Processing topic panel

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Wandora's Processing topic panel is used to run Processing scripts. Scripts can access Wandora's public API classes and methods. In effect, a Processing script can ask Wandora which topic is open, what are topic's associations, etc. Especially, a Processing script can access the topic map in Wandora. Wandora's Processing topic panel is a powerful tool for topic map visualizations and UI experiments. Processing topic panel starts with a menu option View > New panel > Processing. Below is a screen capture viewing Processing topic panel when you start it for the first time. Using Processing topic panel in Wandora requires no additional installations as Processing core is enclosed in Wandora's distribution packages.

Processing 01.gif

Processing topic panel has two tabs labeled as Processing editor and Visual. Editor tab is used to write and edit the Processing script. Processing applet is viewed in Visual tab whenever the script is executed. Processing applet is a running instance of the script written in editor. Both tabs have a button row at the bottom. Editor tab's buttons are

  • New clears current script in editor.
  • Open is used to restore script in editor. Wandora can restore Processing script either from a file or from an occurrence of current topic.
  • Save stores current script in editor. Wandora can store script wither to a file or to an occurrence of current topic. Occurrence script is saved into the topic map and user must export topic map in order to save the script in occurrence.
  • Options opens a configuration window for Processing topic panel. Available configuration options are Autoload, Run window, Autorun.
  • Check tries to compile current Processing script. If compilation fails, an error dialog views compilation errors.
  • Run executes current Processing script. If compilation fails, an error dialog views compilation errors. If compilation is successful, Wandora opens the Visual tab and places running applet into the visual panel.
  • Stop stops running Processing applet.

Visual tab contains only one button, Stop used to stop running Processing applet.

Compiling and running Processing script in Wandora

Wandora compiles the Processing script in editor whenever user clicks the Build or Run button or chooses equal menu option. If compilation fails, Wandora gives user an error message. if compilation is successful, Wandora loads the compiled class, creates an instance of it, and starts the applet. Running Processing applet is placed to Visual tab. Next image illustrates described execution model.

Processing cycle v02.gif

Notice: Wandora version 2012-04-30 has changed the templating mechanism of Processing scripts. Previous version of Processing topic panel injected user code into a predefined Java template that made the user code a PApplet. New version does not wrap user code into a predefined template but tries to compile the user code as such. All enclosed sample sketches have been adjusted to follow this change. If you have written your own Processing sketches and try to use them in Wandora version 2012-04-30 or above, you have to add wrapper explicitly into your sketch in order to compile and run sketches.

Accessing topics and topic maps from Processing

You can request topics and topic maps from your Processing script. Supported methods are

Topic currentTopic = getCurrentTopic();
TopicMap topicMap = getTopicMap();

Method getCurrentTopic returns current topic opened in topic panel. Method getTopicMap returns the topic map in Wandora. Returned objects are real Java objects in Wandora. You can access these object as described in Wandora's API documentation. Perhaps the most important Wandora objects (and interfaces) you need in Processing code are

There is no restrictions in accessing Wandora's topic or topic map objects. Script may contain operations that change topics and the topic map in Wandora. See also TopicTools. It offers some shortcut methods to collect and simplify topic and association data.

Unsupported Processing language features

Wandora compiles the script in editor into a Java class without preprocessing. As a consequence, user script must be valid Java code. Thus, Wandora's Processing support is not perfect and you can't use all features of Processing language. Unsupported Processing language features are

  • color primitive. Use int primitive instead. Notice, highest eight bits of the color value specify alpha. Color value has four sets of eight bits (from lower to upper): blue, green, red and alpha component.
  • You can't omit the method visibility of overridden methods. Thus, you need explicitly specify draw and setup (and some others) methods as public. Usually these methods have underlying implementation in Processing applet and you just override them in your Processing script. Building a source without explicit visibility setting generates a compilation error.


First, Wandora user clicks the Open button. A popup menu is shown. User chooses to load script from file.

Processing 02.gif

User selects one of the example scripts, AssociationArches.

Processing 03.gif

Selected script is loaded to the editor.

Processing 04.gif

Now user clicks the Run button. User can change the association arch from left to right or vice verse by clicking black edge rectangles. Mouse over highlights the edge arches and target nodes.

Processing 05.gif

See also

The documentation provided here doesn't cover Processing language at all. To learn Processing, see documentation at

More information about Wandora's topic panels:

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