Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Yoga: A cross-platform layout engine

code.facebook.com

Post reply on HN
Print view View original

61–70 of 168 posts

Re: Yoga: A cross-platform layout engine

#61

Post by brian-armstrong »

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…

You might be able to accomplish this with emscripten, which is pretty capable. You'd need appopriate bindings to have it control the DOM

Re: Yoga: A cross-platform layout engine

#62

Post by yladiz »

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 since it's not actually in the license itself, only referenced in the readme but if I had a patent and Facebook infringed on it my license is terminated if I assert my patent rights against Facebook even if it is valid and doesn't pertain to specific React technologies. This has been discussed heavily in the past but suffice it to say it's pretty scary and bears thought.

This library looks very useful for those who use React Native or want a layout engine in C# or Java for their mobile app, but as someone who works in an industry (bio/chem engineering) who develops applications around tools in that industry and thinking that Facebook may one day enter that field, or even if we create a software patent for some idea we create while developing the tools, it makes me uneasy whenever a new Facebook open source project, especially one with the potential to become popular in a specific area of software development, is introduced.

Also, another thing to keep in mind is not every big company does this with their open source tech. For example, Angular and Visual Studio Code are both under MIT license.

Re: Yoga: A cross-platform layout engine

#63

Post by emilsjolander »

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…

Yoga itself does not handle animation but by using another animation system on top of Yoga it should be very possible. I have not yet tried it myself but by wrapping a layout change in a UIView animation block the above should be doable (on iOS but similar should hold on other platforms).

Re: Yoga: A cross-platform layout engine

#64

Post by emilsjolander »

king_magic wrote: post #60

Very, very interesting - curious about whether the C# bit supports Xamarin on iOS and Android, or if the C# piece is just Windows-only (not super clear from the documentation).

I'm not very familiar with Xamarin but I think it should work. If it doesn't please file an issue on the repo.

Re: Yoga: A cross-platform layout engine

#65

Post by stefano »

iLoch wrote: post #18
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.

Speaking as someone coming from the web, auto-layout is really awful. You're way better off making UI easy to reason about for web developers transitioning to mobile, because that's where most of the talent comes from. By DSL, do you mean something like HTML/CSS? React Native basically has this with JSX and style properties which use Yoga under the hood.

I have a web background myself, but I always found auto layout a pleasure to work with. I use it with http://snapkit.io/docs/ (a DSL built on top of the iOS APIs) and with programmatically written UIs. I find it so much easier to reason about than CSS.

Re: Yoga: A cross-platform layout engine

#66

Post by oblio »

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…

I'm not sure how you're supposed to use this from C# in real life, though.

Ok, you have a layout engine. For what widgets? Windows.Forms? WPF? Xamarin Forms? Can those even use a third party layout engine?

I'm slightly confused :)

Re: Yoga: A cross-platform layout engine

#67

Post by ams6110 »

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…

Animation effects like this are more annoying than anything else, anyway.

Re: Yoga: A cross-platform layout engine

#68

Post by oblio »

emilsjolander wrote: post #64
king_magic wrote: post #60

Very, very interesting - curious about whether the C# bit supports Xamarin on iOS and Android, or if the C# piece is just Windows-only (not super clear from the documentation).

I'm not very familiar with Xamarin but I think it should work. If it doesn't please file an issue on the repo.

How do you see it being used? I'm especially interested in the C# widget toolkit you used this with, if any.

Re: Yoga: A cross-platform layout engine

#69

Post by ohitsdom »

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…

I'd prefer it the other way around. CSS is already ubiquitous, would it be possible to make an implementation for a cross-platform tool?

Re: Yoga: A cross-platform layout engine

#70

Post by aseipp »

pcwalton wrote: post #55

Why not use parallelism? Parallel layout tends to be a major speed boost in our experience, and we have a parallel implementation of flexbox already. See Meyerovich 2010 [1] for the basic idea; you can adopt it to flexbox relatively easily. Additionally, I'm a bit skeptical about the use of C here: this stuff tends to end up exposed to the user and security-sensitive. [1]: http://citeseerx.ist.psu.edu/viewdoc/downloa…

For React Native, at least, I think the threat model is a little different. Browsers have to deal with any hostile webpage, so all input can be considered hostile to something like the layout engine -- but here, you're baking the application along with the engine and shipping it wholesale. But I guess it depends on the details of how Yoga actually integrates and what its surface area actually is.

That said, I think the more likely conclusion for security vulnerabilities is the one you allude to, where people will probably end up reusing this component elsewhere and exposing the engine to potentially hostile input somewhere along the line, and it might not end well.

Post reply on HN