Category Archives: Tips & Tricks

Multiple LocalHost Sites

I’ve got XAMPP installed on a Windows 7 machine. I wanted a way to test multiple sites locally.

Set up the local host file

In your host file, add (replace with the domains you want):

127.0.0.1    sub.domain.com.dev
127.0.0.1    www.example.com.dev
127.0.0.1    www.unfocus.com.dev

UPDATE: Thanks to xip.io the host file edits are optional if you use the style www.example.com.127.0.0.1.xip.io (replace 127.0.0.1 with your actual IP address). This is compatible with Adobe’s Edge Inspect.

Set up XAMPP config files

In \xampp\apache\conf\httpd.conf uncomment the following at about line 140:

LoadModule vhost_alias_module modules/mod_vhost_alias.so

I’ve used the folder structure of “\xampp\htdocs\www.example.com\web\content\files.php” (for example) and the following config will find the folder with the exact name in the url.

In \xampp\apache\conf\extra\httpd-vhosts.conf:

NameVirtualHost *:80

<virtualhost *:80>
    DocumentRoot C:/xampp/htdocs/
</virtualhost>

# New: No hosts file edits if you use this style
# Replace X.X.X.X with your local IP
<virtualhost X.X.X.X:80>
    # Handle Edge Code IPs
    VirtualDocumentRoot D:/xampp/htdocs/websites/%-7+/web/content/
    ServerAlias *.X.X.X.X.xip.io
    php_admin_value auto_prepend_file D:/xampp/setdocroot.php
</virtualhost>

<virtualhost *:80>
    VirtualDocumentRoot C:/xampp/htdocs/%-2+/web/content/
    ServerAlias *.dev
    php_admin_value auto_prepend_file C:/xampp/setdocroot.php
</virtualhost>

Fix DOCUMENT_ROOT

If you are having issues with DOCUMENT_ROOT, create setdocroot.php at “\xampp\” and put the following in it:

<?php  $_SERVER['DOCUMENT_ROOT'] = str_replace($_SERVER['SCRIPT_NAME'],"",$_SERVER['SCRIPT_FILENAME']);  ?>

References:
https://issues.apache.org/bugzilla/show_bug.cgi?id=26052#c27
http://stackoverflow.com/questions/138162/wildcards-in-a-hosts-file
http://postpostmodern.com/instructional/a-smarter-mamp/

SignalsLite.js, Unit Testing, and Buggy IE

I decided to finally learn unit testing, so I downloaded QUnit (after looking at the 20,000 different unit testing options), and figured I’d give porting tiny SignalsLite to JavaScript a try, and see how the process goes.

While doing that, I found a crazy IE7/IE8 JS bug, that I’m sure has had me scratching my head in the past. Here is a quick unit test to show the problem:

test( "Basic Requirements", function testReqs() {
	expect(1);
	var T;
	(function makeT() {
		T=function T(){}
		T.prototype.test = 1;
	})();
	ok((new T).test, "Instance of exported T should have prototype methods");
});

If you run that IE7 or IE8 it’ll fail!

The cool thing is, without having created unit tests for SignalsLite.js, I would never have known that could be an issue, and instead would continue to scratch my head when stuff like that broke in IE7/8. I found this because I was trying to export SignalLite from within a closure (I try to always define my stuff inside of closures to avoid namespace pollution), with this:

(function() { "use strict"; // standard header

// naming inline functions makes the debug console easier to read.
window.SignalLite = function SignalLite() {
	// stuff
}
SignalLite.prototype = {
	// methods
};

// The fix is to use an anonymous function, or export elsewhere:
// window.SignalLite = SignalLite;

})();

For whatever reason, that doesn’t work in IE7 and IE8. Unit testing is crazy!

If you are interested, go fork SignalsLite.json GitHib.

P.S. You can run the SignalsLite.js unit tests here to see the fail for yourself! I disabled that test in the SignalsLite.js tests.

Performance Benchmarks with AIR 2.7 for iOS

I’ve been working on this Benchmark based on Iain Lobb’s BunnyMark. Being a bit confused sometimes about what things speed things up or slow things down, I didn’t want to guess anymore, so I grabbed Iain’s code base (cause I’m lazy, and didn’t want to start from scratch), and added some tests for things I suspect are slowing things down (or speeding things up). I think this will also help shed some light on why some folks see a huge gain in AIR 2.7 CPU mode, while others do not.

