ActionScript, E4X, and White Space

I've been reading XML into ActionScript 3 for many years, and I still haven't solved all the issues with it. Given that my searches for solutions to these issues turn up so little, I decided to share the solutions I have found, especially when it comes to white space.

I think at least part of the reason that these problems are so hard to solve is that the XML documentation for many of the properties and methods we need to use is frustratingly circular. So let me start by laying out what some of these do in practice.

ignoreWhiteSpace

I think ignoreWhiteSpace is the property we first try to use to correct some of the issues with E4X. This property will, in fact, fix issues that are caused by having "extra" children that you weren't expecting to be parsing when you use normal formatting, like new lines and tabs, in your XML. However, it then causes other white spaces that might have been pretty important to disappear.

An alternative to using ignoreWhiteSpace is to use xmlVar.elements() instead of xmlVar.children(). This works relatively well unless you need to access something that's not an element, like a comment, or you need to pass the XML to Adobe code (like new DataProvider()) that for some reason is not equipped to handle the vagaries of their own E4X implementation.

prettyPrinting

We're all familiar with the problem where the default XML parsing adds even more formatting than we included in the original XML file, so that

<root>
 <p>The quick brown fox jumped over the
 <b>lazy</b> dog.</p>
</root>

becomes

<root>
 <p>The quick brown fox jumped over the 
  <b>lazy</b> 
 dog.</p>
</root>

I'm sure there are some versions of Flash where setting prettyPrinting to false fixes this problem, but in the version of the Flash player we target, setting this property has no effect. The good news is that TextField, the Flash Label component, and the Flex MX Label component support the condenseWhite property, which gets rid of this issue for text you want to display. I guess if you're using a spark label, the skin will need to use something that supports condenseWhite if you need this.

Wrap in CDATA

One of the reasons XML parsing is so thorny is that we're using the XML to store external content, often HTML-formatted. CDATA does work to preserve HTML formatting, but it has its own issues. One issue is that there's no real documentation about how to get the text out of CDATA.

Funny story--I was once on a Flex project where it turned out I needed to wrap the entire XML package I was building in CDATA. Try though I might, I couldn't find anything that told me how to get at the "stuff" inside the CDATA. With deadline fast approaching, I "hacked" it by giving the text to a Spark label (which did know how to do this), then reading the text out again and casting it to XML.

Some months later, I ultimately discovered that String(myNode) will retrieve the contents of a node, whether its contents are wrapped in CDATA or not. Unless the contents are not wrapped in CDATA but contain HTML formatting anyway. This is something that is quite likely to happen on my team, as the people who produce the XML see no reason they shoulld start wrapping everything in CDATA just because we're using ActionScript 3 now.

In addition, even when things are wrapped in CDATA when they should be, you have to dump your text in one line into CDATA because it faithfully reproduces all those \n's and \t's, and you wind up with a bunch of junk nodes if you have to cast the contents back to XML. This results in XML that isn't readable, and readability is one reason to use XML in the first place.

hasComplexContent

So, if you're getting XML and you know that sometimes certain nodes will contain HTML and sometimes that HTML will be wrapped in CDATA and sometimes it won't, what do you do? One thing you can do is create a function that checks for hasComplexContent and calls toString() if it returns false and children().toXMLString() if it returns true.

This works well, but one issue with it is you have to have access to this function wherever you're parsing XML. And since you can't really extend the XML Class, due to its dependence on static methods and properties, that means you either need to use a static method yourself (not my favorite thing) or you need to violate DRY, unless your application lends itself to only parsing XML nodes in exactly one place.

normalize()

This is probably my favorite method, because it gets rid of all the weird child nodes that contain "\n\t\t". This means that I can now parse formatted XML and not have to allow for weird extra junk in there. More importantly, I can pass that XML to "dumber" code, such as the Flash DataProvider constructor, and it works. It also does not take out the spaces around inline HTML tags, so you can normalize() the XML to make for easy parsing that you should get from ignoreWhiteSpace (but don't, due to the removed spaces), then you can call String(myXMLNode) on the node whether it has complex content or not, and it will work in a TextField with condenseWhite set to true. FTW!

