Notes on RichText() Class for Clipper/FiveWin
1/28/97

Author: Tom Marchione
73313,3626@compuserve.com

LEGAL STUFF

All source code is Copyright (C) 1997 Thomas R. Marchione.  As a Clipper/Fivewin user, you are granted the right to use and modify the code for application work, provided that all file headers are kept intact, you do not offer the source code for sale, and do not port the code to another language.  Future versions of this class may or may not be offered for public consumption by the author.  Use the code at your own risk -- no warranties are expressed or implied.  Etc., etc...


GETTING STARTED

If you're really curious about what this thing does, compile and run the sample application (just look at the "BUILDRTF.BAT" batch file -- it's really simple, if you're already a Clipper/Fivewin developer).  Then open the output file (RTFDEMO.RTF) in Microsoft Word (personally, I haven't tested it with anything else).  If you don't have time to to compile and run the app, I've included an unedited copy of the output file in the uploaded ZIP file.


OVERVIEW

RichText() is a class written for Clipper/Fivewin, designed to export formatted data directly to Rich Text Format (RTF) files from within an application.  The class includes the source code, as well as Clipper command directives for simplified xBASE implementation at the application level.

As of this writing, the class is _clearly_ a work in progress; some of the features may not work entirely as intended, and it's fairly finicky overall.  Currently, the class implements a small subset of the RTF specification, as taken from Microsoft documentation.  RTF is a very detailed specification, and my intent was to provide easy access to the most basic and useful features of RTF, including attributes such as page setup, fonts, paragraph formatting, character formatting, headers & footers, tables, etc.  Because the basic structure of all RTF commands is similar, the class can be expanded to include other features, as necessary.

All of my (very much limited) testing, to date, has been done with Microsoft Word.  I have not tried reading the output files in any other application.

Note that RichText() is different from the TRtfFile() class supplied with Fivewin 1.9.1.  The latter provides a simple set of tools for generating Windows help files, whereas RichText() is intended primarily as a tool for generating special-purpose, end-user reports.  However, it would be relatively easy to merge the capabilities of the two classes.  Since I don't own the code to TRtfFile(), I have made no attempt to do this in this version.  I have no idea of what's available in Fivewin 1.9.2.


WHAT IS RTF?

RTF is a Microsoft file specification for transferring formatted text between applications.  As such, it it's a great way to move formatted database information into word processors, in a _true_ word processing format.  For those who are interested, the RTF specification is available as a Microsoft Word document, either from Compuserve or the Microsoft Internet site.  That document is indispensable, if you intend to expand the capabilities of the RichText() class.



WHATôS THE POINT?

Occasions arise when end users would like to manipulate data in word processors.  If your end-users need to integrate output from a Clipper database application into word-processed reports, without manually reformatting documents or writing clumsy macros, then RTF files are an attractive, simple and nearly universal solution.  This type of requirement is what spawned the RichText() class.

The RichText() class is not intended to be a core report generating system for most applications, and the class will likely be a waste of time for many developers with simple reporting requirements.  Fivewin's report class and third-party report generators do a fine job of generating standard reports, and my understanding is that some third party products can even generate RTF output.  At this point, RichText() is not integrated with any other reporting system.

So whatôs the point of this class?

First, itôs cheap (free, in its initial incarnation).  Itôs a simple, low-overhead solution.  If youôre not using a big, third-party report generator already, but only need one or two RTF-formatted outputs (maybe a form letter or two), this is a simpler answer.

Second, itôs extremely flexible.  You can produce one-of-a kind, free-form word-processing documents (for a good example, see the sample provided with the class).  The class is inherently oriented toward paragraphs, bullets, hanging indents, page orientation, etc., not standard database reporting fare such as column headers, subtotals, etc. (although you can easily dump data into nicely-formatted tables).

Third, the output files are true word-processing files, without extraneous spaces, carriage returns, and other "lint" that makes life difficult in a word processing context.  If you have ever tried to pass off a flat text output file as "word processor compatible", you'll know what I mean.  Compatible? Yes.  Usable? Hardly.



ESSENTIAL FEATURES OF RTF

For detailed information about RTF, consult the Microsoft specification, mentioned earlier in this document.  It is also helpful to analyze the contents of RTF files generated from word processors.  Although the xBASE layer of RichText() makes many of the technical details transparent, it will be helpful to clarify a few issues here.

RTF uses 7-bit ASCII characters (0-127) to represent formatting codes and data (higher-order ASCII characters must be represented in hexadecimal, which is handled transparently by RichText()).  The two essential formatting characters in RTF are "\" (backslash) and "{}" (curly braces).  All formatting commands are preceded by a backslash, and all "groups" are enclosed in curly braces.  Groups delineate portions of a document to which combinations of formatting information may apply.  Groups can be nested; the RTF file itself is considered a group, so all RTF files have at least one pair of curly braces, which encloses the entire contents of the file.

All RTF files have an RTF header (which is to be distinguished from the headers and footers that you may place in an RTF document).  The RTF header appears at the top of the file and contains information about fonts, colors, styles, etc.  For example, the font table within the RTF header contains a list of all of the fonts that are used in the document.  To switch fonts later the document, an index into this font table must be used.  A similar system is used for colors.  RichText() takes care of the RTF header for you.

An application that reads RTF files is called an RTF Viewer.  For the most part, data items that you write to an RTF file appear within RTF Viewers in the sequence that they were written.  However certain RTF commands implement alternate "destinations", such as headers and footers.  RTF also supports the "sections" that are found in Microsoft Word, with section-specific layouts and formats.



WHERE TO GO FROM HERE

If you like the capabilities that are demonstrated in the sample, take a look at the source code for the sample (RTFDEMO.PRG).  From there, look at the header file (RICHTEXT.CH), and then dive into the class itself (RICHTEXT.PRG).  It's more tedious than complicated -- if you are willing to learn a few key RTF concepts, you'll find that most of the code is actually very simple and basic.

A word of warning -- it's very easy to break an RTF file.  Surprisingly enough, MS-Word can throw up and die if you misplace even one seemingly innocent code.  So, if you decide to change the base class, make sure that you test each change!

So far, I have made no effort to explore the real possibilities of the class, in terms of integrating it into more traditional reporting systems, or building better application-level components to meet recurring, standard requirements.  If you have any ideas or suggestions, I'd love to hear them.

Have fun!

Tom