QGIS API Documentation
3.0.2-Girona (307d082)
|
Abstract base class for spatial data provider implementations. More...
#include <qgsdataprovider.h>
Classes | |
struct | PreviewContext |
Stores settings related to the context in which a preview job runs. More... | |
Public Types | |
enum | DataCapability { NoDataCapabilities = 0, File = 1, Dir = 1 << 1, Database = 1 << 2, Net = 1 << 3 } |
enum | ProviderProperty { EvaluateDefaultValues, CustomData = 3000 } |
Properties are used to pass custom configuration options into data providers. More... | |
Signals | |
void | dataChanged () |
This is emitted whenever an asynchronous operation has finished and the data should be redrawn. More... | |
void | fullExtentCalculated () |
This is emitted whenever the worker thread has fully calculated the PostGIS extents for this layer, and its event has been received by this provider. More... | |
void | notify (const QString &msg) |
Emitted when datasource issues a notification. More... | |
Public Member Functions | |
QgsDataProvider (const QString &uri=QString()) | |
Create a new dataprovider with the specified in the uri. More... | |
virtual QgsCoordinateReferenceSystem | crs () const =0 |
Returns the coordinate system for the data source. More... | |
virtual QString | dataSourceUri (bool expandAuthConfig=false) const |
Get the data source specification. More... | |
virtual QDateTime | dataTimestamp () const |
Current time stamp of data source. More... | |
virtual QString | description () const =0 |
Return description. More... | |
virtual bool | enterUpdateMode () |
Enter update mode. More... | |
virtual QgsError | error () const |
Get current status error. More... | |
virtual QgsRectangle | extent () const =0 |
Returns the extent of the layer. More... | |
virtual QString | fileRasterFilters () const |
Return raster file filter string. More... | |
virtual QString | fileVectorFilters () const |
Return vector file filter string. More... | |
virtual void | invalidateConnections (const QString &connection) |
Invalidate connections corresponding to specified name. More... | |
virtual bool | isValid () const =0 |
Returns true if this is a valid layer. More... | |
virtual QgsLayerMetadata | layerMetadata () const |
Returns layer metadata collected from the provider's source. More... | |
virtual bool | leaveUpdateMode () |
Leave update mode. More... | |
virtual QString | name () const =0 |
Return a provider name. More... | |
QVariant | providerProperty (ProviderProperty property, const QVariant &defaultValue=QVariant()) const |
Get the current value of a certain provider property. More... | |
QVariant | providerProperty (int property, const QVariant &defaultValue) const |
Get the current value of a certain provider property. More... | |
Q_ENUM (DataCapability) | |
virtual void | reloadData () |
Reloads the data from the source. More... | |
virtual bool | renderInPreview (const QgsDataProvider::PreviewContext &context) |
Returns whether the layer must be rendered in preview jobs. More... | |
virtual void | setDataSourceUri (const QString &uri) |
Set the data source specification. More... | |
virtual void | setLayerOrder (const QStringList &layers) |
Reorder the list of layer names to be rendered by this provider (in order from bottom to top) More... | |
virtual void | setListening (bool isListening) |
Set whether the provider will listen to datasource notifications If set, the provider will issue notify signals. More... | |
void | setProviderProperty (ProviderProperty property, const QVariant &value) |
Allows setting arbitrary properties on the provider. More... | |
void | setProviderProperty (int property, const QVariant &value) |
Allows setting arbitrary properties on the provider. More... | |
virtual void | setSubLayerVisibility (const QString &name, bool vis) |
Set the visibility of the given sublayer name. More... | |
virtual bool | setSubsetString (const QString &subset, bool updateFeatureCount=true) |
Set the subset string used to create a subset of features in the layer. More... | |
void | setUri (const QgsDataSourceUri &uri) |
Set the data source specification. More... | |
virtual uint | subLayerCount () const |
return the number of layers for the current data source More... | |
virtual QStringList | subLayers () const |
Sub-layers handled by this provider, in order from bottom to top. More... | |
virtual QStringList | subLayerStyles () const |
Sub-layer styles for each sub-layer handled by this provider, in order from bottom to top. More... | |
virtual QString | subsetString () const |
Returns the subset definition string (typically sql) currently in use by the layer and used by the provider to limit the feature set. More... | |
virtual bool | supportsSubsetString () const |
Returns true if the provider supports setting of subset strings. More... | |
virtual QDateTime | timestamp () const |
Time stamp of data source in the moment when data/metadata were loaded by provider. More... | |
virtual void | updateExtents () |
Update the extents of the layer. More... | |
QgsDataSourceUri | uri () const |
Get the data source specification. More... | |
virtual bool | writeLayerMetadata (const QgsLayerMetadata &metadata) |
Writes layer metadata to the underlying provider source. More... | |
Static Public Attributes | |
static QString | SUBLAYER_SEPARATOR = QString( "!!::!!" ) |
String sequence used for separating components of sublayers strings. More... | |
Protected Member Functions | |
void | appendError (const QgsErrorMessage &message) |
Add error message. More... | |
void | setError (const QgsError &error) |
Set error message. More... | |
Protected Attributes | |
QgsError | mError |
Error. More... | |
QDateTime | mTimestamp |
Timestamp of data in the moment when the data were loaded by provider. More... | |
Abstract base class for spatial data provider implementations.
