Category Archives: CSS

Innovation, or the lack thereof… W3C, anyone?

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I originally posted this on the OSFlash mailinglist, but i thought it would make a good blog post, so here it is:

My vision of a next generation web application framework.

(or: Innovation, or the lack thereof… W3C, anyone?)

There’s a sh*tload of XML dialects for GUIs either available or being developed at the moment. Just to name a very few: Adobes MXML, Microsofts XAML, Laszlos LZX, Netscapes XUL, and from the OSFlash camp ActionSteps ASML (or Renaissance) and ASWings AWML.

All of them are proprietary formats (plus most of them are direct projections of the underlying, proprietary APIs), and all of them require some decent amount of script code to be written in order to actually make the UIs work. Problems: to author sophisticated applications i need extensive knowledge of the XML dialect itself, of the API and the scripting language, and probably of the underlying platform API too. For most ‘next gen’ RIA platforms much of this is proprietary stuff, so i better choose wisely what technology to dive into for the next months/years. I also better be able to think ‘code’ in order to make my RIA a successful reality.

Wouldn’t it be nice to develop web applications using open, standardized technologies that everyone is already very familiar with? Let me introduce you to the W3C, and please try to forget about browsers in general and men with white beards wearing birkenstocks in particular for a moment.

Contrary to popular belief, the W3C is working on really cool stuff. Some of it you’re already very familiar with: (X)HTML and CSS. The *real* cool stuff though are W3C technologies that haven’t made it into the mainstream yet (because they aren’t supported by mainstream clients, or because they’re being worked on yet). I pick two of those technologies, XFrames and XForms, and briefly introduce them here, as i think that together with XHTML (2) and CSS (3), they pretty much cover everything a RIA framework needs.

XFrames
The technology that is supposed to supersede HTML Frames. XFrames of course is going to support framesets as we know (and hate) them today, but there’s so much more. Using CSS, frames can be styled to appear as floating windows or tabbed panes for example, and using a new URI scheme it will be possible to easily link not only a frameset but also it’s content, example: http://example.org/index.xframes#frames(id1=uri1,id2=uri2,...).

XForms
The technology that is supposed to supersede HTML Forms. XForms is going to significantly change the way we author forms. Basically, it separates the model from view and controller, as you can now have multiple data instances (usually XML, both inline or external) that you can use as data provider for controls and widgets (controls can be bound to data provided by instances using XPath). Validation is handled in a purely declarative way via XML Schema datatypes. But again, there’s much more, for example: <switch> and <case> to show/suppress parts of the UI (to be used for e.g. wizards, tabbed interfaces or dynamic forms), or <repeat> (to be used for e.g. filling tables with rows, or datagrids, or just about anything UI that repeats itself). Of course everything is styleable by CSS and can be bound to data instances. Sounds familiar? It sure is. And did you know that the latest ColdFusion uses XForms under the hood? Yes it does.

I recommend the W3C articles “XForms for HTML Authors” (Part 1 and Part 2) and Micah Dubinkos XForms Institute (hey look, he’s using DENG!) for a leightweight introduction to XForms (The XForms Institute also links a free online version of the O’Reilly book “XForms Essentials” in case you’d like to dive in further)

If you mix all those technologies mentioned above, and throw in some more, like SVG, SMIL, and maybe even XUL, that’ll be my vision of a sane platform for Web 2.0 [sm][tm](c)… ok, Web 3.0 it is then. A sane platform to develop RIAs on. Don’t even get me started ranting about the current state of the web as too many people see it. What the web needs is innovation, not hyped acronyms for old crap, or yet another proprietary markup language.

Of course such a framework needs to be developed yet. With the Flash Player 9 in our hands, the great performance boost compared to version 8 and a way better API (minus native text rendering.. still sucks), i’m sure it’s absolutely doable. If only somebody with some angel $$ would share my views, or if only everybody would work together with open minds instead of cooking their own soup…

We even have a proof of concept, anybody remember DENG? That was Flash Player 6. I’m also writing all this because i think most people misunderstood DENG and see it as a better HTML-enabled TextField or something, or worse, as a HTML browser. It was supposed to be the beginning of an application framework. Of course it’s missing A LOT yet to really become one (and of course Flash Player 6 was way too slow to do such stuff), but again, with Flash Player 9 and some likeminded developers, this could become quite a blast.

