Chapter 1 The GUI Difference

Character-mode and bitmapped (graphical user interface - GUI) environments differ in two significant ways - how the application is displayed and how the user interacts with the application. The following sections describe the issues involved in more detail.

How the Application is Displayed

In a character-mode environment, an application typically consists of screens filled mostly with text fields, and some simulated checkboxes, for entering and displaying data.

The bitmapped environment puts a whole host of graphical widgets in your hands providing different ways of entering values and displaying data. Some examples are checkboxes, radio groups, lists, images, graphics, menu checkboxes and menu radio buttons. Here are some of the things you should consider.

Will the new widgets make your users more productive?
Different widgets are best for different types of data entry. Which ones are more suitable for the kind of data in your application?
Will incorporating images and graphics in your application convey more information about your data to the users?
What kind of screen design will improve your users' productivity?

How the User Interacts with the Application

In a character-mode environment, all user interactions are tightly controlled by the application. For example, when the user is in a text field, the application controls which text field can be navigated to next and which actions are permitted by key triggers and menu options.

You will probably be very familiar with the following scenario. Suppose you have three blocks with the default sequence of block1, block2 and block3. Block1 and block3 are single-record blocks showing order information, and block2 is a multi-record order items block and a detail of block1.

You are in block1 and you are going to create a new order. You enter the values of each field and hit the [Next Field] or [Tab] key to enter the values of each field and hit the [Next Field] or [Tab] key to enter the next value. As you are going through the fields, the KEY-NXTFLD triggers are fired, correctly positioning you for entering the next value, and even populating some fields in block3 about the order before bringing you into the order items block when you are done with the last field in block1.

In block2, you bring up the list of products and it covers part of the screen but still showing relevant context information for that field. You select the product number of the item and hit the [Next Field] key, the KEY-NXTFLD trigger automatically fills in the product description and price, skips over them and waits for input in the quantity field. After you enter the quantity field, the KEY-NXTFLD trigger computes the line total, assured that the quantity and price information are available.

In a character-mode environment, key triggers were used very heavily as opposed to PRE-, POST- and ON-VALIDATE-triggers because they allow restricted built-ins to be called. However, key triggers are precisely the ones that make the character-mode to bitmapped migration a very challenging one.

In a bitmapped environment, the above scenario changes drastically. With a mouse, the user has a lot more freedom than any character-mode application can handle. When the user navigates using the mouse, none of your key triggers will fire. Using the same application as described above, the following are some of the things the user can do in a bitmapped environment and their corresponding consequences.

The product description and price fields are updatable with only the key-triggers preventing the user from navigating there to change their values. However, the user can now click in these fields to change their values, indirectly affecting the line total field.
The user can click in the order items block without firing the key trigger to populate block3.
After entering the quantity, click in another order item, thus not firing the key trigger to compute the line total.
The user can click in block3 and start entering or changing values there when that block is only meant to display additional information about an order.
When the user invokes the product list in a window, that window can now be moved to a different location or even iconified, thus eliminating the overlaid context-sensitive effect in the original application.

These are issues that are characteristic of moving your application from a character-mode to a bitmapped environment, not specifically because you are upgrading to the newest version of Oracle Forms. We will look at these issues in more detail and how you can solve them.

Part #: A32362