Clean up reading/writing of labeling configuration in vector layers

Historically the configuration used to be stored in layer's custom properties, but that does not scale beyond simple rendering and so rule-based labeling introduced storage of configuration natively in XML elements. That left us with two different ways of reading/writing labeling configurations. This work makes all configuration to use native XML elements. To keep compatibility of 2.x projects, reading of configuration from custom properties is preserved. This commit also adds Python APIs for direct manipulation of labeling configuration through vector layer's setLabeling() and labeling() calls.
qgis · May 16, 2017 · 21f03bc · 21f03bc
1 parent 7e345a7
commit 21f03bc
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diff --git a/doc/api_break.dox b/doc/api_break.dox
@@ -1645,6 +1645,7 @@ QgsPalLabeling        {#qgis_api_break_3_0_QgsPalLabeling}
 - labelsWithinRect() was removed. Use takeResults() and methods of QgsLabelingResults instead.
 - isStoredWithProject() and setStoredWithProject() had no effect and were removed.
 - staticWillUseLayer(QString) was removed. Use the variant with QgsVectorLayer argument.
+- readFromLayer() and writeToLayer() have been removed. Labeling is read/written in QgsAbstractVectorLayerLabeling and its subclasses.
 
 
 QgsPalLayerSettings        {#qgis_api_break_3_0_QgsPalLayerSettings}
@@ -1661,6 +1662,7 @@ dataDefinedUseExpression(), dataDefinedProperties() and dataDefinedNames()
 members were removed. Use the QgsProperty framework through dataDefinedProperties()
 and setDataDefinedProperties() instead.
 - readXml() and writeXml() now expect a reference to QgsReadWriteContext.
+- fromLayer() has been reoved. Labeling is read/written in QgsAbstractVectorLayerLabeling and its subclasses.
 
 
 QgsPanelWidgetStack        {#qgis_api_break_3_0_QgsPanelWidgetStack}

diff --git a/python/auto_sip.blacklist b/python/auto_sip.blacklist
@@ -22,6 +22,7 @@ core/qgsrange.sip
 core/qgsrelationmanager.sip
 core/qgsrenderchecker.sip
 core/qgsrendercontext.sip
+core/qgsrulebasedlabeling.sip
 core/qgsrunprocess.sip
 core/qgsruntimeprofiler.sip
 core/qgsscalecalculator.sip

diff --git a/python/core/core.sip b/python/core/core.sip
@@ -141,6 +141,7 @@
 %Include qgsrelationmanager.sip
 %Include qgsrenderchecker.sip
 %Include qgsrendercontext.sip
+%Include qgsrulebasedlabeling.sip
 %Include qgsrunprocess.sip
 %Include qgsruntimeprofiler.sip
 %Include qgsscalecalculator.sip
@@ -170,6 +171,7 @@
 %Include qgsvectorlayerfeaturecounter.sip
 %Include qgsvectorlayerjoinbuffer.sip
 %Include qgsvectorlayerjoininfo.sip
+%Include qgsvectorlayerlabeling.sip
 %Include qgsvectorlayertools.sip
 %Include qgsvectorlayerundocommand.sip
 %Include qgsvectorlayerutils.sip

diff --git a/python/core/qgspallabeling.sip b/python/core/qgspallabeling.sip
@@ -34,9 +34,6 @@ class QgsPalLayerSettings
     QgsPalLayerSettings( const QgsPalLayerSettings &s );
     ~QgsPalLayerSettings();
 
-    //! @note added in 2.4
-    static QgsPalLayerSettings fromLayer( QgsVectorLayer *layer );
-
     /** Placement modes which determine how label candidates are generated for a feature.
      */
     //TODO QGIS 3.0 - move to QgsLabelingEngine
@@ -420,9 +417,6 @@ class QgsPalLayerSettings
      */
     void registerFeature( QgsFeature &f, QgsRenderContext &context );
 
