Manuel Rego: Open Prioritization and CSS Containment

Igalia is a major contributor to all the open source web rendering engines (Blink, Gecko, Servo and WebKit). We have been doing different kind of contributions for years, which has led us to have an important position on the different communities. This allows us to help our customers to solve their problems through upstream contributions that also benefit the whole web community.

Implementing a feature in a rendering engine (or in several) might look very simple at first sight, but contributing them upstream can take a while depending on the standarization status, the related bugs, the browser architecture, and many other factors. You can find examples of things implemented by Igalia in the past on my previous blog posts, and you will realize about all the work behind some of those features.

There’s a common thing everywhere, people usually get really angry because that bug they reported years ago is still not fixed in a given browser. That can be for a variety of reasons, and not simply because the developers of that browser are very lazy and not paying attention to that particular bug. In many cases the answer to why that hasn’t been solved yet is pretty simple: priorities . Different companies and individuals contributing to the projects have their own interests and priorities, they prioritize the different issues and tasks and put the focus and effort on the ones that have a higher priority for them. A possible solution for that, now that major browsers are all open source, would be to look for a consulting company like Igalia that can fix that bug for you; but you as an individual, or even as a company, maybe you don’t have the budget to make that happen.

What would happen if we allow several parties to contribute together to the development of some features? That would make possible that both individuals and organizations that don’t have the power to implement them alone, could contribute their piece of the cake in order to add support for those features on the web platform.

Open Prioritization

Igalia is launching Open Prioritization , a crowd-founding campaign for the web platform. We believe this can open the door to many different people and organizations to prioritize the development of some features on the different web engines. Initially we have defined 6 tasks that can be found on the website, together with a FAQ explaining all the details of the campaign. :rocket:

Let’s hope we can make this happen. If this is a success and some of these items get funded and implemented, probably there’ll be more in the future, including new things or ideas that you canshare with us.

Open Prioritization by Igalia

One of the tasks of the Open Prioritization campaign we’re starting this week is about adding CSS Containment support in WebKit , and we have experience working on that in Chromium.

Why CSS Containment in WebKit?

Briefly speaking CSS Containment is a standard focused in improving the rendering performance of web pages, it allows author to isolate DOM subtrees from the rest of the document, so any change that happens on the “contained” subtree doesn’t affect anything outside that element.

This is the spec behind the contain property , that can have a few values defining the “ type of containment ”: layout , paint , size and style . I’m not going to go deeper into this and I’ll refer to myintroductory post ormy CSSconf EU talk if you’re interested in getting more details about this specification.

So why we think this is important? Currently we have an issue with CSS Containment, it’s supported in Chromium and Firefox (except style containment) but not in WebKit. This might be not a big deal as it’s a performance oriented feature, so if you don’t have support you’ll simply have a worse performance and that’s all. But that’s not completely true as the different type of containments have some restrictions that apply to the contained element (e.g. layout containment makes the element become the containing block of positioned descendants), which might cause interoperability issues if you start to use the contain property in your websites.

The main goal of this task would be add CSS Containment support in WebKit , at least to the level that it’s spec compliant with the other implementations, and if time permits to implement some optimizations based on it. Once we have interoperability you can start using it wihtout any concern in your web pages, as the behavior won’t change between the different browsers and you might get some perf improvements (that will vary depending on each browser implementation).

In addition this will allow WebKit to implement further optimizations thanks to the information that the web authors provide through the contain property. On top of that, this initial support is a requirement in order to implement new features that are based on it; like the new CSS properties content-visibility and contain-intrinsic-size which are part of Display Locking feature.

If you think this is an important feature for you, please go ahead and do your pledge so it can get prioritized and implemented in WebKit upstream.

Really looking forward to seeing how this Open Prioritization campaign goes in the coming weeks.