Batch Import Images into Flash Symbols

When I find a workflow I like, I sometimes assume that everyone has already discovered that workflow, and I'm late to the party. One of the nice things about participating in user forums is that sometimes that helps me realize that a favorite workflow isn't known to everyone. This is great, because then I have something to blog about!

Today, I want to talk about what is probably one of my all-time best productivity tricks in Flash. In a few minutes, I can:

1. Import a series of pngs, jpgs, or whatever into my Flash movie
2. Choose for each image to be wrapped in a symbol or not
3. Have the symbols and images nicely organized into folders in the library, without any extra effort!

Here's how I do it, starting with a folder of images:

Step 1: Browse the folder in Bridge

First, I right-click on the folder of images and select "Browse in Adobe Bridge"

Once it opens, I select the images I want to use. For this post, I just selected everything in the directory, but Bridge has excellent features for finding just the images I want (that could be a blog post in itself). You can drag them around in Bridge to change the order, if you need to.

Step 2: Load the files into PhotoShop Layers

In the Bridge "Tools" menu, I select PhotoShop>Load Files into PhotoShop Layers.



This launches PhotoShop and does all the work to put the files into PhotoShop layers, in the order they were in in Bridge. Once that has finished running, save the result as a .psd.

Step 3: Create a Symbol in Flash to Import into

Whenever I have to create a new Symbol in Flash, I like to start with a rectangle that's the size I want the MovieClip to wind up, so the registration and transformation points fall in predictable places. So, I create a rectangle the size of my images and convert it to a Symbol (F8).

Step 4: Import the PSD

I usually use the keyboard shortcut to import to stage (Ctrl-R). The import dialogue gives me lots of options. For example, I can select all the images and choose to convert them to MovieClips.

I'll usually convert the images to MovieClips if I want to do timeline animation with them or if I want to apply a base Class to the MovieClip. I can also choose to import each to a different layer or to a different keyframe. Both options are useful, depending on the end result I need.

Once the psd has imported, the timeline looks like this.

Note that the frames will be the reverse order of the order they were in in Bridge. I usually select the frames and reverse the frames (there's a right-click menu for it, but I've set up a keyboard shortcut).

Step 5: Edit the Library Symbols

The MovieClips and Images are nicely organized, but usually there is more I want to do to them.

If I'm applying a Base Class, I might want to rename all the Symbols, for instance, to change ".png" to "_png." I like the Search and Replace extension for this.

Flash also allows you to edit more than one library symbol at a time, by selecting several symbols and clicking the Properties button (sorry, if there is a shortcut for this, I haven't found it).

From this dialogue, you could change all the MovieClips to Graphics, for example, or you could set a Base Class on all the MovieClips at once. Tip: if you set a Base Class, Export for ActionsScript will become checked and the drop-down will have "Yes" selected, and you don't have to touch it.

And that's it, my quick and easy workflow for importing a series of images to Flash.



FlashTips #6: Debug refresh issues in your swf

Most of us know that Flash Builder makes it easy to debug a swf on a server by creating a custom debug configuration. Recently, I had a problem where I needed to be able to debug issues that happened when the browser window was refreshed.
Jeffry Houser, the brains behind Flextras.com, apparently had this very same problem, and resolved it by starting a new debugger session that points to about:blank and then connecting that to the swf after the window has been created.
That's a great solution, but the issue I was having was happening pretty much immediately after the window was refreshed--if I went through his steps, I'd "miss the window." So, after limping along for several hours, trying to figure out the problem without having the direct debug information, I finally figured out that the problem was amazingly simple:

1. Create a new "refresh" debug configuration that doesn't point to a page with a swf in it (I didn't yet know that about:blank was an option).
2. Start the original debug configuration, that points to the swf as normal.
3. Get to the problem point in the application.
4. Launch the "refresh" configuration.
5. Refresh the window.
6. Voilà, we are connected, from the very beginning of the bootstrapping process.

Enjoy!

Reusing a Flash Builder Workspace

I use Flash Builder and Flash Pro together, and over time I have learned to just bow to how Flash Builder wants me to do things. What this means is that each "family" of Flash files has to have its own Workspace, because Flash Builder expects the Flash file to be in a subdirectory of the workspace in a directory that's the named the same thing as the Flash file. If that's not where it is, you either have to remember to tell Flash Builder not to use its default or things go very wrong, very fast.