This object needs to inherit from QObject to enable event processing in the Postgres/PostGIS provider (QgsPostgresProvider). It is called here so that this vtable and the vtable for QgsPostgresProvider don't get misaligned - the QgsVectorLayer class factory (which refers to generic QgsVectorDataProvider's) depends on it.
Definition at line 49 of file qgsdataprovider.h.
Enumerator | |
---|---|
NoDataCapabilities | |
File | |
Dir | |
Database | |
Net |
Definition at line 72 of file qgsdataprovider.h.
Properties are used to pass custom configuration options into data providers.
This enum defines a list of custom properties which can be used on different providers. It depends on the provider, which properties are supported. In addition to these default properties, providers can add their custom properties starting from CustomData.
Definition at line 89 of file qgsdataprovider.h.
|
inline |
Create a new dataprovider with the specified in the uri.
Definition at line 98 of file qgsdataprovider.h.
|
inlineprotected |
Add error message.
Definition at line 555 of file qgsdataprovider.h.
|
pure virtual |
Returns the coordinate system for the data source.
If the provider isn't capable of returning its projection then an invalid QgsCoordinateReferenceSystem will be returned.
|
signal |
This is emitted whenever an asynchronous operation has finished and the data should be redrawn.
When emitted from a QgsVectorDataProvider, any cached information such as feature ids should be invalidated.
|
inlinevirtual |
Get the data source specification.
This may be a path or database connection string
expandAuthConfig | Whether to expand any assigned authentication configuration |
Definition at line 129 of file qgsdataprovider.h.
|
inlinevirtual |
Current time stamp of data source.
Reimplemented in QgsRasterDataProvider.
Definition at line 363 of file qgsdataprovider.h.
|
pure virtual |
Return description.
Return a terse string describing what the provider is.
Instead of being pure virtual, might be better to generalize this behavior and presume that none of the sub-classes are going to do anything strange with regards to their name or description?
|
inlinevirtual |
Enter update mode.
This is aimed at providers that can open differently the connection to the datasource, according it to be in update mode or in read-only mode. A call to this method shall be balanced with a call to leaveUpdateMode(), if this method returns true.
Most providers will have an empty implementation for that method.
For backward compatibility, providers that implement enterUpdateMode() should still make sure to allow editing operations to work even if enterUpdateMode() is not explicitly called.
Several successive calls to enterUpdateMode() can be done. So there is a concept of stack of calls that must be handled by the provider. Only the first call to enterUpdateMode() will really turn update mode on.
Definition at line 400 of file qgsdataprovider.h.
|
inlinevirtual |
Get current status error.
This error describes some principal problem for which provider cannot work and thus is not valid. It is not last error after accessing data by block(), identify() etc.
Definition at line 370 of file qgsdataprovider.h.
|
pure virtual |
Returns the extent of the layer.
Implemented in QgsRasterDataProvider.
|
inlinevirtual |
Return raster file filter string.
Returns a string suitable for a QFileDialog of raster file formats supported by the data provider. Naturally this will be an empty string for those data providers that do not deal with plain files, such as databases and servers.
Definition at line 348 of file qgsdataprovider.h.
|
inlinevirtual |
Return vector file filter string.
Returns a string suitable for a QFileDialog of vector file formats supported by the data provider. Naturally this will be an empty string for those data providers that do not deal with plain files, such as databases and servers.
Definition at line 332 of file qgsdataprovider.h.
|
signal |
This is emitted whenever the worker thread has fully calculated the PostGIS extents for this layer, and its event has been received by this provider.
|
inlinevirtual |
Invalidate connections corresponding to specified name.
Definition at line 376 of file qgsdataprovider.h.
|
pure virtual |
Returns true if this is a valid layer.
It is up to individual providers to determine what constitutes a valid layer.
|
inlinevirtual |
Returns layer metadata collected from the provider's source.
Individual data providers must implement this method if they support collecting metadata.
Definition at line 504 of file qgsdataprovider.h.
|
inlinevirtual |
Leave update mode.
This is aimed at providers that can open differently the connection to the datasource, according it to be in update mode or in read-only mode. This method shall be balanced with a successful call to enterUpdateMode().
Most providers will have an empty implementation for that method.
Several successive calls to enterUpdateMode() can be done. So there is a concept of stack of calls that must be handled by the provider. Only the last call to leaveUpdateMode() will really turn update mode off.
Definition at line 419 of file qgsdataprovider.h.
|
pure virtual |
Return a provider name.
