QGIS/python/core/qgsproject.sip

/** \ingroup core
 * Reads and writes project states.


  @note

  Has two general kinds of state to make persistent.  (I.e., to read and
  write.)  First, Qgis proprietary information.  Second plug-in information.

  A singleton since there shall only be one active project at a time; and
  provides canonical location for plug-ins and main app to find/set
  properties.

  Might want to consider moving from Singleton; i.e., allowing more than one
  project.  Just as the GIMP can have simultaneous multiple images, perhaps
  qgis can one day have simultaneous multiple projects.

*/
class QgsProject : QObject
{
%TypeHeaderCode
#include <qgsproject.h>
%End

  public:

    /**
     * @todo XXX Should have semantics for saving project if dirty as last gasp?
     */
    ~QgsProject();

    /// access to canonical QgsProject instance
    static QgsProject * instance();

    /**
     * Every project has an associated title string
     *
     * @deprecated Use setTitle instead.
     */
    //@{
    void title( const QString & title ) /Deprecated/;

    /** Set project title
     *  @note added in 2.4
     */
    void setTitle( const QString& title );

    /** Returns title */
    QString title() const;
    //@}

    /**
     * the dirty flag is true if the project has been modified since the last
     * write()
     */
    //@{
    bool isDirty() const;

    // ### QGIS 3: remove in favor of setDirty(...)
    void dirty( bool b );

    /** Set project as dirty (modified).
     *  @note added in 2.4 */
    void setDirty( bool b );
    //@}


    /**
     * Every project has an associated file that contains its XML
     */
    //@{
    void setFileName( const QString & name );

    /** Returns file name */
    QString fileName() const;
    //@}

    /** Returns QFileInfo object for the project's associated file.
     * @note added in QGIS 2.9
     */
    QFileInfo fileInfo() const;

    /** Clear the project
     * @note added in 2.4
     */
    void clear();


    /** Read project file
     *
     * @note Any current plug-in state is erased
     *
     * @note dirty set to false after successful invocation
     *
     * @note file name argument implicitly sets file
     *
     * @note
     *
     * - Gets the extents
     * - Creates maplayers
     * - Registers maplayers
     *
     * @note it's presumed that the caller has already reset the map canvas, map registry, and legend
     */
    //@{
    bool read( const QFileInfo & file );
    bool read();
    //@}


    /** Read the layer described in the associated Dom node
     *
     * @param layerNode   represents a QgsProject Dom node that maps to a specific layer.
     *
     * QgsProject raises an exception when one of the QgsProject::read()
     * implementations fails.  Since the read()s are invoked from qgisapp,
     * then qgisapp handles the exception.  It prompts the user for the new
     * location of the data, if any.  If there is a new location, the Dom
     * node associated with the layer has its datasource tag corrected.
     * Then that node is passed to this member function to be re-opened.
     *
     */
    bool read( QDomNode & layerNode );


    /** Write project file
     *
     * XXX How to best get read access to Qgis state?  Actually we can finagle
     * that by searching for qgisapp in object hiearchy.
     *
     * @note file name argument implicitly sets file
     *
     * @note dirty set to false after successful invocation
     */
    //@{
    bool write( const QFileInfo & file );
    bool write();
    //@}

    /**
     * removes all project properties
     *
     * ### QGIS 3: remove in favor of clear()
     */
    void clearProperties();


    /* key value mutators
     *
     * keys would be the familiar QSettings-like '/' delimited entries, implying
     * a hierarchy of keys and corresponding values
     *
     * @note The key string must be valid xml tag names in order to be saved to the file.
     */
    //@{
    //! @note available in python bindings as writeEntryBool
    bool writeEntry( const QString & scope, const QString & key, bool value ) /PyName=writeEntryBool/;
    //! @note available in python bindings as writeEntryDouble
    bool writeEntry( const QString & scope, const QString & key, double value ) /PyName=writeEntryDouble/;
    bool writeEntry( const QString & scope, const QString & key, int value );
    bool writeEntry( const QString & scope, const QString & key, const QString & value );
    bool writeEntry( const QString & scope, const QString & key, const QStringList & value );
    //@}

    /** Key value accessors
     *
     * keys would be the familiar QSettings-like '/' delimited entries,
     * implying a hierarchy of keys and corresponding values
     *
     */
    //@{
    QStringList readListEntry( const QString & scope, const QString & key, const QStringList& def = QStringList(), bool *ok = 0 ) const;

    QString readEntry( const QString & scope, const QString & key, const QString & def = QString::null, bool * ok = 0 ) const;
    int readNumEntry( const QString & scope, const QString & key, int def = 0, bool * ok = 0 ) const;
    double readDoubleEntry( const QString & scope, const QString & key, double def = 0, bool * ok = 0 ) const;
    bool readBoolEntry( const QString & scope, const QString & key, bool def = false, bool * ok = 0 ) const;
    //@}


    /** Remove the given key */
    bool removeEntry( const QString & scope, const QString & key );


    /** Return keys with values -- do not return keys that contain other keys
     *
     * @note equivalent to QSettings entryList()
     */
    QStringList entryList( const QString & scope, const QString & key ) const;

    /** Return keys with keys -- do not return keys that contain only values
     *
     * @note equivalent to QSettings subkeyList()
     */
    QStringList subkeyList( const QString & scope, const QString & key ) const;


    /** Dump out current project properties to stderr
     *
     * @todo XXX Now slightly broken since re-factoring.  Won't print out top-level key
     *           and redundantly prints sub-keys.
     */
    void dumpProperties() const;