In a team environment, the process has to be as simple as possible, without a bunch of fiddly steps that people have to remember to do at exactly the right moment, so it's just easier to go with what Flash Builder wants us to do. However, this adds other fiddly steps that people need to do each time they start a new workspace, such as importing snippets and laying out all the panels just so.

So I thought I'd hit on a brilliant plan, which is just to check the workspace settings into version control that live in the .metadata folder. This way, everyone would get a workspace that's already set up when they export the "base" Flash project and they could just start working. And this does work for the intended purpose, but I found that workspace relative paths would break (paths that refer to the ${DOCUMENTS} variable). These would unaccountably point to the original base project directory.

On Windows, for whatever reason a file contents search didn't turn up the offending string. I suspect this has to do with the weird way the .metadata folder starts folder and file names with "." So I was off to Google to try to find out how other people transfer their settings. I found one post that suggested you just copy the .metadata/plugins/org.eclipse.core.runtime/.settings directory. The result I had from that was that the site relative root now pointed to the project I'd copied the directory from. At least now I had it narrowed down to a large handful of files that I could then open and look at individually.

To save you the bother, I'll tell you that the file that contains the location of the workspace for workspace-relative links in the above directory is called org.eclipse.core.resources.prefs, and that file contains the pathVariable.DOCUMENTS string that tells Flash Builder/Eclipse where the workspace thinks it is. I haven't had a chance to play with it to see if simply not putting that file in version control makes things better or borks them, but even if everyone has to manually update that variable when setting up a project it's much better than having to set up every workspace from scratch when we start a new project.

My favorite Flash Builder Code Templates

I hate typing the same code over and over, and DRY can only take you so far. I also hate making the same changes over and over. So I've "tweaked" some of the templates that came with Flash Builder and I've added many to automate the tasks I do frequently. I've made them available for download. You'll need to unzip the file and import the template file into your ActionScript code templates, or you can copy and paste any you find useful.

My version of the fori

I loop through lots of things other than Arrays, and when I do loop through Arrays, I don't like to read the length on every loop. So I've modified the fori template.

for (var ${index}:int = 0; ${index} < ${loopVar}; ${index}++) {
 ${line_selection}${cursor}
}

Looping through MovieClip/Sprite Children

A lot of times, I have a Class where I just know I'll have "some" instances of a specific type, but I don't want to dictate in advance how many that will be. So often I'll have code to find those children. I call this template "childLoop."

var loops:int = numChildren;

for (var i:int = 0; i < loops; i++) {
 var ${varName}:${search_type} = getChildAt(i) as ${search_type};
 if (${varName}) {
  ${cursor}
 }
}

Push into an Array/Vector

Often, inside a child loop, I'm inserting the children that match into a Vector. It's supposed to be faster to use the length property of an Array or Vector to add to it instead of using push(), so when I'm adding to the end of one of these, I use my "fastpush" template.

${arrayOrVector}[${arrayOrVector}.length] = ${newItem};

Sort the Vector

Often, the instances aren't added to the stage in the correct order to match each with the piece of data that goes with it, so I have various sorting functions on hand, such as "leftToRightSort" that can be applied as the sort function to the Vector.

protected function leftToRight(btnA:DisplayObject, btnB:DisplayObject):Number {
 return (btnA.x - btnB.x);
}

If setter value has changed

Flash Builder has a great feature to generate a getter/setter pair from a variable declaration. Even through I'm working in Flash, I often check the box that allows you to dispatch a custom binding event (which doesn't do much in Flash, unless you wire it up yourself). What I do get from that is auto-generated code that checks to see if the variable's value has changed before doing something, such as removing/adding event listeners. Sometimes I forget to check that box or I decide that I don't want the overhead of having the event dispatched and I think that deleting that extra code is more effort than what advantage I get out of using the check box. In those cases, I add essentially the same code with the "ifValueChanged" template.

if(${myVar} != value) {
 ${myVar} = value;
 ${cursor}
}

Do you have favorite code templates? Please share in the comments section.