[FEATURE][labeling] Add option for obstacle only layers

nyalldawson · nyalldawson · commit 388e4047a75d · 2015-07-15T16:08:24.000+10:00
This allows users to set a layer as just an obstacle for other
layer's labels without rendering any labels of its own.

Ideas for UI improvements are welcome!
diff --git a/python/core/qgspallabeling.sip b/python/core/qgspallabeling.sip
@@ -294,6 +294,15 @@ class QgsPalLayerSettings
 
     // whether to label this layer
     bool enabled;
+    
+    /** Whether to draw labels for this layer. For some layers it may be desirable
+     * to register their features as obstacles for other labels without requiring
+     * labels to be drawn for the layer itself. In this case drawLabels can be set
+     * to false and obstacle set to true, which will result in the layer acting
+     * as an obstacle but having no labels of its own.
+     * @note added in QGIS 2.12
+     */
+    bool drawLabels;
 
     //-- text style
 
diff --git a/src/app/qgslabelinggui.cpp b/src/app/qgslabelinggui.cpp
@@ -84,10 +84,6 @@ QgsLabelingGui::QgsLabelingGui( QgsVectorLayer* layer, QgsMapCanvas* mapCanvas,
 
   mRefFont = lblFontPreview->font();
 
-  // main layer label-enabling connections
-  connect( chkEnableLabeling, SIGNAL( toggled( bool ) ), mFieldExpressionWidget, SLOT( setEnabled( bool ) ) );
-  connect( chkEnableLabeling, SIGNAL( toggled( bool ) ), mLabelingFrame, SLOT( setEnabled( bool ) ) );
-
   // connections for groupboxes with separate activation checkboxes (that need to honor data defined setting)
   connect( mBufferDrawChkBx, SIGNAL( toggled( bool ) ), this, SLOT( updateUi() ) );
   connect( mShapeDrawChkBx, SIGNAL( toggled( bool ) ), this, SLOT( updateUi() ) );
@@ -293,9 +289,16 @@ void QgsLabelingGui::init()
   blockInitSignals( true );
 
   // enable/disable main options based upon whether layer is being labeled
-  chkEnableLabeling->setChecked( lyr.enabled );
-  mFieldExpressionWidget->setEnabled( chkEnableLabeling->isChecked() );
-  mLabelingFrame->setEnabled( chkEnableLabeling->isChecked() );
+  if ( !lyr.enabled )
+  {
+    mLabelModeComboBox->setCurrentIndex( 0 );
+  }
+  else
+  {
+    mLabelModeComboBox->setCurrentIndex( lyr.drawLabels ? 1 : 2 );
+  }
+  mFieldExpressionWidget->setEnabled( mLabelModeComboBox->currentIndex() == 1 );
+  mLabelingFrame->setEnabled( mLabelModeComboBox->currentIndex() == 1 );
 
   // set the current field or add the current expression to the bottom of the list
   mFieldExpressionWidget->setField( lyr.fieldName );
@@ -572,7 +575,8 @@ QgsPalLayerSettings QgsLabelingGui::layerSettings()
 {
   QgsPalLayerSettings lyr;
 
-  lyr.enabled = chkEnableLabeling->isChecked();
+  lyr.enabled = mLabelModeComboBox->currentIndex() > 0;
+  lyr.drawLabels = mLabelModeComboBox->currentIndex() == 1;
 
   bool isExpression;
   lyr.fieldName = mFieldExpressionWidget->currentField( &isExpression );
@@ -1617,6 +1621,13 @@ void QgsLabelingGui::updateSvgWidgets( const QString& svgPath )
   mShapeSVGUnitsLabel->setEnabled( validSVG && outlineWidthParam );
 }
 
+void QgsLabelingGui::on_mLabelModeComboBox_currentIndexChanged( int index )
+{
+  bool labelsEnabled = ( index == 1 );
+  mFieldExpressionWidget->setEnabled( labelsEnabled );
+  mLabelingFrame->setEnabled( labelsEnabled );
+}
+
 void QgsLabelingGui::on_mShapeSVGSelectorBtn_clicked()
 {
   QgsSvgSelectorDialog svgDlg( this );
diff --git a/src/app/qgslabelinggui.h b/src/app/qgslabelinggui.h
@@ -53,6 +53,7 @@ class APP_EXPORT QgsLabelingGui : public QWidget, private Ui::QgsLabelingGuiBase
     void updatePlacementWidgets();
     void updateSvgWidgets( const QString& svgPath );
 