-    void readFromLayer( QgsVectorLayer *layer );
-    void writeToLayer( QgsVectorLayer *layer );
-
     /** Read settings from a DOM element
      * @note added in 2.12
      */

diff --git a/python/core/qgsrulebasedlabeling.sip b/python/core/qgsrulebasedlabeling.sip
@@ -0,0 +1,74 @@
+
+
+class QgsRuleBasedLabeling : QgsAbstractVectorLayerLabeling
+{
+%TypeHeaderCode
+#include "qgsrulebasedlabeling.h"
+%End
+  public:
+    typedef QList<QgsRuleBasedLabeling::Rule *> RuleList;
+
+    class Rule
+    {
+%TypeHeaderCode
+#include "qgsrulebasedlabeling.h"
+%End
+      public:
+        Rule( QgsPalLayerSettings *settings /Transfer/, int scaleMinDenom = 0, int scaleMaxDenom = 0, const QString &filterExp = QString(), const QString &description = QString(), bool elseRule = false );
+        ~Rule();
+
+        enum RegisterResult
+        {
+          Filtered,
+          Inactive,
+          Registered
+        };
+
+        QgsPalLayerSettings *settings() const;
+        bool dependsOnScale() const;
+        int scaleMinDenom() const;
+        int scaleMaxDenom() const;
+        QString filterExpression() const;
+        QString description() const;
+        bool active() const;
+        bool isElse() const;
+        QString ruleKey() const;
+        void setSettings( QgsPalLayerSettings *settings /Transfer/ );
+        void setScaleMinDenom( int scaleMinDenom );
+        void setScaleMaxDenom( int scaleMaxDenom );
+        void setFilterExpression( const QString &filterExp );
+        void setDescription( const QString &description );
+        void setActive( bool state );
+        void setIsElse( bool iselse );
+        void setRuleKey( const QString &key );
+        const QgsRuleBasedLabeling::RuleList &children() const;
+        QgsRuleBasedLabeling::RuleList descendants() const;
+        QgsRuleBasedLabeling::Rule *parent();
+        void appendChild( QgsRuleBasedLabeling::Rule *rule /Transfer/ );
+        void insertChild( int i, QgsRuleBasedLabeling::Rule *rule /Transfer/ );
+        void removeChildAt( int i );
+        const QgsRuleBasedLabeling::Rule *findRuleByKey( const QString &key ) const;
+        QgsRuleBasedLabeling::Rule *clone() const /Factory/;
+        static QgsRuleBasedLabeling::Rule *create( const QDomElement &ruleElem, const QgsReadWriteContext &context ) /Factory/;
+        QDomElement save( QDomDocument &doc, const QgsReadWriteContext &context ) const;
+        bool requiresAdvancedEffects() const;
+
+      private:
+        Rule( const QgsRuleBasedLabeling::Rule &rh );
+    };
+
+    explicit QgsRuleBasedLabeling( QgsRuleBasedLabeling::Rule *root /Transfer/ );
+    ~QgsRuleBasedLabeling();
+
+    QgsRuleBasedLabeling::Rule *rootRule();
+
+    static QgsRuleBasedLabeling *create( const QDomElement &element, const QgsReadWriteContext &context ) /Factory/;
+
+    virtual QString type() const;
+    virtual QgsRuleBasedLabeling *clone() const /Factory/;
+    virtual QDomElement save( QDomDocument &doc, const QgsReadWriteContext &context ) const;
+    virtual QStringList subProviders() const;
+    virtual QgsPalLayerSettings settings( const QString &providerId = QString() ) const;
+    virtual bool requiresAdvancedEffects() const;
+
+};
diff --git a/python/core/qgstextrenderer.sip b/python/core/qgstextrenderer.sip
@@ -182,16 +182,8 @@ class QgsTextBufferSettings
 
     void readFromLayer( QgsVectorLayer *layer );
 %Docstring
- Reads settings from a layer's custom properties.
+ Reads settings from a layer's custom properties (for QGIS 2.x projects).
  \param layer source vector layer
-.. seealso:: writeToLayer()
-%End
-
-    void writeToLayer( QgsVectorLayer *layer ) const;
-%Docstring
- Writes settings to a layer's custom properties.
- \param layer target vector layer
-.. seealso:: readFromLayer()
 %End
 
