Feature #8725-revival: Fast rendering of geometries with provider simplification support

python/core/core.sip

@@ -37,6 +37,7 @@
 %Include qgsfield.sip
 %Include qgsgeometry.sip
 %Include qgsgeometryvalidator.sip
+%Include qgsgeometrysimplifier.sip
 %Include qgsgml.sip
 %Include qgsgmlschema.sip
 %Include qgshttptransaction.sip
@@ -75,6 +76,7 @@
 %Include qgsrunprocess.sip
 %Include qgsscalecalculator.sip
 %Include qgsscaleutils.sip
+%Include qgssimplifymethod.sip
 %Include qgssnapper.sip
 %Include qgsspatialindex.sip
 %Include qgstolerance.sip
@@ -86,6 +88,7 @@
 %Include qgsvectorlayerimport.sip
 %Include qgsvectorlayerjoinbuffer.sip
 %Include qgsvectorlayerundocommand.sip
+%Include qgsvectorsimplifymethod.sip
 %Include qgsfontutils.sip
 
 %Include qgscachedfeatureiterator.sip

python/core/qgsgeometrysimplifier.sip

@@ -0,0 +1,23 @@
+
+/** Abstract base class for simplify geometries using a specific algorithm */
+class QgsAbstractGeometrySimplifier
+{
+%TypeHeaderCode
+#include "qgsgeometrysimplifier.h"
+%End
+
+  public:
+    virtual ~QgsAbstractGeometrySimplifier();
+
+    /** Returns a simplified version the specified geometry */
+    virtual QgsGeometry* simplify( QgsGeometry* geometry ) const = 0;
+    /** Simplifies the specified geometry */
+    virtual bool simplifyGeometry( QgsGeometry* geometry ) const = 0;
+
+    // MapToPixel simplification helper methods
+  public:
+    /** Returns whether the device-envelope can be replaced by its BBOX when is applied the specified tolerance */
+    static bool canbeGeneralizedByDeviceBoundingBox( const QgsRectangle&   envelope, float mapToPixelTol = 1.0f );
+    /** Returns whether the device-geometry can be replaced by its BBOX when is applied the specified tolerance */
+    static bool canbeGeneralizedByDeviceBoundingBox( const QVector<QPointF>& points, float mapToPixelTol = 1.0f );
+};

python/core/qgssimplifymethod.sip

@@ -0,0 +1,42 @@
+
+/** This class contains information about how to simplify geometries fetched from a QgsFeatureIterator */
+class QgsSimplifyMethod
+{
+%TypeHeaderCode
+#include "qgssimplifymethod.h"
+%End
+
+  public:
+    enum MethodType
+    {
+      NoSimplification,     //!< No simplification is applied
+      OptimizeForRendering, //!< Simplify using the map2pixel data to optimize the rendering of geometries
+      PreserveTopology      //!< Simplify using the Douglas-Peucker algorithm ensuring that the result is a valid geometry
+    };
+
+    //! construct a default method
+    QgsSimplifyMethod();
+    //! copy constructor
+    QgsSimplifyMethod( const QgsSimplifyMethod& rh );
+
+    /** Sets the simplification type */
+    void setMethodType( MethodType methodType );
+    /** Gets the simplification type */
+    MethodType methodType() const;
+
+    /** Sets the tolerance of simplification. Represents the maximum distance between two coordinates which can be considered equal */
+    void setTolerance( double tolerance );
+    /** Gets the tolerance of simplification */
+    double tolerance() const;
+
+    /** Returns the optimal tolerance for Douglas-Peucker simplification algorithms */
+    double toleranceForDouglasPeuckerAlgorithms() const;
+
+    /** Sets whether the simplification executes after fetch the geometries from provider, otherwise it executes, when supported, in provider before fetch the geometries */
+    void setForceLocalOptimization( bool localOptimization );
+    /** Gets whether the simplification executes after fetch the geometries from provider, otherwise it executes, when supported, in provider before fetch the geometries */
+    bool forceLocalOptimization() const;
+
+    /** Creates a geometry simplifier according to specified method */
+    static QgsAbstractGeometrySimplifier* createGeometrySimplifier( const QgsSimplifyMethod& simplifyMethod );
+};

python/core/qgsvectorlayer.sip

@@ -999,25 +999,18 @@ class QgsVectorLayer : QgsMapLayer
     /** @note not available in python bindings */
     // inline QgsGeometryCache* cache();
 