+    void on_mLabelModeComboBox_currentIndexChanged( int index );
     void on_mPreviewSizeSlider_valueChanged( int i );
     void on_mFontSizeSpinBox_valueChanged( double d );
     void on_mFontCapitalsComboBox_currentIndexChanged( int index );
diff --git a/src/core/qgspallabeling.cpp b/src/core/qgspallabeling.cpp
@@ -91,6 +91,7 @@ QgsPalLayerSettings::QgsPalLayerSettings()
     , expression( 0 )
 {
   enabled = false;
+  drawLabels = true;
   isExpression = false;
   fieldIndex = 0;
 
@@ -333,6 +334,7 @@ QgsPalLayerSettings::QgsPalLayerSettings( const QgsPalLayerSettings& s )
   // copy only permanent stuff
 
   enabled = s.enabled;
+  drawLabels = s.drawLabels;
 
   // text style
   fieldName = s.fieldName;
@@ -717,6 +719,7 @@ void QgsPalLayerSettings::readFromLayer( QgsVectorLayer* layer )
   // NOTE: set defaults for newly added properties, for backwards compatibility
 
   enabled = layer->labelsEnabled();
+  drawLabels = layer->customProperty( "labeling/drawLabels", true ).toBool();
 
   // text style
   fieldName = layer->customProperty( "labeling/fieldName" ).toString();
@@ -927,6 +930,7 @@ void QgsPalLayerSettings::writeToLayer( QgsVectorLayer* layer )
   layer->setCustomProperty( "labeling", "pal" );
 
   layer->setCustomProperty( "labeling/enabled", enabled );
+  layer->setCustomProperty( "labeling/drawLabels", drawLabels );
 
   // text style
   layer->setCustomProperty( "labeling/fieldName", fieldName );
@@ -1410,6 +1414,15 @@ void QgsPalLayerSettings::calculateLabelSize( const QFontMetricsF* fm, QString t
 
 void QgsPalLayerSettings::registerFeature( QgsFeature& f, const QgsRenderContext& context, QString dxfLayer )
 {
+  if ( !drawLabels )
+  {
+    if ( obstacle )
+    {
+      registerObstacleFeature( f, context, dxfLayer );
+    }
+    return;
+  }
+
   QVariant exprVal; // value() is repeatedly nulled on data defined evaluation and replaced when successful
   mCurFeat = &f;
 //  mCurFields = &layer->pendingFields();
@@ -2199,6 +2212,58 @@ void QgsPalLayerSettings::registerFeature( QgsFeature& f, const QgsRenderContext
   lbl->setIsPinned( labelIsPinned );
 }
 
+void QgsPalLayerSettings::registerObstacleFeature( QgsFeature& f, const QgsRenderContext& context, QString dxfLayer )
+{
+  mCurFeat = &f;
+
+  const QgsGeometry* geom = f.constGeometry();
+  if ( !geom )
+  {
+    return;
+  }
+
+  const GEOSGeometry* geos_geom = 0;
+  QScopedPointer<QgsGeometry> scopedPreparedGeom;
+
+  if ( QgsPalLabeling::geometryRequiresPreparation( geom, context, ct, extentGeom ) )
+  {
+    scopedPreparedGeom.reset( QgsPalLabeling::prepareGeometry( geom, context, ct, extentGeom ) );
+    if ( !scopedPreparedGeom.data() )
+      return;
+    geos_geom = scopedPreparedGeom.data()->asGeos();
+  }
+  else
+  {
+    geos_geom = geom->asGeos();
+  }
+
+  if ( geos_geom == NULL )
+    return; // invalid geometry
+
+  GEOSGeometry* geos_geom_clone;
+  geos_geom_clone = GEOSGeom_clone_r( QgsGeometry::getGEOSHandler(), geos_geom );
+
+  QgsPalGeometry* lbl = new QgsPalGeometry( f.id(), QString(), geos_geom_clone );
+
+  lbl->setDxfLayer( dxfLayer );
+
+  // record the created geometry - it will be deleted at the end.
+  geometries.append( lbl );
+
+  //  feature to the layer
+  try
+  {
+    if ( !palLayer->registerFeature( lbl->strId(), lbl, 0, 0 ) )
+      return;
+  }
+  catch ( std::exception &e )
+  {
+    Q_UNUSED( e );
+    QgsDebugMsgLevel( QString( "Ignoring feature %1 due PAL exception:" ).arg( f.id() ) + QString::fromLatin1( e.what() ), 4 );
+    return;
+  }
+}
+
 bool QgsPalLayerSettings::dataDefinedValEval( const QString& valType,
     QgsPalLayerSettings::DataDefinedProperties p,
     QVariant& exprVal )
@@ -3136,26 +3201,29 @@ int QgsPalLabeling::prepareLayer( QgsVectorLayer* layer, QStringList& attrNames,
   QgsPalLayerSettings lyrTmp;
   lyrTmp.readFromLayer( layer );
 
