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

Public Member Functions

 ~QgsProject ()
 
void clear ()
 Clear the project. More...
 
void clearProperties ()
 syntactic sugar for property lists More...
 
QgsLayerTreeGroupcreateEmbeddedGroup (const QString &groupName, const QString &projectFilePath)
 Create layer group instance defined in an arbitrary 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...
 
void dumpProperties () const
 dump out current project properties to stderr More...
 
QStringList entryList (const QString &scope, const QString &key) const
 return keys with values – do not return keys that contain other keys More...
 
QString error () const
 Return error message from previous read/write. More...
 
QString homePath () const
 Return project's home path. More...
 
QString layerIsEmbedded (const QString &id) const
 Returns project file path if layer is embedded from other project file. More...
 
QgsLayerTreeRegistryBridgelayerTreeRegistryBridge () const
 Return pointer to the helper class that synchronizes map layer registry with layer tree. More...
 
QgsLayerTreeGrouplayerTreeRoot () const
 Return pointer to the root (invisible) node of the project's layer tree. More...
 
bool read (QDomNode &layerNode)
 read the layer described in the associated Dom node More...
 
QString readPath (QString filename) const
 turn filename read from the project file to an absolute path More...
 
QgsRelationManagerrelationManager () const
 
bool removeEntry (const QString &scope, const QString &key)
 remove the given key More...
 
void setBadLayerHandler (QgsProjectBadLayerHandler *handler)
 Change handler for missing layers. 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...
 
void setTopologicalEditing (bool enabled)
 Convenience function to set topological editing. 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...
 
QStringList subkeyList (const QString &scope, const QString &key) const
 return keys with keys – do not return keys that contain only values More...
 
bool topologicalEditing () const
 Convenience function to query topological editing status. More...
 
QString writePath (QString filename, QString relativeBasePath=QString::null) const
 prepare a filename to save it to the project file 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

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

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.

Definition at line 67 of file qgsproject.h.

Constructor & Destructor Documentation

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

Definition at line 351 of file qgsproject.cpp.

Member Function Documentation

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

Definition at line 747 of file qgsproject.cpp.

void QgsProject::clear ( )

Clear the project.

Note
added in 2.4

Definition at line 422 of file qgsproject.cpp.

void QgsProject::clearError ( )
protected

Clear error message.

Definition at line 1668 of file qgsproject.cpp.

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()

Definition at line 1190 of file qgsproject.cpp.

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

Definition at line 1797 of file qgsproject.cpp.

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

Definition at line 1689 of file qgsproject.cpp.

void QgsProject::dirty ( bool  b)

Definition at line 396 of file qgsproject.cpp.

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.

Definition at line 1448 of file qgsproject.cpp.

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()

Definition at line 1410 of file qgsproject.cpp.

QString QgsProject::error ( ) const

Return error message from previous read/write.

Definition at line 1663 of file qgsproject.cpp.

QString QgsProject::fileName ( ) const

returns file name

Definition at line 417 of file qgsproject.cpp.

QString QgsProject::homePath ( ) const

Return project's home path.

Returns
home path of project (or QString::null if not set)

Definition at line 2032 of file qgsproject.cpp.

void QgsProject::initializeEmbeddedSubtree ( const QString &  projectFilePath,
QgsLayerTreeGroup group 
)
protected
Note
not available in python bindings

Definition at line 1871 of file qgsproject.cpp.

QgsProject * QgsProject::instance ( )
static

access to canonical QgsProject instance

Definition at line 362 of file qgsproject.cpp.

bool QgsProject::isDirty ( ) const

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

Definition at line 390 of file qgsproject.cpp.

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

Definition at line 1679 of file qgsproject.cpp.

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

Definition at line 332 of file qgsproject.h.

QgsLayerTreeGroup * QgsProject::layerTreeRoot ( ) const

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

Note
added in 2.4

Definition at line 2046 of file qgsproject.cpp.

void QgsProject::loadEmbeddedNodes ( QgsLayerTreeGroup group)
protected
Note
not available in python bindings

Definition at line 964 of file qgsproject.cpp.

