Add an example of custom icon with Markers

[yukinarit]

Add an example of custom icon with Markers

[yukinarit]

Hi @shimatar0!
Oh, It seems my prior implementation for MarkerOptions is pretty much incomplete! This issue shouldn't have "good first issue" label 😂

Can you please try if this implementation works?

impl MarkerOptions {
   pub fn build(mut self) -> JsValue {
       let obj: js_sys::Object = serde_wasm_bindgen::to_value(&self).unwrap().into();
       if let Some(element) = self.element.take() {
           js_sys::Object::define_property(&obj, &JsValue::from_str("element"), &*element).into()
       } else {
           obj.into()
       }
    }
}

[yukinarit]

Yes, element needs to have #[serde(skip)], because it's not serializable. My implementation serializes MarkerOptions without element into JsValue first. Then it appends element property of HtmlElement into the JsValue. Hope this will work.

[shimatar0]

@yukinarit
Sorry. It took me a while to check😂
I understand, but there still seemed to be a problem, so I put out a PR for WIP and commented!

[shimatar0]

@yukinarit
Hi! In addressing this issue, found some concerns.
Perhaps this requires creating an HttpElement to customize the MakerOption structure,
but the HttpElement is likely to skip serialization.
https://github.com/yukinarit/mapbox-gl-rs/blob/main/src/marker.rs#L15-L16

I think that HttpElement may be a bit difficult to deal with as it does not seem to have a serialize/deserialize trait🤔
I can't really think of a better idea😂

[shimatar0]

@yukinarit
Thanks!
I feel that this would allow the structure members themselves to be serialized when passing through the build method.

However, I think the following structure definitions may be the bottleneck.(HtmlElement)
e.g.
MarkerOptions
https://github.com/yukinarit/mapbox-gl-rs/blob/main/src/marker.rs#L15-L16

    ...
    // todo keep serialization from skipping.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub element: Option<web_sys::HtmlElement>,
    ...

Is this error likely?

the trait bound `HtmlElement: Serialize` is not satisfied
the following other types implement trait `Serialize`:

[yukinarit]

Done in #42