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Yoga: A cross-platform layout engine

code.facebook.com

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Re: Yoga: A cross-platform layout engine

#81

Post by andrewflnr »

on_and_off wrote: post #27
adamnemecek wrote: post #13

Why not just embrace Cassowary ( https://en.wikipedia.org/wiki/Cassowary_(software) ) aka the algorithm behind Cocoa's Auto Layout? Auto Layout isn't perfect but I think that it's fundamentally the API/UI that you are working with, the concepts are definitely at the right level of abstraction. Some sort of DSL could really solve this. Flexbox could be implemented as a framework on top of this.

Android has started embracing it with ConstraintLayout. It implements a Cassowary solver in order to resolve the constraint imputed by the dev. I have been using it for some time and it is an huge step in the right direction. A downside of Yoga seems to be its tooling, ConstraintLayout is very well integrated with Android Studio. Actually they created it hand in hand with a rewrite of its layout editor.

I think you're thinking of RelativeLayout? I don't have ConstraintLayout in my IDE right now, but RelativeLayout sounds like what you're talking about.

Re: Yoga: A cross-platform layout engine

#82

Post by vjeux »

amelius wrote: post #54

Okay, question: can it perform the following task elegantly? Say, I build a declarative tree describing a layout, and I render it. Now I remove one item from the tree. Can the layout engine efficiently remove the item from the view, and... (now it comes) provide an animation for it? As in, the item slowly losing opacity, then the surrounding items moving closer together? (Or a different animation depending on setting…

One motivation for reimplementing a layout engine for React Native was to solve this exact problem that CSS doesn't address.

We have LayoutAnimation inside of React Native which lets you do that. It's not very well documented and the delete method is not implemented, but the idea is there :)

https://facebook.github.io/react-native/docs/layoutanimation...

Re: Yoga: A cross-platform layout engine

#83

Post by emilsjolander »

afro88 wrote: post #51
BinaryIdiot wrote: post #25

I like the concept and the C# code is just hands down the best example out of all of them (yet another reason I miss coding in C#). I'm curious though, will this be eventually ported to JavaScript? Yeah yeah I know "flexbox is already on the web!" but if you could write a layout in this fashion versus using style sheets then you could take it and directly apply it to any of your applications (even if you have to conv…

They totally could have done it clean like this for Swift and I struggle to understand why they did it in the old Obj-C way: extension methods with yg_ prefix, static constants instead of enums, unnecessary configuration after instantiation.

I just happen to be more familiar with obj-c :) I agree that a swift API would probably look very cool. Would be fun to see this come from the community.

Re: Yoga: A cross-platform layout engine

#84

Post by RyanZAG »

vortico wrote: post #29
sickbeard wrote: post #12

Looks nice but the naming is wrong. We shouldn't expropriate well known names for tech solutions

I think it's nice. It describes its function perfectly and "facebook yoga" will soon return this project in the first result.

Could be a big part behind companies re-purposing common words? If you give it a unique word, it becomes it's own thing. But if it's something like "Yoga", then you will always have to refer to it as "Facebook Yoga" which is very good for the Facebook brand.

Re: Yoga: A cross-platform layout engine

#85

Post by evv »

vjeux wrote: post #35
adamnemecek wrote: post #13

Why not just embrace Cassowary ( https://en.wikipedia.org/wiki/Cassowary_(software) ) aka the algorithm behind Cocoa's Auto Layout? Auto Layout isn't perfect but I think that it's fundamentally the API/UI that you are working with, the concepts are definitely at the right level of abstraction. Some sort of DSL could really solve this. Flexbox could be implemented as a framework on top of this.

(Original author of css-layout here) I've spend a few months playing with Cassowary before working on css-layout and had long chats with its creator Greg Badros and the people behind https://gridstylesheets.org/ . Cassowary underlying abstraction is a linear inequation solver. So you give it a bunch of constraints of the form ax + by + cz + d ## There are two innovations in Cassowary: 1) There's a concept of strength…

Hey vjeux! I'm sure everyone here on HN would really love the story of how you first implemented css-layout.

