[flexcoders] Re: redundancy in custom ItemRenderer
> 2) I don't think you can make a variable bindable by putting [Bindable]
> AFTER the variable (unless you were intending to make your button
> variable bindable on dataChange).
--
right, that was an error in my code. it should go before the getter,
as in:
=
// Make the data property bindable.
[Bindable("dataChange")]
public function get data():Object {
return _data;
}
=
thanks for pointing that out.
[flexcoders] Re: redundancy in custom ItemRenderer
--- In flexcoders@yahoogroups.com, "flexrookie" wrote: > > not an answer to my question, but a follow up for new itemrenderer > coders. i just changed my implementation of the renderer from a canvas > to a UIComponent, following alex harui's performance recommendation. Some suggestions: 1) Use a flag in set data so that you don't go through your logic in commitProperties that's only relevant when data changes when commitProperties is called for other reasons. 2) I don't think you can make a variable bindable by putting [Bindable] AFTER the variable (unless you were intending to make your button variable bindable on dataChange). 3) There's a lot of overhead in adding and removing children. Consider hiding and showing instead.
[flexcoders] Re: redundancy in custom ItemRenderer
not an answer to my question, but a follow up for new itemrenderer
coders. i just changed my implementation of the renderer from a canvas
to a UIComponent, following alex harui's performance recommendation.
here's the updated renderer code (big thanks to peter ent's renderer
post at
http://weblogs.macromedia.com/pent/archives/2008/04/itemrenderers_p_4.html):
===
package {
import mx.core.UIComponent;
import mx.controls.Button;
import mx.controls.listClasses.IListItemRenderer;
import mx.events.FlexEvent;
import flash.display.Shape;
public class StockInfoRenderer extends UIComponent implements
IListItemRenderer {
private var _data:Object;
// Make the data property bindable.
[Bindable("dataChange")]
protected var button:Button;
public function StockInfoRenderer () {
trace("");
trace("StockInfoRenderer CONSTRUCTOR CALLED.");
}
override protected function createChildren ():void {
trace("StockInfoRenderer CREATE CHILDREN CALLED.");
super.createChildren();
if (button == null) {
button = new Button();
button.width = 100;
addChild(button);
var tmp:Shape = new Shape();
tmp.graphics.beginFill(0);
tmp.graphics.drawRect(0,0,10,10);
tmp.graphics.endFill();
addChild(tmp);
mask = tmp;
}
}
override protected function commitProperties ():void {
trace("StockInfoRenderer COMMIT PROPERTIES CALLED for ID: " +
data.id);
super.commitProperties();
if (data.id != null) {
button.label = data.stockInfo.getPrice();
} else {
if (button && contains(button)) {
removeChild(button);
}
}
}
// Define the getter method.
public function get data():Object {
return _data;
}
// Define the setter method, and dispatch an event when the property
// changes to support data binding.
public function set data(value:Object):void {
_data = value;
dispatchEvent(new FlexEvent(FlexEvent.DATA_CHANGE));
trace("StockInfoRenderer SET DATA CALLED for ID: " + data.id);
invalidateProperties()
}
override protected function updateDisplayList (unscaledWidth:Number,
unscaledHeight:Number):void {
super.updateDisplayList(unscaledWidth, unscaledHeight);
if (button) {
button.setActualSize(100, 50);
}
if (mask) {
mask.width = unscaledWidth;
mask.height = unscaledHeight;
}
setActualSize(unscaledWidth, unscaledHeight);
}
}
}
===
~flexrookie
--- In flexcoders@yahoogroups.com, "flexrookie" wrote:
>
> ok, new code, this time with IDs on dataProvider items for tracking.
> yes, i know there's no direct renderer-to-provider relationship. i now
> realize that the extra renderer instance is created for measurment
> (according to alex harui). but i'm still looking for an explanation on
> the multiple set data and commitProperties() calls.
[flexcoders] Re: redundancy in custom ItemRenderer
thanks amy, i found that info confirmed by alex harui's famous itemrenderer post, under recycling, here: http://blogs.adobe.com/aharui/2007/03/thinking_about_item_renderers_1.html ~flexrookie --- In flexcoders@yahoogroups.com, "Amy" wrote: > > --- In flexcoders@yahoogroups.com, "flexrookie" wrote: > > > > another question about ItemRenderers, using my previous stock example. > > > > i have noticed that my custom item renderer seems to be performing > > redundant executions. for a single dataProvider item, i see two > > renderer instances created. and for each instance, set data and > > commitProperties() are called repeatedly. > > http://flexdiary.blogspot.com/2008/04/is-horizontallist-faster-than- > hbox-with.html >
[flexcoders] Re: redundancy in custom ItemRenderer
ok, new code, this time with IDs on dataProvider items for tracking.
yes, i know there's no direct renderer-to-provider relationship. i now
realize that the extra renderer instance is created for measurment
(according to alex harui). but i'm still looking for an explanation on
the multiple set data and commitProperties() calls.
i am curious, partly from a performance perspective, and partly
because i want to understand how this works so i can slowly become
better at architecting flex apps. code follows.
