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Introduction to Behaviors

Both IMS Web Spinner and IMS Web Engine include two simple
behaviors that can be assigned to your Objects. These behaviors can
set an Object's visibility while the page is first loading, after it has
loaded or on a mouse over or mouse leave event. These Behaviors
are a useful way to create several special effects that toggle an
Object's visibility.

IMS Web Engine includes the ability to create far more complex
behaviors based on many different interrelated events. The effective
use of these Behaviors is probably the most complex aspect of
learning to use IMS Web Engine.

We have tried to simplify several common uses for Behaviors by
incorporating them into the IMS Web Engine Wizards. These
include the creation of drop menus, strobe effects, and the
management of several animation effects. Mastering the use of the
Behavior dialog however, will give you the ability to create
complex interactive web pages including DHTML games, business
presentations and educational courseware.

A Behavior works by switching between an 'Active' and a 'Not
Active' state. Don't be misled by the terms. There is nothing
intrinsically different between the two states other than what you
decide to assign to them. In other words, an Object could just as
easily be invisible when 'Active' as when 'Not Active'.

The Behavior is composed of two components. The first is an Event
that triggers a Behavior 'Active' or 'Not Active'. The second is an
Action that will be performed when the Behavior enters either of
these two states. The user defines a Behavior by deciding what the
trigger mechanisms are and what actions will be performed as the
Behavior switch between the two states.

As an example, we can use a simple Mouse Over Behavior to make
an Object Visible and Invisible.


The trigger events in this example are the mouse moving over and
off the Object. By default, the Object starts in a 'Not Active' state.
As the cursor is moved over the Object, it triggers the Object into its
'Active' state. As the cursor moves off the Object it triggers its 'Not
Active' state. The Behavior's 'Actions' are to make the Object
'Visible' when it is triggered into its 'Active' state and 'Invisible'
when triggered into its 'Not Active' state.

As I mentioned previously, there is no intrinsic difference between
an Object's 'Active' and 'Not Active' state. Figure is20fig2 illustrates
this with two examples. Example 1 will make an Object Visible as
the mouse moves over it. Example 2 does the reverse.

This example is of course very simple and can be more efficiently
done by setting an Objects Visibility in the Object Editor. The
principle for more advanced Behaviors remains the same. The
difference lies in the types of Events that can trigger a Behavior and
the Actions that can be performed by the Behavior.

Is20fig3 illustrates some of the Behavior dialogs including Triggers and Actions that
can be applied to a Behavior. User Triggers include Mouse Over,
Mouse Select or a keyboard character. Dynamic triggers include
Time, when two Objects intersect or don't intersect, or when an
Object's internal value equates to a simple test. An event can also be
triggered by another Object when its Events are triggered.

There are many Actions a Behavior can perform when an Event is
triggered. These include setting an Object's visibility, starting or
stopping its Action or Sound Component if it has one, or triggering
the Event of another Object's Behavior. Actions can also include
applying a mathematical formula to any Object or performing a
Metamorph operation on an Object. Despite the big word, this
simply means changing one or more of an Object's Components. An
example would be switching an Objects Action component that
traces a rectangle to an Action component that traces a polygon.

These operations may seem complicated when taken in their
entirety. When looked at individually however, they are far easier to

The Virtual Mechanics Behaviors demo illustrates two simple
Behaviors to make a series of Text Objects visible as the mouse or
the Bird Object moves over them. There are many other examples in
the demo section and at the dhtml magic site including an
educational interactive map.. You can also look at the Web Engine
tutorials if you have not already done so for more information on
creating Behavior.

I will look at some specific Behaviors and how to implement them
interspersed with articles that also apply to IMS Web Spinner and
IMS Web Dwarf users over the next few issues.

"IMS Web Tips" ISSN 1488-7088
© Copyright 1999 Virtual Mechanics

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