-    /** Set the Map2pixel simplification threshold for fast rendering of features */
-    void setSimplifyDrawingTol( float simplifyDrawingTol );
-    /** Returns the Map2pixel simplification threshold for fast rendering of features */
-    float simplifyDrawingTol() const;
-
     /** Simplification flags for fast rendering of features */
     enum SimplifyHint
     {
       NoSimplification           = 0, //!< No simplification can be applied
       GeometrySimplification     = 1, //!< The geometries can be simplified using the current map2pixel context state
-      EnvelopeSimplification     = 2, //!< The geometries can be fully simplified by its BoundingBox using the current map2pixel context state
-      AntialiasingSimplification = 4, //!< The geometries can be rendered with 'AntiAliasing' disabled because of it is '1-pixel size'
-      DefaultSimplification      = 3, //!< Default simplification hints can be applied ( Geometry + Envelope )
-      FullSimplification         = 7, //!< All simplification hints can be applied ( Geometry + Envelope + AA-disabling )
+      AntialiasingSimplification = 2, //!< The geometries can be rendered with 'AntiAliasing' disabled because of it is '1-pixel size'
+      FullSimplification         = 3, //!< All simplification hints can be applied ( Geometry + AA-disabling )
     };
-    /** Set the Map2pixel simplification hints for fast rendering of features */
-    void setSimplifyDrawingHints( int simplifyDrawingHints );
-    /** Returns the Map2pixel simplification hints for fast rendering of features */
-    int simplifyDrawingHints() const;
+    /** Set the simplification settings for fast rendering of features  */
+    void setSimplifyMethod( const QgsVectorSimplifyMethod& simplifyMethod );
+    /** Returns the simplification settings for fast rendering of features  */
+    const QgsVectorSimplifyMethod& simplifyMethod() const;
 
     /** Returns whether the VectorLayer can apply the specified simplification hint */
     bool simplifyDrawingCanbeApplied( int simplifyHint ) const;

python/core/qgsvectorsimplifymethod.sip

@@ -0,0 +1,29 @@
+
+/** This class contains information how to simplify geometries fetched from a vector layer */
+class QgsVectorSimplifyMethod
+{
+%TypeHeaderCode
+#include "qgsvectorsimplifymethod.h"
+%End
+
+  public:
+    //! construct a default object
+    QgsVectorSimplifyMethod();
+    //! copy constructor
+    QgsVectorSimplifyMethod( const QgsVectorSimplifyMethod& rh );
+
+    /** Sets the simplification hints of the vector layer managed */
+    void setSimplifyHints( int simplifyHints );
+    /** Gets the simplification hints of the vector layer managed */
+    int simplifyHints() const;
+
+    /** Sets the simplification threshold of the vector layer managed */
+    void setThreshold( float threshold );
+    /** Gets the simplification threshold of the vector layer managed */
+    float threshold() const;
+
+    /** Sets where the simplification executes, after fetch the geometries from provider, or when supported, in provider before fetch the geometries */
+    void setForceLocalOptimization( bool localOptimization );
+    /** Gets where the simplification executes, after fetch the geometries from provider, or when supported, in provider before fetch the geometries */
+    bool forceLocalOptimization();
+};

src/app/qgsoptions.cpp

@@ -562,9 +562,9 @@ QgsOptions::QgsOptions( QWidget *parent, Qt::WFlags fl ) :
   chkUseRenderCaching->setChecked( settings.value( "/qgis/enable_render_caching", false ).toBool() );
 
   // Default simplify drawing configuration
-  mSimplifyDrawingGroupBox->setChecked( settings.value( "/qgis/simplifyDrawingHints", ( int )QgsVectorLayer::DefaultSimplification ).toInt() != QgsVectorLayer::NoSimplification );
-  mSimplifyDrawingSlider->setValue(( int )( 5.0f * ( settings.value( "/qgis/simplifyDrawingTol", QGis::DEFAULT_MAPTOPIXEL_THRESHOLD ).toFloat() - 1 ) ) );
-  mSimplifyDrawingPanel->setVisible( mSimplifyDrawingSlider->value() > 0 );
+  mSimplifyDrawingGroupBox->setChecked( settings.value( "/qgis/simplifyDrawingHints", ( int )QgsVectorLayer::GeometrySimplification ).toInt() != QgsVectorLayer::NoSimplification );
+  mSimplifyDrawingSpinBox->setValue( settings.value( "/qgis/simplifyDrawingTol", QGis::DEFAULT_MAPTOPIXEL_THRESHOLD ).toFloat() );
+  mSimplifyDrawingAtProvider->setChecked( !settings.value( "/qgis/simplifyLocal", true ).toBool() );
 
