[FEATURE] Import a vector layer from a datasource to a different one

Merge of another part of my Summer of Code work (remote-tracking branch 'brushtyler/import_layer')

python/core/core.sip

@@ -84,6 +84,7 @@
 %Include qgsvectordataprovider.sip
 %Include qgsvectorfilewriter.sip
 %Include qgsvectorlayer.sip
+%Include qgsvectorlayerimport.sip
 %Include qgsvectoroverlay.sip
 
 %Include qgsnetworkaccessmanager.sip

python/core/qgsproviderregistry.sip

@@ -60,8 +60,6 @@ class QgsProviderRegistry
      * @note this method was added in QGIS 1.1
      */
     virtual QString protocolDrivers() const;
-
-
 
   private:
 

python/core/qgsvectorlayerimport.sip

@@ -0,0 +1,65 @@
+
+/**
+ There are two possibilities how to use this class:
+ 1. static call to QgsVectorLayerImport::importLayer(...) which saves the whole vector layer
+ 2. create an instance of the class and issue calls to addFeature(...)
+ */
+class QgsVectorLayerImport
+{
+%TypeHeaderCode
+#include <qgsvectorlayerimport.h>
+#include <qgsfield.h>
+%End
+
+public:
+
+    enum ImportError
+    {
+      NoError = 0,
+      ErrDriverNotFound,
+      ErrCreateDataSource,
+      ErrCreateLayer,
+      ErrAttributeTypeUnsupported,
+      ErrAttributeCreationFailed,
+      ErrProjection,
+      ErrFeatureWriteFailed,
+      ErrInvalidLayer, 
+      ErrInvalidProvider,
+      ErrProviderUnsupportedFeature,
+      ErrConnectionFailed
+    };
+
+    /** Write contents of vector layer to a different datasource */
+    static ImportError importLayer( QgsVectorLayer* layer,
+                                    const QString& uri,
+                                    const QString& providerKey,
+                                    const QgsCoordinateReferenceSystem *destCRS,
+                                    bool onlySelected = FALSE,
+                                    QString *errorMessage /Out/ = 0,
+                                    bool skipAttributeCreation = FALSE,
+                                    QMap<QString, QVariant> *options = 0
+                                  );
+
+    /** create a empty layer and add fields to it */
+    QgsVectorLayerImport( const QString &uri,
+                          const QString &provider,
+                          const QgsFieldMap& fields,
+                          QGis::WkbType geometryType,
+                          const QgsCoordinateReferenceSystem* crs,
+                          bool overwrite = false,
+                          const QMap<QString, QVariant> *options = 0
+                        );
+
+    /** checks whether there were any errors */
+    ImportError hasError();
+
+    /** retrieves error message */
+    QString errorMessage();
+
+    /** add feature to the new created layer */
+    bool addFeature( QgsFeature& feature );
+
+    /** close the new created layer */
+    ~QgsVectorLayerImport();
+};
+

src/core/CMakeLists.txt

@@ -101,6 +101,7 @@ SET(QGIS_CORE_SRCS
   qgsvectordataprovider.cpp
   qgsvectorfilewriter.cpp
   qgsvectorlayer.cpp
+  qgsvectorlayerimport.cpp
   qgsvectorlayerjoinbuffer.cpp
   qgsvectorlayerundocommand.cpp
   qgsvectoroverlay.cpp
@@ -333,6 +334,7 @@ SET(QGIS_CORE_HDRS
   qgsvectordataprovider.h
   qgsvectorfilewriter.h
   qgsvectorlayer.h
+  qgsvectorlayerimport.h
   qgsvectoroverlay.h
   qgstolerance.h
 

src/core/qgsproviderregistry.cpp

@@ -30,6 +30,7 @@
 #include "qgslogger.h"
 #include "qgsmessageoutput.h"
 #include "qgsprovidermetadata.h"
+#include "qgsvectorlayer.h"
 
 
 // typedefs for provider plugin functions of interest
@@ -468,7 +469,7 @@ void * QgsProviderRegistry::function( QString const & providerKey,
   return 0;
 }
 
-QLibrary *QgsProviderRegistry::providerLibrary( QString const & providerKey )
+QLibrary *QgsProviderRegistry::providerLibrary( QString const & providerKey ) const
 {
   QString lib = library( providerKey );
 

src/core/qgsproviderregistry.h

@@ -28,7 +28,8 @@
 
 class QgsDataProvider;
 class QgsProviderMetadata;
-
+class QgsVectorLayer;
+class QgsCoordinateReferenceSystem;
 
 
 /** \ingroup core
@@ -78,7 +79,7 @@ class CORE_EXPORT QgsProviderRegistry
     void *function( const QString & providerKey,
                     const QString & functionName );
 
-    QLibrary *providerLibrary( const QString & providerKey );
+    QLibrary *providerLibrary( const QString & providerKey ) const;
 
     /** Return list of available providers by their keys */
     QStringList providerList() const;

src/core/qgsvectorfilewriter.h

@@ -116,6 +116,8 @@ class CORE_EXPORT QgsVectorFileWriter
     /** add feature to the currently opened shapefile */
     bool addFeature( QgsFeature& feature );
 
+    QMap<int, int> attrIdxToOgrIdx() { return mAttrIdxToOgrIdx; }
+
     /** close opened shapefile for writing */
     ~QgsVectorFileWriter();