QGIS API Documentation  3.9.0-Master (635e245143)
Signals | Public Member Functions | Protected Member Functions | List of all members
QgsVectorFileWriterTask Class Reference

QgsTask task which performs a QgsVectorFileWriter layer saving operation as a background task. More...

#include <qgsvectorfilewritertask.h>

Inheritance diagram for QgsVectorFileWriterTask:
Inheritance graph
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Signals

void completed (const QString &newFilename, const QString &newLayer)
 Emitted when writing the layer is successfully completed. More...
 
void errorOccurred (int error, const QString &errorMessage)
 Emitted when an error occurs which prevented the file being written (or if the task is canceled). More...
 
void writeComplete (const QString &newFilename)
 Emitted when writing the layer is successfully completed. More...
 
- Signals inherited from QgsTask
void begun ()
 Will be emitted by task to indicate its commencement. More...
 
void progressChanged (double progress)
 Will be emitted by task when its progress changes. More...
 
void statusChanged (int status)
 Will be emitted by task when its status changes. More...
 
void taskCompleted ()
 Will be emitted by task to indicate its successful completion. More...
 
void taskTerminated ()
 Will be emitted by task if it has terminated for any reason other then completion (e.g., when a task has been canceled or encountered an internal error). More...
 

Public Member Functions

 QgsVectorFileWriterTask (QgsVectorLayer *layer, const QString &fileName, const QgsVectorFileWriter::SaveVectorOptions &options)
 Constructor for QgsVectorFileWriterTask. More...
 
void cancel () override
 Notifies the task that it should terminate. More...
 
- Public Member Functions inherited from QgsTask
 QgsTask (const QString &description=QString(), QgsTask::Flags flags=AllFlags)
 Constructor for QgsTask. More...
 
 ~QgsTask () override
 
void addSubTask (QgsTask *subTask, const QgsTaskList &dependencies=QgsTaskList(), SubTaskDependency subTaskDependency=SubTaskIndependent)
 Adds a subtask to this task. More...
 
bool canCancel () const
 Returns true if the task can be canceled. More...
 
QList< QgsMapLayer *> dependentLayers () const
 Returns the list of layers on which the task depends. More...
 
QString description () const
 Returns the task's description. More...
 
qint64 elapsedTime () const
 Returns the elapsed time since the task commenced, in milliseconds. More...
 
Flags flags () const
 Returns the flags associated with the task. More...
 
void hold ()
 Places the task on hold. More...
 
bool isActive () const
 Returns true if the task is active, ie it is not complete and has not been canceled. More...
 
double progress () const
 Returns the task's progress (between 0.0 and 100.0) More...
 
void setDependentLayers (const QList< QgsMapLayer *> &dependentLayers)
 Sets a list of layers on which the task depends. More...
 
void setDescription (const QString &description)
 Sets the task's description. More...
 
TaskStatus status () const
 Returns the current task status. More...
 
void unhold ()
 Releases the task from being held. More...
 
bool waitForFinished (int timeout=30000)
 Blocks the current thread until the task finishes or a maximum of timeout milliseconds. More...
 

Protected Member Functions

void finished (bool result) override
 If the task is managed by a QgsTaskManager, this will be called after the task has finished (whether through successful completion or via early termination). More...
 
bool run () override
 Performs the task's operation. More...
 
- Protected Member Functions inherited from QgsTask
bool isCanceled () const
 Will return true if task should terminate ASAP. More...
 

Additional Inherited Members

- Public Types inherited from QgsTask
enum  Flag { CanCancel = 1 << 1, AllFlags = CanCancel }
 Task flags. More...
 
enum  SubTaskDependency { SubTaskIndependent = 0, ParentDependsOnSubTask }
 Controls how subtasks relate to their parent task. More...
 
enum  TaskStatus {
  Queued, OnHold, Running, Complete,
  Terminated
}
 Status of tasks. More...
 
- Protected Slots inherited from QgsTask
void setProgress (double progress)
 Sets the task's current progress. More...
 

Detailed Description

QgsTask task which performs a QgsVectorFileWriter layer saving operation as a background task.

This can be used to save a vector layer out to a file without blocking the QGIS interface.

See also
QgsVectorLayerExporterTask
QgsRasterFileWriterTask
Since
QGIS 3.0

Definition at line 35 of file qgsvectorfilewritertask.h.

Constructor & Destructor Documentation

◆ QgsVectorFileWriterTask()

QgsVectorFileWriterTask::QgsVectorFileWriterTask ( QgsVectorLayer layer,
const QString &  fileName,
const QgsVectorFileWriter::SaveVectorOptions options 
)

Constructor for QgsVectorFileWriterTask.

Takes a source layer, destination fileName and save options.

Definition at line 21 of file qgsvectorfilewritertask.cpp.

Member Function Documentation

◆ cancel()

void QgsVectorFileWriterTask::cancel ( )
overridevirtual

Notifies the task that it should terminate.

Calling this is not guaranteed to immediately end the task, rather it sets the isCanceled() flag which task subclasses can check and terminate their operations at an appropriate time. Any subtasks owned by this task will also be canceled. Derived classes must ensure that the base class implementation is called from any overridden version.

See also
isCanceled()

Reimplemented from QgsTask.

Definition at line 42 of file qgsvectorfilewritertask.cpp.

◆ completed

void QgsVectorFileWriterTask::completed ( const QString &  newFilename,
const QString &  newLayer 
)
signal

Emitted when writing the layer is successfully completed.

The newFilename parameter indicates the file path for the written file. When applicable, the newLayer parameter indicates the layer name used.

◆ errorOccurred

void QgsVectorFileWriterTask::errorOccurred ( int  error,
const QString &  errorMessage 
)
signal

Emitted when an error occurs which prevented the file being written (or if the task is canceled).

The writing error and errorMessage will be reported.

◆ finished()

void QgsVectorFileWriterTask::finished ( bool  result)
overrideprotectedvirtual

If the task is managed by a QgsTaskManager, this will be called after the task has finished (whether through successful completion or via early termination).

The result argument reflects whether the task was successfully completed or not. This method is always called from the main thread, so it is safe to create widgets and perform other operations which require the main thread. However, the GUI will be blocked for the duration of this method so tasks should avoid performing any lengthy operations here.

Reimplemented from QgsTask.

Definition at line 61 of file qgsvectorfilewritertask.cpp.

◆ run()

bool QgsVectorFileWriterTask::run ( )
overrideprotectedvirtual

Performs the task's operation.

This method will be called when the task commences (ie via calling start() ), and subclasses should implement the operation they wish to perform in the background within this method.

A task must return a boolean value to indicate whether the task was completed successfully or terminated before completion.

Implements QgsTask.

Definition at line 48 of file qgsvectorfilewritertask.cpp.

◆ writeComplete

void QgsVectorFileWriterTask::writeComplete ( const QString &  newFilename)
signal

Emitted when writing the layer is successfully completed.

The newFilename parameter indicates the file path for the written file.

Note
this signal is deprecated in favor of completed().

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