Another good itemRenderer Resource

The longer I use Flex, the more firmly I believe that the key to understanding it is the component life cycle. Specifically, the life cycle as it applies to item renderers. Today on Flex Coders, Douglas Knudsen posted a link to this great presentation on the component life cycle by Eli Greenspan. I can't for the life of me figure out how to bookmark to a pdf, but if I post a link here, I'll be able to find it forever :-).

Great ItemRenderer Resource

I really struggle with itemRenderers--what goes where to make what you want to occur happen when you want it to. So I've been talking to various people and reading, reading, reading trying to make sense of it all. From the posts on the yahoo FlexCoders group, it seems like I'm not the only one experiencing confusion.

I think the biggest problem is that there don't seem to be many "from the ground up" resources on this subject. But that doesn't mean there aren't any. In addition to the Flex help and LiveDocs, which, let's face it, confuse us as much as inform us, there are several blogs that tackle this subject. Today I found Peter Ent's blog, which contains a five part series just on itemRenderers. Thanks, Peter!

Working with Dates in AS3

The Date examples that come with Flex (and, presumably, Flash) are all very well and good, but to me they don't seem to be very...practical. And it doesn't help that the documentation doesn't provide any clues about how to do simple things like, oh, figuring out how many days there are in a month. There's probably very good code for these things in opensource projects like the Flex scheduler, but I think you have to know where to dig.

So I played around with the Date object, and I discovered that you can use numbers outside the integers 1-31 in the date parameter (new Date(year, month, date)) and get some interesting results. Such as if you use 0, you get the last day of the previous month. As you might expect, negative numbers will go further back into the previous month. I suspect numbers higher than the last day of the month you're dealing with will continue into the next month, though I haven't tried it.

What I was trying to do was create an ArrayCollection that could be used as a dataprovider for a TileList and then that TileList could display a calendar page just like what you see when you look at the calendar on your wall...i.e. the first few days might be in the previous month and the last few days might be in the next month, because only February ever has a shot at fitting exactly in a grid that is seven days wide. I figured that I'd share my class, since I'm probably not the first or last person to ever want to do this. Note that it's not finished...you'll need to add the last few days when the end of the month doesn't fall on Saturday, but that's not rocket science.



package com.magnoliamultimedia.vo
{
import mx.collections.ArrayCollection;
public class DisplayMonth
{
private var _year:int;
private var _month:int;
private var _startIndex:int;
private var _dateColl:ArrayCollection;
public function DisplayMonth(monthNumber:int, yearNumber:int)
{
_month=monthNumber;
_year=yearNumber;
var tmpArray:Array=new Array();
var firstDay:Date=new Date(yearNumber, monthNumber);
var lastDay:Date=new Date(yearNumber, monthNumber +1, 0);
var lastDayNum:int = lastDay.date;
_startIndex = firstDay.day;
var tempDay:Date;
var i:int;
//fill blank days before beginning of month
for (i=0; i<_startindex; i++)
tempday = new Date(yearNumber, monthNumber);
tempday.date -= 6-i;
tmpArray.push(tempday);
}
//fill in the rest of the dates here...
}
}
}



Sorry about the crap formatting...I haven't figured out the spiffy scrolling thing some other bloggers manage.

Updated 5/28/10. I noticed that part of the code had been "eaten" by Blogger. I replaced the relevant code, but may not have put back everything that was once there. For a better example of how to do this, look at my GroupingCollection example.