HOWTO: Extend the Web Publishing Wizard with Custom Layouts

ID: Q194204

The information in this article applies to:

Microsoft Visual FoxPro for Windows, version 6.0

SUMMARY

Visual FoxPro 6.0 ships with a new wizard called the Web Publishing Wizard. This is one of the most powerful wizards that has ever shipped with Visual FoxPro. It is built entirely on top of the GENHTML engine, so it has a completely open architecture to allow for user created custom layouts and styles.

MORE INFORMATION

Most of the inner workings of the Web Publishing Wizard reside on Step 3 that includes both data layouts and visual styles. All of the information you see in the two lists are metadata stored in the Genhtml.dbf file stored in your Visual FoxPro root directory.

NOTE: This file is automatically recreated if you delete it (it is stored internally in the _HTML.VCX class library).

The Genhtml.dbf table has a field called "Type" that determines the contents of each list. You can create a layout or style by simply inserting a new record into the GENHTML table and setting its Type field to either Layout or Style (HINT: Make sure you change the Save field to .T. so that new versions of the Web Publishing Wizard retain your custom records). The Wizard specifically uses the Text and Desc fields to describe what the layout/style does.

Data Layouts

Records marked with a field Type = "Layout" are included in the Data Layouts list. A data layout is simply a functional representation of the way data is laid out on your Web page. For example, you may want a layout with data listed in columns using static HTML table tags. Layouts encompass both the data orientation (tabular vs. columnar) as well as the process driving the data display. You can have layouts with static HTML tags, or dynamic ones using technologies such as ASPs, ActiveX Data Objects (ADO), Remote Data Service (RDS), Tabular Data Controls, and so forth. The Web Publishing Wizard includes several layouts that use the Tabular Data Control.

Since layouts function to generate data that is displayed on a Web page, you need some mechanism to plug in your custom Visual FoxPro code. The Classname and Classlib fields serve this exact purpose. A public variable called _oHTML is created from your class by the Genhtml.prg engine and used to drive an entire data generation process by calling a method named "Generate". So, if you write your own class, make sure to have a Generate method. The best solution, however, is to subclass an existing layout called _HTMLTABLE in the _HTML.vcx file.

NOTE: _TabDataControl in the _HTMLSTY.VCX file is an example of this.

By doing this, you can call a common method such as GenerateTable.

The Genhtml.dbf file also contains provisions allowing you to hook into the class code and control various options before and/or after execution of code. You can use the PreScript memo field to execute code before calling the data generate method. Here is an example that sets a specific property of the class and the background color of the Web page. Remember that the _oHTML global is already created so you can make many property settings before actually having the table generated. For example:


   _oHTML.nTableStyle=1
   _oHTML.Body.bgColor="silver"

There is also a PostScript memo field for executing code after you generate the table. The combination of these two fields and the class definition you use for the layout provide the developer with lots of flexibility.

The primary purpose of a layout is to generate and return HTML that you use in the Web page. This can be a bit messy when you append many strings together to create the HTML/script. In addition, you may find the need for script reuse. The Genhtml.dbf file has special fields (Script and HTML) to simplify these issues. The HTML field contains HTML that gets embedded in your Web page's HTML output. For example, the _TabDataControl class has code that embeds HTML from the FilterScript record into the Genhtml.dbf file. For example:


   THIS.Body.AddGenHTMLField("HTML",,"FilterScript")

Many of the Visual Styles make use of the Script field. In fact, many of these records call another Script record with Id = "SetBodyImage".

Layout Options

If you are somewhat familiar with the Web Publishing Wizard, you may have noticed that the Options dialog box is also meta-driven. The Properties field controls this setting. For example, the TabCtlList record has the following:


   Options=TabListOptions

This indicates that you should lookup a record in the Genhtml.dbf file with fields Type = "OPTIONS" and Id = "TabListOptions". The classname and classlib fields reference class information that you need to display and handle options particular to the layout. You need to design this to handle properties specific to your layout. You use the Options dialog box to set properties for your layout class. As with the PreScript and PostScript fields, you can have the Wizard set properties before and after data generation.

It is highly recommended that you subclass your custom layout dialogs from either _Options or _StaticOptions classes in the _HTMLSTY.vcx file. The _Options class contains details of how to register properties (See the RegisterSetting method). To get an idea of how to accomplish this, look at the classes stored in the _HTMLSTY.vcx file that correspond to each layout.

Visual Styles

Records with field Type = "Style" are in the Visual Styles list. A style is a visual enhancement to the selected layout. You can have multiple styles on a Web page, however, you can only have a single layout. A common visual style commonly sets the background color/image as well as special tags such as a title description. Many of these are included with the Wizard.

Most of the visual styles included merely set the background image of the Web page. Some add a specific HTML tag, while others work in setting cascading style sheet settings (See the Style field). In general, the script in the Genhtml.dbf file controls the visual style information.

Inner Wizard Workings

So, how does the Wizard work to coordinate the user selected layout and Styles? Again, everything goes through the Genhtml.prg engine. Let's look at the parameter statement as follows:


 LPARAMETERS tcOutFile,tvSource,tnShow,tvIELink,tcStyle,tcScope,tcHTMLClass

Notice the fifth parameter. This corresponds to the Id field in the Genhtml.dbf file. You can pass it any record Id in this table (The Genhtml.prg does not care about the Type field). The Wizard has an output option allowing export to a script. Here is an example of some code in the script:


   DO (_GENHTML) WITH "C:\VFP6\OFFICES.HTM",ALIAS(),2,,"_RX71AACKD"

The Wizard actually creates a new record in GENTHML (Id = "_RX71AACKD") that is called by the script. The Links field in this record points to the layout and style records used. This field actually inherits the behavior of these other records. There is virtually unlimited potential with the entire Web Publishing Wizard/Genhtml architecture.

Additional query words: kbInternet kbWizard kbVFp600 PGFest600

Keywords :
Version : WINDOWS:6.0
Platform : WINDOWS
Issue type : kbhowto