Change in handling of missing layers within QgsProject. Instead of th…

…rowing an exception, now a custom handler is called

that might try to fix the missing layers. There's a default handler (QgsProjectBadLayerDefaultHandler) which simply ignores
all missing layers. Then there's a GUI handler (QgsProjectBadLayerGuiHandler) in GUI library which asks user about
the path for missing layers. QGIS application automatically installs the GUI handler on startup.

This should allow python plugins/applications to work with QgsProject without a fear of a segfault as there are no more
exceptions thrown during load/save of the project files.

Some further notes:
- removed QgsProjectBadLayerException class and (now empty) qgsexception.cpp file
- openFilesRememberingFilter() moved to QgisGui namespace (was duplicated: QgisApp vs QgsOpenVectorLayerDialog)
- removed deprecated buildVectorFilters_ methods
- added python bindings for new classes/methods


git-svn-id: http://svn.osgeo.org/qgis/trunk@12350 c8812cc2-4d05-0410-92ff-de0c093fc19c

python/core/qgsproject.sip

@@ -235,6 +235,11 @@ public:
       @note added in 1.4 */
     QString error() const;
 
+    /** Change handler for missing layers.
+      Deletes old handler and takes ownership of the new one.
+      @note added in 1.4 */
+    void setBadLayerHandler( QgsProjectBadLayerHandler* handler );
+
   protected:
 
     /** Set error message from read/write operation
@@ -259,3 +264,30 @@ public:
 
 }; // QgsProject
 
+
+/** Interface for classes that handle missing layer files when reading project file.
+  @note added in 1.4 */
+class QgsProjectBadLayerHandler
+{
+%TypeHeaderCode
+#include <qgsproject.h>
+%End
+
+public:
+  virtual void handleBadLayers( QList<QDomNode> layers, QDomDocument projectDom ) = 0;
+  virtual ~QgsProjectBadLayerHandler();
+};
+
+
+/** Default bad layer handler which ignores any missing layers.
+  @note added in 1.4 */
+class QgsProjectBadLayerDefaultHandler : QgsProjectBadLayerHandler
+{
+%TypeHeaderCode
+#include <qgsproject.h>
+%End
+
+public:
+  virtual void handleBadLayers( QList<QDomNode> layers, QDomDocument projectDom );
+
+};

python/gui/gui.sip

@@ -22,6 +22,7 @@
 %Include qgsmaptoolzoom.sip
 %Include qgsmapoverviewcanvas.sip
 %Include qgsmessageviewer.sip
+%Include qgsprojectbadlayerguihandler.sip
 %Include qgsprojectionselector.sip
 %Include qgsquickprint.sip
 %Include qgsrubberband.sip

python/gui/qgsprojectbadlayerguihandler.sip

@@ -0,0 +1,21 @@
+
+/** \ingroup gui
+  Handler for missing layers within project.
+
+  Gives user a chance to select path to the missing layers.
+
+  @note added in 1.4
+ */
+class QgsProjectBadLayerGuiHandler : QObject, QgsProjectBadLayerHandler
+{
+%TypeHeaderCode
+#include <qgsprojectbadlayerguihandler.h>
+%End
+
+  public:
+    QgsProjectBadLayerGuiHandler();
+
+    /** implementation of the handler */
+    virtual void handleBadLayers( QList<QDomNode> layers, QDomDocument projectDom );
+
+};

src/app/ogr/qgsopenvectorlayerdialog.cpp

@@ -97,11 +97,11 @@ QStringList QgsOpenVectorLayerDialog::openFile()
 
   QStringList selectedFiles;
   QgsDebugMsg( "Vector file filters: " + mVectorFileFilter );
-  QString enc;
+  QString enc = encoding();
   QString title = tr( "Open an OGR Supported Vector Layer" );
-  openFilesRememberingFilter( "lastVectorFileFilter", mVectorFileFilter, selectedFiles,
-                              title );
-  mEnc = enc;
+  QgisGui::openFilesRememberingFilter( "lastVectorFileFilter", mVectorFileFilter, selectedFiles, enc,
+                                       title );
+
   return selectedFiles;
 }
 
@@ -306,68 +306,6 @@ void QgsOpenVectorLayerDialog::on_buttonSelectSrc_clicked()
 
 }
 
-/**
-  Open files, preferring to have the default file selector be the
-  last one used, if any; also, prefer to start in the last directory
-  associated with filterName.
-
-  @param filterName the name of the filter; used for persistent store
-  key
-  @param filters    the file filters used for QFileDialog
-
-  @param selectedFiles string list of selected files; will be empty
-  if none selected
-  @param title      the title for the dialog
-  @note
-
-  Stores persistent settings under /UI/.  The sub-keys will be
-  filterName and filterName + "Dir".
-
-  Opens dialog on last directory associated with the filter name, or
-  the current working directory if this is the first time invoked
-  with the current filter name.
-
-*/
-void QgsOpenVectorLayerDialog::openFilesRememberingFilter( QString const &filterName,
-    QString const &filters, QStringList & selectedFiles, QString &title )
-{
-
-  bool haveLastUsedFilter = false; // by default, there is no last
-  // used filter
-
-  QSettings settings;         // where we keep last used filter in
-
-  // persistant state
-
-  haveLastUsedFilter = settings.contains( "/UI/" + filterName );
-  QString lastUsedFilter = settings.value( "/UI/" + filterName,
-                           QVariant( QString::null ) ).toString();
-
-  QString lastUsedDir = settings.value( "/UI/" + filterName + "Dir", "." ).toString();
-  QgsDebugMsg( "Opening file dialog with filters: " + filters );
-
-  if ( haveLastUsedFilter )
-  {
-    selectedFiles = QFileDialog::getOpenFileNames( 0, title, lastUsedDir, filters, &lastUsedFilter );
-  }
-  else
-  {
-    selectedFiles = QFileDialog::getOpenFileNames( 0, title, lastUsedDir, filters );
-  }
-
-  if ( !selectedFiles.isEmpty() )
-  {
-    QString myFirstFileName = selectedFiles.first();
-    QFileInfo myFI( myFirstFileName );
-    QString myPath = myFI.path();
-
-    QgsDebugMsg( "Writing last used dir: " + myPath );
-
-    settings.setValue( "/UI/" + filterName, lastUsedFilter );
-    settings.setValue( "/UI/" + filterName + "Dir", myPath );
-  }
-}   // openFilesRememberingFilter_
-
 
 
 //********************auto connected slots *****************/

src/app/ogr/qgsopenvectorlayerdialog.h

@@ -46,9 +46,6 @@ class QgsOpenVectorLayerDialog : public QDialog, private Ui::QgsOpenVectorLayerD
     //! Returns the connection type
     QString dataSourceType();
   private:
-    //! Shows a dialog remembering the last directory and filter selected */
-    void openFilesRememberingFilter( QString const &filterName,
-                                     QString const &filters, QStringList & selectedFiles, QString &title );
     //! Stores the file vector filters */
     QString mVectorFileFilter;
     //! Stores the selected datasources */