1 files changed, 53 insertions, 0 deletions
diff --git a/components/script/image_listener.rs b/components/script/image_listener.rs
new file mode 100644
index 00000000000..7bf81c80d76
--- /dev/null
+++ b/components/script/image_listener.rs
@@ -0,0 +1,53 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+use crate::dom::bindings::conversions::DerivedFrom;
+use crate::dom::bindings::refcounted::Trusted;
+use crate::dom::bindings::reflector::DomObject;
+use crate::dom::node::{window_from_node, Node};
+use crate::task_source::TaskSource;
+use ipc_channel::ipc;
+use ipc_channel::ipc::IpcSender;
+use ipc_channel::router::ROUTER;
+use net_traits::image_cache::{ImageResponse, PendingImageResponse};
+
+pub trait ImageCacheListener {
+    fn generation_id(&self) -> u32;
+    fn process_image_response(&self, response: ImageResponse);
+}
+
+pub fn generate_cache_listener_for_element<
+    T: ImageCacheListener + DerivedFrom<Node> + DomObject,
+>(
+    elem: &T,
+) -> IpcSender<PendingImageResponse> {
+    let trusted_node = Trusted::new(elem);
+    let (responder_sender, responder_receiver) = ipc::channel().unwrap();
+
+    let window = window_from_node(elem);
+    let (task_source, canceller) = window
+        .task_manager()
+        .networking_task_source_with_canceller();
+    let generation = elem.generation_id();
+    ROUTER.add_route(
+        responder_receiver.to_opaque(),
+        Box::new(move |message| {
+            let element = trusted_node.clone();
+            let image = message.to().unwrap();
+            debug!("Got image {:?}", image);
+            let _ = task_source.queue_with_canceller(
+                task!(process_image_response: move || {
+                    let element = element.root();
+                    // Ignore any image response for a previous request that has been discarded.
+                    if generation == element.generation_id() {
+                        element.process_image_response(image);
+                    }
+                }),
+                &canceller,
+            );
+        }),
+    );
+
+    responder_sender
+}