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QgsProject Class Reference

Reads and writes project states. More...

#include <qgsproject.h>

Inheritance diagram for QgsProject:
Inheritance graph
[legend]

Classes

struct  Imp
 

Signals

void readProject (const QDomDocument &)
 emitted when project is being read More...
 
void writeProject (QDomDocument &)
 emitted when project is being written More...
 
void readMapLayer (QgsMapLayer *mapLayer, const QDomElement &layerNode)
 Emitted, after the basic initialisation of a layer from the project file is done. More...
 
void writeMapLayer (QgsMapLayer *mapLayer, QDomElement &layerElem, QDomDocument &doc)
 Emitted, when a layer is being saved. More...
 
void projectSaved ()
 emitted when the project file has been written and closed More...
 
void oldProjectVersionWarning (QString)
 emitted when an old project file is read. More...
 
void layerLoaded (int i, int n)
 emitted when a layer from a projects was read More...
 
void loadingLayer (QString)
 
void snapSettingsChanged ()
 

Public Member Functions

 ~QgsProject ()
 
void clear ()
 Clear the project. More...
 
bool read (QDomNode &layerNode)
 read the layer described in the associated Dom node More...
 
void clearProperties ()
 syntactic sugar for property lists More...
 
bool removeEntry (const QString &scope, const QString &key)
 remove the given key More...
 
QStringList entryList (const QString &scope, const QString &key) const
 return keys with values – do not return keys that contain other keys More...
 
QStringList subkeyList (const QString &scope, const QString &key) const
 return keys with keys – do not return keys that contain only values More...
 
void dumpProperties () const
 dump out current project properties to stderr More...
 
QString writePath (QString filename, QString relativeBasePath=QString::null) const
 prepare a filename to save it to the project file More...
 
QString readPath (QString filename) const
 turn filename read from the project file to an absolute path More...
 
QString error () const
 Return error message from previous read/write. More...
 
void setBadLayerHandler (QgsProjectBadLayerHandler *handler)
 Change handler for missing layers. More...
 
QString layerIsEmbedded (const QString &id) const
 Returns project file path if layer is embedded from other project file. More...
 
bool createEmbeddedLayer (const QString &layerId, const QString &projectFilePath, QList< QDomNode > &brokenNodes, QList< QPair< QgsVectorLayer *, QDomElement > > &vectorLayerList, bool saveFlag=true)
 Creates a maplayer instance defined in an arbitrary project file. More...
 
QgsLayerTreeGroupcreateEmbeddedGroup (const QString &groupName, const QString &projectFilePath)
 Create layer group instance defined in an arbitrary project file. More...
 
void setSnapSettingsForLayer (const QString &layerId, bool enabled, QgsSnapper::SnappingType type, QgsTolerance::UnitType unit, double tolerance, bool avoidIntersection)
 Convenience function to set snap settings per layer. More...
 
bool snapSettingsForLayer (const QString &layerId, bool &enabled, QgsSnapper::SnappingType &type, QgsTolerance::UnitType &units, double &tolerance, bool &avoidIntersection) const
 Convenience function to query snap settings of a layer. More...
 
void setTopologicalEditing (bool enabled)
 Convenience function to set topological editing. More...
 
bool topologicalEditing () const
 Convenience function to query topological editing status. More...
 
QString homePath () const
 Return project's home path. More...
 
QgsRelationManagerrelationManager () const
 
QgsLayerTreeGrouplayerTreeRoot () const
 Return pointer to the root (invisible) node of the project's layer tree. More...
 
QgsLayerTreeRegistryBridgelayerTreeRegistryBridge () const
 Return pointer to the helper class that synchronizes map layer registry with layer tree. More...
 
void title (const QString &title)
 Every project has an associated title string. More...
 
void setTitle (const QString &title)
 Set project title. More...
 
const QString & title () const
 returns title More...
 
bool isDirty () const
 the dirty flag is true if the project has been modified since the last write() More...
 
void dirty (bool b)
 
void setDirty (bool b)
 Set project as dirty (modified). More...
 
void setFileName (const QString &name)
 Every project has an associated file that contains its XML. More...
 
QString fileName () const
 returns file name More...
 
bool read (const QFileInfo &file)
 read project file More...
 
bool read ()
 presuming that the caller has already reset the map canvas, map registry, and legend More...
 
bool write (const QFileInfo &file)
 write project file More...
 
bool write ()
 
bool writeEntry (const QString &scope, const QString &key, bool value)
 
bool writeEntry (const QString &scope, const QString &key, double value)
 
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)
 
QStringList readListEntry (const QString &scope, const QString &key, QStringList def=QStringList(), bool *ok=0) const
 key value accessors More...
 