    /** Prepare a filename to save it to the project file */
    QString writePath( const QString& filename, const QString& relativeBasePath = QString::null ) const;

    /** Turn filename read from the project file to an absolute path */
    QString readPath( QString filename ) const;

    /** Return error message from previous read/write */
    QString error() const;

    /** Change handler for missing layers.
     * Deletes old handler and takes ownership of the new one.
     */
    void setBadLayerHandler( QgsProjectBadLayerHandler* handler /Transfer/ );

    /** Returns project file path if layer is embedded from other project file. Returns empty string if layer is not embedded*/
    QString layerIsEmbedded( const QString& id ) const;

    /** Creates a maplayer instance defined in an arbitrary project file. Caller takes ownership
     * @return the layer or 0 in case of error
     * @note not available in Python bindings
     */
    /*
    bool createEmbeddedLayer( const QString& layerId, const QString& projectFilePath, QList<QDomNode>& brokenNodes,
                              QList< QPair< QgsVectorLayer*, QDomElement > >& vectorLayerList, bool saveFlag = true );
    */

    /** Create layer group instance defined in an arbitrary project file.
     * @note: added in version 2.4
     */
    QgsLayerTreeGroup* createEmbeddedGroup( const QString& groupName, const QString& projectFilePath, const QStringList &invisibleLayers );

    /** Convenience function to set snap settings per layer */
    void setSnapSettingsForLayer( const QString& layerId, bool enabled, QgsSnapper::SnappingType type, QgsTolerance::UnitType unit, double tolerance,
                                  bool avoidIntersection );

    /** Convenience function to query snap settings of a layer */
    bool snapSettingsForLayer( const QString& layerId, bool& enabled /Out/, QgsSnapper::SnappingType& type /Out/, QgsTolerance::UnitType& units /Out/, double& tolerance /Out/,
                               bool& avoidIntersection /Out/ ) const;

    /** Convenience function to set topological editing */
    void setTopologicalEditing( bool enabled );

    /** Convenience function to query topological editing status */
    bool topologicalEditing() const;

    /** Convenience function to query default distance measurement units for project.
     * @note added in QGIS 2.14
     */
    QGis::UnitType distanceUnits() const;

    /** Return project's home path
      @return home path of project (or QString::null if not set) */
    QString homePath() const;

    QgsRelationManager* relationManager() const;

    /** Return pointer to the root (invisible) node of the project's layer tree
     * @note added in 2.4
     */
    QgsLayerTreeGroup* layerTreeRoot() const;

    /** Return pointer to the helper class that synchronizes map layer registry with layer tree
     * @note added in 2.4
     */
    QgsLayerTreeRegistryBridge* layerTreeRegistryBridge() const;

    /** Returns pointer to the project's visibility preset collection.
     * @note added in QGIS 2.12
     */
    QgsVisibilityPresetCollection* visibilityPresetCollection();

  protected:

    /** Set error message from read/write operation
     * @note not available in Python bindings
     */
    //void setError( const QString& errorMessage );

    /** Clear error message
     * @note not available in Python bindings
     */
    //void clearError();

    //! Creates layer and adds it to maplayer registry
    //! @note not available in python bindings
    // bool addLayer( const QDomElement& layerElem, QList<QDomNode>& brokenNodes, QList< QPair< QgsVectorLayer*, QDomElement > >& vectorLayerList );

    //! @note not available in python bindings
    // void initializeEmbeddedSubtree( const QString& projectFilePath, QgsLayerTreeGroup* group );

    //! @note not available in python bindings
    // void loadEmbeddedNodes( QgsLayerTreeGroup* group );

  signals:
    //! emitted when project is being read
    void readProject( const QDomDocument & );

    //! emitted when project is being written
    void writeProject( QDomDocument & );

    /**
     * Emitted, after the basic initialisation of a layer from the project
     * file is done. You can use this signal to read additional information
     * from the project file.
     *
     * @param mapLayer  The map layer which is being initialized
     * @param layerNode The layer node from the project file
     */
    void readMapLayer( QgsMapLayer *mapLayer, const QDomElement &layerNode );

    /**
     * Emitted, when a layer is being saved. You can use this method to save
     * additional information to the layer.
     *
     * @param mapLayer  The map layer which is being initialized
     * @param layerElem The layer element from the project file
     * @param doc The document
     */
    void writeMapLayer( QgsMapLayer *mapLayer, QDomElement &layerElem, QDomDocument &doc );

    //! emitted when the project file has been written and closed
    void projectSaved();

    //! emitted when an old project file is read.
    void oldProjectVersionWarning( const QString& );

    //! emitted when a layer from a projects was read
    // @param i current layer
    // @param n number of layers
    void layerLoaded( int i, int n );

    void loadingLayer( const QString& );

    void snapSettingsChanged();

  private:

    QgsProject(); // private 'cause it's a singleton

}; // QgsProject


/** Interface for classes that handle missing layer files when reading project file. */
class QgsProjectBadLayerHandler
{
%TypeHeaderCode
#include <qgsproject.h>
%End

  public:
    virtual void handleBadLayers( const QList<QDomNode>& layers, const QDomDocument& projectDom ) = 0;
    virtual ~QgsProjectBadLayerHandler();
};


/** Default bad layer handler which ignores any missing layers. */
class QgsProjectBadLayerDefaultHandler : QgsProjectBadLayerHandler
{
%TypeHeaderCode
#include <qgsproject.h>
%End

  public:
    virtual void handleBadLayers( const QList<QDomNode>& layers, const QDomDocument& projectDom );

};