Macromedia flex 2 Manuel

Writing an effect for a transition

241

Flex uses the following rules to determine the start and end values of effect properties when 
you use the effect in a transition: 

1.

If the effect defines the values of any properties, it uses the properties in the transition, as 
the following example shows:

<mx:Transition fromState="*" toState="*">

<mx:Sequence id="t1" targets="{[p1,p2,p3]}">

 <mx:Parallel>

<mx:Move duration="400"/>
<mx:Resize duration="400"/>

</mx:Parallel>

 <mx:Blur duration="100" 

</mx:Sequence>

</mx:Transition>

In this example, the two Blur filters define the properties of the effect.

2.

If the effect does not define the start values of the effect, the effect determines the values 
from the 

EffectInstance.propertyChanges

 property passed to the effect instance. Flex 

sets the 

propertyChanges

 property by using information from the current settings of the 

component, as defined by the current view state. For more information on the 

propertyChanges

 property, see 

In the example in step 1, notice that the Move and Resize effects do not define start values. 
Therefore, Flex determines the start values from the current size and position of the effect 
targets in the current view state, and passes that information to each effect instance by 
using the 

propertyChanges

 property.

3.

If the effect does not define the end values of the effect, the effect determines the values 
from the 

Effectinstance.propertyChanges

 property passed to the effect instance. Flex 

sets the 

propertyChanges

 property by using information about the component, as defined 

by the destination view state. For more information on the 

propertyChanges

 property, 

see 

.

In the example in rule 1, Flex determines the end values of the Move and Resize effects 
from the size and position of the effect targets in the destination view state. In some cases, 
the destination view state defines those values. If the destination view state does not define 
the values, Flex determines them from the setting of the base view state, and passes that 
information to each effect instance by using the 

propertyChanges

 property. 

4.

If there are no explicit values, and Flex cannot determine values from the current or 
destination view states, the effect uses its default property values.