filter that will check if this rule applies.

Returns
An expression

Definition at line 239 of file qgsrulebasedrenderer.h.

◆ filterExpression()

QString QgsRuleBasedRenderer::Rule::filterExpression ( ) const
inline

A filter that will check if this rule applies.

Returns
An expression

Definition at line 245 of file qgsrulebasedrenderer.h.

◆ findRuleByKey()

QgsRuleBasedRenderer::Rule * QgsRuleBasedRenderer::Rule::findRuleByKey ( const QString & key)

Try to find a rule given its unique key.

Definition at line 129 of file qgsrulebasedrenderer.cpp.

◆ hasActiveChildren()

bool QgsRuleBasedRenderer::Rule::hasActiveChildren ( ) const

Returns true if the rule has any active children.

Note
Must be called after startRender()
Since
QGIS 3.30

Definition at line 550 of file qgsrulebasedrenderer.cpp.

◆ initFilter()

void QgsRuleBasedRenderer::Rule::initFilter ( )
protected

Definition at line 67 of file qgsrulebasedrenderer.cpp.

◆ insertChild()

void QgsRuleBasedRenderer::Rule::insertChild ( int i,
QgsRuleBasedRenderer::Rule * rule )

add child rule, take ownership, sets this as parent

Definition at line 93 of file qgsrulebasedrenderer.cpp.

◆ isElse()

bool QgsRuleBasedRenderer::Rule::isElse ( ) const
inline

Check if this rule is an ELSE rule.

Returns
true if this rule is an else rule

Definition at line 465 of file qgsrulebasedrenderer.h.

◆ isFilterOK()

bool QgsRuleBasedRenderer::Rule::isFilterOK ( const QgsFeature & f,
QgsRenderContext * context = nullptr ) const

Check if a given feature shall be rendered by this rule.

Parameters
fThe feature to test
contextThe context in which the rendering happens
Returns
true if the feature shall be rendered

Definition at line 287 of file qgsrulebasedrenderer.cpp.

◆ isScaleOK()

bool QgsRuleBasedRenderer::Rule::isScaleOK ( double scale) const

Check if this rule applies for a given scale.

The scale value indicates the scale denominator, e.g. 1000.0 for a 1:1000 map. If set to 0, it will always return true.

Returns
If the rule will be evaluated at this scale

Definition at line 297 of file qgsrulebasedrenderer.cpp.

◆ label()

QString QgsRuleBasedRenderer::Rule::label ( ) const
inline

Definition at line 214 of file qgsrulebasedrenderer.h.

◆ legendKeysForFeature()

QSet< QString > QgsRuleBasedRenderer::Rule::legendKeysForFeature ( const QgsFeature & feature,
QgsRenderContext * context = nullptr )

Returns which legend keys match the feature.

Definition at line 706 of file qgsrulebasedrenderer.cpp.

◆ legendSymbolItems()

QgsLegendSymbolList QgsRuleBasedRenderer::Rule::legendSymbolItems ( int currentLevel = -1) const

Definition at line 270 of file qgsrulebasedrenderer.cpp.

◆ maximumScale()

double QgsRuleBasedRenderer::Rule::maximumScale ( ) const
inline

Returns the maximum map scale (i.e.

most "zoomed in" scale) at which the rule will be active. The scale value indicates the scale denominator, e.g. 1000.0 for a 1:1000 map. A scale of 0 indicates no maximum scale visibility.

See also
minimumScale()
setMaximumScale()

Definition at line 224 of file qgsrulebasedrenderer.h.

◆ minimumScale()

double QgsRuleBasedRenderer::Rule::minimumScale ( ) const
inline

Returns the minimum map scale (i.e.

most "zoomed out" scale) at which the rule will be active. The scale value indicates the scale denominator, e.g. 1000.0 for a 1:1000 map. A scale of 0 indicates no minimum scale visibility.

See also
maximumScale()
setMinimumScale()

Definition at line 233 of file qgsrulebasedrenderer.h.

◆ needsGeometry()

bool QgsRuleBasedRenderer::Rule::needsGeometry ( ) const

Returns true if this rule or one of its children needs the geometry to be applied.

Definition at line 230 of file qgsrulebasedrenderer.cpp.