Thanks for listening :)

Addendum: Some good and valid remarks and questions i got in the OSFlash mailinglist:

This is, in my mind, a brilliant idea especially when you throw in Haxe‘s planned ability to render to different (and future) runtimes (I assume that you would use Haxe to do this).

One of the most frequent issues on the Haxe list is the lack of a component written for Haxe. I think that a project like this would solve that issue for Haxe.

I’ve looked into Haxe. It sure looks promising, and It’d be a major plus that a framework written in Haxe potentially wouldn’t have to be tied exclusively to the Flash Player. The first thing i would do if i would start to develop such a framework in Haxe is write a compliant DOM3 Core implementation that works exactly the same in Flash 6, 7, 8 and 9 and in all mainstream browsers. That alone would already kick some serious bottom.

I glanced through the XForms documents on w3c and was wondering if it would be possible to leverage one of the existing component sets (specifically ActionStep or ASWing) to complete this task? To me, it would seem like a much smaller job if we used an existing framework.

But could we imagine to bind a standard Flash XFrames/XForms/CSS parser with any/a few GUI toolkits? That would actually be great, but is it possible to achieve?

I have been asked this question many times already. Theoretically, this is possible. However, if i would develop such a framework, i would surely want to implement CSS3 which features styling and skinning mechanisms that imho beat those implemented in all current GUI toolkits together, and integrates perfectly into all mentioned W3C technologies. So depending on what toolkit you use, you probably can only implement a subset of CSS3. I also think that it wouldn’t be very easy to integrate custom component sets, or rather, i think it wouldn’t be worth the pain.

Flash Player 8.5 – SPEED!

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You heard the news already, Macromedia launched their Labs site today, along with public alphas of Flash Player 8.5, Flex Builder 2 and the Flex Framework 2.

Among the first things i did with those alpha goodies was porting the DENG CSS 3 parser to Actionscript 3.

Results of first benchmark (Parsing a 20kb CSS file into an object DOM):

  • AS2, Flash Player 8: around 1000ms
  • AS3, Flash Player 8.5: around 80ms

That’s a 12.5x performance boost, without FP8.5 specific optimizations.
Flash is fun again!

I’m going to prepare a live demo of the parser in the next days for you to play with it.

XFrames: New Working Draft published today

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The W3C published a new working draft of their XFrames specification today, an XML application designed to replace HTML Frames.

XFrames solves most usability problems known from HTML Frames (Back button, bookmarking, page reloads, search engine woes, etc) by introducing a new URI reference notation:

http://example.org/home.xframes#frames(id1=uri1,id2=uri2,...)

In addition to vertically and horizontally tiled frames, XFrames introduces two new composition modes “single” (one frame visible at a time, navigation through tabs, for example) and “free” (movable, overlapping windows), making it an extremely simple but powerful tool for web application development.

DENG 1.0 already features an experimental XFrames implementation, and even better support for the latest spec is one of the priorities for DENG 2.0.

DENG 2.0 Roadmap (first draft)

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Macromedia announced the Flash Player 8.5 today, featuring a completely new virtual machine (AVM2), E4X, RegExp, Binary Sockets and W3C DOM Events.

Flash Player 8.5 (along with the Flex 2 Framework and Flex Builder 2) will be released as public alpha on October 17th.

This marks the beginning of the development of DENG 2.0, a completely refactored DENG version targeted for Flash Player 8.5 and above.

