# ezgui notes This is a GUI + 2D drawing + data viz library I've built up for A/B Street. I'm considering cleaning up the API surface and making it a proper standalone crate. ## Running the demo [Example code](examples/demo.rs) ``` git clone https://github.com/dabreegster/abstreet.git cd abstreet/ezgui cargo run --example demo ``` ![demo](demo.gif) If you want a more thorough idea of what this crate can do, see [A/B Street](https://abstreet.org). ## Features ### Runs in lots of places Runs on Linux, Mac, Windows via [glium](https://github.com/glium/glium/). Also works in the browser using WebAssembly and [glow](https://github.com/grovesNL/glow/), but text support still coming in [a few months](https://github.com/RazrFalcon/resvg/issues/229). Why OpenGL? My requirements are super simple; I don't need the power of Vulkan or other new stuff. I want something simple that runs everywhere. If you want to make this work with WGPU or something else, it should be easy. The 3 backend implementations ([glium](src/backend_glium.rs), [glow on native](src/backend_glow.rs), [glow on wasm](src/backend_wasm.rs)) are each about 300 lines. ### 2D drawing Everything is a colored polygon. Upload stuff once, redraw many times with a simple camera transform. Panning and smooth zooming. One extremely simple shader. Thanks to [usvg](https://github.com/RazrFalcon/resvg) and [lyon](https://github.com/nical/lyon/), SVGs and text are transformed into colored polygons. Programatically swap colors, rotate, scale stuff. Find bounds for precise mouseover. ### GUI Widgets like buttons (with keybindings), checkboxes, sliders, pop-up menus, text entry, and some data viz things. You can combine these in `Composite`s to dispatch event handling and drawing. Styling (background colors, outline, padding) and Flexbox-ish layouting via [stretch](https://vislyhq.github.io/stretch/). The API / programming style is kind of funny; see the [demo](examples/demo.rs) to get a sense of it. No callbacks. You manually feed events into your `Composite`s of widgets and ask about what happened. There's no smart diffing of widget trees; most of the time it's fine to completely recreate a `Composite` from scratch when something changes, or replace a single widget in an existing `Composite`. (This is not a performance critical library. The perf bottlenecks in A/B Street are not in the GUI, and I probably won't invest much time speeding things up here until they are. (Or if somebody else winds up using this library and hits a problem.)) ### Data visualization Not exactly sure how this wound up in here too, but at some point I needed histograms and line plots that update live over time and show some info when you mouseover points, so here it is. ## Big problems to solve before release When you ask a `Composite` what action happened (what button was clicked), it hands you back `Option`. Not so typesafe. How boilerplatey is it to associate buttons with a user-provided enum? There are hardcoded colors / padding in lots of places. Need to make style easily configurable, with good defaults. The error handling is pretty bad; lots of unwraps and panics to clean up. ## Why another Rust GUI library? When I started, nothing did what I needed, or it required awkward callbacks. Today, [iced](https://github.com/hecrj/iced) looks awesome, but wgpu doesn't work on my laptop. This is a dealbreaker -- I want to build stuff that runs ~anywhere. I looked into adding an OpenGL backend, but the current structure of iced has a [huge](https://github.com/hecrj/iced/blob/master/native/src/renderer/null.rs) API surface to implement for a new backend. For the moment, I don't have enough time to get something else on-par with this library and port A/B Street over, so I'll continue to invest in this library. If there's lots of interest in other people using this library, I'll invest much more and make it a real contender. ## Naming I never wanted to call this "ezgui." :( - coldbrew (stronger than iced coffee? ;) and what generally powers me ) - allegro (where most pivotal meetings with my UX designer have happened, but this is also the name of some library) - coco (for the geom library) - abstgui (too obvious)