Clay – UI Layout Library | Hacker News Reader

Clay – UI Layout Library

nicbarker.com

460 pointsivmoreau87 comments

Looks very nice, I just watch a great YT video from the developer here https://www.youtube.com/watch?v=DYWTw19_8r4

It's so rare to see such a clear and intuitive explanation. This video is amazing.

This. It is a rare and unique thing for the author to a) have the skills to put together such a presentation and b) take the time to do so. Thankyou.

Just watched some of his videos and they are really good. Kudos @nicoburns

The developer is rediscovering the concept of a GUI library. The modern variant is the mouse-driven GUI developed by Xerox in the 1970s (and later commercialized by them as Xerox Star) which Jobs famously copied to create Apple’s Lisa, and Gates famously mimicked to create MS Windows. Since they determine the look and feel of a platform and their design determines the ease with which developers can create apps for the platform, GUI frameworks became pivotal to platform wars across all sorts of products, from OSs to browsers, graphics engines and anything else whose success was determined largely by the interface developer experience.

I'm a gray beard like you probably but I disagree with this statement.

This library makes use of modern composable components, is declarative driven and not imperative; and doesn't do immediate rendering in all cases.

It can target incredibly different backends, e.g. DOM/canvas/raylib.

All of this in modern C as a `.h` library alone.

These are great features and not just a 'youngster discovers' project.

Maybe a README that shows how it works and what it does would help. As it is it is quite opaque IMO, with just a few high level comments.

It's in the repo; landing pages are usually for generating interest.

https://github.com/nicbarker/clay

The README for the project is one of the most detailed READMEs I’ve ever seen. The landing page for the website has as much detail as you can reasonably expect, even including a couple of feature demos. There are clear links to the docs and the code.

The developer has clearly put a lot of thought into this content. Worth taking a second or two to see what’s available before criticising it.

I swear to god, I thought this is AI generated response.

I’m still not sure it isn’t

Nice! It's pretty cool what you can make in a few thousand lines. Though Flex isn't my favorite as I prefer full CSS Grid. So I ended up making a CSS Grid layout library that I'm proud of in pure Nim (1). Though I'll have to checkout Clay and compare some of the layout algorithms.

It's neat to see boxes resizing themselves using an algorithm you implemented. Wonder if I could expose a C interface?

The reason I like CSS Grid is that I could imitate the formatting like this:

      test "compute others":
        var gt: GridTemplate

        parseGridTemplateColumns gt, ["first"] 40'ux \
          ["second", "line2"] 50'ux \
          ["line3"] auto \
          ["col4-start"] 50'ux \
          ["five"] 40'ux ["end"]

1: https://github.com/elcritch/cssgrid

Cool! I also have a standalone implementation of CSS Grid [1]. Implemented in Rust in my case (and we also support Flexbox and Block layout). Looks like the licenses are both MIT (although you may want to add a LICENSE file to make that easier to find) so feel free to steal bits if you want. We aim to be fully web compatible, although we're not quite there yet.

One thing we have that you may be particularly interested is a reasonably substantial test suite. The tests are defined as HTML snippets that we run through Chrome using webdriver in order the scrape (hopefully) correct assertions, and then format into pure-code unit tests. If you wanted to you could write your own test generator and reuse our snippets. (this test infrastructure is also partially shared with Yoga [2], the C++ Flexbox implementation that powers React Native)

1: https://github.com/DioxusLabs/taffy

2: https://github.com/facebook/yoga

Hey thanks! That's awesome and great to see other implementations. Figuring out test cases is half the battle and I've really only done the basics. I'll definitely look to stealing things. ;)

> Looks like the licenses are both MIT (although you may want to add a LICENSE file to make that easier to find) so feel free to steal bits if you want.

Good call, I'll add the license file.

Would be so awesome if single header file also includes the grid layout algorithm.

I think a new framework for lightweight native app development can be built on top. Lightweight flutter sort of.

Correct CSS grid layout calculation is about solving system of equations and constraints. In simple cases, when there are no spanned cells (like in flexbox), it can be done relatively trivially.

Otherwise solving that system is far from being trivial, you will need simplex solver or the like, for example https://constraints.cs.washington.edu/solvers/cassowary-toch...

