1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146

use crate::errors::Error;
use crate::window::get_window;
use futures::channel::oneshot::{channel, Receiver, Sender};
use futures::task::{Context, Poll};
use futures::Future;
use log::info;
use std::pin::Pin;
use wasm_bindgen::prelude::*;
use wasm_bindgen::JsCast;
use web_sys::*;

pub struct Image {
    pub url: String,
    pub img: Option<HtmlImageElement>,
    state: ImageState,
    closure_holders: Option<(Closure<dyn FnMut()>, Closure<dyn FnMut(JsValue)>)>,
}

enum ImageState {
    Empty,
    Loading {
        receiver_err: Receiver<JsValue>,
        receiver_success: Receiver<()>,
    },
}

//See: https://github.com/rustwasm/wasm-bindgen/issues/1126
//
impl Future for Image {
    //impl Future for Image {
    type Output = Result<HtmlImageElement, Error>;

    fn poll(mut self: Pin<&mut Self>, ctx: &mut Context) -> Poll<Self::Output> {
        //fn poll(&mut self) -> Poll<Self::Item, Self::Error> {
        match &mut self.state {
            ImageState::Empty => {
                let img = HtmlImageElement::new()?;
                let has_same_origin = same_origin(&self.url)?;
                if !has_same_origin {
                    img.set_cross_origin(Some(&"anonymous"));
                }

                img.set_src(&self.url);

                //success callback
                let waker = ctx.waker().clone();
                let (sender_success, receiver_success): (Sender<()>, Receiver<()>) = channel();
                let mut sender_success = Option::from(sender_success);
                let closure_success = Closure::wrap(Box::new(move || {
                    sender_success.take().unwrap().send(()).unwrap();
                    waker.wake_by_ref();
                }) as Box<dyn FnMut()>);

                img.set_onload(Some(closure_success.as_ref().unchecked_ref()));

                //error callback
                let waker = ctx.waker().clone();
                let (sender_err, receiver_err): (Sender<JsValue>, Receiver<JsValue>) = channel();
                let mut sender_err = Option::from(sender_err);
                let closure_err = Closure::wrap(Box::new(move |err| {
                    sender_err.take().unwrap().send(err).unwrap();
                    waker.wake_by_ref();
                }) as Box<dyn FnMut(JsValue)>);

                //self.closure_err = Some(closure_err);
                img.set_onerror(Some(closure_err.as_ref().unchecked_ref()));

                //Assign stuff to myself
                self.img = Some(img);
                self.state = ImageState::Loading {
                    receiver_err,
                    receiver_success,
                };
                self.closure_holders = Some((closure_success, closure_err));

                //notify the task that we're now loading
                ctx.waker().wake_by_ref();

                Poll::Pending
            }

            ImageState::Loading {
                receiver_err,
                receiver_success,
            } => {
                //if let Poll::Ready(value) = Receiver::poll(Pin::new(receiver_err), ctx) {

                let mut is_cancelled = false;

                let error_state = match receiver_err.try_recv() {
                    Ok(result) => result,
                    _ => {
                        is_cancelled = true;
                        None
                    }
                };

                let success_state = match receiver_success.try_recv() {
                    Ok(result) => result,
                    _ => {
                        is_cancelled = true;
                        None
                    }
                };

                if let Some(result) = error_state {
                    Poll::Ready(Err(result.into()))
                } else if let Some(_) = success_state {
                    Poll::Ready(Ok(self.img.as_ref().unwrap().clone()))
                } else {
                    if !is_cancelled {
                        //ctx.waker().wake_by_ref();
                    }
                    Poll::Pending
                }
            }
        }
    }
}

impl Image {
    pub fn new(url: &str) -> Self {
        //can't seem to avoid this
        //but realistically, loading images is a slow and memory intensive operation
        //and urls are going to be on the smaller side too... so, no biggie
        let url = url.to_owned();

        Self {
            url,
            img: None,
            state: ImageState::Empty,
            closure_holders: None,
        }
    }
}

pub fn same_origin(url: &str) -> Result<bool, JsValue> {
    //FOLLOWUP: https://github.com/rustwasm/wasm-bindgen/issues/1150
    if url.starts_with("http://") || url.starts_with("https://") {
        let location_origin = get_window()?.location().origin()?;
        let url_origin = Url::new(url)?.origin();
        Ok(url_origin == location_origin)
    } else {
        Ok(true)
    }
}