◆ operator=()

Rule & QgsRuleBasedRenderer::Rule::operator= ( const Rule & rh)
delete

◆ parent()

QgsRuleBasedRenderer::Rule * QgsRuleBasedRenderer::Rule::parent ( )
inline

The parent rule.

Returns
Parent rule

Definition at line 428 of file qgsrulebasedrenderer.h.

◆ removeChild()

void QgsRuleBasedRenderer::Rule::removeChild ( QgsRuleBasedRenderer::Rule * rule)

delete child rule

Definition at line 100 of file qgsrulebasedrenderer.cpp.

◆ removeChildAt()

void QgsRuleBasedRenderer::Rule::removeChildAt ( int i)

delete child rule

Definition at line 107 of file qgsrulebasedrenderer.cpp.

◆ renderFeature()

QgsRuleBasedRenderer::Rule::RenderResult QgsRuleBasedRenderer::Rule::renderFeature ( QgsRuleBasedRenderer::FeatureToRender & featToRender,
QgsRenderContext & context,
QgsRuleBasedRenderer::RenderQueue & renderQueue )

Render a given feature, will recursively call subclasses and only render if the constraints apply.

Parameters
featToRenderThe feature to render
contextThe rendering context
renderQueueThe rendering queue to which the feature should be added
Returns
The result of the rendering. In explicit if the feature is added to the queue or the reason for not rendering the feature.

Definition at line 599 of file qgsrulebasedrenderer.cpp.

◆ ruleKey()

QString QgsRuleBasedRenderer::Rule::ruleKey ( ) const
inline

Unique rule identifier (for identification of rule within renderer).

Definition at line 264 of file qgsrulebasedrenderer.h.

◆ rulesForFeature()

QgsRuleBasedRenderer::RuleList QgsRuleBasedRenderer::Rule::rulesForFeature ( const QgsFeature & feature,
QgsRenderContext * context = nullptr,
bool onlyActive = true )

Returns the list of rules used to render the feature in a specific context.

Parameters
featureThe feature for which rules have to be find
contextThe rendering context
onlyActivetrue to search for active rules only, false otherwise

Definition at line 756 of file qgsrulebasedrenderer.cpp.

◆ save()

QDomElement QgsRuleBasedRenderer::Rule::save ( QDomDocument & doc,
QgsSymbolMap & symbolMap ) const

Definition at line 327 of file qgsrulebasedrenderer.cpp.

◆ setActive()

void QgsRuleBasedRenderer::Rule::setActive ( bool state)
inline

Sets if this rule is active.

Parameters
stateDetermines if the rule should be activated or deactivated

Definition at line 311 of file qgsrulebasedrenderer.h.

◆ setDescription()

void QgsRuleBasedRenderer::Rule::setDescription ( const QString & description)
inline

Set a human readable description for this rule.

Parameters
descriptionDescription

Definition at line 305 of file qgsrulebasedrenderer.h.

◆ setFilterExpression()

void QgsRuleBasedRenderer::Rule::setFilterExpression ( const QString & filterExp)

Set the expression used to check if a given feature shall be rendered with this rule.

Parameters
filterExpAn expression

Definition at line 264 of file qgsrulebasedrenderer.cpp.

◆ setIsElse()

void QgsRuleBasedRenderer::Rule::setIsElse ( bool iselse)

Sets if this rule is an ELSE rule.

Parameters
iselseIf true, this rule is an ELSE rule

Definition at line 157 of file qgsrulebasedrenderer.cpp.

◆ setLabel()

void QgsRuleBasedRenderer::Rule::setLabel ( const QString & label)
inline

Definition at line 273 of file qgsrulebasedrenderer.h.

◆ setMaximumScale()

void QgsRuleBasedRenderer::Rule::setMaximumScale ( double scale)
inline

Sets the maximum map scale (i.e.

most "zoomed in" scale) at which the rule will be active. The scale value indicates the scale denominator, e.g. 1000.0 for a 1:1000 map. A scale of 0 indicates no maximum scale visibility.

See also
maximumScale()
setMinimumScale()

Definition at line 291 of file qgsrulebasedrenderer.h.

◆ setMinimumScale()

void QgsRuleBasedRenderer::Rule::setMinimumScale ( double scale)
inline

Sets the minimum map scale (i.e.

most "zoomed out" scale) at which the rule will be active. The scale value indicates the scale denominator, e.g. 1000.0 for a 1:1000 map. A scale of 0 indicates no minimum scale visibility.