   // Slightly awkard here at the settings value is true to use QImage,
   // but the checkbox is true to use QPixmap
@@ -1098,14 +1098,15 @@ void QgsOptions::saveOptions()
   settings.setValue( "/qgis/capitaliseLayerName", capitaliseCheckBox->isChecked() );
 
   // Default simplify drawing configuration
-  int simplifyDrawingHints = QgsVectorLayer::NoSimplification;
+  int simplifyHints = QgsVectorLayer::NoSimplification;
   if ( mSimplifyDrawingGroupBox->isChecked() )
   {
-    simplifyDrawingHints |= QgsVectorLayer::DefaultSimplification;
-    if ( mSimplifyDrawingSlider->value() > 0 ) simplifyDrawingHints |= QgsVectorLayer::AntialiasingSimplification;
+    simplifyHints |= QgsVectorLayer::GeometrySimplification;
+    if ( mSimplifyDrawingSpinBox->value() > 1 ) simplifyHints |= QgsVectorLayer::AntialiasingSimplification;
   }
-  settings.setValue( "/qgis/simplifyDrawingHints", simplifyDrawingHints );
-  settings.setValue( "/qgis/simplifyDrawingTol", 1.0f + 0.2f*mSimplifyDrawingSlider->value() );
+  settings.setValue( "/qgis/simplifyDrawingHints", simplifyHints );
+  settings.setValue( "/qgis/simplifyDrawingTol", mSimplifyDrawingSpinBox->value() );
+  settings.setValue( "/qgis/simplifyLocal", !mSimplifyDrawingAtProvider->isChecked() );
 
   // project
   settings.setValue( "/qgis/projOpenAtLaunch", mProjectOnLaunchCmbBx->currentIndex() );
@@ -2084,9 +2085,3 @@ void QgsOptions::saveDefaultDatumTransformations()
 
   s.endGroup();
 }
-
-void QgsOptions::on_mSimplifyDrawingSlider_valueChanged( int value )
-{
-  mSimplifyDrawingPanel->setVisible( value > 0 );
-}
-

src/app/qgsoptions.h

@@ -240,8 +240,6 @@ class APP_EXPORT QgsOptions : public QgsOptionsDialogBase, private Ui::QgsOption
     void on_mRemoveDefaultTransformButton_clicked();
     void on_mAddDefaultTransformButton_clicked();
 
-    void on_mSimplifyDrawingSlider_valueChanged( int value );
-
   private:
     QStringList i18nList();
     void initContrastEnhancement( QComboBox *cbox, QString name, QString defaultVal );

src/app/qgsvectorlayerproperties.cpp

@@ -393,9 +393,21 @@ void QgsVectorLayerProperties::syncToLayer( void )
   cbMaximumScale->setScale( 1.0 / layer->maximumScale() );
 
   // get simplify drawing configuration
-  mSimplifyDrawingGroupBox->setChecked( layer->simplifyDrawingHints() != QgsVectorLayer::NoSimplification );
-  mSimplifyDrawingSlider->setValue(( int )( 5.0f * ( layer->simplifyDrawingTol() - 1 ) ) );
-  mSimplifyDrawingPanel->setVisible( mSimplifyDrawingSlider->value() > 0 );
+  const QgsVectorSimplifyMethod& simplifyMethod = layer->simplifyMethod();
+  mSimplifyDrawingGroupBox->setChecked( simplifyMethod.simplifyHints() != QgsVectorLayer::NoSimplification );
+  mSimplifyDrawingSpinBox->setValue( simplifyMethod.threshold() );
+
+  if ( !( layer->dataProvider()->capabilities() & QgsVectorDataProvider::SimplifyGeometries ) )
+  {
+    mSimplifyDrawingAtProvider->setChecked( false );
+    mSimplifyDrawingAtProvider->setEnabled( false );
+    mSimplifyDrawingAtProvider->setText( QString( "%1 (%2)" ).arg( mSimplifyDrawingAtProvider->text(), tr( "Not supported" ) ) );
+  }
+  else
+  {
+    mSimplifyDrawingAtProvider->setChecked( !simplifyMethod.forceLocalOptimization() );
+    mSimplifyDrawingAtProvider->setEnabled( mSimplifyDrawingGroupBox->isChecked() );
+  }
 
