EZ
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1 Using The EZ Widget Library

This chapter is a tutorial of the EZ widget library.

There are two classes of widgets in the EZ widget library: a class of simple widgets each of which is implemented using exactly one X window; and a class of composite widgets which are made from a group of simple widgets. Label, frame, buttons, menu-items, entry and sliders are examples of simple widgets while text widget, list box, notebook and notebook-page are composite widgets.

EZ widgets are event-driven. Interaction between an application and the EZ widget library is achieved via callbacks and event handlers. Typically, an EZwgl application contains five components: initialization, creating and configuring widgets, registering widget callbacks and/or event handlers, mapping widgets and handling events.

For some applications, especially interactive graphical applications, it may be desirable to use a "polling" style programming. The EZ widget library also provides an event "polling" routine, EZ_ServiceEvents(), which does no-waiting event processing.

The EZ widget library supports application resources. Appearance of an EZwgl application is completely configurable by resource files.

The EZ widget library implements a simple geometry manager (rectangle packer). The size and location of EZ widgets are computed semi-automatically by the geometry manager, in the sense that applications specify some controlling information about how to arrange a set of widgets, the geometry manager assigns a size and location to each widget.

The EZwgl also supports a more advanced grid bag geometry management.

Warning: There are some subtle differences between simple widgets and composite widgets.


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