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
 

Static Public Member Functions

static QgsProjectinstance ()
 access to canonical QgsProject instance More...
 

Protected Member Functions

void setError (QString errorMessage)
 Set error message from read/write operation. More...
 
void clearError ()
 Clear error message. More...
 
bool addLayer (const QDomElement &layerElem, QList< QDomNode > &brokenNodes, QList< QPair< QgsVectorLayer *, QDomElement > > &vectorLayerList)
 
void initializeEmbeddedSubtree (const QString &projectFilePath, QgsLayerTreeGroup *group)
 
void loadEmbeddedNodes (QgsLayerTreeGroup *group)
 

Detailed Description

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.

Constructor & Destructor Documentation

QgsProject::~QgsProject ( )
Todo:
XXX Should have semantics for saving project if dirty as last gasp?

Member Function Documentation

bool QgsProject::addLayer ( const QDomElement &  layerElem,
QList< QDomNode > &  brokenNodes,
QList< QPair< QgsVectorLayer *, QDomElement > > &  vectorLayerList 
)
protected
Note
not available in python bindings
void QgsProject::clear ( )

Clear the project.

Note
added in 2.4
void QgsProject::clearError ( )
protected

Clear error message.

void QgsProject::clearProperties ( )

syntactic sugar for property lists

extra properties, typically added by plug-ins

This allows for extra properties to be associated with projects. Think of it as a registry bound to a project.

Properties are arbitrary values keyed by a name and associated with a scope. The scope would presumably refer to your plug-in. E.g., "openmodeller".

Note

E.g., open modeller might use:

"QgsProject::instance()->properties("openmodeller")["foo"].

Todo:
"properties" is, overall, a good name; but that might imply that the qgis specific state properites are different since they aren't accessible here. Actually, what if we make "qgis" yet another scope that stores its state in the properties list? E.g., QgsProject::instance()->properties()["qgis"]?

removes all project properties

QGIS 3: remove in favor of clear()

QgsLayerTreeGroup * QgsProject::createEmbeddedGroup ( const QString &  groupName,
const QString &  projectFilePath 
)

Create layer group instance defined in an arbitrary project file.

Note
: added in version 2.4
bool QgsProject::createEmbeddedLayer ( const QString &  layerId,
const QString &  projectFilePath,
QList< QDomNode > &  brokenNodes,
QList< QPair< QgsVectorLayer *, QDomElement > > &  vectorLayerList,
bool  saveFlag = true 
)

Creates a maplayer instance defined in an arbitrary project file.

Caller takes ownership

Returns
the layer or 0 in case of error
void QgsProject::dirty ( bool  b)
void QgsProject::dumpProperties ( ) 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.
QStringList QgsProject::entryList ( const QString &  scope,
const QString &  key 
) const

return keys with values – do not return keys that contain other keys

Note
equivalent to QSettings entryList()
QString QgsProject::error ( ) const

Return error message from previous read/write.

QString QgsProject::fileName ( ) const

returns file name

QString QgsProject::homePath ( ) const

Return project's home path.

Returns
home path of project (or QString::null if not set)
void QgsProject::initializeEmbeddedSubtree ( const QString &  projectFilePath,
QgsLayerTreeGroup group 
)
protected
Note
not available in python bindings
QgsProject * QgsProject::instance ( )
static

access to canonical QgsProject instance

bool QgsProject::isDirty ( ) const

the dirty flag is true if the project has been modified since the last write()

QString QgsProject::layerIsEmbedded ( const QString &  id) const

Returns project file path if layer is embedded from other project file.

Returns empty string if layer is not embedded

void QgsProject::layerLoaded ( int  i,
int  n 
)
signal

emitted when a layer from a projects was read

QgsLayerTreeRegistryBridge* QgsProject::layerTreeRegistryBridge ( ) const
inline

Return pointer to the helper class that synchronizes map layer registry with layer tree.

Note
added in 2.4
QgsLayerTreeGroup * QgsProject::layerTreeRoot ( ) const

Return pointer to the root (invisible) node of the project's layer tree.

Note
added in 2.4
void QgsProject::loadEmbeddedNodes ( QgsLayerTreeGroup group)
protected
Note
not available in python bindings
void QgsProject::loadingLayer ( QString  )
signal
void QgsProject::oldProjectVersionWarning ( QString  )
signal

emitted when an old project file is read.

void QgsProject::projectSaved ( )
signal

emitted when the project file has been written and closed

bool QgsProject::read ( const QFileInfo &  file)

read project file

Please note that most of the contents were copied from qgsproject.