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

Definition at line 805 of file qgsproject.cpp.

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.

Definition at line 817 of file qgsproject.cpp.

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.

Definition at line 1007 of file qgsproject.cpp.

bool QgsProject::readBoolEntry ( const QString &  scope,
const QString &  key,
bool  def = false,
bool *  ok = 0 
) const

Definition at line 1371 of file qgsproject.cpp.

double QgsProject::readDoubleEntry ( const QString &  scope,
const QString &  key,
double  def = 0,
bool *  ok = 0 
) const

Definition at line 1341 of file qgsproject.cpp.

QString QgsProject::readEntry ( const QString &  scope,
const QString &  key,
const QString &  def = QString::null,
bool *  ok = 0 
) const

Definition at line 1281 of file qgsproject.cpp.

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".

Definition at line 1250 of file qgsproject.cpp.

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

Definition at line 1312 of file qgsproject.cpp.

QString QgsProject::readPath ( QString  filename) const

turn filename read from the project file to an absolute path

Definition at line 1455 of file qgsproject.cpp.

void QgsProject::readProject ( const QDomDocument &  )
signal

emitted when project is being read

QgsRelationManager * QgsProject::relationManager ( ) const

Definition at line 2041 of file qgsproject.cpp.

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

remove the given key

Definition at line 1399 of file qgsproject.cpp.

void QgsProject::setBadLayerHandler ( QgsProjectBadLayerHandler handler)

Change handler for missing layers.

Deletes old handler and takes ownership of the new one.

Definition at line 1673 of file qgsproject.cpp.

void QgsProject::setDirty ( bool  b)

Set project as dirty (modified).

Note
added in 2.4

Definition at line 401 of file qgsproject.cpp.

void QgsProject::setError ( QString  errorMessage)
protected

Set error message from read/write operation.

Definition at line 1658 of file qgsproject.cpp.

void QgsProject::setFileName ( const QString &  name)

Every project has an associated file that contains its XML.

Definition at line 408 of file qgsproject.cpp.

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.

Definition at line 1892 of file qgsproject.cpp.

void QgsProject::setTitle ( const QString &  title)

Set project title.

Note
added in 2.4

Definition at line 378 of file qgsproject.cpp.

void QgsProject::setTopologicalEditing ( bool  enabled)

Convenience function to set topological editing.

Definition at line 2016 of file qgsproject.cpp.

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.

Definition at line 1949 of file qgsproject.cpp.

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()

Definition at line 1428 of file qgsproject.cpp.

void QgsProject::title ( const QString &  title)

Every project has an associated title string.

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

Definition at line 371 of file qgsproject.cpp.

QString const & QgsProject::title ( ) const

returns title

Definition at line 384 of file qgsproject.cpp.

bool QgsProject::topologicalEditing ( ) const

Convenience function to query topological editing status.

Definition at line 2022 of file qgsproject.cpp.

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

Definition at line 1016 of file qgsproject.cpp.

bool QgsProject::write ( )

Definition at line 1024 of file qgsproject.cpp.

bool QgsProject::writeEntry ( const QString &  scope,
const QString &  key,
bool  value 
)
Note
available in python bindings as writeEntryBool

Definition at line 1200 of file qgsproject.cpp.

bool QgsProject::writeEntry ( const QString &  scope,
const QString &  key,
double  value 
)
Note
available in python bindings as writeEntryDouble

Definition at line 1209 of file qgsproject.cpp.

bool QgsProject::writeEntry ( const QString &  scope,
const QString &  key,
int  value 
)

Definition at line 1219 of file qgsproject.cpp.

bool QgsProject::writeEntry ( const QString &  scope,
const QString &  key,
const QString &  value 
)

Definition at line 1228 of file qgsproject.cpp.

bool QgsProject::writeEntry ( const QString &  scope,
const QString &  key,
const QStringList &  value 
)

Definition at line 1238 of file qgsproject.cpp.

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

Definition at line 1564 of file qgsproject.cpp.

void QgsProject::writeProject ( QDomDocument &  )
signal

emitted when project is being written


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