2 Building Your Application

The GEOS system is complex and provides so many services that the documentation at first may seem rather daunting. This chapter is meant to help you through the application process by directing you to the proper chapters for various functions.

This chapter is by no means a comprehensive list of all functions supported by GEOS. It is intended to be a guide to the chapters that cover some of the more widely-used functions and features.

2.1 What Everyone Should Read

Anyone who wants to program a GEOS application should read at least the first several chapters of the Concepts Book. Among the chapters you should read before going too far are

• “System Architecture,” Chapter 3
  This chapter describes the GEOS system in an overview format. It can give you a good idea of how the system works and the features it might provide for your application. You should read this chapter now if you haven’t already.

• “First Steps: Hello World,” Chapter 4
  This chapter describes the Geode Parameters file as well as an example of a simple application. The application puts up a window, uses a menu and a dialog box, and draws graphic-based text within a scrolling window. It also shows how GEOS messaging works, how a message is sent and handled, and how objects interact with each other.

• “GEOS Programming,” Chapter 5
  This chapter details the basics and even many of the finer points of programming with the Goc preprocessor. Goc has many keywords used for object and class definition, message sending and handling, and resource definition. Before programming for GEOS, you must know how to use several of these keywords (though you can learn several of the most important ones from the sample applications).

• “The GEOS User Interface,” Chapter 10
  This chapter describes the basic generic and visual UI object classes available. It also details a simple application which uses visual objects that draw themselves in a window, intercept mouse clicks, and allow the user to drag them around the screen. The sample application also illustrates how to create your own objects from the base GEOS visual classes.

2.2 Topics Listing

Listed below are many of the topics related to creating an application. Accompanying the topic is a list of chapters you will probably want to read to fully understand that topic.

2.2.1 Defining Your User Interface

“The GEOS User Interface”, Chapter 10, gives an overview of the User Interface and which objects you will want to use. Many user interface functions, objects, and features are listed below.

• Overview of all the UI Objects
  All the generic and visual UI classes are discussed in “The GEOS User Interface”, Chapter 10. This chapter is a must-read for nearly everyone.

• The Primary Application Window
  Almost all applications will have a primary window. “First Steps: Hello World”, Chapter 4 and “GenDisplay / GenPrimary”, Chapter 4 of the Object Reference Book discuss how to create and use the window in detail.

• Menus and Dialog Boxes
  Menus and dialog boxes are created with the use of GenInteraction objects, described in “GenInteraction”, Chapter 7 of the Object Reference Book.

• Monikers and Icons
  Monikers are labels of objects that are drawn on the screen to represent the object. Icons are special monikers. Both of these are discussed in “GenClass”, Chapter 2 of the Object Reference Book.

• Scrolling and Non-Scrolling Graphics Windows
  The GenView will be used by most applications. Described in “GenView”, Chapter 9 of the Object Reference Book is the process of creating a graphics window and drawing into it.

• Triggers and Buttons
  Triggers and buttons are described fully in “GenTrigger”, Chapter 5 of the Object Reference Book.

• Lists
  Dynamic, static, and scrolling lists are all described in “The List Objects”, Chapter 11 of the Object Reference Book.

• Value Setters
  The GenValue object allows the user to set a value within a given range. It is described in “GenValue”, Chapter 8 of the Object Reference Book.

• Tool Boxes and Other Controllers
  An application can define or use controller objects that automatically get and apply a user’s choices. These controllers can be placed automatically within floating “tool boxes” by the user. Controllers and tool boxes are discussed in “Generic UI Controllers”, Chapter 12 of the Object Reference Book.

• File Selector Dialog Boxes
  A standard dialog box for finding and selecting files is provided by GEOS and is described in “GenFile Selector”, Chapter 14 of the Object Reference Book.

• Multiple Windows
  Your application can display multiple windows using the GenDisplay and GenDisplayControl objects described in “GenDisplay / GenPrimary”, Chapter 4 of the Object Reference Book.

• Text Editing, Display, and Input
  All text functions are handled by the text objects, GenText and VisText. These are incredibly sophisticated and complete, and they are described in “The Text Objects”, Chapter 10 of the Object Reference Book.

• Providing Help
  An application can include an object that automatically provides context-sensitive help to the user. This object is discussed in “Help Object Library”, Chapter 15 of the Object Reference Book.

• Handling Input
  Many applications may want to track mouse or keyboard input. Input management is discussed in “Input”, Chapter 11.

2.2.2 Providing Other User Interface

Besides the generic UI functions and objects described above, GEOS provides a number of sophisticated graphics commands and powerful graphic objects. Graphics must be drawn to a GEOS document and the document displayed in a GenView.

