Stefan on Flex

Flex Charting with LARGE datasets

2009-11-10T13:51:00.000-08:00

A quick note and demo on something I've been working on for a while. As many of you know, it's pretty hard to render 5000+ points in the standard version of Flex Charts... the GUI hangs and won't respond until the rendering is done.. This is what I've been working on to overcome this:

The demo works better in AIR, there's still some optimizing left for flash player..

Autosized DataGrid Columns

2009-11-01T13:00:00.001-08:00

The other day I was looking for a simple enough implementation of a datagrid which adjusted its columns based on the content. As most of the posts on this topic emphasize, it is pretty tricky since this kind of functionality needs to traverse the complete dataset to find the longest strings in a data set. I first tried to implement this using the measureText function to measure each string individually, which turned out to be a very bad idea since the measureText is a quite expensive operation.

To increase the performance I replaced the measureText with a precalculated character size average multiplied with the string length, which turned out to dramatically improve the performance of the calculations.

Download source with example

Here's an example where you can test the performance yourself by:

1: Specify the collection size ( each item will have 12 fields )

2: Specify the maximum length of the randomized strings

3: Create the dataset (don't mind the performance issues here, this is not what we're testing)

4: Add the dataset to the datagrid (this is where we're concerned about the performance)

Implicit Data Paging in Flex 3

2009-11-01T03:49:00.000-08:00

I'm currently working on a project where we need to be able to handle search queries with large responses. We let the user choose to either display the results in a grid or a list (ala Windows Explorer), and we use the DataGrid and TileList to accommodate this. I googled "data paging flex 3" and found several interesting posts, but I couldn't really find a generic solution. The best solution I found was Badonger's extended DataGrid, but this just partially solves my problem since it doesn't provide a solution for all data view components.

My contribution is inspired by Badonger's DataGrid, but pulls the paging back to be handled by the Collection, and can therefore be reused in many data view components. My solution is pretty straightforward without any (major) fancy extras. It's a fresh implementation of ICollectionView (with a corresponding IViewCursor) and can be used as a dataprovider to any of the standard flex data components.

Download the source with an example

Here's an example of three components (DataGrid, TileList, List) which shares a PagedCollection with 100 000 000 entries ( I'm using a simulated data service which returns randomized strings).

My contribution

2009-11-01T03:43:00.000-08:00

I woke up this morning and realized I'd become a code leech - I browse a tremendous amount of code blogs and forums daily - but I never really contribute with anything myself. I'll try to remedy that with this blog