LzTimerClass

LzTimerClass
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Name

LzTimerClass — Handles calling of a delegate after a specified number of milliseconds.

Synopsis

JavaScript: LzTimerClass
Type: Class
Access: public
Topic: LFC.Services
Declared in: WEB-INF/lps/lfc/services/LzTimer.lzs

Description

LzTimer is used to invoke functionality after a specific amount of time. By using a LzDelegate to refer to a particular method, and then by adding a timer to that delegate, the developer can control the timing of the method's start. Use LzTimer to tweak sequence and timing of visual animations, delay the effects of user events, or implement user experiences with expiration features.

It should be noted that the time passed to the LzTimer service describes the time before which the delegate may not run -- it is not guaranteed that the delegate will run at that time. Depending on application needs and client performance, the specified delegate may be invoked at any time after the amount of time specified.

The following example displays some text when a button is clicked, and uses LzTimer to fade the text away after three seconds.

Example 16. Using LzTimer to invoke method

 <canvas height="50" >
 
     <button text="Show then Fade" onclick="canvas.showText()" />
     <text name="myText" opacity="0.0" bgcolor="#CCCCCC">The Invisible Man</text>
     <simplelayout axis="y" spacing="10" />
 
     <method name="showText">
         this.myText.setAttribute( "opacity", 1.0 );
         this.fadeDelegate = new LzDelegate( this, "fadeText" );
         LzTimer.addTimer( this.fadeDelegate, 3000 );
     </method>
 
     <method name="fadeText">
         this.myText.animate( "opacity", 0.0, 1000 );
     </method>
 
 </canvas>

Development Note

The timer calls a given delegate in a specified number of miliseconds.Unfortunately the original semantics of LzTimer allows one to add more than one timer to a single delegate, but only allows one to remove the oldest timer from a delegate -- there's no way of specifying which one. The logic below is faithful to the original while still attempting to be efficient. In the common case of one timer per delegate, we simply store the timer id in the delegate's timer list entry. If the program attempts to store more than one timer with a single delegate, we shift to storing an array of them in the timer list entry. This saves an array allocation in the common single-timer case, at the cost of increased code complexity.

Superclass Chain

LzTimerClass

Known Subclasses

Details

Properties (1)

timerList: private var timerList = { ... };

Methods (5)

addTimer(): public function addTimer(d : LzDelegate, milisecs : Number);

Adds a timer. NB: The timer guarantees that the delegate will not be called before the number of miliseconds specified here, but cannot guarantee that it will be called at exactly that time.
countTimers(): public function countTimers(d);
removeTimer(): public function removeTimer(d : LzDelegate);

Removes the first timer that calls the given delegate from the timerlist.
removeTimerWithID(): private function removeTimerWithID(d : LzDelegate, id);

Removes the timer with the given id that calls the given delegate from the timerlist.
resetTimer(): public function resetTimer(d : LzDelegate, milisecs);

Resets the timer for the given delegate to the new amount of time. If the delegate is not found, a new timer is created.

JavaScript Synopsis

public LzTimerClass {

private var timerList = { ... };

prototype public function addTimer (d : LzDelegate, milisecs : Number);

prototype public function countTimers (d);

prototype public function removeTimer (d : LzDelegate);

prototype private function removeTimerWithID (d : LzDelegate, id);

prototype public function resetTimer (d : LzDelegate, milisecs);

}

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