You definitely don't need a general constraint solver for CSS Grid. The algorithm (including for cases where there are spanned cells) is well defined in the spec [1], and can be translated directly into code.

1: https://www.w3.org/TR/css-grid-1/#algo-content

Just a funny note—there’s a button at the end to switch between HTML and Canvas. I think it is neat how little difference it makes… normally.

But with iOS Safari + Dark Reader, at least on my side, the HTML page is turned into dark mode with Dark Reader, while the canvas page is not. So, it basically ruins the wow factor, haha.

But it still looks nice.

Text selection and zoomng is also problematic.

Zooming is indeed an issue but selection works fine for me on safari ios.

On Windows/Firefox, text selection doesn't work. Also not working is Home/End and wheel click scrolling. Cool project otherwise.

My Firefox on Linux zooms fine with both renderers. Text selection doesn't work though. Also the cursor doesn't adapt when hovering text, a button etc.

It won’t help with dark mode, but the canvas-place-element proposal (https://github.com/WICG/canvas-place-element) should allow those interactions on canvas-rendered text backed by a text element placed under the canvas.

In Chrome, it selects sometimes but sometimes it seems to unselect itself, probably due to the animation happening somewhere else on the page.

The HTML renderer is definitely faster in Chrome. Why is that, I wonder? The Canvas one is also reasonably fast, but noticable in that "High performance" animation and also when scrolling.

It says:

> There's even an HTML renderer - you're looking at it right now!

Jokes on them, I already switched to Canvas renderer when I read it.

Just wanted to drop a note - everything following the animation cannot be selected - seems focus is stolen somehow - whenever I try to select text, it immediately deselects it.

this happens to me on mobile using all chromium and gecko based browsers

what's also interesting is how much worse Firefox is at rendering this page; example =>

https://imgur.com/a/DNYe2WN

If you mean the text position that overflows, that seems to be computed by the library. The same happens in chromium at some resolutions.

It's probably because it does it a full reset every frame, and there's an animation playing.

This is a delightful take on a style of UI I really love. Separating the UI logic from drawing with a set of draw commands is an excellent and very versatile idea - I first saw it in microui, and the separation allowed me to easily use the library in the browser using WASM and Canvas2D. (https://rxi.github.io/microui_v2_an_implementation_overview....)

Also, doing layout in WASM and rendering to HTML is a great idea that I can't believe I never thought of before.

Okey i was going to complain about what's the point of doing it in C, when it could be done more safely in Haskell/OCaml

But 2000 lines of C, and no dependencies is pretty cool!

Hey at least this way other languages can use it

There is also taffy (Rust) which has WIP C bindings.

https://crates.io/crates/taffy

It's a good first draft. I do find it a shame that the HTML output is only div elements. I think a little accessibility would go a long way. I also can't select text in many places before some re-render de-selects before I can hit control-c.

Serious question: am I the only one who finds writing a webpage like this to be a little too much (even if the concept is cool):

