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Building a Gantt Chart Component in Flex

Here’s my intial attempt at making something that resembles a Gantt chart. There’s been some good discussion about this recently on flexcoders. People have suggested a few different ways of making a Gantt chart. Here I’ll outline the main ideas that have been thrown around and then I’ll go over the example that I came up with.

Option 1: Use the DataGrid as the base. This was the approach that Andrew Trice used. This is also the approach that I took, see the example below. The idea here is that each row of the DataGrid will serve as each item of the Gantt chart, and all we need to do is specify a custom itemRenderer to display it.

Option 2: Use the charting classes as the base. Ely Greenfield’s got an example of making a chart similar to a Gantt chart (follow the link and find: Series Type >> Columns and Bars >> Floating Bars). The basic idea here is that you use the chart classes and extend them to turn them into a Gantt chart. I decided against this because 1) I haven’t investigated custom charting and reading Ely’s blog makes it seem fairly complicated (Ely, I know you try to make it easy for us :) ) and 2) I liked the itemRenderer and itemEditor approach that a DataGrid takes, which would allow me to have editable controls in there.

Option 3: Use the scheduling framework from Adobe Consulting as the base. I really like this idea. It was mentioned on flexcoders after I started working on a solution using DataGrid, but I think this way is definitely worth exploring. I haven’t played with the scheduling framework yet, but at first glance it seems like much of the work they did for that would carry over very well for a Gantt chart.

So like I said, I went with the DataGrid option. The basic idea is the same as on Andrew Trice’s post, I just went a little further. In my example you can manipulate the data in the chart. Each item is represented by a slider that allows you to adjust the starting point, the end point, and the percent complete for each task. To try this in the example just click on one of the items and the slider thumbs should appear.

Another cool thing this shows is some skinning and customization of the Slider component. To get these sliders looking like they do I had to make the Slider apply different skins to the first, second, and third thumbs. I also needed different highlighting skins for the two portions of the slider track. And you can drag the entire region (that’s something that came from a previous post about draggable sliders). Deep down those are just Slider components, but they look and act fairly differently.

So I’m not going to go into heavy duty explanation of how this works. And I didn’t comment the code up very much (if at all). It’s not complete by any means, no axis is shown, etc. This is sort of my first draft and if you want to download the source and figure it out for yourself, go for it.

The example below shows a gantt chart with my plans for world domination. There are two charts here with the same data, but they show different skinning options.

View the source.


Anonymous said...

see for Gantt implementation

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