You should store imageData inside a JS pointer, like so (assuming ImageData
is also a #[dom_struct])
#[dom_struct]
pub struct ImageRequest {
reflector_: Reflector,
state : ImageState,
currentUrl : URL,
imageData : JS<ImageData>,
}
See XMLHttpRequest::Upload
<https://github.com/servo/servo/blob/2dab0e15845f3ae625ca4b89facd62c2f2adb8b3/components/script/dom/xmlhttprequest.rs#L464>
for an example of this pattern being used in a getter. You can do the same
with the `url` attribute; however in this case it might be preferable to
store a parsed URL (url::Url <http://doc.servo.org/url/struct.Url.html>),
instead of a Javascript URL object (dom::url::URL
<http://doc.servo.org/script/dom/url/struct.URL.html>). You can use
URL::new_inherited() to create a JS URL from a regular one.
The reason it expects Root is because these are Javascript objects, and the
DOM structs are just the "Rust side of things"). Root/JS wraps around the
struct and includes things like how it interacts with the JS garbage
collector.
The only time you should be returning a non-Root type is if it's a
primitive, string, or a webidl-defined enum (e.g. WebSocket::BinaryType
<https://github.com/servo/servo/blob/2dab0e15845f3ae625ca4b89facd62c2f2adb8b3/components/script/dom/websocket.rs#L374>,
defined here
<https://github.com/servo/servo/blob/2dab0e15845f3ae625ca4b89facd62c2f2adb8b3/components/script/dom/webidls/WebSocket.webidl#L7>
).
Looking at your PR, you'll also need to add the webidl file (as well as a
dom module) for ImageData
<https://html.spec.whatwg.org/multipage/scripting.html#imagedata>.
Do you have a link to the spec for ImageRequest? I couldn't find it after
some quick searching.
Let me know if you need more help!
Thanks,
-Manish Goregaokar
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