mirror of
https://github.com/a-b-street/abstreet.git
synced 2024-12-23 06:12:12 +03:00
0133685eb7
as part of this, wound up grabbing fresh OSM and GTFS. but actually cant reimport OSM right now, because fixes reference old OSM IDs and things break. so sticking with old OSM, but new GTFS. urgh.
113 lines
4.2 KiB
Markdown
113 lines
4.2 KiB
Markdown
# ezgui notes
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This is a GUI + 2D drawing + data viz library I've built up for A/B Street. I'm
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considering cleaning up the API surface and making it a proper standalone crate.
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## Running the demo
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[Example code](examples/demo.rs)
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```
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git clone https://github.com/dabreegster/abstreet.git
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cd abstreet/ezgui
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cargo run --example demo
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```
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If you want a more thorough idea of what this crate can do, see
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[A/B Street](https://abstreet.org).
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## Features
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### Runs in lots of places
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Runs on Linux, Mac, Windows via [glium](https://github.com/glium/glium/). Also
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works in the browser using WebAssembly and
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[glow](https://github.com/grovesNL/glow/), but text support still coming in
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[a few months](https://github.com/RazrFalcon/resvg/issues/229).
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Why OpenGL? My requirements are super simple; I don't need the power of Vulkan
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or other new stuff. I want something simple that runs everywhere. If you want to
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make this work with WGPU or something else, it should be easy. The 3 backend
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implementations ([glium](src/backend_glium.rs),
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[glow on native](src/backend_glow.rs), [glow on wasm](src/backend_wasm.rs)) are
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each about 300 lines.
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### 2D drawing
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Everything is a colored polygon. Upload stuff once, redraw many times with a
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simple camera transform. Panning and smooth zooming. One extremely simple
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shader.
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Thanks to [usvg](https://github.com/RazrFalcon/resvg) and
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[lyon](https://github.com/nical/lyon/), SVGs and text are transformed into
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colored polygons. Programatically swap colors, rotate, scale stuff. Find bounds
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for precise mouseover.
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### GUI
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Widgets like buttons (with keybindings), checkboxes, sliders, pop-up menus, text
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entry, and some data viz things. You can combine these in `Composite`s to
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dispatch event handling and drawing. Styling (background colors, outline,
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padding) and Flexbox-ish layouting via
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[stretch](https://vislyhq.github.io/stretch/).
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The API / programming style is kind of funny; see the [demo](examples/demo.rs)
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to get a sense of it. No callbacks. You manually feed events into your
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`Composite`s of widgets and ask about what happened. There's no smart diffing of
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widget trees; most of the time it's fine to completely recreate a `Composite`
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from scratch when something changes, or replace a single widget in an existing
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`Composite`.
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(This is not a performance critical library. The perf bottlenecks in A/B Street
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are not in the GUI, and I probably won't invest much time speeding things up
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here until they are. (Or if somebody else winds up using this library and hits a
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problem.))
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### Data visualization
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Not exactly sure how this wound up in here too, but at some point I needed
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histograms and line plots that update live over time and show some info when you
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mouseover points, so here it is.
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## Big problems to solve before release
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When you ask a `Composite` what action happened (what button was clicked), it
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hands you back `Option<String>`. Not so typesafe. How boilerplatey is it to
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associate buttons with a user-provided enum?
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There are hardcoded colors / padding in lots of places. Need to make style
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easily configurable, with good defaults.
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The error handling is pretty bad; lots of unwraps and panics to clean up.
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## Why another Rust GUI library?
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When I started, nothing did what I needed, or it required awkward callbacks.
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Today, [iced](https://github.com/hecrj/iced) looks awesome, but wgpu doesn't
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work on my laptop. This is a dealbreaker -- I want to build stuff that runs
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~anywhere. I looked into adding an OpenGL backend, but the current structure of
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iced has a
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[huge](https://github.com/hecrj/iced/blob/master/native/src/renderer/null.rs)
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API surface to implement for a new backend.
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For the moment, I don't have enough time to get something else on-par with this
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library and port A/B Street over, so I'll continue to invest in this library. If
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there's lots of interest in other people using this library, I'll invest much
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more and make it a real contender.
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## Naming
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I never wanted to call this "ezgui." :(
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- coldbrew (stronger than iced coffee? ;) and what generally powers me )
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- allegro (where most pivotal meetings with my UX designer have happened, but
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this is also the name of some library)
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- coco (for the geom library)
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- abstgui (too obvious)
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## Future work
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- Draggable panels
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