If you haven’t checked out Tour de Flex I suggest you do. It is an Air app that contains over 200 working applications, all with source code. Everything from simple Flex components to advanced filters and working with Air is covered, so there’s something for everyone, beginners to advanced developers alike.
Just in time for Christmas, Kap Lab has released version 1.1.0 of its data visualization components. In addition, two new developer tools have been released: the Cairngorm Console and the PureMVC Console. All Kap Lab’s components are free and are extremely useful. I suggest you give them a look.
One of the bad things about using itemRenderers in a DataGridColumn is that you lose the dataTip functionality that it normally provides. Well, here is a way to fake that functionality.
First, add the dataTipField or dataTipFunction to the DataGridColumn like you normally would.
Then, in your itemRenderer add the following code to be able to tap into that information and display a tooltip instead.
private function getToolTip():String{
if(func != null){
}else if(dg.columns[listData.columnIndex].dataTipField.length){
}else{
}
}
override protected function updateDisplayList(unscaledWidth:Number, unscaledHeight:Number):void{
}
This works with both dataTipFields and dataTipFunctions and lets you treat the dataTips in your columns the same way, regardless of whether you’re using an itemRenderer or not. The only minor difference is the positioning of the label, but that can be easily modified with styles. You can download the full source code here, for a functional example of how this works.
In a previous post I explained how a rendering bug in Flex was causing items to disappear in an itemRenderer. In the example below, you can see that when you scroll, the items in the list disappear. This is caused by the varying heights of the elements. If you explicitly set the height for each element or set variableRowHeights to false, then the problem goes away.
What was causing the problem was apparent but the solution was not. Thankfully, Olivier Lalonde was nice enough to shed some light on an easy fix. The itemRenderer needs to be validated as the user scrolls. So, as Olivier suggests, you simply need to listen for the dataChange event and execute the validateNow() function.
You can see in the example below that the list now has varying row heights… and the data no longer disappears. NICE! The key point to focus on here is the following line: <mx:VBox dataChange=”validateNow()” verticalGap=”0″>
<mx:itemRenderer>
</mx:HBox>
<mx:Text text=”{data.description}” width=”100%” />
</mx:VBox>
</mx:Component>
</mx:itemRenderer>
</mx:List>
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