Features i plan for DENG 2.0 (incomplete, vague, and subject to change, just to give you a rough overview):

  • Improved performance
  • Flex 2.0 Integration, targeted for AVM2
  • 100% compliant CSS 3 parser
  • Compliant implementations of SVG-T, XForms 1.1
  • Better support for XHTML, SMIL, XFrames etc.
  • Support for subsets of XUL
  • Support for W3C DOM
  • Better CSS box model implementation (DENG currently doesn’t support absolute/relative positioning and inline-boxes, the tables implementation is not perfect, etc.)
  • Better CSS line box model implementation (DENG uses the native TextField object of the Flash Player to render inline text. This won’t change, but improvements in the Flash Player since version 6 allow some more sophisticated features (e.g. a:hover, left/right floats).
  • GIF, PNG and SVG images (DENG currently supports JPEG only), background images

CSS 3 modules and envisioned compliance:

  • Syntax/Grammar (full)
  • Selectors (full)
  • Values and Units (full)
  • Value Assignment, Cascade, Inheritance (full)
  • Box Model, Vertical (as full as possible)
  • Positioning (as full as possible)
  • Color, Gamma, Color Profiles (partial)
  • Colors and Backgrounds (full)
  • Line Box Model (partial)
  • Text (partial)
  • Fonts (partial)
  • Ruby (none)
  • Generated Content, Markers (as full as possible)
  • Replaced Content (as full as possible)
  • Paged media (as full as possible)
  • User interface (as full as possible)
  • WebFonts (partial)
  • ACSS (none)
  • SMIL (as full as possible)
  • Tables (partial)
  • Columns (partial)
  • SVG (as full as possible)
  • Math (partial)
  • BECSS (none)
  • Media queries (as full as possible)

Stay tuned.

Display SVG in 97% of all Web Browsers

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Inspired by a blog post by John Dowdell, who was raising the question if it would be possible to trigger a SVG rendering SWF to do the work in case the user’s browser is not SVG enabled, i sat down last night to figure out if this could be solved using mod_rewrite on the serverside in combination with DENG.

It actually is possible, with a few constraints. Check out these SVGs (and make sure you have at least the Flash Player 6 installed and enabled):

You should notice that although the SVGs are physically located in /stuff/svg/ on my server, your browser loads the DENG engine (75kb, and only the first time, as then it is cached), which then loads the original SVG and renders it.

To get the SVG without the redirect, append ?raw to the URLs above.

I am using mod_rewrite to redirect requests for SVGs to DENG:

<ifmodule mod_rewrite.c>
RewriteEngine On
Options FollowSymLinks
RewriteBase /stuff/svg/
RewriteCond %{QUERY_STRING} !(raw) [NC]
RewriteCond %{HTTP_ACCEPT} !(image/svg\+xml) [NC]
RewriteRule ([A-Za-z0-9-]+).svg$ deng/index.php?filename=/stuff/svg/$1.svg.orig [L,T=text/html]
RewriteRule ([A-Za-z0-9-]+).svg.orig$ $1.svg?raw [L]
</ifmodule>

I am in no way a mod_rewrite/Apache/whatever expert, so the rules may be simplified yet, i don’t know. Comments on that are welcome.

The constraints are:

  • I am checking the HTTP_ACCEPT header field for image/svg+xml and do not redirect in case it is set. Unfortunately, neither Opera 8 nor IE6 with the Adobe SVG control set this mime type, that’s why DENG is always triggered in those browsers. I don’t know how Firefox 1.1 is going to behave, but my guess is that this is actually going to work in Firefox.
  • This method obviously does not work if you want to embed SVG inline (like via <img src="flashenabled.svg"> or <object>
  • DENG1 is still somewhat limited, so if you want to have full SVG-T compliance, you’d have to wait for DENG2

DENG 2.0

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DENG 1.0 has been around for a long time now (almost three years), and there hasn’t been any new code release for quite a while, so some of you might wonder what we’ve been up to, and what the plans are.

We started developing DENG in difficult times. DotCom had just crashed hard, and demand for XForms renderers was low (the W3C XForms WG was still working on it). It was very hard to find contributors as most Flash developers generally disliked everything the W3C produced, and the proprietary nature of Macromedia products made it hard for people outside of the Macromedia world to join such a project. Also, it was nearly impossible to get funding. Nevertheless, we worked hard to make DENG a reality, found a few contributors who saw the potential, and even had a bit of funding (well, at least enough to pay the rent for a while).

