Merge pull request #3320 from mhugo/fix_snapping2

Data dependency between layers + snapping fix

Author: Hugo Mercier

ci/travis/linux/qt5/blacklist.txt

@@ -9,6 +9,7 @@ PyQgsSipCoverage
 PyQgsSpatialiteProvider
 PyQgsVirtualLayerDefinition
 PyQgsVirtualLayerProvider
+PyQgsLayerDependencies
 qgis_composermapgridtest
 qgis_composerutils
 ProcessingGrass7AlgorithmsImageryTest

images/images.qrc

@@ -665,6 +665,7 @@
         <file>themes/default/mActionAddAfsLayer.svg</file>
         <file>themes/default/mIconFormSelect.svg</file>
         <file>themes/default/mActionMultiEdit.svg</file>
+        <file>themes/default/dependencies.svg</file>
     </qresource>
     <qresource prefix="/images/tips">
         <file alias="symbol_levels.png">qgis_tips/symbol_levels.png</file>

images/themes/default/dependencies.svg

@@ -80,6 +80,7 @@
 %Include qgslogger.sip
 %Include qgsmaphittest.sip
 %Include qgsmaplayer.sip
+%Include qgsmaplayerdependency.sip
 %Include qgsmaplayerlegend.sip
 %Include qgsmaplayermodel.sip
 %Include qgsmaplayerproxymodel.sip

python/core/core.sip

@@ -676,6 +676,32 @@ class QgsMapLayer : QObject
      */
     void emitStyleChanged();
 
+    /**
+     * Sets the list of layers that may modify data/geometries of this layer when modified.
+     * @see dependencies()
+     *
+     * @param layersIds IDs of the layers that this layer depends on
+     * @returns false if a dependency cycle has been detected (the change dependency set is not changed in that case)
+     */
+    virtual bool setDataDependencies( const QSet<QString>& layersIds );
+
+    /**
+     * Sets the list of layers that may modify data/geometries of this layer when modified.
+     * @see dependencies()
+     *
+     * @param set of QgsMapLayerDependency. Only user-defined dependencies will be added
+     * @returns false if a dependency cycle has been detected (the change dependency set is not changed in that case)
+     */
+    bool setDataDependencies( const QSet<QgsMapLayerDependency>& layers );
+
+    /**
+     * Gets the list of dependencies. This includes data dependencies set by the user (@see setDataDependencies)
+     * as well as dependencies given by the provider
+     *
+     * @returns a set of QgsMapLayerDependency
+     */
+    virtual QSet<QgsMapLayerDependency> dependencies() const;
+
   signals:
 
     /** Emit a signal with status (e.g. to be caught by QgisApp and display a msg on status bar) */
@@ -766,4 +792,7 @@ class QgsMapLayer : QObject
     void appendError( const QgsErrorMessage &error );
     /** Set error message */
     void setError( const QgsError &error );
+
+    //! Checks if new change dependency candidates introduce a cycle
+    bool hasDataDependencyCycle( const QSet<QgsMapLayerDependency>& layersIds ) const;
 };

python/core/qgsmaplayer.sip

@@ -0,0 +1,36 @@
+class QgsMapLayerDependency
+{
+%TypeHeaderCode
+#include "qgsmaplayerdependency.h"
+%End
+ public:
+  //! Type of dependency
+  enum Type
+  {
+    PresenceDependency = 1, // The layer must be already present (in the registry) for this dependency to be resolved
+    DataDependency     = 2  // The layer may be invalidated by data changes on another layer
+  };
+
+  //! Origin of the dependency
+  enum Origin
+  {
+    FromProvider = 0,  // Dependency given by the provider, the user cannot change it
+    FromUser     = 1   // Dependency given by the user
+  };
+
+  //! Standard constructor
+  QgsMapLayerDependency( QString layerId, Type type = DataDependency, Origin origin = FromUser );
+
+  //! Return the dependency type
+  Type type() const;
+
+  //! Return the dependency origin
+  Origin origin() const;
+
+  //! Return the ID of the layer this dependency depends on
+  QString layerId() const;
+
+  bool operator==( const QgsMapLayerDependency& other ) const;
+};
+
+

python/core/qgsmaplayerdependency.sip

@@ -368,7 +368,7 @@ class QgsVectorDataProvider : QgsDataProvider
     /**
      * Get the list of layer ids on which this layer depends. This in particular determines the order of layer loading.
      */
-    virtual QSet<QString> layerDependencies() const;
+    virtual QSet<QgsMapLayerDependency> dependencies() const;
 
   signals:
     /** Signals an error in this provider */

python/core/qgsvectordataprovider.sip

@@ -422,9 +422,23 @@ class QgsVectorLayer : QgsMapLayer
     const QList<QgsVectorJoinInfo> vectorJoins() const;
 