   // load appropriate symbology page (V1 or V2)
   updateSymbologyPage();
@@ -535,14 +547,17 @@ void QgsVectorLayerProperties::apply()
   layer->setMetadataUrlFormat( mLayerMetadataUrlFormatComboBox->currentText() );
 
   //layer simplify drawing configuration
-  int simplifyDrawingHints = QgsVectorLayer::NoSimplification;
+  int simplifyHints = QgsVectorLayer::NoSimplification;
   if ( mSimplifyDrawingGroupBox->isChecked() )
   {
-    simplifyDrawingHints |= QgsVectorLayer::DefaultSimplification;
-    if ( mSimplifyDrawingSlider->value() > 0 ) simplifyDrawingHints |= QgsVectorLayer::AntialiasingSimplification;
+    simplifyHints |= QgsVectorLayer::GeometrySimplification;
+    if ( mSimplifyDrawingSpinBox->value() > 1 ) simplifyHints |= QgsVectorLayer::AntialiasingSimplification;
   }
-  layer->setSimplifyDrawingHints( simplifyDrawingHints );
-  layer->setSimplifyDrawingTol( 1.0f + 0.2f*mSimplifyDrawingSlider->value() );
+  QgsVectorSimplifyMethod simplifyMethod = layer->simplifyMethod();
+  simplifyMethod.setSimplifyHints( simplifyHints );
+  simplifyMethod.setThreshold( mSimplifyDrawingSpinBox->value() );
+  simplifyMethod.setForceLocalOptimization( !mSimplifyDrawingAtProvider->isChecked() );
+  layer->setSimplifyMethod( simplifyMethod );
 
   // update symbology
   emit refreshLegend( layer->id(), QgsLegendItem::DontChange );
@@ -1083,7 +1098,14 @@ void QgsVectorLayerProperties::on_mMaximumScaleSetCurrentPushButton_clicked()
   cbMaximumScale->setScale( 1.0 / QgisApp::instance()->mapCanvas()->mapRenderer()->scale() );
 }
 
-void QgsVectorLayerProperties::on_mSimplifyDrawingSlider_valueChanged( int value )
+void QgsVectorLayerProperties::on_mSimplifyDrawingGroupBox_toggled( bool checked )
 {
-  mSimplifyDrawingPanel->setVisible( value > 0 );
+  if ( !( layer->dataProvider()->capabilities() & QgsVectorDataProvider::SimplifyGeometries ) )
+  {
+    mSimplifyDrawingAtProvider->setEnabled( false );
+  }
+  else
+  {
+    mSimplifyDrawingAtProvider->setEnabled( mSimplifyDrawingGroupBox->isChecked() );
+  }
 }

src/app/qgsvectorlayerproperties.h

@@ -119,7 +119,7 @@ class APP_EXPORT QgsVectorLayerProperties : public QgsOptionsDialogBase, private
     void on_mMinimumScaleSetCurrentPushButton_clicked();
     void on_mMaximumScaleSetCurrentPushButton_clicked();
 
-    void on_mSimplifyDrawingSlider_valueChanged( int value );
+    void on_mSimplifyDrawingGroupBox_toggled( bool checked );
 
   signals:
 

src/core/CMakeLists.txt

@@ -75,6 +75,7 @@ SET(QGIS_CORE_SRCS
   qgsgeometrycache.cpp
   qgsgeometryvalidator.cpp
   qgsgeometrysimplifier.cpp
+  qgssimplifymethod.cpp
   qgsgml.cpp
   qgsgmlschema.cpp
   qgshttptransaction.cpp
@@ -129,6 +130,7 @@ SET(QGIS_CORE_SRCS
   qgsvectorlayerimport.cpp
   qgsvectorlayerjoinbuffer.cpp
   qgsvectorlayerundocommand.cpp
+  qgsvectorsimplifymethod.cpp
 
   qgsnetworkaccessmanager.cpp
 

src/core/composer/qgscomposermap.cpp

@@ -208,7 +208,7 @@ void QgsComposerMap::draw( QPainter *painter, const QgsRectangle& extent, const
          mComposition->plotStyle() == QgsComposition::Postscript )
     {
       //if outputing composer, disable optimisations like layer simplification
-      theRendererContext->setRenderingPrintComposition( true );
+      theRendererContext->setUseRenderingOptimization( false );
     }
 
     // force vector output (no caching of marker images etc.)