A big up goes to Stefano Debenedetti, who was working on a Flash XHTML/CSS renderer for Benetton at the same time i was working on DENG. He quit his day job just a few weeks after we made first contact to come from Italy to Germany for a few months to join the core team and work on DENG fulltime. He eventually implemented the DENG XForms module, as well as an experimental SMIL module.

After we got DENG 1.0 out the door, open source, and with a lot of features (significant subsets of CSS3, XHTML, XForms, SVG, XFrames, etc), we started an open discussion about the future of DENG. The Flash Player 7 was released by Macromedia, introducing Actionscript 2 (an ECMAScript 4 implementation), but not much more that would be relevant for DENG. We thought about porting DENG to Actionscript 2, even wrote some proof of concept modules (Jim Cheng did a DOM implementation, i ported the DENG CSS parser etc).

The UGO initiative was given birth, at first as an attempt to develop an open source framework for the Flash Player. UGO was drawing the attention of quite some developers (both Flash and non-Flash), and some very interesting discussions were going on. The UGO initiative today focuses on providing reliable standards support on ECMAScript-like platforms and is an ongoing project. Current results are a deployment system, a module loader and a non-Flash, ECMAScript XForms implementation for current browsers, developed by Stefano, who luckily found a new employer (Dreamlab) being very pro open source and open standards and actually made all this possible.

I was very busy the last year, working on commercial Flash projects (and I still am). I also moved to Brazil some months ago, and currently am in progress of setting up a company here, so time was very limited thus far to work on DENG or UGO. I feel very bad for that, but unfortunately this was necessary.

With the Flash Player 8 on the horizon, i am now going to catch up with the development of DENG, and push it to version 2.0.

DENG 2.0 will be targeted for Flash Player 8. That means that the current code base will be completely refactored and DENG will leverage all the new features that are going to be introduced by the new Player (many of the new features are not yet published by Macromedia, but some are, like big improvements in drawing API and performance) – along with features developed in the UGO initiative (standards compliant API).

I have high expectations. I am working towards 100% compliance of XForms, SVG Tiny and CSS3 and as much of XHTML compliance as possible, with a strong focus on CSS3 and XForms.

Please contact me at claus at codeazur.com.br in case you want to contribute code (although it will take some time yet for code contributors to be able to join as the Flash Player 8 is not released yet) or in case you are looking for an open source, zero install, pure clientside, lightweight, modular renderer of XForms, XHTML, SVG etc (you name it) with CSS3. I also haven’t given up hope to get decent funding for that project, in order to make this a fulltime job again, either for me, or for other contributors. Thanks.

CSS3 Selectors

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Recently, i continued porting the DENG1 CSS parser to ECMAScript 4 (AS2, to be specific), and making it fully compliant to the CSS3 specification. The current AS1 version of the parser already has many CSS3 features implemented, but not all of them (like the nth-child(), nth-last-child(), nth-of-type() and nth-last-of-type() pseudo classes for example, that required a special type of argument that wasn’t supported by the parser yet).

Part of the work was commenting changes in the grammar, to know what was added or changed from the CSS2.1 grammar, and to verify if the existing code fully conforms to the CSS3 grammar.

I figured this might be an interesting read for some of you, so here it is. Disclaimer: Please note that the comments might not be accurate or complete. In doubt, please refer directly to the Selectors module of the CSS3 specification at W3C.

Commented grammar for CSS3 Selectors Module

It is now specified that only one pseudo element is allowed in a selector, and that this pseudo element has to occur as the very last element. Pseudo classes can occur anywhere in a simple selector sequence.

selector
  /* there is at least one sequence of simple selectors */
  /* in a selector and the pseudo-elements occur only */
  /* in the last sequence; only one pseudo-element may */
  /* occur */
  : [ simple_selector_sequence combinator ]*
       simple_selector_sequence [ pseudo_element ]?
  ;

New combinators ~ (indirect adjacent combinator) and * (descendant combinator) have been introduced (the * combinator is not contained in the current CSS3 grammar though).

combinator
  /* combinators can be surrounded by white space */
  : S* [ '+' | '>' | '~' | /* empty */ ] S*
  ;

Typeselectors and the universal selector (*) have an optional namespace prefix now. Both the typeselector and the universal selector are optional.