void LandingPageDesktop() { CLAY(CLAY_ID("LandingPage1Desktop"), CLAY_LAYOUT({ .sizing = { .width = CLAY_SIZING_GROW(), .height = CLAY_SIZING_FIT({ .min = windowHeight - 70 }) }, .childAlignment = {.y = CLAY_ALIGN_Y_CENTER}, .padding = { .x = 50 } })) { CLAY(CLAY_ID("LandingPage1"), CLAY_LAYOUT({ .sizing = { CLAY_SIZING_GROW(), CLAY_SIZING_GROW() }, .childAlignment = {.y = CLAY_ALIGN_Y_CENTER}, .padding = { 32, 32 }, .childGap = 32 }), CLAY_BORDER({ .left = { 2, COLOR_RED }, .right = { 2, COLOR_RED } })) { CLAY(CLAY_ID("LeftText"), CLAY_LAYOUT({ .sizing = { .width = CLAY_SIZING_PERCENT(0.55f) }, .layoutDirection = CLAY_TOP_TO_BOTTOM, .childGap = 8 })) { CLAY_TEXT(CLAY_STRING("Clay is a flex-box style UI auto layout library in C, with declarative syntax and microsecond performance."), CLAY_TEXT_CONFIG({ .fontSize = 56, .fontId = FONT_ID_TITLE_56, .textColor = COLOR_RED })); CLAY(CLAY_ID("LandingPageSpacer"), CLAY_LAYOUT({ .sizing = { .width = CLAY_SIZING_GROW(), .height = CLAY_SIZING_FIXED(32) } })) {} CLAY_TEXT(CLAY_STRING("Clay is laying out this webpage right now!"), CLAY_TEXT_CONFIG({ .fontSize = 36, .fontId = FONT_ID_TITLE_36, .textColor = COLOR_ORANGE })); } CLAY(CLAY_ID("HeroImageOuter"), CLAY_LAYOUT({ .layoutDirection = CLAY_TOP_TO_BOTTOM, .sizing = { .width = CLAY_SIZING_PERCENT(0.45f) }, .childAlignment = { CLAY_ALIGN_X_CENTER }, .childGap = 16 })) { LandingPageBlob(1, 32, COLOR_BLOB_BORDER_5, CLAY_STRING("High performance"), CLAY_STRING("/clay/images/check_5.png")); LandingPageBlob(2, 32, COLOR_BLOB_BORDER_4, CLAY_STRING("Flexbox-style responsive layout"), CLAY_STRING("/clay/images/check_4.png")); LandingPageBlob(3, 32, COLOR_BLOB_BORDER_3, CLAY_STRING("Declarative syntax"), CLAY_STRING("/clay/images/check_3.png")); LandingPageBlob(4, 32, COLOR_BLOB_BORDER_2, CLAY_STRING("Single .h file for C/C++"), CLAY_STRING("/clay/images/check_2.png")); LandingPageBlob(5, 32, COLOR_BLOB_BORDER_1, CLAY_STRING("Compile to 15kb .wasm"), CLAY_STRING("/clay/images/check_1.png")); } } } }

Source: https://github.com/nicbarker/clay/blob/35d72e5fba6872be48d15...

If you don't use some kind of layouting language (like XML/HTML), this is inevitably what you will always end up with. See: AWT[1], SWT[2], Swing[3], Qt[4]†, Fyne[5], etc., etc., etc.

[1] https://docs.oracle.com/javase/7/docs/api/java/awt/GridLayou...

[2] https://github.com/eclipse-platform/eclipse.platform.swt/blo...

[3] https://stackoverflow.com/a/12867862/243613

[4] https://stackoverflow.com/questions/37304684/qwidgetsetlayou...

† Qt actually has a (XML-based, I think) layouting system, but you can also just do stuff in code, which is generally discouraged.

[5] https://gist.github.com/ledongthuc/9686787fe51bbe763fa1e5038...

Qt has uic xml layout engine which was cumbersome to use, you weren’t discouraged from using c++ classes instead. The discouragement came later when Qt shifted towards qml (a bad shift as it’s just as unweildly, imo), now they discourage writing qml in c++ because the qml engine can get out of sync. Qt can prevent this but they want you to pay for a premium license for it. Slint is a sister to qt that does not have this restriction afaik.

I wish there would be an elegant c++ class/function based ui framework again.

Agreed that a C++ API for qml would be great. qml by itself is great though, I don't see why it is unweildy. If anything it's unpolished, there is stuff that is more difficult than it should be, but it's miles ahead of what there was before imo.

It is unwieldily because it abstracts logic into a different language and paradigm. You need double the cognitive understanding of qt now to know how it operates.

As someone with 10,000+ lines of C++ code and 10,000+ lines of QML code in his app[1] I can say this is false. It's actually much easier and straightforward to decouple the UI (QML) and logic (C++). It also makes such a great combo - QML is amazing to write UIs in and C++ is a fast, battle tested compiled language. I wrote a little bit about my app development if you're curious[2].

[1] https://get-notes.com

[2] https://rubymamistvalove.com/block-editor

By the same metric c++ qwidgets is amazing to write UIs and by keeping everything in c++ there is easily less abstraction, I can easily navigate my code, not jump between two different systems. There really is no great reason why qml objects couldn’t be c++ classes/functions. Decoupling does what for me, but introduce more syntax, documentation, and learning curves. You should give writing a Kde6 Kirigami app a try and experience the absolute pleasure of adding another abstraction layer onto qml, c++ to muck things up. Qml is the cooler brother of Uic, but at least uic was optional.