     void readXml( const QDomElement &elem );
@@ -676,16 +668,8 @@ class QgsTextBackgroundSettings
 
     void readFromLayer( QgsVectorLayer *layer );
 %Docstring
- Reads settings from a layer's custom properties.
+ Reads settings from a layer's custom properties (for QGIS 2.x projects).
  \param layer source vector layer
-.. seealso:: writeToLayer()
-%End
-
-    void writeToLayer( QgsVectorLayer *layer ) const;
-%Docstring
- Writes settings to a layer's custom properties.
- \param layer target vector layer
-.. seealso:: readFromLayer()
 %End
 
     void readXml( const QDomElement &elem, const QgsReadWriteContext &context );
@@ -976,16 +960,8 @@ class QgsTextShadowSettings
 
     void readFromLayer( QgsVectorLayer *layer );
 %Docstring
- Reads settings from a layer's custom properties.
+ Reads settings from a layer's custom properties (for QGIS 2.x projects).
  \param layer source vector layer
-.. seealso:: writeToLayer()
-%End
-
-    void writeToLayer( QgsVectorLayer *layer ) const;
-%Docstring
- Writes settings to a layer's custom properties.
- \param layer target vector layer
-.. seealso:: readFromLayer()
 %End
 
     void readXml( const QDomElement &elem );
@@ -1239,16 +1215,8 @@ class QgsTextFormat
 
     void readFromLayer( QgsVectorLayer *layer );
 %Docstring
- Reads settings from a layer's custom properties.
+ Reads settings from a layer's custom properties (for QGIS 2.x projects).
  \param layer source vector layer
-.. seealso:: writeToLayer()
-%End
-
-    void writeToLayer( QgsVectorLayer *layer ) const;
-%Docstring
- Writes settings to a layer's custom properties.
- \param layer target vector layer
-.. seealso:: readFromLayer()
 %End
 
     void readXml( const QDomElement &elem, const QgsReadWriteContext &context );

diff --git a/python/core/qgsvectorlayer.sip b/python/core/qgsvectorlayer.sip
@@ -1045,7 +1045,18 @@ changeGeometry() instead.
  :rtype: int
 %End
 
+    const QgsAbstractVectorLayerLabeling *labeling() const;
+%Docstring
+ Access to labeling configuration. May be null if labeling is not used.
+.. versionadded:: 3.0
+ :rtype: QgsAbstractVectorLayerLabeling
+%End
 
+    void setLabeling( QgsAbstractVectorLayerLabeling *labeling /Transfer/ );
+%Docstring
+ Set labeling configuration. Takes ownership of the object.
+.. versionadded:: 3.0
+%End
 
