Window::create_image_bitmap_with_canvas_rendering_context_2d throws error

[JohnScience]

Describe the Bug

I wanted to conveniently create an ImageBitmap from CanvasRenderingContext2d. When I found Window::create_image_bitmap_with_canvas_rendering_context_2d, I expected that it's a convenience method for doing so.

However, when I used it, I received the following error:

TypeError: Failed to execute 'createImageBitmap' on 'Window': The provided value is not of type '(Blob or HTMLCanvasElement or HTMLImageElement or HTMLVideoElement or ImageBitmap or ImageData or OffscreenCanvas or SVGImageElement or VideoFrame)'.

Steps to Reproduce

async fn update_buf_dims_gracefully(
    canvas: &HtmlCanvasElement,
    ctx: &CanvasRenderingContext2d,
    window: &Window,
) {
    let client_width= canvas.client_width();
    let client_height = canvas.client_height();

    let image_bitmap: JsFuture = window.
        create_image_bitmap_with_canvas_rendering_context_2d(ctx)
        .unwrap()
        .into();

    let image_bitmap = image_bitmap.await;
    match image_bitmap {
        Ok(image_bitmap) => { log(&image_bitmap) },
        Err(err) => { log(&err) }
    }

    canvas.set_width(client_width as u32);
    canvas.set_height(client_height as u32);
}

The code above is an incomplete implementation of a function relying on Window::create_image_bitmap_with_canvas_rendering_context_2d.

Expected Behavior

Window::create_image_bitmap_with_canvas_rendering_context_2d should either be removed or be functional

Actual Behavior

Results in an error.

Additional Context

No additional context.

[jneem]

My reading of this is that ImageBitmapSource should be defined as CanvasImageSource or Blob or ImageData, and then inlining the definition of CanvasImageSource gives the HTMLXXElements, ImageBitmap, VideoFrame, and OffscreenCanvas. The BufferSource variant seems to come from here, but I can't find any source for the CanvasRenderingContext2d variant.

[Liamolucko]

Yeah, that shouldn't be there. It's there because wasm-bindgen's WebIDL was initially taken from Firefox, which for whatever reason non-standardly supports passing CanvasRenderingContext2D to createImageBitmap.

The BufferSource variant is also broken, since the overload it's supposed to be a part of has a completely different signature to the regular createImageBitmap:

Promise<ImageBitmap> createImageBitmap (BufferSource buffer, long offset, long length, ImageFormat format, ImagePixelLayout layout);

It doesn't seem like that standard ever really went anywhere, either (the repo is archived).

So, I think they should both be removed. That is of course a breaking change, but I think it makes sense to do since any attempt to use them wouldn't work anyway (cc @alexcrichton).