Monday, July 11, 2011

Random Rant On CSS3 Transitions

Thanks to @gregersrygg for his link and hints, this is a hackish way to solve the problem apparently cross browser and trustable ... still a hack!

// this save one char, how cool is that!

// (C) WebReflection (As It Is) - Mit Style

// we all love function declarations
function redraw() {

// clientHeight returns 0 if not present in the DOM
// e.g. document.removeChild(document.documentElement);
// also some crazy guy may swap runtime the whole HTML element
// this is why the documentElement should be always discovered
// and if present, it should be a node of the document
// In all these cases the returned value is true
// otherwise what is there cannot really be considered as painted

return !!(document.documentElement || 0).clientHeight;

// ideally an Object.defineProperty
// unfortunately some engine will complain
// if used against DOM objects
document.redraw = redraw;

// tested with Opera, Firefox, Chrome, WebKit

... at the end of the day, nothing changed about this post because the summary is still that we do not have an official/standard way to do things properly and we need to use hacks to simplify our daily tasks.

so here the summary: there is no fucking way to use CSS3 transitions properly!

The Problem

We put everything on the DOM and we let nodes come in and out all the time or we are screwed!
CSS3 transitions are freaking cool and freaking painful at the same time.
The classic scenario is to pollute the whole DOM once or many times with our random appended/inserted HTMLElements.
The goal is to keep the DOM as clean as possible still being able to let things land on the DOM in our desired way.

setImmediate bullshit

Rather than improve the single setTimeout(callback, 0) classic case, the classic hack that supposes to make things work as expected and at the same time the classic timeout rarely stored as integer to clearTimeout later does not scale.
This is the reason vendors/HTML5 people/whoever decided to add another unshimmable function: setImmediate, which supposes to be used the same way "setTimeout with zero delay" is commonly used.
If vendors screw a bit up the same way FireFox did, where somebody pushed in some release a requestAnimationFrame without thinking about the counterpart clearRequestAnimationFrame, setImmediate becomes useless as well as setTimeout 0 is if nobody takes care of clearTimeout or clearImmediate function.

The Problem, Once Again

We appendChild a node with margin-left: -100px, a transition property equal to margin, and we add the className that supposes to put the margin-left: 0.
To solve this we need to appendChild the node then abstractly wait for the browser to paint and after, eventually, set the new class.

var div = document.body.appendChild(
); = "-1000px";
// now we want the transition to marginLeft = 0 ... HOW?????

If by CSS3 above div has transition margin monitored, the only way to trigger the transition is to set a random timeout expecting that the browser renders in the meanwhile ... caus if it does not happen, we won't simply see it.

Why It Is So Hard

Unfortunately is most likely Web Developers fault, in the meaning that browsers are doing everything possible to optimize callbacks.
What we think is synchronous is just a matter of asynchronous, impossible to control, redraw actions behind the scene, where of course if we change 3 times classes to the same node browsers just consider last status and that's what they draw.

The Missing API

The more we have illusion of powerful features the more we screw up our architectures and layouts .... there's not much to do here except a bloody synchronous document.redraw() method, something that supposes to tell the engine: hey, I wanna you to consider the current layout so that after I can change it and you can consider these changes.

Will it be too hard for the CPU/GPU? Who cares, I mean, with all uncontrolled and theoretically optimized redraws/repaint operations we have every N milliseconds, how can a developer choice hurt so much?


About Events, the cool part is that we can create them on JavaScript side and dispatch them whenever we want. Now, this paragraph notification is something we cannot fire in a meaningful way but it supposes to tell us ... exactly what? No idea, because the problem is that I do not want to control the status of the DOM via unpredictable setTimeout behavior, I wanna be able to tell the browser that status is OK now, would be so kind to draw the whole fucking thing for me, please?

As Summary

I hate lack of power under the HTML5 is for developers flag, I see setImmediate as a joke that I will be forced to use at some point for who knows which reason, but I still miss the possibility to properly control all these CSS3 transitions power via JavaScript, and once again, messing up between the view, and the controller.

Told'ya it was a rant!

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