-  if ( lyrTmp.fieldName.isEmpty() )
-  {
-    return 0;
-  }
-
-  if ( lyrTmp.isExpression )
+  if ( lyrTmp.drawLabels )
   {
-    QgsExpression exp( lyrTmp.fieldName );
-    if ( exp.hasEvalError() )
+    if ( lyrTmp.fieldName.isEmpty() )
     {
-      QgsDebugMsgLevel( "Prepare error:" + exp.evalErrorString(), 4 );
       return 0;
     }
-  }
-  else
-  {
-    // If we aren't an expression, we check to see if we can find the column.
-    if ( layer->fieldNameIndex( lyrTmp.fieldName ) == -1 )
+
+    if ( lyrTmp.isExpression )
     {
-      return 0;
+      QgsExpression exp( lyrTmp.fieldName );
+      if ( exp.hasEvalError() )
+      {
+        QgsDebugMsgLevel( "Prepare error:" + exp.evalErrorString(), 4 );
+        return 0;
+      }
+    }
+    else
+    {
+      // If we aren't an expression, we check to see if we can find the column.
+      if ( layer->fieldNameIndex( lyrTmp.fieldName ) == -1 )
+      {
+        return 0;
+      }
     }
   }
 
@@ -3166,52 +3234,55 @@ int QgsPalLabeling::prepareLayer( QgsVectorLayer* layer, QStringList& attrNames,
 
   lyr.mCurFields = &( layer->pendingFields() );
 
-  // add field indices for label's text, from expression or field
-  if ( lyr.isExpression )
+  if ( lyrTmp.drawLabels )
   {
-    // prepare expression for use in QgsPalLayerSettings::registerFeature()
-    QgsExpression* exp = lyr.getLabelExpression();
-    exp->prepare( layer->pendingFields() );
-    if ( exp->hasEvalError() )
+    // add field indices for label's text, from expression or field
+    if ( lyr.isExpression )
     {
-      QgsDebugMsgLevel( "Prepare error:" + exp->evalErrorString(), 4 );
+      // prepare expression for use in QgsPalLayerSettings::registerFeature()
+      QgsExpression* exp = lyr.getLabelExpression();
+      exp->prepare( layer->pendingFields() );
+      if ( exp->hasEvalError() )
+      {
+        QgsDebugMsgLevel( "Prepare error:" + exp->evalErrorString(), 4 );
+      }
+      foreach ( QString name, exp->referencedColumns() )
+      {
+        QgsDebugMsgLevel( "REFERENCED COLUMN = " + name, 4 );
+        attrNames.append( name );
+      }
     }
-    foreach ( QString name, exp->referencedColumns() )
+    else
     {
-      QgsDebugMsgLevel( "REFERENCED COLUMN = " + name, 4 );
-      attrNames.append( name );
+      attrNames.append( lyr.fieldName );
     }
-  }
-  else
-  {
-    attrNames.append( lyr.fieldName );
-  }
 