I'm very fond of QML's syntax, so can't quite understand why you don't like it. It has a learning curve, but I studied all the basics in a day (it's just so simple and intuitive, imo).

Not sure how "QML in C++" would look like, but it doesn't sound pretty. Recently someone published a declarative UI inside C++[1] (without a different syntax) but I felt a bit off with this approach. Maybe that's something you mean?

[1] https://github.com/brisklib/brisk

[2] https://news.ycombinator.com/item?id=42450963

I don’t know how else to explain it that compared to qwidgets where everything can be handled in code. Qml might be all the things it claims , elegance, separation of concerns, simple syntax, etc, but that still doesn’t eclipse my initial issue that it’s an unnecessary abstraction. You might not think it’s pretty but I think it’s pretty to only use c++.

It's not difficult or disorganized to layout GUIs in a programming language. HTML exists as an alternative to having nothing. If you have a programming language you can give the data to the GUI library directly without having to learn a new markup language, have the bloat of a new markup language or learn the quirks a new markup language. You can also put format it and put newlines in there.

The thing is, most GUIs by necessity involve fairly deep hierarchies of graphical objects so you're either going to have deeply nested calls like this, or you're going to scatter the fragments across a number of files in a way that they need to be reassembled in the reader's head in order to understand what's going on.

most GUIs by necessity involve fairly deep hierarchies of graphical objects

First, this isn't really true. You might typically have a window, a container, a layout object and then your gui components.

Second you don't need nested calls, you just add one component to another.

or you're going to scatter the fragments across a number of files

Why would that be true?

they need to be reassembled in the reader's head in order to understand what's going on.

This is a bizarre way to make a GUI let alone thinking it's necessary. Where is this idea coming from?

FLTK, JUCE, Tk, ImGUI, Swing and Qt are not like this at all.

It's not all that much different than html or even React. You can assign each part to named functions and turn it into something more like this:

    LandingPageDesktop(landingPageDesktopId, landingPageDesktopProperties) {
      LandingPage(landingPageId, landingPageProperties) {
        LeftText() {
          etc...
        }
      }
    }

The real issue is trying to represent graphical objects, and the relationship between those objects, with text. Graphical builders/RAD tools seem like such an obvious solution, but that approach has largely been abandoned.

cool stuff! selectable text is a MUST in the browser for me. In clients and apps that do not need that or can provide it themselves, this seems to be a very nice and tiny solution.

it's weird to watch it break text selection/copy-and-paste : feels like it might be fixable, though.

I'm a stuck record on this, but I really feel like the regressions in clipboard universality are one of most understated losses of UI shifts in the last few years (along with linkability and embedding)

Should that be part of a layout engine though? I’d expect to insert a tree of nodes with styling information that affect layout and receive a tree with calculated x, y, width and height for its elements.

Right and middle click on links behaves like a left click on the website.

Instant recycle bin.

So cool. I wonder if it'd work for a Raspberry Pi Pico + https://pimoroni.com/picodisplay or similar devices.

The d for debugging is so cool. Fantastic library. C is also such a good language. If I wasn't doing Rust, I would have gone back to C.

> C is also such a good language. If I wasn't doing Rust, I would have gone back to C.

Wouldn’t you try Zig instead?

I'm not sure I would have. There is a terseness in C which zig lags. I think. To be fair, I haven't played with Zig that much.

Would be fun to combine this with the single-file Impeller header from the Flutter people.

The API approach could be implemented extremely cleanly in Clojure and Java, and then the whole thing would be runtime-dynamic, since Clojure generates new Java functions on the fly, and the JVM's JIT makes them fast.

If anyone wants a fun project over the holidays…

This looks pretty cool, but from the page I can't tell if there's any interactivity supported...there's a button example but it seems to have no click handler?

Okay, from the examples there's something like this:

   if (isMouseDown && !scrollbarData.mouseDown && Clay_PointerOver(Clay_GetElementId(CLAY_STRING("ScrollBar")))) {

I'm not a frontend person. Can anyone explain why this is better than using CSS directly or a CSS framework/library? Seems like added complexity when there are already hundreds of CSS frameworks available that seem like they do the same thing.