Some caveats – this only tests instances of flash.display.Bitmap on the display list, at the size they are, moving the way they move. It’s on my list to add Blitting (I have some initial work on that done, thanks to Iain, but I need to add the rotation, and alpha settings to it), and I’d like to add a vector test, and maybe some extra sized Bitmaps (I’ve heard that makes a difference).

Enough! Here are some results – quality had no effect on GPU mode, so I included only one line:

Note: some are reporting they see a difference in GPU mode, but I still don’t. Update: It appears some users are confusing “Mobile Performance Tester” with BunnyMark, which explains the discrepancy. BunnyMark is not currently in any App Store, which is one key distinguishing feature. ;-)

BunnyMark Results – 500 Bunnies
Alpha
Rotation
CaB
CaBM
iPhone 3GS – GPU
FPS 24 18 17 22 13 13 19 1 19
iPhone 3GS – CPU
FPS-L 28 21 19 9 19 5 7 5 5
FPS-M 28 21 19 4 18 3 7 5 3
FPS-H 28 21 19 3 18 2 7 5 2
FPS-B 28 21 19 3 18 2 7 5 2
iPhone 4 (Retina) – GPU
FPS 25 21 20 25 13 13 16 0.5 16
iPhone 4 (Retina) – CPU
FPS-L 32 23 20 10 21 6 8 6 7
FPS-M 32 23 20 5 20 3 8 6 3
FPS-H 32 23 19 4 20 2 8 6 2
FPS-B 32 23 19 4 20 2 8 6 2

Notes about the Benchmark:

  • In general, the CPU mode seems pretty consistent with the way you’d expect things to work on the desktop – the same optimizations you’d apply for the browser plugin, you’d also apply to mobile for CPU mode.
  • Rotation in this benchmark is not continuous – the Bunny graphics are only rotated at the edge of the stage, which is why cacheAsBitmap works to speed those up. If they were constantly updated, it would likely be much more expensive on CPU mode (probably more like rotation without CaB).
  • Alpha is continuous – the alpha value of each Bunny is based on the y position and is updated every frame. I would like to add a mode similar to the rotation, so see what effect CaB has on alpha transparent objects that don’t constantly change.
  • iPhone 4 and 3GS numbers aren’t directly comparable for practical purposes. The Bitmaps on the screen on 3GS take up much more real estate, since the 3GS screen res has 1/4 as many pixels as the iPhone 4. In a normal app, we’d probably resize things to look comparable between the two devices. I’ll try to add a mode that makes this more comparable (because I suspect we’ll find that 3GS can keep up with iPhone 4 with similar looking content).
  • Touching the screen seems to cost about 4 fps across the board.
  • I think there may be an issue with returning to rotation = 0 costing some performance in GPU mode. Still have to test that.
  • I’m definitely getting some variance on default speeds – basically, before any settings are messed with on some runs I get the faster numbers (the baseline numbers in the tables above). Other times it runs at default settings a couple of FPS slower (on start, or after resetting the switches). With any of the settings, everything is consistent across multiple runs.

 

It’d be nice to have more benchmarks for more devices, but I only have the above devices available. This should run just fine on Android, Blackberry Playbook, and iPads. If anyone wants to contribute a set of benchmarks, hit the comments. Here is the source. One of these days I’ll make another post, and try to draw some conclusions, maybe wrap the bullet points into a narrative, and edit some of this, but the tables are there, and the source code, and that’s the important stuff.

In the midst of playing with this benchmark, I found (or was pointed at) some great resources. Here are some of them:

Here is the Benchmark to see it in action:

A Simple State Manager for History Keeper

Someone asked how to store a key value pair in HistoryKeeper recently, and this was my answer.

History Keeper does not provide any state management features beyond the information you store on the actual deep link (URL hash). However, you should be able to use the deep link information to grab the data you need out of a standard JS object (using it like a hash table):

var storage = {
    "/": {
        key: "home value"
    },
    "/about": {
        key: "about value"
    }
};

Once you have your values stored like that you can use the storage object to lookup your chunk of data by the deep link string:

function onHistoryChange(hash) {
    alert(storage[hash].key);
}
unFocus.History.addEventListener('historyChange', onHistoryChange);

You can make the “value” as deep as you want ( key: {more: “complex”} ), I only used a simple string for demonstration purposes.

