Creating PDA Applications

Last Updated: 9/18/2008

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Topics in this section:
Rethinking the User Interface
Writing your first Delphi App
Images and Graphics
Extending Intraweb
Working with COM
Working with ClientDataSets
Creating PDA Applications
Error Handling
Control Size
Reading and writing custom cookies
Miscellaneous
Advanced Development
Session Locking

PDA / HTML 3.2 Applications

To support PDA's, old browsers or users who have everything locked down, IntraWeb has an HTML 3.2 Mode. In this mode the output generated by IW applications is using pure HTML 3.2 without any additional JavaScript or Cascading Style Sheets. Since HTML 3.2 is a standard that nearly all devices on the market support, it is a good option for developing web applications focused on PDA's. The HTML 3.2 Mode is by nature somewhat limited though - this limitation lies in the way how HTML 3.2 works and is not an IntraWeb limitation.

An IntraWeb application may have normal (HTML 4) forms and HTML 3.2 forms. IntraWeb detects the browser that starts a session and will show the form that fits best.

Developing 3.2 Applications

When developing PDA applications, you need to use Applications forms (alternatively Page forms) that are of the class TIWAppForm32 (TIWPageForm32). This can be accomplished either using the Wizard to create a new application and selecting "Main Form 3.2" or adding a 3.2 form to an existing application.

Using 3.2 controls

PDA applications are restricted to controls that are of the class 3.2. However, due to the restrictions imposed by HTML 3.2, these counterpart controls sometimes do not have all the functionality that the 4.0 (or normal) IW controls have. You can ONLY use 3.2 controls for PDA applications.

Using IntraWeb for Delphi 3.2 controls

There are two tabs on the component palette that have the corresponding 3.2 version component of the standard IW components.

Rendering and layout

By default, when placing 3.2 controls on a form, these are rendered in vertically in tab order. This is ideal for testing your application before finalizing the UI aspects of it. The reason for the vertical placement is due to the fact that PDA's do not support CSS and therefore positioning cannot be accomplished directly. To allow correct positioning, you have two alternatives. The first is to use a TIWLayoutMgrHTML32 component and design your form using the editor. The second option is to use a TIWTemplateProcessor32 and use templates to design the look of the application. However, it is important to remember that when using an external editor to design 3.2 forms, you need to restrict the HTML elements to 3.2 standard. Most HTML editors allow you to set this option before editing.

Setting the main form

As with normal IW applications, PDA versions need to have a main form defined. To do this in IntraWeb for Delphi, use the SetAsMainForm method in the initialization section of the form you require to be the main form.

If your application is meant to serve both, HTM 4.0 and HTML 3.2, then you have to set one Main form for each mode.

Running the application

During development, it is much easier to test PDA applications using the computer you develop on. IW allows you to do this by launching your normal browser and testing the PDA version. To do so, you have two alternatives:

Using the Standalone application, click on the PDA icon before launching the browser with the Launch Browser button.
Directly type the URL in the browser appending 32 at the end, e.g. http://127.0.0.1:8888/32

This will allow you to see the results of your IW PDA application on the browser.

When using the application directly from a PDA device, IW will detect the browser that the PDA device uses and automatically launch the PDA application.

Note: The error message "no main form is defined" occurs when you try to access an application that doesn't have HTML 3.2 forms with a browser that it's not able to display HTML 4.0. This might occur with Netscape 4, as Netscape 4 doesn't have full support for HTML 4.0 and JavaScript.