-  // add field indices of data defined expression or field
-  QMap< QgsPalLayerSettings::DataDefinedProperties, QgsDataDefined* >::const_iterator dIt = lyr.dataDefinedProperties.constBegin();
-  for ( ; dIt != lyr.dataDefinedProperties.constEnd(); ++dIt )
-  {
-    QgsDataDefined* dd = dIt.value();
-    if ( !dd->isActive() )
+    // add field indices of data defined expression or field
+    QMap< QgsPalLayerSettings::DataDefinedProperties, QgsDataDefined* >::const_iterator dIt = lyr.dataDefinedProperties.constBegin();
+    for ( ; dIt != lyr.dataDefinedProperties.constEnd(); ++dIt )
     {
-      continue;
-    }
+      QgsDataDefined* dd = dIt.value();
+      if ( !dd->isActive() )
+      {
+        continue;
+      }
 
-    // NOTE: the following also prepares any expressions for later use
+      // NOTE: the following also prepares any expressions for later use
 
-    // store parameters for data defined expressions
-    QMap<QString, QVariant> exprParams;
-    exprParams.insert( "scale", ctx.rendererScale() );
+      // store parameters for data defined expressions
+      QMap<QString, QVariant> exprParams;
+      exprParams.insert( "scale", ctx.rendererScale() );
 
-    dd->setExpressionParams( exprParams );
+      dd->setExpressionParams( exprParams );
 
-    // this will return columns for expressions or field name, depending upon what is set to be used
-    QStringList cols = dd->referencedColumns( layer ); // <-- prepares any expressions, too
+      // this will return columns for expressions or field name, depending upon what is set to be used
+      QStringList cols = dd->referencedColumns( layer ); // <-- prepares any expressions, too
 
-    //QgsDebugMsgLevel( QString( "Data defined referenced columns:" ) + cols.join( "," ), 4 );
-    foreach ( QString name, cols )
-    {
-      attrNames.append( name );
+      //QgsDebugMsgLevel( QString( "Data defined referenced columns:" ) + cols.join( "," ), 4 );
+      foreach ( QString name, cols )
+      {
+        attrNames.append( name );
+      }
     }
   }
 
@@ -3233,7 +3304,7 @@ int QgsPalLabeling::prepareLayer( QgsVectorLayer* layer, QStringList& attrNames,
 
   Layer* l = mPal->addLayer( layer->id().toUtf8().data(),
                              arrangement,
-                             priority, lyr.obstacle, true, true,
+                             priority, lyr.obstacle, true, lyr.drawLabels,
                              lyr.displayAll );
 
   if ( lyr.placementFlags )
@@ -4187,6 +4258,8 @@ void QgsPalLabeling::drawLabeling( QgsRenderContext& context )
     }
 
     const QgsPalLayerSettings& lyr = layer( layerName );
+    if ( !lyr.drawLabels )
+      continue;
 
     // Copy to temp, editable layer settings
     // these settings will be changed by any data defined values, then used for rendering label components
diff --git a/src/core/qgspallabeling.h b/src/core/qgspallabeling.h
@@ -270,6 +270,15 @@ class CORE_EXPORT QgsPalLayerSettings
     // whether to label this layer
     bool enabled;
 
+    /** Whether to draw labels for this layer. For some layers it may be desirable
+     * to register their features as obstacles for other labels without requiring
+     * labels to be drawn for the layer itself. In this case drawLabels can be set
+     * to false and obstacle set to true, which will result in the layer acting
+     * as an obstacle but having no labels of its own.
+     * @note added in QGIS 2.12
+     */
+    bool drawLabels;
+
     //-- text style
 
     QString fieldName;
@@ -561,6 +570,9 @@ class CORE_EXPORT QgsPalLayerSettings
     @return true if above size, false if below*/
     bool checkMinimumSizeMM( const QgsRenderContext& ct, const QgsGeometry* geom, double minSize ) const;
 
+    /** Registers a feature as an obstacle only (no label rendered)
+     */
+    void registerObstacleFeature( QgsFeature &f, const QgsRenderContext &context, QString dxfLayer );
 
     QMap<DataDefinedProperties, QVariant> dataDefinedValues;
     QgsExpression* expression;
diff --git a/src/ui/qgslabelingguibase.ui b/src/ui/qgslabelingguibase.ui
