MACROMEDIA FLEX - DEVELOPING COMPONENTS AND THEMES Uživatelský manuál stáhnout pdf (Strana 13)

UNDERSTANDING+THE+FLEX+3+COMPONENT+AND+FRAMEWORK+LIFECYCLE!

13!

©!2009!DevelopmentArc!LLC,!All!rights!reserved.!

Figure'3')' Invalidation'/'Validation'Cycle'

Earlier!in!this!paper!we!talked!about!how!the!Flex!Framework!does!the!“wait!a!

frame”!for!us!to!manage!and!mitigate!performance!within!our!applications.!!The!

Invalidation‐Validation!cycle!is!the!first!place!in!the!component!lifecycle!that!really!

demonstrates!the!power!the!Flex!Framework!provides!us.!

The!Invalidation‐Validation!cycle!provides!a!decoupling!process.!!One!that!separates!

changing!of!values!(invalidating,!i.e.!making!the!old!values!no!long!valid)!from!

processing!values!(validating,!i.e.!applying!the!new!values).!!By!decoupling!this!

process!we!get!a!lot!of!added!benefits,!such!as!postponing!processor!heavy!

computation!until!the!last!possible!code!execution!stage!(just!before!the!player!

draws!to!the!screen)!and!preventing!unnecessary!code!from!being!executed!over!

and!over.!Let’s!look!at!an!example.!

myButton.width = 20;

myButton.width = 25;

Figure'4')' Setting'Width'Multiple'Times'Example'

In!the!code!above,!let’s!imagine!that!calling!the!width!setter!did!all!the!calculations!

to!update!the!component’s!size!right!away;!this!change!would!set!the!components!

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MACROMEDIA FLEX - DEVELOPING COMPONENTS AND THEMES Uživatelský manuál Strana 13