See also
minimumScale()
setMaximumScale()

Definition at line 282 of file qgsrulebasedrenderer.h.

◆ setNormZLevels()

void QgsRuleBasedRenderer::Rule::setNormZLevels ( const QMap< int, int > & zLevelsToNormLevels)

assign normalized z-levels [0..N-1] for this rule's symbol for quick access during rendering

Note
not available in Python bindings

Definition at line 579 of file qgsrulebasedrenderer.cpp.

◆ setRuleKey()

void QgsRuleBasedRenderer::Rule::setRuleKey ( const QString & key)
inline

Override the assigned rule key (should be used just internally by rule-based renderer).

Definition at line 269 of file qgsrulebasedrenderer.h.

◆ setSymbol()

void QgsRuleBasedRenderer::Rule::setSymbol ( QgsSymbol * sym)

Sets a new symbol (or nullptr). Deletes old symbol.

Definition at line 259 of file qgsrulebasedrenderer.cpp.

◆ startRender()

bool QgsRuleBasedRenderer::Rule::startRender ( QgsRenderContext & context,
const QgsFields & fields,
QString & filter )

prepare the rule for rendering and its children (build active children array)

Definition at line 444 of file qgsrulebasedrenderer.cpp.

◆ stopRender()

void QgsRuleBasedRenderer::Rule::stopRender ( QgsRenderContext & context)

Stop a rendering process.

Used to clean up the internal state of this rule

Parameters
contextThe rendering context

Definition at line 776 of file qgsrulebasedrenderer.cpp.

◆ symbol()

QgsSymbol * QgsRuleBasedRenderer::Rule::symbol ( )
inline

Definition at line 213 of file qgsrulebasedrenderer.h.

◆ symbols()

QgsSymbolList QgsRuleBasedRenderer::Rule::symbols ( const QgsRenderContext & context = QgsRenderContext()) const

Returns a list of the symbols used by this rule and all children of this rule.

Definition at line 245 of file qgsrulebasedrenderer.cpp.

◆ symbolsForFeature()

QgsSymbolList QgsRuleBasedRenderer::Rule::symbolsForFeature ( const QgsFeature & feature,
QgsRenderContext * context = nullptr )

tell which symbols will be used to render the feature

Definition at line 690 of file qgsrulebasedrenderer.cpp.

◆ takeChild()

QgsRuleBasedRenderer::Rule * QgsRuleBasedRenderer::Rule::takeChild ( QgsRuleBasedRenderer::Rule * rule)

take child rule out, set parent as nullptr

Definition at line 113 of file qgsrulebasedrenderer.cpp.

◆ takeChildAt()

QgsRuleBasedRenderer::Rule * QgsRuleBasedRenderer::Rule::takeChildAt ( int i)

take child rule out, set parent as nullptr

Definition at line 121 of file qgsrulebasedrenderer.cpp.

◆ toSld() [1/2]

bool QgsRuleBasedRenderer::Rule::toSld ( QDomDocument & doc,
QDomElement & element,
QgsSldExportContext & context ) const

Saves the rule to SLD.

Since
QGIS 3.44

Definition at line 366 of file qgsrulebasedrenderer.cpp.

◆ toSld() [2/2]

void QgsRuleBasedRenderer::Rule::toSld ( QDomDocument & doc,
QDomElement & element,
QVariantMap props ) const

Saves the symbol layer as SLD.

Deprecated
QGIS 3.44. Use the version with QgsSldExportContext instead.

Definition at line 359 of file qgsrulebasedrenderer.cpp.

◆ usedAttributes()

QSet< QString > QgsRuleBasedRenderer::Rule::usedAttributes ( const QgsRenderContext & context) const

Returns the attributes used to evaluate the expression of this rule.

Returns
A set of attribute names

Definition at line 212 of file qgsrulebasedrenderer.cpp.

◆ willRenderFeature()

bool QgsRuleBasedRenderer::Rule::willRenderFeature ( const QgsFeature & feature,
QgsRenderContext * context = nullptr )

only tell whether a feature will be rendered without actually rendering it

Definition at line 654 of file qgsrulebasedrenderer.cpp.


The documentation for this class was generated from the following files: