As you’ve already seen, transitions use effects. That means you can create custom transitions
the same way you create custom effects. The only difference when creating
custom transitions is that the effect instance class needs to handle the
fallback rules for automatically determining the starting and ending
property values. For example, we’ve seen that if you don’t explicitly set
the xFrom
, yFrom
, xTo
,
and yTo
properties for an effect used
as a transition, the values are automatically retrieved from the target in
the from and to states. When you create an effect instance class that you
intend to use as a transition, you should include the ability to
automatically detect these default property values.
EffectInstance
subclasses
automatically inherit a property called propertyChanges
, which is of type mx.effects.effectClasses.PropertyChanges
. The
propertyChanges
property has two
properties: start
and end
. These properties are associative arrays
containing the affected property values of the target in the from and to
states.