6.1. boing — Creating and managing pipelines

Developers can easily deploy Boing pipelines by invoking the toolkit’s API in their Python code. The most important element is the function boing.create(), which is used to instantiate the nodes of the pipeline.

boing.create(expr, parent=None)

Return a new node created as defined in the expression expr, with parent object parent. If expr is composed by a single URI, the returned object will be a new node correspondent to the provided URI; if expr is formed by an URI expression, the returned object will be a composed node.

All the available nodes are listed and described in the Nodes reference table.

In order to compose the pipeline, the nodes can be attached using the Python operators + and |, which work the same as the operators used in the URI expressions. As an example, consider the following code:

n1 = boing.create("in.tuio:")
n2 = boing.create("viz:")
n3 = boing.create("dump:")
pipeline = n1 + (n2 | n3)

The same pipeline can be obtained using the following code:

pipeline = boing.create("in.tuio:+(viz:|dump:)")

In order to run the pipeline it is necessary to launch the Qt Application that should have been initialized before creating the pipeline. The following code can be used as an example for creating custom Boing pipelines:

#!/usr/bin/env python3
import sys
import PyQt4
import boing

# Init application
app = PyQt4.QtGui.QApplication(sys.argv)

# Create nodes
n1 = boing.create("in.tuio:")
n2 = boing.create("viz:")
n3 = boing.create("dump:?request=$..contacts")

# Compose the pipeline
graph = n1 + (n2 | n3)

# Run
sys.exit(app.exec_())

6.1.1. Global configuration

Any global configuration variable can be stored in the attribute boing.config.

boing.config

dict object used to store any global configuration variable. Boing‘s own variables:

• "--no-gui": defines whether the GUI widgets are enabled. If set to True, nodes likes viz:, rec:, player:, etc., cannot be created.
• "--no-raise": defines whether the GUI widgets should be automatically raised as they are initialized (see method QtGui.QWidget.raise_()).

6.1.2. Dynamic configuration

Todo

Describe how to configure the pipeline dinamically

boing.activateConsole(url="", locals=None, banner=None)

Enable a Python interpreter at url.

The optional locals argument specifies the dictionary in which code will be executed; it defaults to a newly created dictionary with key “__name__” set to “__console__” and key “__doc__” set to None.

The optional banner argument specifies the banner to print before the first interaction; by default it prints a banner similar to the one printed by the real Python interpreter.