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use wasm_bindgen::prelude::*; |
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use wasm_bindgen::JsCast; |
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use web_sys::{window, HtmlInputElement, HtmlElement}; |
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use console_error_panic_hook; |
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use std::cell::RefCell; |
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// ---------------------- |
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// PART 1: Shared State |
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// ---------------------- |
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struct SharedState { |
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data: Vec<f32>, |
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} |
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impl SharedState { |
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fn new(len: usize) -> Self { |
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Self { |
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data: vec![0.0; len], |
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} |
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} |
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fn set_value(&mut self, index: usize, val: f32) { |
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self.data[index] = val; |
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} |
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fn get_value(&self, index: usize) -> f32 { |
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self.data[index] |
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} |
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} |
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// A single-thread “thread-local” global. Each thread would have its own instance. |
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// For most Wasm setups, there's only one thread anyway. |
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thread_local! { |
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static SHARED_STATE: RefCell<SharedState> = RefCell::new(SharedState::new(10)); |
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} |
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// Helpers to modify/read the state. Use `SHARED_STATE.with(...)`. |
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fn set_shared_value(index: usize, val: f32) { |
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SHARED_STATE.with(|cell| { |
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cell.borrow_mut().set_value(index, val); |
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}); |
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} |
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fn get_shared_value(index: usize) -> f32 { |
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SHARED_STATE.with(|cell| cell.borrow().get_value(index)) |
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} |
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// ---------------------- |
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// PART 2: Startup Code |
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// ---------------------- |
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#[wasm_bindgen(start)] |
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pub fn main_js() -> Result<(), JsValue> { |
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console_error_panic_hook::set_once(); |
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// Let's store an initial value to prove it's working |
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set_shared_value(0, 50.0); |
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// 1) Grab document & body |
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let document = window() |
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.and_then(|win| win.document()) |
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.ok_or("failed to get document")?; |
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let output_div = document |
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.get_element_by_id("output") |
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.ok_or("no #output element")? |
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.dyn_into::<HtmlElement>()?; |
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// 2) Grab the slider |
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let slider = document |
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.get_element_by_id("slider") |
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.ok_or("no #slider element")? |
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.dyn_into::<HtmlInputElement>()?; |
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// Clone them for the closure |
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let slider_clone = slider.clone(); |
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let output_div_clone = output_div.clone(); |
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// 3) Create a closure that updates the shared array and the DOM |
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let closure = Closure::wrap(Box::new(move || { |
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let val = slider_clone.value().parse::<f32>().unwrap_or(0.0); |
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set_shared_value(0, val); |
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let stored = get_shared_value(0); |
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output_div_clone.set_inner_text(&format!("Stored value is: {:.2}", stored)); |
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}) as Box<dyn FnMut()>); |
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// 4) Attach the closure as input event listener |
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slider.add_event_listener_with_callback("input", closure.as_ref().unchecked_ref())?; |
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// keep closure alive |
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closure.forget(); |
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// 5) Run it once at startup |
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slider.dispatch_event(&web_sys::Event::new("input")?)?; |
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Ok(()) |
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} |
