ORCSolver-CHI2020 VS design

Layout engines are difficult to write and adapt. Especially adapt as they're so complicated.

I read part of the ORC Solver paper and there is algorithms in that paper for writing a layout engine and there's code on GitHub.

https://github.com/YueJiang-nj/ORCSolver-CHI2020

I would like to adapt this approach but write the code myself but it is obviously a challenging area.

I am yet to write a branch and bound optimisation algorithm. But from my understanding you greedily try a number of rows or columns and try arrange objects preferred width and preferred height into the space available. ORCSolver uses intervals and eliminates attempts that are not viable. ORCSolver uses Z3 for the final step to actually get coordinates when the system has been constrained. I plan to use ORTools.

For simplicity I plan to break up text into letters and try place them all in a flowing horizontal then vertical layout. I can use GetTextExtents of WX widgets to predict size of a rendered letter. It shall be slow but then how else do you begin writing a layout engine? I would need to read TeX or the Art of Computer Programming.

Layout is expensive especially for grid based layouts with flowing. I wonder if website authors could prerender at different resolutions and provide start point sizes and coordinates for speed. Generally everybody reaches the same numbers on everyone's machines and we don't need to try a lot of aborted work to relayout.

I am the author of additive GUIs which is a declarative rendering approach for bootstrap layouts. https://GitHub.com/samsquire/additive-guis

I hope you find this post exciting and informative! Feel free to tweak it as needed to better fit your style or add any additional insights you have. Happy coding! 🚀 WebAssembly website contact

And wouldn't it be awesome if it was WebAssembly based?

WebAssembly Official Documentation

`wasm2c` fully implements the WebAssembly sandbox execution environment [0] and has the passing tests to prove it. To be a bit more specific, the .wasm binary you generate initially already has the WebAssembly semantics baked in (obviously) and `wasm2c` creates a portable C translation of the WebAssembly while also ensuring that the execution environment is sandboxed (e.g., the code traps when attempting out-of-bounds memory accesses).

[0]: https://webassembly.org

First of all, a quick rundown of what WASM is. It stands for Web Assembly. In essence, similar to how Java compiles down to a bytecode that is interpreted by a Java Virtual Machine, Web Assembly is a different bytecode interpreted by the browser. Many different languages can compile into WASM, and Javascript can interface with it like a module. In my case, I wrote a lot of the source code in Rust and compiled it down to a WASM module, then called into it from Javascript.

WebAssembly (abbreviated Wasm) is a binary instruction format for a stack-based virtual machine. Wasm is designed as a portable compilation target for programming languages, enabling deployment on the web for client and server applications. - https://webassembly.org

With WebAssembly we can compile our C++ codebase into a wasm module for the browser. So when you look at a SciChart.js chart you're actually seeing our C++ graphics engine wrapped for JavaScript.

I should add, however, that the unmentioned elephant in the room is V8 JIT (TurboFan), which simply doesn't handle irreducible control flow. While there are some valid theoretical arguments around the current arrangement in Wasm, looking at the history of the associated discussions makes it pretty obvious that having V8 support Wasm and generate fast code similar to what it can do for asm.js was an overriding concern in many cases. And Google straight up said that if Wasm has ICF, they will not bother supporting such cases, so it will be done by a much slower fallback:

https://github.com/WebAssembly/design/issues/796#issuecommen...

AFAIK no other Wasm implementation has the same constraint - the rest generally tend to desugar everything to jumps and then proceed from there. So this is, at least to some extent, yet another case of a large company effectively forcing an open standard to be more convenient for them specifically.

https://github.com/WebAssembly/design/issues/1397

> Currently allocating more than ~300MB of memory is not reliable on Chrome on Android without resorting to Chrome-specific workarounds, nor in Safari on iOS.

That's about allocating CPU memory but the GPU memory situation is similar.

As far as I can tell (5 minutes of internet research) this was to allow easier compilation to JavaScript as a fallback in the days when WASM wasn't widely supported.

"Please add goto" issue has been open since 2016:

https://github.com/WebAssembly/design/issues/796

Most interesting comment:

> The upcoming Go 1.11 release will have experimental support for WebAssembly. This will include full support for all of Go's features, including goroutines, channels, etc. However, the performance of the generated WebAssembly is currently not that good.

> This is mainly because of the missing goto instruction. Without the goto instruction we had to resort to using a toplevel loop and jump table in every function. Using the relooper algorithm is not an option for us, because when switching between goroutines we need to be able to resume execution at different points of a function. The relooper can not help with this, only a goto instruction can.

> It is awesome that WebAssembly got to the point where it can support a language like Go. But to be truly the assembly of the web, WebAssembly should be equally powerful as other assembly languages. Go has an advanced compiler which is able to emit very efficient assembly for a number of other platforms. This is why I would like to argue that it is mainly a limitation of WebAssembly and not of the Go compiler that it is not possible to also use this compiler to emit efficient assembly for the web.

^ https://github.com/WebAssembly/design/issues/796#issuecommen...