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MGitWriteSparkline is an example of a file writer for the iTools system. It creates a PNG file representing a sparkline for vector data. Sparklines are intense, word-like graphics like 55. Readers and writers are some of the simplest components to add to an iTool and a good place to start learning how to create custom iTools.

In order to run this demo, you will need the the MGitWriteSparkline class (doc), the calling program (doc), and the original sparklines routine (doc and see this article about the sparklines routine).

Continue reading “File writers for iTools: sparklines example.”

Every component in the iTools has a unique identifier placing it in a hierarchy of components for the tool. This identifier is necessary to programmatically use the component. So how do you find the identifier of some component? The standard technique is to use the IDLitTool::findIdentifiers method. Alternatively, mg_itbrowser allows interactive browsing of all the identifiers (and their properties) of an iTool. This is very useful for learning and exploring the components that make up an iTool.

Here is the source code and docs for mg_itbrowser.

Continue reading “iTools identifier browser.”

When rendering object graphics atoms with transparency, the order the atoms are rendered (i.e. the order the atoms are created and added to the hierarchy) determines what can be seen. You want to draw the atoms from back to front when the front items are transparent. The same principle holds true for iTools since they use object graphics.

Continue reading “Rendering order in the iTools.”

The iTools are easy to use interactively (O.K., easy once you learn some of the conventions and jargon). But they also have the ability to be extended and controlled programmatically. I have given a couple examples of extending an iTool with new operations (data operation, general operation). I’ll post more extending iTools visualizations, file readers/writers, manipulators, user interface services, and custom user interfaces in the weeks to follow. But programmatically controlling an iTool is both fairly easy and extremely useful, especially in situations where a visualization needs to be created which further needs to be explored interactively.

Continue reading “Create isosurfaces programmatically in iVolume.”

For simple operations, subclassing IDLitDataOperation is an easy way to quickly add an operation to the iTools system. See previous post “Creating an iTool data operation” for more information about IDLitDataOperation. If you want to do anything more complicated than a numeric operation on the dependent variable of the currently selected visualization, then you want to subclass IDLitOperation. We will examine a fairly simple subclass of IDLitOperation, MGitOpDerivative, which calculates the derivative of data in a plot visualization.

Continue reading “Creating an iTool generalized operation.”

The ability to extend the itools is one of their main strengths. This can be adding a button for an operation (like our example here), the capability to read/write new file types, new visualizations, or new ways to manipulate visualizations. Plus, the user interface can be customized to various levels. Toolbars and panels can be added to the standard configuration, but a totally custom interface can be created also. Capabilities can also be removed to provide a simpler interface for a specific task.

This example adds an adaptive histogram equalization operation to iimage.

There are two files for this demo program: mgitopadapthistequal__define.pro (doc) to define the operation and mg_dataop_demo.pro (doc) to setup using the operation. To run the demo, make sure both files are compiled or in your path and run mg_dataop_demo.

Continue reading “Creating an iTool data operation.”