You had a really inspiring use of fuzz testing and TDD. You used a hilarious technique to implement it in several languages at once. And I heard a rumor you did it all over your paternity leave?!

Re: Yoga: A cross-platform layout engine

#87

Post by yodon »

yladiz wrote: post #62

One thing I've thought about recently is Facebook's Patent grants, and it's one thing that makes me uneasy about using any open source technology from Facebook like React (I currently do but am thinking to move to Preact because of the nicer MIT license and that it's analogous to React in many ways) because they're generally given a patent grant. I'm not a lawyer so I don't know if the grant would hold up in court si…

This is one of the reasons companies seek patents, called a defensive patent strategy. The goal is to discourage competitors from suing you for patent violations by making sure you own a patent your competitors are likely to have violated. It creates a kind of "mutually assured destruction" that discourages either party from launching a patent war (this only works against real competitors, not against patent trolls, but it can still be a viable part of a company's IP strategy).

In the case you describe, what it boils down to is yeah, if your business intends to sue Facebook for patent infringement, you probably shouldn't be dependent on any of Facebook's IP or patents for your business. There are lots of things companies do to discourage other companies from suing them. Giving out free software is one of the nicer ways a company can choose to go about it.

Re: Yoga: A cross-platform layout engine

#88

Post by yladiz »

comex wrote: post #80
yladiz wrote: post #62

One thing I've thought about recently is Facebook's Patent grants, and it's one thing that makes me uneasy about using any open source technology from Facebook like React (I currently do but am thinking to move to Preact because of the nicer MIT license and that it's analogous to React in many ways) because they're generally given a patent grant. I'm not a lawyer so I don't know if the grant would hold up in court si…

This project is under the BSD license, which is equally silent about patent rights to the MIT license, making it ambiguous whether it applies to patents. The patent license is on top of that; Facebook's approach is basically strictly more permissive, patents-wise, than typical use of the MIT license. (But not as permissive as the Apache 2 license, which contains explicit patent grants with a "don't sue us" condition…

That's fair, and I respect Facebook's want to have specific patents language in their licenses. But my main fear is that the language is too broad and taken at face value wouldn't allow any kind of patent infringement to be fought against, regardless of its merits. I also wish that the language was in the license itself rather than as a separate grant because it's potentially confusing. I had a friend I was telling this about didn't know about this at all, and said he's happy that his company has lawyers that review this stuff because he would just copy the license without the separate grant and be done with it, which wouldn't suffice.

Re: Yoga: A cross-platform layout engine

#89

Post by Steeeve »

yladiz wrote: post #62

One thing I've thought about recently is Facebook's Patent grants, and it's one thing that makes me uneasy about using any open source technology from Facebook like React (I currently do but am thinking to move to Preact because of the nicer MIT license and that it's analogous to React in many ways) because they're generally given a patent grant. I'm not a lawyer so I don't know if the grant would hold up in court si…

I am curious to hear of anyone who has reviewed this license with their lawyers / legal departments and received a positive, non-cautionary response to go ahead and use the software and libraries covered under it.

Re: Yoga: A cross-platform layout engine

#90

Post by yladiz »

yodon wrote: post #87
yladiz wrote: post #62

One thing I've thought about recently is Facebook's Patent grants, and it's one thing that makes me uneasy about using any open source technology from Facebook like React (I currently do but am thinking to move to Preact because of the nicer MIT license and that it's analogous to React in many ways) because they're generally given a patent grant. I'm not a lawyer so I don't know if the grant would hold up in court si…

This is one of the reasons companies seek patents, called a defensive patent strategy. The goal is to discourage competitors from suing you for patent violations by making sure you own a patent your competitors are likely to have violated. It creates a kind of "mutually assured destruction" that discourages either party from launching a patent war (this only works against real competitors, not against patent trolls,…

Let's say I have a patent for a technology outside of React, and even outside of software, such as some hardware patent. Why should me suing for infringement of that patent preclude me from using React when it (the patent infringement and React) are completely independent?
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