Comprehensive in scope, this book provides complete coverage of using Visual Objects for Clipper within the Windows environment. It also features an object-oriented programming tutorial, which includes ODBC, SQL, DDE and OLE programming techniques.

This outstanding and extensive tutorial explaining and illustrating all details of programming in Visual Objects provides complete orientation to the VO Interactive Development Environment, highlights object-oriented programming and event-driven programming, shows how to develop complete Windows Multiple Document Interface applications from scratch, and more.

Wessel, a computing trainer and author, and Bless, an advisor and coach for object technology, describe how to develop CA-Visual Object 2.6 programs which can stand up in a world of modern Office applications and which use the options of e-mail and the Internet. Emphasis is on the use of efficient API interfaces for Windows, COM, and XML. All examp

A Visual Objects expert introduces readers to the principles of object-oriented programming with CA-Visual Objects. Stephen Straley covers advanced programming and offers a thorough introduction to the object oriented paradigm. Extensive examples, illustrations, and source-code listings are provided. The disk includes source-code listings, data files for all examples in the book, plus a Class library.

Displaying multiple levels of data visually has been proposed to address the challenge of limited screen space. Although many previous empirical studies have addressed different aspects of this question, the information visualization research community does not currently have a clearly articulated consensus on how, when, or even if displaying data at multiple levels is effective. To shed more light on this complex topic, we conducted a systematic review of 22 existing multi-level interface studies to extract high-level design guidelines. To facilitate discussion, we cast our analysis findings into a four-point decision tree: (1) When are multi-level displays useful? (2) What should the higher visual levels display? (3) Should the different visual levels be displayed simultaneously, or one at a time? (4) Should the visual levels be embedded in a single display, or separated into multiple displays? Our analysis resulted in three design guidelines: (1) the number of levels in display and data should match; (2) high visual levels should only display task-relevant information; (3) simultaneous display, rather than temporal switching, is suitable for tasks with multi-level answers. Table of Contents: Introduction / Terminology / Methodology / Summary of Studies / Decision 1: Single or Multi-level Interface? / Decision 2: How to Create the High-Level Displays? / Decision 3: Simultaneous or Temporal Displays of the Multiple Visual Levels / Decision 4: How to Spatially Arrange the Visual Levels, Embedded or Separate? / Limitations of Study / Design Recommendations / Discussion and Future Work