Django and Flex

This isn't a blog about Flex bugs - honest. But I found another yesterday.

If you have a bunch of components in a Flex Canvas, and show/hide/animate them with states and transitions, the components can change z-order on you without warning. I had a pernicious problem today with something like:

<mx:Canvas> 
 <mx:Panel id='content'/> 
 <mx:Panel id='tool_palette'/> 
</mx:Canvas>

Where content started out behind tool_palette, but when the latter got hidden (using a RemoveChild node in a state), and reappeared (by transitioning back) it was shown behind the content panel. Clearly a problem.

The solution I found was to separate the objects into two canvases:

<mx:Canvas> 
 <mx:Canvas height="100%" width="100%"> 
  <mx:Panel id='content'/> 
 </mx:Canvas> 
 <mx:Canvas height="100%" width="100%"> 
  <mx:Panel id='tool_palette'/> 
 </mx:Canvas> 
</mx:Canvas>

which is a bit of a hack, but works. This is the first time I've missed old-flash's z-depth model.

Posted by Ian at 01:53 PM | Permalink | Comments (5) | TrackBacks (0)

Just a quickie.

Discovered today that if you try to programatically deselect the currently selected item in a ListBase subclass with selectedItem=null the change doesn't propagate to anything bound to {my_list.selectedItem}. In fact in my application it seems to permanently break the data binding.

Instead, to deselect a list item, do selectedIndex=-1, that seems to work.

So I've got something like:

 <mx:Button label="Clear" click="entries.selectedIndex=-1"/> 
 <mx:List id="entries" dataProvider="{my_data}"/> 
 <components:MyEntryDisplay entry="{entries.selectedItem}"/>

which is fine for me.

Posted by Ian at 01:56 PM | Permalink | Comments (0) | TrackBacks (0)

Today's challenge has been to allow a Flex app to create images, and have the new images uploaded back to the server as a bitmap. The application is for a simple buddy-icon editing application: users can upload their photos, drag in bits of clip art, resize and so on, then use their generated buddy icon on the site. The same could be useful for doing basic image editing, uploading for print.

There are two issues. First is getting uploaded images into Flex. That's a topic for a future post (but basically you have to upload them to the server, then download them again).

The second is uploading a final image generated by Flex. And it turns out this is surprisingly easy.

Continue reading "Sending Images From Flex to a Server" »

Posted by Ian at 01:00 PM | Permalink | Comments (1) | TrackBacks (0)