StockApp.mxml
http://www.adobe.com/2006/mxml";
layout="absolute"
applicationComplete="applicationCompleteListener(event)">
StockInfoRenderer.as
package {
import mx.containers.Canvas;
import mx.controls.Button;
public class StockInfoRenderer extends Canvas {
protected var button:Button;
public function StockInfoRenderer () {
trace("");
trace("StockInfoRenderer CONSTRUCTOR CALLED.");
}
override protected function createChildren ():void {
trace("StockInfoRenderer CREATE CHILDREN CALLED.");
super.createChildren();
if (button == null) {
button = new Button();
button.width = 100;
}
addChild(button);
}
override protected function commitProperties ():void {
trace("StockInfoRenderer COMMIT PROPERTIES CALLED for ID: " +
data.id);
super.commitProperties();
button.label = data.stockInfo.getPrice();
}
override public function set data (value:Object):void {
super.data = value;
trace("StockInfoRenderer SET DATA CALLED for ID: " + data.id);
invalidateProperties()
}
}
}
StockInfo.as
package {
import flash.events.Event;
import flash.events.EventDispatcher;
import flash.events.TimerEvent;
import flash.utils.Timer;
public class StockInfo extends EventDispatcher {
private var t:Timer;
public function StockInfo () {
t = new Timer(1000);
t.addEventListener(TimerEvent.TIMER, timerListener);
t.start();
}
public function timerListener (e:TimerEvent):void {
dispatchEvent(new Event("UPDATE"));
}
public function getPrice ():Number {
return Math.floor(Math.random()*1000)/100;
}
}
}
output
StockInfoRenderer CONSTRUCTOR CALLED.
StockInfoRenderer CREATE CHILDREN CALLED.
StockInfoRenderer SET DATA CALLED for ID: 1
StockInfoRenderer COMMIT PROPERTIES CALLED for ID: 1
StockInfoRenderer SET DATA CALLED for ID: 1
StockInfoRenderer COMMIT PROPERTIES CALLED for ID: 1
StockInfoRenderer CONSTRUCTOR CALLED.
StockInfoRenderer SET DATA CALLED for ID: 1
StockInfoRenderer CREATE CHILDREN CALLED.
StockInfoRenderer COMMIT PROPERTIES CALLED for ID: 1
~flexrookie
--- In flexcoders@yahoogroups.com, "Tracy Spratt" wrote:
>
> Why do you think the renderer's commitProperties is being called
more than
> once for a single item? Your trace statements do not identify the item.
> You understand that there is no direct relationship between the
number of
> items and the number of renderer instances? The number of instances
depends
> on the number of visible rows, plus a few for buffering.
>
>
>
> And are you just curious? The specific renderer instantiation
behavior is
> normally not of concern to a developer, but such concern sometimes
> indicates misuse.
>
>
>
> Tracy
>
>
>
> _
>
> From: flexcoders@yahoogroups.com [mailto:flexcod...@yahoogroups.com] On
> Behalf Of flexrookie
> Sent: Saturday, February 28, 2009 9:35 PM
> To: flexcoders@yahoogroups.com
> Subject: [flexcoders] redundancy in custom ItemRenderer
>
>
>
> another question about ItemRenderers, using my previous stock example.
>
> i have noticed that my custom item renderer seems to be performing
> redundant executions. for a single dataProvider item, i see two
> renderer instances created. and for each instance, set data and
> commitProperties() are called repeatedly.
>
> here's my code:
>
> StockApp.mxml
> ===
>
> http://www.adobe.
> com/2006/mxml"
> layout="absolute"
> applicationComplete="applicationCompleteListener(event)">
>
>
>
>
> ===
>
> StockInfoRenderer.as
> ===
> package {
> import mx.containers.Canvas;
> import mx.controls.Button;
>
> public class StockInfoRenderer extends Canvas {
> protected var button:Button;
>
> public function StockInfoRenderer () {
> trace("StockInfoRenderer CONSTRUCTOR CALLED.");
> }
>
> override protected function createChildren ():void {
> trace("StockInfoRenderer CREATE CHILDREN CALLED.");
> super.createChildren();
>
> if (button == null) {
> button = new Button();
> butt
[flexcoders] Re: redundancy in custom ItemRenderer
> ~flashrookie -- er... flexrookie (flash masta!) ; )
[flexcoders] Re: redundancy in custom ItemRenderer
--- In flexcoders@yahoogroups.com, "flexrookie" wrote: > > another question about ItemRenderers, using my previous stock example. > > i have noticed that my custom item renderer seems to be performing > redundant executions. for a single dataProvider item, i see two > renderer instances created. and for each instance, set data and > commitProperties() are called repeatedly. http://flexdiary.blogspot.com/2008/04/is-horizontallist-faster-than- hbox-with.html