Maybe you want the compile some C to wasm and render to canvas. Then it's pretty neat.

This isn't really meant to replace such things an environment where you have a rendering engine that supports CSS— I think demoing it on the page is more for showing off how portable it is with WASM. Off the top of my head, a few uses for this:

- Mapping components or structured document data with something like MDX or slate on to Clay components to render in different contexts outside the browser reasonably closely to what shows up in a browser preview, for example content for HUDs, in-world display panels or documents in games, or batch rendering printed documents

- Layout for UI where something like Electron or React Native would be overkill, or isn't supported

This UI library can be re-targeted to Raylib, Canvas, HTML from its markup ... Good luck doing that with just CSS.

Put another way, this library is a step into writing an agnostic UI layer for your application which it just invokes from its business logic. If you can decouple your UI from your application code ala MVC or MVP architecture, as a developer you can find the right tool for the components that compose the sum of your project.

The main goal is to enable nice UI without the requirement of a whole web browser in order to get CSS. The fact that it can be used to layout web pages is just showing off to get the attention of the billion web devs out there.

Using CSS translations to place elements on the page is... cursed to say the least. It's probably why text selection works (assuming it qualifies as working) in such a weird way when the cursor goes between blocks.

So cool! For some reason navigating to Github/Discord by clicking the links is slow on my phone (old galaxy s20fe). The click highlight of the button is normal, just going to the sites is slow.

Looks impressive! What are the connection/comparison with imgui though?

Both use immediate mode rendering. Both have the “single header” design. There doesn’t appear to be any shared implementation.

The examples use Raylib as a renderer behind the layout engine. I suppose it would be possible to use Dear Imgui as a renderer, but you might have to write some glue code.

My question may be to obvious but, how can you incorporate js to mutate your layout based on user interaction and api calls? Do you have a dynamic website example?

The canvas renderer tried on iPhone feels weird. The scroll is completely different from regular, also no scroll bounce. That alone is a deal breaker

Getting an empty, cream-rose-colored page, followed by a warning that the script on the page is slowing the browser down with an offer to stop the script. Just FYI.

Excellent. If these compiled data structures were the web standard instead of HTML, www would be ridiculously fast.

I'm not proficient in C. Does this "just work" or do you need to provide some sort of rendering environment like SDL?

This is just a layout library, it doesn't do any rendering at all.

No, the library is about doing the layout only.

Yes, the repo offers a couple of example renderers.

The idea is that you already have a rendering pipeline (e.g. in your game engine), but want to lay out more complex UIs in it. Then you can use this library to make nice settings / chat / stats / whatever screens, or even render realistic content onto screens of in-game computers, pages of books, etc.

Highlighting is degraded for me running on Firefox, it's wigging out every time I nudge my cursor

Press "d" to debug didn't work for me. On Chrome in Mac.

the inspector at the end was a neat surprise! I had some issues trying to build the examples on windows but I think it's an opportunity to contribute to the project

This is basically what Flutter web is doing - its own canvas, rendering UI, and leveraging Wasm

If Android had provided an defining UI API like this entirely in C without using Java, Android would have 100% monopolized the mobile OS market. So fast, efficient.

Somehow I don't think it's that easy. But yeah, the way Java was used and with XML etc was horrible. Android development continues to be pretty horrible to this day, but due to a variety of reasons.

If I need to target Android natively today, I first consider Flutter (non-web).

For iOS only apps there's little reason to stay away from Swift.

Oh sweet jesus, the preprocessor? Go away.

Cool, so if i look for 'clay', i'll find your lib?

You mean, like, using a search engine? I don't think anyone here is in any special position to be able to answer that question.

"clay ui" or "clay layout" will find it, which seems ok to me.

"clay ui" actually fails. My top hit is: https://clayui.com/docs/get-started/how-to-use-clay which is a completely different UI library from what I can tell, and probably had the name first too as the Git repo has commits from 4 years ago.

why it's not written in rust?! now every cool kid writes in rust)) Jokes aside this is nice!

Reply on news.ycombinator.com