     /**
-     * Get the list of layer ids on which this layer depends. This in particular determines the order of layer loading.
+     * Sets the list of layers that may modify data/geometries of this layer when modified.
+     * This is meant mainly to declare database triggers between layers.
+     * When one of these layers is modified (feature added/deleted or geometry changed),
+     * dataChanged() will be emitted, allowing users of this layer to refresh / update it.
+     *
+     * @param layersIds IDs of the layers that this layer depends on
+     * @returns false if a dependency cycle has been detected (the change dependency set is not changed in that case)
+     */
+    bool setDataDependencies( const QSet<QString>& layersIds );
+
+    /**
+     * Gets the list of dependencies. This includes data dependencies set by the user (@see setDataDependencies)
+     * as well as dependencies given by the provider
+     *
+     * @returns a set of QgsMapLayerDependency
      */
-    virtual QSet<QString> layerDependencies() const;
+    virtual QSet<QgsMapLayerDependency> dependencies() const;
 
     /**
      * Add a new field which is calculated by the expression specified

python/core/qgsvectorlayer.sip

@@ -52,6 +52,7 @@
 #include "qgsdatasourceuri.h"
 #include "qgsrenderer.h"
 #include "qgsexpressioncontext.h"
+#include "layertree/qgslayertreelayer.h"
 
 #include <QMessageBox>
 #include <QDir>
@@ -291,6 +292,27 @@ QgsVectorLayerProperties::QgsVectorLayerProperties(
 
   QString title = QString( tr( "Layer Properties - %1" ) ).arg( mLayer->name() );
   restoreOptionsBaseUi( title );
+
+  mLayersDependenciesTreeGroup.reset( QgsProject::instance()->layerTreeRoot()->clone() );
+  QgsLayerTreeLayer* layer = mLayersDependenciesTreeGroup->findLayer( mLayer->id() );
+  layer->parent()->takeChild( layer );
+  mLayersDependenciesTreeModel.reset( new QgsLayerTreeModel( mLayersDependenciesTreeGroup.data() ) );
+  // use visibility as selection
+  mLayersDependenciesTreeModel->setFlag( QgsLayerTreeModel::AllowNodeChangeVisibility );
+
+  mLayersDependenciesTreeGroup->setVisible( Qt::Unchecked );
+
+  QSet<QString> dependencySources;
+  Q_FOREACH ( const QgsMapLayerDependency& dep, mLayer->dependencies() )
+  {
+    dependencySources << dep.layerId();
+  }
+  Q_FOREACH ( QgsLayerTreeLayer* layer, mLayersDependenciesTreeGroup->findLayers() )
+  {
+    layer->setVisible( dependencySources.contains( layer->layerId() ) ? Qt::Checked : Qt::Unchecked );
+  }
+
+  mLayersDependenciesTreeView->setModel( mLayersDependenciesTreeModel.data() );
 } // QgsVectorLayerProperties ctor
 
 
@@ -558,6 +580,18 @@ void QgsVectorLayerProperties::apply()
   QgsExpressionContextUtils::setLayerVariables( mLayer, mVariableEditor->variablesInActiveScope() );
   updateVariableEditor();
 
+  // save layer dependencies
+  QSet<QString> deps;
+  Q_FOREACH ( const QgsLayerTreeLayer* layer, mLayersDependenciesTreeGroup->findLayers() )
+  {
+    if ( layer->isVisible() )
+      deps << layer->layerId();
+  }
+  if ( ! mLayer->setDataDependencies( deps ) )
+  {
+    QMessageBox::warning( nullptr, tr( "Dependency cycle" ), tr( "This configuration introduces a cycle in data dependencies and will be ignored" ) );
+  }
+
   // update symbology
   emit refreshLegend( mLayer->id() );
 

src/app/qgsvectorlayerproperties.cpp

@@ -25,6 +25,8 @@
 #include "qgscontexthelp.h"
 #include "qgsmaplayerstylemanager.h"
 #include "qgsvectorlayer.h"
+#include "layertree/qgslayertreemodel.h"
+#include "layertree/qgslayertreegroup.h"
 
 class QgsMapLayer;
 
@@ -193,6 +195,9 @@ class APP_EXPORT QgsVectorLayerProperties : public QgsOptionsDialogBase, private
 
     QgsExpressionContext createExpressionContext() const override;
 
+    QScopedPointer<QgsLayerTreeGroup> mLayersDependenciesTreeGroup;
+    QScopedPointer<QgsLayerTreeModel> mLayersDependenciesTreeModel;
+
   private slots:
     void openPanel( QgsPanelWidget* panel );
 };

src/app/qgsvectorlayerproperties.h

@@ -111,6 +111,22 @@ bool QgsLayerDefinition::loadLayerDefinition( QDomDocument doc, QgsLayerTreeGrou
         joinNode.toElement().setAttribute( "joinLayerId", newid );
       }
     }
+
+    // change IDs of dependencies
+    QDomNodeList dataDeps = doc.elementsByTagName( "dataDependencies" );
+    for ( int i = 0; i < dataDeps.size(); i++ )
+    {
+      QDomNodeList layers = dataDeps.at( i ).childNodes();
+      for ( int j = 0; j < layers.size(); j++ )
+      {
+        QDomElement elt = layers.at( j ).toElement();
+        if ( elt.attribute( "id" ) == oldid )
+        {
+          elt.setAttribute( "id", newid );
+        }
+      }
+    }
+
   }
 
   QDomElement layerTreeElem = doc.documentElement().firstChildElement( "layer-tree-group" );