This example is JavaScript, but the concepts are the same for Actionscript as well.

I hope that helps!

The Pixels Explode. Explode!

Update: I posted a follow up an exploding video!

Well I guess technically the pixels don’t explode as much as the DisplayObject explodes into pixels! I recently needed an effect that would make a bitmap image look sparkley, so I did some goggling, and game across a Firefly particle effect on a blog post belonging to Erik Hallander (at least I think so, the blog has been down for months, so I can’t double check). This pretty impressive effect looks like the following example (I hope reposting it here is not a problem).

Note: This is a modified version of the original adding the Stats.as box, and autolooping – and removes the actual firefly affect (I didn’t need that part for my purposes).

Very nice start! I don’t get an FPS problem – on my computer the example above rocks 62/60 fps (25% CPU on my Core 2 Duo)! So FPS was not the big problem. This example uses over ~19-23MB of RAM (with a lot of fluctuation)! And that is with 2×2 pixels, it goes up higher with 1×1 pixels. Additionally, this example already has an optimization in it to skip over empty (black) pixels in the DisplayObject it works on – which leads to a significant RAM savings.

Using the display list this way – and two filters per DisplayObject – it began causing the player to kick up a lot of invalid BitmapData/null reference errors (which I’m guessing is what happens when you run out of memory, since many many checks confirmed that the BitmapData was not invalid) – especially when I tried to make it work on 1×1 pixels to animate every pixel.

So the first thing I did was to clean up some of the obvious stuff, to bring down the memory usage – in the original blog post, Erik noted that this was unoptimized code, so I knew what I was getting into. I did things like remove the extra nested DisplayObjects (each pixel was a subclasses Sprite instance, with a BitmapData added to it), and cleaned up extra variables that were laying around, moved a lot of things inline, reused as many variables as I could, cutting down on object instantiation – and followed a lot of the other tips in a conveniently timed ByteArray post. Doing that really helped – I cut the memory use about in half – and on the initial animation (a black and white logo) the affect seemed worked quite well. But it didn’t scale well – larger images simply wouldn’t work.

I still wanted to use this affect, and I’ve seen many thousands of pixels being animated before – so I knew it was possible. So a radical departure. I’ve been reading about drawing directly to Bitmaps for quite a while, and that was going to be my path. So more optimizations – removed the display list code completely, changed the Pixel class to a simply property class (where are the enums?!), and used that to store information about where in the original source to look for the pixel data as well as other relevant animation data (most of which was already done for me – thanks!) for each pixel block. I also removed dependence on TweenMax – which is what the original uses for all the animations – and used the easing equations directly, within an ENTER_FRAME event.

The result is a RAM reduction by 25% and a steadier memory usage, coming in at ~5MB with 4x as many pixels (and roughly the same amount of CPU). The changes utilize copyPixels and a linked list, with an accumulation buffer like effect – for a total of 3 bitmaps (the original, which is rendered from the DisplayObject and stored, the scattered one the pixels get copied into, and the copy of that that gets blurred by the BlurFilter – a hidden memory cost illuminated by Thibault Imbert).

There are further optimizations that can be used as well (and should really be used for full image per pixel animations) – such as writing to an opaque BitmapData, rather than one with Alpha, and reducing the BlurFilter quality – getting a better handle on type marshaling, etc. It might also be faster to store the RGB value of each pixel, and draw those directly instead of using copyPixels, but I haven’t tried that yet.

I got so much help from the Flash community on this, that it would be irresponsible not to share this back, so feel free to check out the source.

Some Notes:

The memory usage applies to both swfs on this page – so you can’t see the memory usage difference in these examples. I quoted the standalone Flash Player in this post.

Also, I’m getting some kind of performance problem in plugin browsers (everything except IE) on Windows, and on every browser on mac but Firefox which is limiting both of these to around 30FPS. I have no idea what’s causing it.

On the code quality – the code isn’t all that messy IMHO, but it is not well documented, and a lot of the configuration hooks I left in are not really being utilized in a decent API – I may refactor at some point to clean that up. There is also a limitation of the skip pixel check that will keep it from working well for greater than 1×1 pixel size (since it only checks the top left corner of the size rect).

Enjoy!