• The GEOS Graphics System
  The GEOS coordinate space is based on real-world units and is device-independent. It is described in full in “Graphics Environment”, Chapter 23.

• Creating Your Own UI Objects
  Using the visible classes, you can create your own objects that draw themselves, handle user input, and do any number of other things. See “The GEOS User Interface”, Chapter 10 and “VisClass,” Chapter 23 of the Object Reference Book for descriptions of the visible object classes and how to use them.

• Drawing Standard Graphics
  Graphics may be drawn by calling several different graphics commands. These commands are described in “Drawing Graphics”, Chapter 24.

• Using Graphic Objects
  The Graphic Object Library provides many different graphic objects that know how to position, resize, and draw themselves as well as handle user input. This library is described in “Drawing Graphics”, Chapter 24 and “Graphic Object Library”, Chapter 18 of the Object Reference Book.

2.2.3 Documents and Data Structures

Applications that save files, print documents, or display multiple documents will be concerned with several of the topics listed below.

• Creating and Using Documents
  The GenDocument and document control objects provide standard document management including document file management and interaction with the display objects. See “GenDocument,” Chapter 13 of the Object Reference Book.

• Importing and Exporting Data Formats
  Data of other applications can be imported and GEOS data files exported to other formats via the Impex Library and its associated format translators. These are discussed in “Impex Library”, Chapter 16 of the Object Reference Book.

• Using Memory
  “Memory Management”, Chapter 15 describes the GEOS memory model and memory manager and how an application can use them.

• Using Files
  Applications that save document files should use the document objects (see above). Otherwise, the application will use either GEOS virtual memory files (see “Virtual Memory”, Chapter 18) or normal files (see “File System”, Chapter 17).

• Keeping Track of Database Items
  GEOS provides an item database manager that you can use to manipulate database items and files. This is described in “Database Library”, Chapter 19.

• Using an Entire Spreadsheet
  GEOS also provides a spreadsheet object that implements the basic functionality of a spreadsheet and which can be included in an application. This object is described in “Spreadsheet Objects”, Chapter 20 of the Object Reference Book.

• Printing
  If your application will print anything to a printer or to a file, you should read “The Spool Library”, Chapter 17 of the Object Reference Book.

2.2.4 Accessing Hardware

GEOS is designed to allow applications to be as device-independent as possible. Some applications will need to access hardware directly, however.

• Serial and Parallel Ports
  An application that needs to access the serial and parallel ports can do so using streams and the serial and parallel drivers. These are discussed in “Using Streams”, Chapter 21.

• Disks, Drives, and CD ROM Drives
  Applications that work directly with disks and drives (utility programs especially) will use many of the features described in “File System”, Chapter 17.

• Sound Hardware
  The standard PC speaker can be accessed through the sound library, discussed in “Sound Library”, Chapter 13. Drivers and libraries to allow applications to use more sophisticated sound hardware may be added later.

• Video Hardware
  In general, GEOS takes care of all video driver operations; applications deal with the graphics system, which sends commands to the video drivers. For more information, see “Graphics Environment”, Chapter 23.

2.2.5 Programming Topics

A number of programming topics specific to Goc are described in “GEOS Programming”, Chapter 5. This chapter discusses the various Goc keywords and their uses. It also describes how to create and destroy objects, how to create classes, and how to send and receive messages. You should read this chapter if you plan on programming for GEOS using the C programming language.

For information on programming in assembly, see the Esp manual. It explains GEOS’s extensions to standard 80x86 assembly-language programming

2.2.6 Other Topics

Many other topics are discussed throughout the documentation. Some of those more commonly used are listed below.

• Saving User Options
  Generic objects typically provide the features of option saving. If you need to enhance this, however, you can use the GEOS.INI file to save application-specific user options or information. This is discussed in “Applications and Geodes” Chapter 6.

• Using Event Timers
  Many applications and libraries will use event timers. Timers are discussed in “Applications and Geodes” Chapter 6.

• Supporting Quick-Transfer and Using the Clipboard
  To support the Edit menu’s Cut, Copy, and Paste functions, see “The Clipboard”, Chapter 7.

• Serving International Markets
  GEOS is designed to allow easy translation of applications and libraries to other languages. See “Localization”, Chapter 8 for full details.

• Using Multiple Threads
  Because GEOS is multithreaded, any application can create new threads for itself at any time. The issues and procedures of multiple threads are described in “Threads and Semaphores”, Appendix B.

Introduction <–    table of contents    –> System Architecture