Note
Any current plug-in state is erased
dirty set to false after successful invocation
file name argument implicitly sets file
  • 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 QgsProject::read ( )

presuming that the caller has already reset the map canvas, map registry, and legend

Shows a warning when an old project file is read.

bool QgsProject::read ( QDomNode &  layerNode)

read the layer described in the associated Dom node

Parameters
layerNoderepresents 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 QgsProject::readBoolEntry ( const QString &  scope,
const QString &  key,
bool  def = false,
bool *  ok = 0 
) const
double QgsProject::readDoubleEntry ( const QString &  scope,
const QString &  key,
double  def = 0,
bool *  ok = 0 
) const
QString QgsProject::readEntry ( const QString &  scope,
const QString &  key,
const QString &  def = QString::null,
bool *  ok = 0 
) const
QStringList QgsProject::readListEntry ( const QString &  scope,
const QString &  key,
QStringList  def = QStringList(),
bool *  ok = 0 
) const

key value accessors

keys would be the familiar QSettings-like '/' delimited entries, implying a hierarchy of keys and corresponding values

Note
The key string must include '/'s. E.g., "/foo" not "foo".
void QgsProject::readMapLayer ( QgsMapLayer mapLayer,
const QDomElement &  layerNode 
)
signal

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.

Parameters
mapLayerThe map layer which is being initialized
layerNodeThe layer node from the project file
int QgsProject::readNumEntry ( const QString &  scope,
const QString &  key,
int  def = 0,
bool *  ok = 0 
) const
QString QgsProject::readPath ( QString  filename) const

turn filename read from the project file to an absolute path

void QgsProject::readProject ( const QDomDocument &  )
signal

emitted when project is being read

QgsRelationManager * QgsProject::relationManager ( ) const
bool QgsProject::removeEntry ( const QString &  scope,
const QString &  key 
)

remove the given key

void QgsProject::setBadLayerHandler ( QgsProjectBadLayerHandler handler)

Change handler for missing layers.

Deletes old handler and takes ownership of the new one.

void QgsProject::setDirty ( bool  b)

Set project as dirty (modified).

Note
added in 2.4
void QgsProject::setError ( QString  errorMessage)
protected

Set error message from read/write operation.

void QgsProject::setFileName ( const QString &  name)

Every project has an associated file that contains its XML.

void QgsProject::setSnapSettingsForLayer ( const QString &  layerId,
bool  enabled,
QgsSnapper::SnappingType  type,
QgsTolerance::UnitType  unit,
double  tolerance,
bool  avoidIntersection 
)

Convenience function to set snap settings per layer.

void QgsProject::setTitle ( const QString &  title)

Set project title.

Note
added in 2.4
void QgsProject::setTopologicalEditing ( bool  enabled)

Convenience function to set topological editing.

void QgsProject::snapSettingsChanged ( )
signal
bool QgsProject::snapSettingsForLayer ( const QString &  layerId,
bool &  enabled,
QgsSnapper::SnappingType type,
QgsTolerance::UnitType units,
double &  tolerance,
bool &  avoidIntersection 
) const

Convenience function to query snap settings of a layer.

QStringList QgsProject::subkeyList ( const QString &  scope,
const QString &  key 
) const

return keys with keys – do not return keys that contain only values

Note
equivalent to QSettings subkeyList()
void QgsProject::title ( const QString &  title)

Every project has an associated title string.

QGIS 3: remove in favor of setTitle(...)

QString const & QgsProject::title ( ) const

returns title

bool QgsProject::topologicalEditing ( ) const

Convenience function to query topological editing status.

bool QgsProject::write ( const QFileInfo &  file)

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
dirty set to false after successful invocation
bool QgsProject::write ( )
bool QgsProject::writeEntry ( const QString &  scope,
const QString &  key,
bool  value 
)
Note
available in python bindings as writeEntryBool
bool QgsProject::writeEntry ( const QString &  scope,
const QString &  key,
double  value 
)
Note
available in python bindings as writeEntryDouble
bool QgsProject::writeEntry ( const QString &  scope,
const QString &  key,
int  value 
)
bool QgsProject::writeEntry ( const QString &  scope,
const QString &  key,
const QString &  value 
)
bool QgsProject::writeEntry ( const QString &  scope,
const QString &  key,
const QStringList &  value 
)
void QgsProject::writeMapLayer ( QgsMapLayer mapLayer,
QDomElement &  layerElem,
QDomDocument &  doc 
)
signal

Emitted, when a layer is being saved.

You can use this method to save additional information to the layer.

Parameters
mapLayerThe map layer which is being initialized
layerElemThe layer element from the project file
docThe document
QString QgsProject::writePath ( QString  filename,
QString  relativeBasePath = QString::null 
) const

prepare a filename to save it to the project file

void QgsProject::writeProject ( QDomDocument &  )
signal

emitted when project is being written


The documentation for this class was generated from the following files: