Python GUI Tools

New tools with python

If ParaView has been compiled with the Python wrapping, some advanced features become available to the user such as: - Accessing a Python Shell - Trace recording - Macros - Save ParaView state as a Python script

Those features can be reached from the Tools menu for the Shell and Trace access. The management of macros is done inside the Macros menu. To save the state as a Python script, just go to the File menu and choose Save state without forgetting to switch the file type to be Python *.py.

Macros

Macros allow the user to define a Python script as built-in actions that become accessible from the Macros menu or directly inside the Toolbar.

Once a local file is defined as a Macro the given file is copied inside the user specific ParaView directory. No reference is kept to the original file. Therefore, if you keep editing the original file, the changes won't affect the macro itself.

The macros list is build dynamically at the ParaView startup by listing the content of the ParaView/Macros directory as well as the user specific ParaView/Macros directory. Note: if you want to rename a macro just rename the file in one of the given directory.

Deleted Macro DO NOT delete the file, but just renamed with a "." before the original filename and they stay in the same directory.

Macros are displayed in the macros menu and the macros toolbar. The macros toolbar can be shown/hidden from the paraview main menu: View --> Toolbars --> Macro Toolbar. The toolbar may be hidden by default.

Note: python is not initialized until you open the python shell for the first time. If you run a macro from the macro toolbar or menu before the python shell has been opened for the first time, you will notice a slight delay as python initializes itself. You should see a wait cursor while python is initializing.

Trace

Trace as been introduced in ParaView 3.6.2 as a new module. It can be imported with 'from paraview import smtrace', but normally the user never needs to directly use the trace module. The trace menu items provides everything for controlling trace:

• Start trace - starts trace. If an active trace was previously started, it will be stopped, cleared, and restarted.
• Stop trace- stops trace. The trace output generated so far will not be cleared until trace is started again or the python shell is reset. Some internal trace data structures hold references to c++ objects, so if you want to make sure everything is cleaned up try resetting the shell.
• Edit trace- opens the built in editor, creates a new document and fills it with the current trace output
• Save trace- opens a prompt for the user to specify a filename and saves trace to disk.

TIP: It's a good idea to stop trace before executing a trace script you just recorded. What I do is click the Disconnect server button in the paraview toolbar. This will clear the current pipeline objects, stop trace, and reset the python interpreter.

TIP: Trace only records property values as they are modified. If you have initialized a render view or a color lookup table prior to starting trace then the generated trace script may not perfectly reflect the state of the view or lookup table. For best results, start trace before performing any other actions. Also, see the CaptureAllProperties flag in the Trace Verbosity section below.

Trace verbosity

Because of the way the GUI initializes certain proxies, some parts of the trace will be more verbose than others. For example, every time a data representation is created, seven or eight properties related to selection are modified. It might be a nice feature to provide the user with a way to specify property suppressions.

Trace can run with different verbose levels. In full property verbose mode, trace records all properties of a proxy when the proxy is registered. Normally, trace only records properties when they are modified from their default values. Control over the verbosity level is not currently available in the gui, but you can start trace manually in verbose mode using the python shell:

from paraview import smtrace
smtrace.start_trace(CaptureAllProperties=True)

# actions in the gui

smtrace.stop_trace()

Known issues with trace

It is possible to perform actions in the GUI that do not translate properly to trace. Here is a list of things that do not currently work:

• views other than 3D render view (also have not tested mpi render view)
• time
• the start/stop trace buttons are not synced if trace is started manually from python

New built in editor

For convenience there is a new built in script editor. When the editor is opened on OSX, the editor's menubar temporarily replaces paraview's menubar. If this becomes too obtrusive the menu could be replaced by toolbar buttons. It might be a nice feature to allow the user to specify a command to launch an external editor.

New C++ API

New classes have been introduced under Qt/Python. They depend on classes in Qt/Core but not Qt/Components. A new class named pqPythonManager is available globally through the pqApplicationCore instance:

  pqPythonManager* manager = qobject_cast<pqPythonManager*>(
    pqApplicationCore::instance()->manager("PYTHON_MANAGER"));

The python manager has a public method:

  pqPythonDialog* pythonShellDialog();

Calling this method will return the python shell. Python will be initialized on the first call to this method and the returned pqPythonDialog will be ready to use. pqPythonDialog offers public methods for executing python files and strings of python code.

If you plan to call methods in the python c api, you must make the python interpreter active:

  pqPythonDialog* dialog = manager->pythonShellDialog();
  dialog->shell()->makeCurrent();

  // Calls to python c api

  dialog->shell()->releaseControl();

When the python interpreter is reset, pqPythonDialog emits a signal 'interpreterInitialized()'. The pqPythonManager listens for this signals and imports the paraview modules. So when this signal is triggered, it is not guaranteed that paraview python modules have been imported yet. After the paraview python modules are imported, the pqPythonManager emits a signal 'paraviewPythonModulesImported()'.