Here's another recap on the state of responsive images. This one from the Filament Group, who was involved in the Boston Globe redesign. It discusses their solutions and the problems with them and then the newly suggested picture html element and a call for the need of bandwidth detecting media queries. I'm still concerned about bandwidth detection. I think somehow there should be a setting that lets users decide if they want high res images (when supported) or the faster low res images. If I'm just browsing on a laptop tethered to a phone with 4g and paying for every kilobyte, I may not want to download a large image just because I can. I agree we need better ways to server appropriately sized images, but I don't want to force anything on a user. Although a popup asking them if they want every large image is not practical either… I'm glad this discussion is continuing though!
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The state of responsive images | Feature | .net magazine
Designer/developer Mat “Wilto” Marquis takes a look at the img tag, explains why a largest-size-fits-all approach to images is untenable and discusses different solutions in this ongoing saga
To get the url of the html page that contains the flash/swf file we need a little help from the browser. I’ve written about the following methods before, but they were in as2 with “Get current url to Flash swf using an External Interface call” and “Get Current URL and Query String Parameters to Flash in as2“. In as3, we’ll still need access to javascript in the form of ExternalInterface, so if you want to do this on a site that doesn’t allow javascript you’ll have to keep searching (or jump to the bottom for an alternative method). We don’t need to do anything with the javascript or have access to the pages source code, javascript just has to be enabled, and it works in every browser I have access to. All we do is call a javascript line from within the swf which gets the url in the browser, namely: window.location.href
That is the javascript we need to call. But we do it from an externalInterface call like so: ExternalInterface.call("window.location.href.toString")
or to make sure all browsers play nicely we can wrap it in a function in case the browser doesn’t want to execute that as a line, this seems to work more solidly: ExternalInterface.call("function(){ return window.location.href.toString();}")
also note that we’re specifically applying the toString method, this is needed so the javascript actually executes something and can return it.
Other things you may want to do related to this is getting the query string variables form the url, which also uses externalInterface. You can also use this same method to get the domain, path, protocol, and even referrer. You could use some nice regex or substrings to find these from the full url, but it is already accessible. I can see a potential need for the speed to get the full url and then use internal code to cut it however I need it. But, I’m not convinced that using an external interface call takes that much time (but it’d be an interesting experiment to say the least).
You may want to find the url to the actual swf, and this doesn’t require javascript at all, the swf does know where it is even if it doesn’t know where it is embedded. We can use the loderInfo object and the url property. This returns the url to the swf file regardless of what page or even domain it is embedded on: this.loaderInfo.url
For ExternalInterface to work in IE you need valid classid and id attributes in the
If your set up fails it may be because it throws a security error. To solve this to set the param allowScriptAccess to ‘always’ and in your actionscript add your domain, in order to enable the use of ExternalInterface.
This demo, gets all of the above mentioned values/properties and more. I threw in what I could think of that may be useful or interesting. It shows a couple ways to get the window location href as well as a way it won’t work. Then there are the rest of the properties available using this same method: href, host, hostname, hash (anchor link ‘#’), pathname (url after the domain), port, protocol, search (query string values), the document title and even referrer. Then from the loaderInfo object we can access the url of the swf as well as other things but most used is the bytesTotal and bytesLoaded. Now check out the demo here (adding an fpo hash and query string to the link just for demonstration purposes, feel free to play with the url and see the values updated.
[cc lang=”actionscript”]
import flash.external.ExternalInterface;
Finally a method I’ve used in my video players when I want users to be able to share the link through the player is send an explicit ‘permalink’ in the flashvars or xml playlist. Then the video can be embedded on any site and users can share the original video url. Plus then I don’t have to rely on javascript. I’ve written about flashvars in the past though, so I’ll leave it to you to put 2 and 2 together. Flashvars is one more plug for swfobject to me though, because it makes it so I only have to declare them once and it handles all the browser specific code.
Anyways, this demo has been tested in mac firefox, chrome, safari and windows ie7, ie8, firefox and chrome. If you have a different browser please comment that it works (or not) so we can get a full spectrum, thanks!
Often we need to have different parts of a website talk to each other. This can get tricky when we are using multiple technologies and need the communication in real-time. Going from flash to html is done through javascript on the browser side and in actionscript we use something called ExternalInterface. The ExternalInterface class is an application programming interface that enables straightforward communication between ActionScript and the SWF container– for example, an HTML page with JavaScript or a desktop application that uses Flash Player to display a SWF file. We can send things form actionscript to javascript as well as from the html and javascript into flash and actionscript.
I’ve written about this before. It got old though and I had reports that it was having issues in certain browsers, so I had a minute to look at it and decided it needed a rebuild. This version uses as3 and swfobject. I was tempted to throw jQuery in there as well, but didn’t want to confuse anyone. This is simple javascript. I did have to throw some css3 on it for style though. I did use swfobject because it makes life easier, but it’s not required.
So, just like in as2, communication between actionscript and javascript still requires our friend ExternalInterface to link them but the setup/syntax changed a bit with as3. From the docs here are a few pointers of what we can accomplish with External Interface:
From ActionScript, you can do the following on the HTML page:
Call any JavaScript function.
Pass any number of arguments, with any names.
Pass various data types (Boolean, Number, String, and so on).
Receive a return value from the JavaScript function.
From JavaScript on the HTML page, you can:
Call an ActionScript function.
Pass arguments using standard function call notation.
Return a value to the JavaScript function.
It’s really cool that we can pass various data types. Here I’ve got an example that simply sends a string back and forth. We have the actionscript to javascript lane as well as the javascript to actionscript lane. So to set it up we need to know the names of our functions. Here I’ve tried to name them exactly what they are. There is a function in my javascript to both send and receive text to actionscript. Also, there are corresponding functions in my actionscript code: one to send and one to receive. These functions pass the data back and forth.
The magic is set up with the call and addCallback methods of ExternalInterface.
To call a javascript function from actionscript we use the call method. The first argument is the name of the javascript function as a String and any following (optional) arguments are the parameters that are passed to said function. So we need a function in the javascript on that page which is set up to accept some data or at least set up to do something (we don’t actually have to pass data, it could be just a trigger for something on the page). Then in our actionscript we call: ExternalInterface.call("name_of_js_function", "data passed to js");
Then to go back from javascript to actionscript there is a little bit more set-up involved. We will use the addCallback method here and this sets the actionscript function to be able to accept a call from javascript. The first argument is the function name in javascript (again as a String), and the second argument is the function name in actionscript that you want to be called: ExternalInterface.addCallback("name_of_js_function", name_of_as3_function);
Then you write your actionscript function to do what you want: function name_of_as3_function():String {
//do something
return something;
}
//Set up Javascript to Actioscript
ExternalInterface.addCallback(“sendTextFromJS”, receiveTextFromJS);
function receiveTextFromJS(t:String):void {
theText.text = t;
}
//Actionscript to Javascript
function sendTextFromAS3(e:MouseEvent):void {
ExternalInterface.call(“receiveTextFromAS3”, theText.text);
theText.text = “”;
}
button.addEventListener(MouseEvent.CLICK, sendTextFromAS3);
button.buttonMode = true;
[/cc]
Source Files
Download the source files here: FLA, HTML, SWF, ZIP.
