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video white

A recent task I had to achieve was to play a video for several seconds and extract a frame as a JPG several seconds in. I did not know the dimensions of the video ahead of time, so hoped to extract that information out of the video metadata, and create the video object at this point. Sounds simple enough!

However, this only seemed to work about 75% of the time. Occasionally I was seeing just white in certain videos, like they weren't attached correctly to the Video object(despite receiving the metadata correctly). My theory was that perhaps the metadata was received after the FLV began playing, and that perhaps there can be problems creating a Video object and attaching a NetStream to it, after it has begun playing.

So I tried creating the Video object and then resizing after receiving the FLV metadata, but the resize seemed to have no effect when extracting the Bitmap Data. But finally found a solution - the Bitmap Data extracted correctly, if I placed the Video object inside a MovieClip and extracted the Bitmap Data of the MovieClip instead of the resized Video object.

SharedObject not updating between tabs

Just created an app which required persistent data, so used a local SharedObject. However discovered that if one person had the app open in two different places(eg. 2 tabs) the persistent data in one tab wasn't updating in the other tab. To remedy this I tried reloading the SharedObject(SharedObject.getLocal) every time I extracted a variable, and yet this SharedObject variable still wasn't updating.

Discovered that, strangely, the only way to update the SharedObject, is to first set it to null. Set it to null and then reload it forces an update.

Frustrating Flex problems solved #7 - Removing DragDrop animation

In Flex was building a simple drag and drop from a library list to another simple list. I also wanted to build the functionality of dragging the item out of the simple list to automatically remove the item from the list, and return the item to the library.

I managed to handle this with one problem remaining. As the dragged item thought it wasn't going to be accepted, it automatically played an animation of it returning to the simple list before my code displayed it back in the library. The animation was completely misleading but I couldn't find a way to turn it off!

My solution in the end was to create a custom ListItemDragProxy component. I included this in the list with:
dragIndicatorClass="display.CustomListItemDragProxy"

and in the custom class, I merely set visible=0 onMouseUp. Simple solution that works perfectly.

Frustrating Flex problems solved #6 - Keydown

Spent some time screaming "Why can't my component receive keyboard events? "

Crazy, I'm not sure why i never knew this, but for a component to receive keyboard events, it needs to implement IFocusMangerComponent. And then, however you're trying to receive keyboard events, by overriding keyDownHandler, or listening for a keydown event, it should now receive these events...

easy when you know how!

implements="mx.managers.IFocusManagerComponent"

Frustrating Flex problems solved #5 - ButtonBarButton bugs

So i had a series of custom Buttons all set up perfectly in a ButtonBar, when I realised that the design dictated that one of the buttons was a different size than was happening with the automatic sizing system...

So after discovering that the ButtonBar does not allow facility for resizing the width of a button, I had the choice. If i was going to extract the buttons from the ButtonBar, it probably would make sense to have them as a different type - Button for example. But reskinning my buttons as a different type could be time-consuming so I thought I'd see how I go just using ButtonBarButtons that aren't in a ButtonBar!

All turned out fine, except that my labels weren't appearing. A little delving into the code and I discovered the following code inside spark.components.supportClasses.ButtonBase:

// Push down to the part only if the label was explicitly set
if (_content !== undefined)
labelDisplay.text = label;

For my two cents, there's something strange going on there... So to set the label, I need to put the text inside the label property, and i need to ensure that content is not undefined. Set content to something arbitrary and the label appears! weird...

<s:ButtonBarButton label="Title" content="nada"/>

XML read error in AIR

Back to blogging, working on a couple of projects:

I was importing an XML file using the standard technique of using a URLLoader, and in the result handler, setting the XML file with:
var result:XML = new XML(event.target.data);

But I found I had to move this to the FileStream class in an AIR application because the user had to specify the XML file to load. So I used:
var result:XML = new XML(stream.readUTFBytes(stream.bytesAvailable));

Suddenly I was getting a 1088 error on this line:
TypeError: Error #1088: The markup in the document following the root element must be well-formed.

After checking and rechecking the XML, I found that for some reason, there was a byte at the beginning of the byteString, which was causing havoc with reading the XML. So the String being returned by the readUTFBytes method had to truncate the first character. Like so:
var fileData:String = stream.readUTFBytes(stream.bytesAvailable);
var result:XML = new XML(fileData.substr(1));