softbuffer/src/web.rs
2023-01-14 05:48:44 +00:00

96 lines
3.1 KiB
Rust

use raw_window_handle::WebWindowHandle;
use wasm_bindgen::Clamped;
use wasm_bindgen::JsCast;
use web_sys::CanvasRenderingContext2d;
use web_sys::HtmlCanvasElement;
use web_sys::ImageData;
use crate::SoftBufferError;
/// Display implementation for the web platform.
///
/// This just caches the document to prevent having to query it every time.
pub struct WebDisplayImpl {
document: web_sys::Document,
}
impl WebDisplayImpl {
pub(super) fn new() -> Result<Self, SoftBufferError> {
let document = web_sys::window()
.ok_or_else(|| {
SoftBufferError::PlatformError(
Some("`window` is not present in this runtime".into()),
None,
)
})?
.document()
.ok_or_else(|| {
SoftBufferError::PlatformError(
Some("`document` is not present in this runtime".into()),
None,
)
})?;
Ok(Self { document })
}
}
pub struct WebImpl {
canvas: HtmlCanvasElement,
ctx: CanvasRenderingContext2d,
}
impl WebImpl {
pub fn new(display: &WebDisplayImpl, handle: WebWindowHandle) -> Result<Self, SoftBufferError> {
let canvas: HtmlCanvasElement = display
.document
.query_selector(&format!("canvas[data-raw-handle=\"{}\"]", handle.id))
// `querySelector` only throws an error if the selector is invalid.
.unwrap()
.ok_or_else(|| {
SoftBufferError::PlatformError(
Some("No canvas found with the given id".into()),
None,
)
})?
// We already made sure this was a canvas in `querySelector`.
.unchecked_into();
let ctx = canvas
.get_context("2d")
.map_err(|_| {
SoftBufferError::PlatformError(
Some("Canvas already controlled using `OffscreenCanvas`".into()),
None,
)
})?
.ok_or_else(|| {
SoftBufferError::PlatformError(
Some("A canvas context other than `CanvasRenderingContext2d` was already created".into()),
None,
)
})?
.dyn_into()
.expect("`getContext(\"2d\") didn't return a `CanvasRenderingContext2d`");
Ok(Self { canvas, ctx })
}
pub(crate) unsafe fn set_buffer(&mut self, buffer: &[u32], width: u16, height: u16) {
self.canvas.set_width(width.into());
self.canvas.set_height(height.into());
let bitmap: Vec<_> = buffer
.iter()
.copied()
.flat_map(|pixel| [(pixel >> 16) as u8, (pixel >> 8) as u8, pixel as u8, 255])
.collect();
// This should only throw an error if the buffer we pass's size is incorrect, which is checked in the outer `set_buffer` call.
let image_data =
ImageData::new_with_u8_clamped_array(Clamped(&bitmap), width.into()).unwrap();
// This can only throw an error if `data` is detached, which is impossible.
self.ctx.put_image_data(&image_data, 0.0, 0.0).unwrap();
}
}