Comments on: Understanding Custom Flex Component Development

By: Bill

Bill — Mon, 28 Jun 2010 16:26:00 +0000

Good point. I’ve been hit by that little issue a few times myself! I’ll make a note of it in the article.

By: Maulik

Maulik — Mon, 28 Jun 2010 11:56:23 +0000

Great article! Thanks for taking time. However, something many articles forget to mention is that measure() will not be called when width and height are explicitly set. You should consider mentioning it.

By: Eugene Lee

Eugene Lee — Fri, 28 May 2010 14:59:16 +0000

It’s awesome.
I know I must get through custom component well if I want to be an expert of FLEX.
And you’ve given me great help!

By: Shally

Shally — Sat, 17 Apr 2010 04:17:07 +0000

Thanks a lot. Well summarised…

By: Sander

Sander — Wed, 03 Feb 2010 17:11:16 +0000

Very helpfull, thanks!

By: walv

walv — Sat, 21 Nov 2009 10:57:09 +0000

Excellent explanation. Wonderful example.

Thank you very much!!!

By: John

John — Tue, 13 Oct 2009 13:53:33 +0000

This is a great post. I’ve been working with a Datagrids updateDisplayList method trying to reposition the vertical scrollbar to the left side of a datagrid. This can be extremely helpful when the number of rows exceeds the width of the datagrid. Setting the following verticalScrollBar.x = 0; moves the scrollbar but does not move the header or reposition the other columns. Have you ever come across this? Any help would be great. Thanks!

By: David

David — Tue, 19 May 2009 03:42:51 +0000

Excellent summary!!! Thank you!!

By: Troy

Troy — Thu, 18 Dec 2008 19:14:33 +0000

This was REALLY helpful. I’ve been extremely frustrated with some code I’ve been working on and this solved all my problems.

The world is now a better place :)

I never new the order of precedence you so easily described:
* The component’s constructor
* The commitProperties() method
* The createChildren() method
* The measure() method
* The updateDisplayList() method

Thanks Bill!

By: Bill

Bill — Wed, 09 Apr 2008 18:43:20 +0000

Chris,

Without having seen the code, I would just have to make a few guesses:

1. Check the path of the URL and make sure that it will work consistently on the local machine and the server. For example when I reference an external jpg into my Flex App with a URL like this ‘/images/myimage.jpg’, you have to keep in mind that on the server, it will search from the root of the webapp so you will have to place the images in the root of the webapp directory, not the root of the project.. In my case, with Tomcat, I had to put them in an images folder in the ROOT folder of the Tomcat webapps directory.

2. Troubleshoot it through simplification. Try a new project with a panel containing a single image. Then deploy it on the server and make sure it works there. Once that works you should be able to duplicate that way of making it work over to your larger, more complex application. Following the ‘fresh start’ path like this usually exposes what you are doing wrong in short order.

Based on your last statement, I think you are correct about the instantiation issue. It could have something to do with the fact that the component has not fully loaded the image when it is displayed. Maybe you component that contains the image should call invalidateDisplayList or updateDisplayList once the image has loaded. This example shows how to listen for the image to finish loading. Then you could dispatch the event afterward? Just guessing

Hope that helps.