     virtual bool isEditable() const;
 %Docstring

diff --git a/python/core/qgsvectorlayerlabeling.sip b/python/core/qgsvectorlayerlabeling.sip
@@ -0,0 +1,121 @@
+/************************************************************************
+ * This file has been generated automatically from                      *
+ *                                                                      *
+ * src/core/qgsvectorlayerlabeling.h                                    *
+ *                                                                      *
+ * Do not edit manually ! Edit header and run scripts/sipify.pl again   *
+ ************************************************************************/
+
+
+
+
+
+
+class QgsAbstractVectorLayerLabeling
+{
+%Docstring
+ Abstract base class - its implementations define different approaches to the labeling of a vector layer.
+
+.. versionadded:: 3.0
+%End
+
+%TypeHeaderCode
+#include "qgsvectorlayerlabeling.h"
+%End
+  public:
+
+    QgsAbstractVectorLayerLabeling();
+    virtual ~QgsAbstractVectorLayerLabeling();
+
+    virtual QString type() const = 0;
+%Docstring
+Unique type string of the labeling configuration implementation
+ :rtype: str
+%End
+
+    virtual QgsAbstractVectorLayerLabeling *clone() const = 0 /Factory/;
+%Docstring
+Return a new copy of the object
+ :rtype: QgsAbstractVectorLayerLabeling
+%End
+
+
+    virtual QDomElement save( QDomDocument &doc, const QgsReadWriteContext &context ) const = 0;
+%Docstring
+Return labeling configuration as XML element
+ :rtype: QDomElement
+%End
+
+    virtual QStringList subProviders() const;
+%Docstring
+Get list of sub-providers within the layer's labeling.
+ :rtype: list of str
+%End
+
+    virtual QgsPalLayerSettings settings( const QString &providerId = QString() ) const = 0;
+%Docstring
+they are identified by their ID (e.g. in case of rule-based labeling, provider ID == rule key)
+ :rtype: QgsPalLayerSettings
+%End
+
+    virtual bool requiresAdvancedEffects() const = 0;
+%Docstring
+ Returns true if drawing labels requires advanced effects like composition
+ modes, which could prevent it being used as an isolated cached image
+ or exported to a vector format.
+.. versionadded:: 3.0
+ :rtype: bool
+%End
+
+
+    static QgsAbstractVectorLayerLabeling *create( const QDomElement &element, const QgsReadWriteContext &context ) /Factory/;
+%Docstring
+Try to create instance of an implementation based on the XML data
+ :rtype: QgsAbstractVectorLayerLabeling
+%End
+
+  private:
+    QgsAbstractVectorLayerLabeling( const QgsAbstractVectorLayerLabeling &rhs );
+};
+
+class QgsVectorLayerSimpleLabeling : QgsAbstractVectorLayerLabeling
+{
+%Docstring
+ Basic implementation of the labeling interface.
+
+ The configuration is kept in layer's custom properties for backward compatibility.
+
+.. versionadded:: 3.0
+%End
+
+%TypeHeaderCode
+#include "qgsvectorlayerlabeling.h"
+%End
+  public:
+    explicit QgsVectorLayerSimpleLabeling( const QgsPalLayerSettings &settings );
+%Docstring
+Constructs simple labeling configuration with given initial settings
+%End
+
+    virtual QString type() const;
+    virtual QgsAbstractVectorLayerLabeling *clone() const /Factory/;
+    virtual QDomElement save( QDomDocument &doc, const QgsReadWriteContext &context ) const;
+    virtual QgsPalLayerSettings settings( const QString &providerId = QString() ) const;
+    virtual bool requiresAdvancedEffects() const;
+
+
+    static QgsVectorLayerSimpleLabeling *create( const QDomElement &element, const QgsReadWriteContext &context );
+%Docstring
+Create the instance from a DOM element with saved configuration
+ :rtype: QgsVectorLayerSimpleLabeling
+%End
+
+};
+
+/************************************************************************
+ * This file has been generated automatically from                      *
+ *                                                                      *
+ * src/core/qgsvectorlayerlabeling.h                                    *
+ *                                                                      *
+ * Do not edit manually ! Edit header and run scripts/sipify.pl again   *
+ ************************************************************************/
diff --git a/src/app/dwg/qgsdwgimportdialog.cpp b/src/app/dwg/qgsdwgimportdialog.cpp
@@ -25,6 +25,7 @@
 #include "qgisapp.h"
 #include "qgsdwgimporter.h"
 #include "qgsvectorlayer.h"
+#include "qgsvectorlayerlabeling.h"
 #include "qgsvectordataprovider.h"
 #include "qgsproject.h"
 #include "qgsfeatureiterator.h"
@@ -399,7 +400,7 @@ void QgsDwgImportDialog::createGroup( QgsLayerTreeGroup *group, QString name, QS
     pls.dataDefinedProperties().setProperty( QgsPalLayerSettings::Rotation, QgsProperty::fromExpression( QStringLiteral( "angle*180.0/pi()" ) ) );
 
     pls.placement = QgsPalLayerSettings::OrderedPositionsAroundPoint;
-    pls.writeToLayer( l );
+    l->setLabeling( new QgsVectorLayerSimpleLabeling( pls ) );
   }
 
   l = layer( layerGroup, layerFilter, "points" );