The grammar for negation is missing in the current CSS3 grammar, it should look similar to the rule for pseudo_class, with a function identifier not() and one or more negation_args as function argument. The grammar is incomplete here. Example: a:not([href]).

simple_selector_sequence
  /* the universal selector is optional */
  : [ type_selector | universal ]?
        [ HASH | 
          class | 
          attrib | 
          pseudo_class | 
          negation ]+ |
    type_selector | universal
  ;

type_selector
  : [ namespace_prefix ]? element_name
  ;

element_name
  : IDENT
  ;

A namespace prefix, if used, needs a preceding @namespace rule, where the namespace prefix is associated with a namespace URL. Let’s assume we want to mix SVG and XHTML markup in the same document. Both SVG and XHTML feature the <a> element. We most likely want the <a> element to appear different in the SVG context (i.e. shape appears with a stroke) than in the XHTML context (text appears underlined).

Using the @namespace rule and namespaced prefixes we can write rules that apply either to SVG’s or to XHTML’s <a> element:

@namespace xhtml url(http://www.w3.org/1999/xhtml);
@namespace svg url(http://www.w3.org/2000/svg);
xhtml|a[href] { text-decoration: underlined; }
svg|a[href] { stroke-width: 2px; }
namespace_prefix
  : [ IDENT | '*' ]? '|'
  ;

universal
  : [ namespace_prefix ]? '*'
  ;

class
  : '.' IDENT
  ;

Attribute simple selectors allow an optional namespace prefix for the attribute ident now.

Prefixmatch (^=), suffixmatch ($=) and substringmatch (*=) operators have been introduced.

Example: we want to style <a> elements with the href attribute set to an URL starting with "http://wahlers.com.br" differently than other <a> elements. we are using the prefixmatch operator:

a[href] {
   font-weight: bold;
}
a[href ^= "http://wahlers.com.br"] {
   font-style: italic;
}

All <a> elements with the href attribute set appear bold, <a> elements with a href attribute starting with "http://wahlers.com.br" appear bold and italic.

attrib
  : '[' S* [ namespace_prefix ]? IDENT S*
        [ [ PREFIXMATCH |
            SUFFIXMATCH |
            SUBSTRINGMATCH |
            '=' |
            INCLUDES |
            DASHMATCH ] S* [ IDENT | STRING ] S*
        ]? ']'
  ;

pseudo_class
  /* a pseudo-class is an ident, or a function taking */
  /* an ident or a string or a number or a simple  */
  /* selector (excluding negation and pseudo- */
  /* elements) or a an+b expression for argument */
  : ':' [ IDENT | functional_pseudo ]
  ;

"an+b" expressions have been introduced as argument for functional pseudo classes (select nodes depending on their position). Allowed argument types include string, number, "an+b" expression and negation now, in addition to ident (the only allowed argument type in CSS2.1).

Example: style even and odd rows of a table differently:

tr { background-color: #eee; }
tr:nth-child(2n) { background-color: #ccc; }
functional_pseudo
  : FUNCTION S* [ IDENT | STRING | NUMBER |
      expression | negation_arg ] S* ')'
  ;

expression
  :  [ [ '-' | INTEGER ]? 'n' [ SIGNED_INTEGER ]? ] |
      INTEGER
  ;

negation_arg
  : type_selector |
    universal |
    HASH |
    class |
    attrib |
    pseudo_class
  ;

Pseudo elements are now prefixed by :: (instead of : in CSS2.1) to distinguish between pseudo elements and pseudo classes. For backwards compatibility with CSS2.1 and previous, user agents have to accept the : notation for pseudo elements defined in earlier specs (like :before and :after).

pseudo_element
  : [ ':' ]? ':' IDENT
  ;
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