Documentation/Nightly/Developers/IO
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Contents
Read
Main classes
vtkSlicerXYZNode
is a storable node that represents the data from file (e.g. [vtkMRMLModelNode)vtkSlicerXYZStorageNode
is the file reader. It populates the storable node using the methodvtkMRMLXYZStorageNode::ReadData(vtkMRMLStorableNode*,bool)
.vtkSlicerXYZsLogic
is the MRML logic of theXYZ
module. It exposes a convenient methodAddXYZ(const char* fileName, const char* nodeName=0);
that creates a MRML XYZ node (vtkMRMLXYZNode
)and its associated storage node (vtkMRMLXYZStorageNode
), add them into the scene, and callvtkMRMLXYZStorageNode::ReadData(vtkMRMLStorableNode*,bool);
on the storage node to load the file. If the loading fails, it removes the previously created nodes from the scene.qSlicerXYZsIO
is a plugin that is registered by modules into theqSlicerCoreIOManager
. It is the interface between Qt and MRML logics. It internally callsvtkSlicerXYZsLogic::AddXYZ
().qSlicerXYZsIOOptionsWidget
is a widget that sets loading options that gets passed to the logic.qSlicerCoreIOManager
is the central class where any IO operation must go through. qSlicerIOs can be registered usingqSlicerCoreIOManager::registerIO(qSlicerIO*)
and nodes can be loaded usingqSlicerCoreIOManager::loadNodes(...)
. It exposes a set of convenient methods such as "what reader must be used for what file".qSlicerDataDialog
is the dialog that allows the user to select the files to load.
How to add support for reading a new file format ?
- Write method
vtkMRMLXYZStorageNode::ReadDataInternal(vtkMRMLStorableNode*, bool temporary);
- Write method
vtkMRMLXYZsLogic::AddXYZ(const char* fileName, const char nodeName =0);
- Write class
qSlicerXYZsIO
- Optional: Write class
qSlicerXYZsIOOptionsWidget
if you want the user to optionally specify loading options. - In
qSlicerXYZsModule::setup()
, instantiate and registerqSlicerXYZsIO
toqSlicerCoreIOManager
- Add file format to [Documentation/Nightly/SlicerApplication/SupportedDataFormat|SupportedDataFormat] wiki page
ModifiedSinceRead
In order to inform the user what data has been changed since it was last read, a ModifiedSinceRead mechanism is in place to track when was the file last read and when was the data last modified. If a modification happened , the storable node vtkMRMLStorableNode::GetModifiedSinceRead()
must return true. If the data in the node is the same as in the file, then vtkMRMLStorableNode::GetModifiedSinceRead()
must return false.
vtkMRMLStorageNode
keeps track of when a file was last read or written (vtkTimeStamp* vtkMRMLStorageNode::StoredTime
). vtkMRMLStorableNode
keeps track of when the data was last modified (vtkTimeStamp vtkMRMLStorableNode::StorableModifiedTime
). Anytime a vtkMRMLStorableNode
property that is saved in file is modified, the StorableModifiedTime
time stamp must be modified.
At exit time (qSlicerMainWindow::closeEvent()
), vtkMRMLStorableNode::GetModifiedSinceRead()
is called to check if the data in the node is the same as in the file or if it has been modified after the file was last read or written. It internally checks vtkTimeStamp* vtkMRMLStorageNode::StoredTime
and vtkTimeStamp vtkMRMLStorableNode::StorableModifiedTime
. If the data is more recent, then a message dialog is shown to the user telling him that some data is different from file; leaving without saving will loose the changes.
Example
- Models
How to load files programmatically
C++ | Python |
---|---|
qSlicerCoreIOManager* coreIOManager = qSlicerCoreApplication::application()->coreIOManager(); qSlicerIO::IOProperties fileParameters; fileParameters["filename"] = "/path/of/file.ext"; vtkMRMLNode* volumeNode = coreIOManager->loadNodesAndGetFirst("VolumeFile", parameters); Works also with "ModelFile", "TransformFile", "SceneFile"... |
>>> volumeNode = slicer.util.loadVolume('/path/of/file.ext') It works also with loadModel, loadTransform, loadScene... |
Note that IO dialogs should be used as often as possible.
Write
The mechanism is similar to Read. vtkMRMLXYZStorageNode::WriteDataInternal(...)
and qSlicerXYZWriter
must implemented.
How to save files programmatically
C++ | Python |
---|---|
qSlicerCoreIOManager* coreIOManager = qSlicerCoreApplication::application()->coreIOManager(); qSlicerIO::IOProperties fileParameters; fileParameters["nodeID"] = volumeNode->GetID(); fileParameters["filename"] = "/path/of/file.ext"; coreIOManager->saveNodes("VolumeFile", parameters); Works also with "ModelFile", "TransformFile", "SceneFile"... |
>>> slicer.util.saveNode(volumeNode, '/path/of/file.ext') |
Note that IO dialogs should be used as often as possible.
IO Dialogs
qSlicerFileDialog
is the base class to override a custom dialog.qSlicerStandardFileDialog
is a multi-purpose file dialog.qSlicerDataDialog.h
is the default dialog to load files.qSlicerSaveDataDialog
is the default dialog to save files.
By default, all the IOs must be done through qSlicerDataDialog
for reading files and qSlicerSaveDataDialog
for writting files. However, due to historical reasons, it is possible to have custom dialogs for each node types.
It can be useful to create your own IO dialog to add custom behavior to the Slicer drag&drop default behavior.
How to register a dialog ?
C++ | Python |
---|---|
Register dialogs in qSlicerXYZModule::setup(): qSlicerIOManager* ioManager = qSlicerApplication::application()->ioManager(); ioManager->registerDialog(new qSlicerXYZDialog(this)); ioManager->registerDialog(new qSlicerSaveXYZDialog(this)); |
Declare an XYZFileDialog in your XYZ.py module file. For example: class XYZFileDialog: def __init__(self, parent): self.parent = parent parent.fileType = 'XYZFile' parent.description = 'XYZ' parent.action = slicer.qSlicerFileDialog.Read def isMimeDataAccepted(self): accept = self.parent.mimeData().hasFormat("text/uri-list") self.parent.acceptMimeData(accept) def dropEvent(self): self.parent.dropEvent().accept() def execDialog(self): print 'exec' |
How to order the list of drag&drop dialogs ?
By controlling the order of module initialization. This is done by adding module dependencies. Make your module dependent of of the "Data" would make it initialize after the Data module that registers the "Any Data" dialogs:
C++ | Python |
---|---|
QStringList qSlicerXYZModule::dependencies() const { QStringList moduleDependencies; moduleDependencies << "Data"; return moduleDependencies; } |
def __init__(self, parent): ... parent.dependencies = ["Data"] class XYZFileDialog: ... |