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#![cfg(target_arch = "wasm32")]
use std::cell::RefCell;
use compositor::{Compositor, FrameDescriptor, RenderFrameOptions};
use gpu::wgpu;
use js_sys::Object;
use wasm_bindgen::{JsCast, JsValue, prelude::wasm_bindgen};
use crate::gpu::{
import_canvas_texture, read_offscreen_canvas_property, read_serde_property, read_u32_property,
with_gpu_runtime,
};
use crate::perf;
struct CompositorRuntime {
canvas: web_sys::HtmlCanvasElement,
compositor: Compositor,
}
thread_local! {
static COMPOSITOR_RUNTIME: RefCell<Option<CompositorRuntime>> = const { RefCell::new(None) };
}
#[wasm_bindgen(js_name = initCompositor)]
pub fn init_compositor(width: u32, height: u32) -> Result<(), JsValue> {
with_gpu_runtime(|gpu_runtime| {
// On WebGL, wgpu is bound to a specific canvas; reuse it so the UI
// can mount the output directly instead of copying pixels through
// an intermediate 2D canvas every frame. On WebGPU, surface rendering
// works against any canvas so we create a fresh one.
let canvas = if let Some(gl_canvas) = gpu_runtime.context.gl_canvas() {
gl_canvas.clone()
} else {
let document = web_sys::window()
.and_then(|window| window.document())
.ok_or_else(|| JsValue::from_str("Document is not available"))?;
document
.create_element("canvas")?
.dyn_into::<web_sys::HtmlCanvasElement>()
.map_err(|_| JsValue::from_str("Failed to create compositor canvas"))?
};
canvas.set_width(width);
canvas.set_height(height);
let compositor = Compositor::new(&gpu_runtime.context);
COMPOSITOR_RUNTIME.with(|runtime| {
runtime.replace(Some(CompositorRuntime { canvas, compositor }));
});
Ok(())
})
}
#[wasm_bindgen(js_name = resizeCompositor)]
pub fn resize_compositor(width: u32, height: u32) -> Result<(), JsValue> {
COMPOSITOR_RUNTIME.with(|runtime| {
let mut borrow = runtime.borrow_mut();
let Some(runtime) = borrow.as_mut() else {
return Err(JsValue::from_str(
"Compositor is not initialized. Call initCompositor() first.",
));
};
runtime.canvas.set_width(width);
runtime.canvas.set_height(height);
Ok(())
})
}
#[wasm_bindgen(js_name = getCompositorCanvas)]
pub fn get_compositor_canvas() -> Result<web_sys::HtmlCanvasElement, JsValue> {
COMPOSITOR_RUNTIME.with(|runtime| {
let borrow = runtime.borrow();
let Some(runtime) = borrow.as_ref() else {
return Err(JsValue::from_str(
"Compositor is not initialized. Call initCompositor() first.",
));
};
Ok(runtime.canvas.clone())
})
}
#[wasm_bindgen(js_name = uploadTexture)]
pub fn upload_texture(options: JsValue) -> Result<(), JsValue> {
let UploadTextureOptions {
id,
source,
width,
height,
} = parse_upload_texture_options(options)?;
with_gpu_runtime(|gpu_runtime| {
COMPOSITOR_RUNTIME.with(|runtime| {
let mut borrow = runtime.borrow_mut();
let Some(runtime) = borrow.as_mut() else {
return Err(JsValue::from_str(
"Compositor is not initialized. Call initCompositor() first.",
));
};
let texture = import_canvas_texture(
&gpu_runtime.context,
&source,
width,
height,
"compositor-upload-texture",
);
runtime.compositor.upsert_texture(id, texture);
Ok(())
})
})
}
#[wasm_bindgen(js_name = releaseTexture)]
pub fn release_texture(id: String) -> Result<(), JsValue> {
COMPOSITOR_RUNTIME.with(|runtime| {
let mut borrow = runtime.borrow_mut();
let Some(runtime) = borrow.as_mut() else {
return Err(JsValue::from_str(
"Compositor is not initialized. Call initCompositor() first.",
));
};
runtime.compositor.release_texture(&id);
Ok(())
})
}
#[wasm_bindgen(js_name = renderFrame)]
pub fn render_frame(options: JsValue) -> Result<(), JsValue> {
perf::reset();
let t_deserialize = perf::now_ms();
let frame: FrameDescriptor = serde_wasm_bindgen::from_value(options)
.map_err(|error| JsValue::from_str(&format!("Invalid frame descriptor: {error}")))?;
perf::record("wasm.deserialize", perf::now_ms() - t_deserialize);
with_gpu_runtime(|gpu_runtime| {
COMPOSITOR_RUNTIME.with(|runtime| {
let mut borrow = runtime.borrow_mut();
let Some(runtime) = borrow.as_mut() else {
return Err(JsValue::from_str(
"Compositor is not initialized. Call initCompositor() first.",
));
};
if gpu_runtime.context.supports_surface_rendering() {
let t_surface = perf::now_ms();
let surface = gpu_runtime
.context
.instance()
.create_surface(wgpu::SurfaceTarget::Canvas(runtime.canvas.clone()))
.map_err(|error| JsValue::from_str(&error.to_string()))?;
perf::record("wasm.surfaceCreate", perf::now_ms() - t_surface);
let t_render = perf::now_ms();
let result = runtime
.compositor
.render_frame(
&gpu_runtime.context,
RenderFrameOptions {
frame: &frame,
surface: &surface,
},
)
.map_err(|error| JsValue::from_str(&error.to_string()));
perf::record("wasm.renderFrameToSurface", perf::now_ms() - t_render);
result
} else {
// WebGL surface-renders to the canvas its GL context was created
// on; `init_compositor` already pointed `runtime.canvas` at that
// same canvas, so presenting writes directly to the canvas the
// UI mounts. No intermediate copy.
let t_composite = perf::now_ms();
let texture = runtime
.compositor
.render_frame_to_texture(&gpu_runtime.context, &frame)
.map_err(|error| JsValue::from_str(&error.to_string()))?;
perf::record("wasm.compositeToTexture", perf::now_ms() - t_composite);
let t_present = perf::now_ms();
gpu_runtime
.context
.render_texture_to_gl_canvas_surface(&texture, frame.width, frame.height)
.map_err(|error| JsValue::from_str(&error.to_string()))?;
perf::record("wasm.presentToGlCanvas", perf::now_ms() - t_present);
Ok(())
}
})
})
}
#[derive(Debug)]
struct UploadTextureOptions {
id: String,
source: wgpu::web_sys::OffscreenCanvas,
width: u32,
height: u32,
}
fn parse_upload_texture_options(value: JsValue) -> Result<UploadTextureOptions, JsValue> {
let object: Object = value
.dyn_into()
.map_err(|_| JsValue::from_str("uploadTexture expects an options object"))?;
Ok(UploadTextureOptions {
id: read_serde_property(&object, "id")?,
source: read_offscreen_canvas_property(&object, "source")?,
width: read_u32_property(&object, "width")?,
height: read_u32_property(&object, "height")?,
})
}
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