Essentially just returns the provider key. Should be used to build file dialogs so that providers can be shown with their supported types. Thus if more than one provider supports a given format, the user is able to select a specific provider to open that file.
Instead of being pure virtual, might be better to generalize this behavior and presume that none of the sub-classes are going to do anything strange with regards to their name or description?
|
signal |
QVariant QgsDataProvider::providerProperty | ( | QgsDataProvider::ProviderProperty | property, |
const QVariant & | defaultValue = QVariant() |
||
) | const |
Get the current value of a certain provider property.
It depends on the provider which properties are supported.
Definition at line 30 of file qgsdataprovider.cpp.
QVariant QgsDataProvider::providerProperty | ( | int | property, |
const QVariant & | defaultValue = QVariant() |
||
) | const |
Get the current value of a certain provider property.
It depends on the provider which properties are supported.
Definition at line 35 of file qgsdataprovider.cpp.
QgsDataProvider::Q_ENUM | ( | DataCapability | ) |
|
inlinevirtual |
Reloads the data from the source.
Needs to be implemented by providers with data caches to synchronize with changes in the data source
Definition at line 357 of file qgsdataprovider.h.
|
virtual |
Returns whether the layer must be rendered in preview jobs.
The context argument gives useful information which can be used to determine whether the layer should be rendered or not.
The base implementation returns true if lastRenderingTimeMs <= maxRenderingTimeMs.
Definition at line 45 of file qgsdataprovider.cpp.
|
inlinevirtual |
Set the data source specification.
This may be a path or database connection string
uri | source specification |
Definition at line 115 of file qgsdataprovider.h.
|
inlineprotected |
Set error message.
Definition at line 558 of file qgsdataprovider.h.
|
inlinevirtual |
Reorder the list of layer names to be rendered by this provider (in order from bottom to top)
Definition at line 264 of file qgsdataprovider.h.
|
virtual |
Set whether the provider will listen to datasource notifications If set, the provider will issue notify signals.
The default implementation does nothing.
Definition at line 40 of file qgsdataprovider.cpp.
void QgsDataProvider::setProviderProperty | ( | QgsDataProvider::ProviderProperty | property, |
const QVariant & | value | ||
) |
Allows setting arbitrary properties on the provider.
It depends on the provider which properties are supported.
Definition at line 20 of file qgsdataprovider.cpp.
void QgsDataProvider::setProviderProperty | ( | int | property, |
const QVariant & | value | ||
) |
Allows setting arbitrary properties on the provider.
It depends on the provider which properties are supported.
Definition at line 25 of file qgsdataprovider.cpp.
|
inlinevirtual |
Set the visibility of the given sublayer name.
Definition at line 278 of file qgsdataprovider.h.
|
inlinevirtual |
Set the subset string used to create a subset of features in the layer.
This may be a sql where clause or any other string that can be used by the data provider to create a subset. Must be implemented in the dataprovider.
Definition at line 191 of file qgsdataprovider.h.
|
inline |
|
inlinevirtual |
return the number of layers for the current data source
Definition at line 253 of file qgsdataprovider.h.
|
inlinevirtual |
Sub-layers handled by this provider, in order from bottom to top.
Sub-layers are used when the provider's source can combine layers it knows about in some way before it hands them off to the provider.
Reimplemented in QgsRasterDataProvider.
Definition at line 225 of file qgsdataprovider.h.
|
inlinevirtual |
Sub-layer styles for each sub-layer handled by this provider, in order from bottom to top.
Sub-layer styles are used to abstract the way the provider's source can symbolise layers in some way at the server, before it serves them to the provider.
Definition at line 244 of file qgsdataprovider.h.
|
inlinevirtual |
Returns the subset definition string (typically sql) currently in use by the layer and used by the provider to limit the feature set.
Must be overridden in the dataprovider, otherwise returns a null QString.
Definition at line 211 of file qgsdataprovider.h.
|
inlinevirtual |
Returns true if the provider supports setting of subset strings.
Definition at line 203 of file qgsdataprovider.h.
|
inlinevirtual |
Time stamp of data source in the moment when data/metadata were loaded by provider.
Reimplemented in QgsRasterDataProvider.
Definition at line 360 of file qgsdataprovider.h.
|
inlinevirtual |
Update the extents of the layer.
Not implemented by default.
Definition at line 179 of file qgsdataprovider.h.
|
inline |
|
inlinevirtual |
Writes layer metadata to the underlying provider source.
Support depends on individual provider capabilities.
Returns true if metadata was successfully written to the data provider.
Definition at line 514 of file qgsdataprovider.h.
|
protected |
Error.
Definition at line 552 of file qgsdataprovider.h.
|
protected |
Timestamp of data in the moment when the data were loaded by provider.
Definition at line 549 of file qgsdataprovider.h.
|
static |
String sequence used for separating components of sublayers strings.
Definition at line 235 of file qgsdataprovider.h.