Extract canvas operations for reuse by OffscreenCanvas.

components/script/dom/dedicatedworkerglobalscope.rs

@@ -38,6 +38,7 @@ use js::jsapi::{JSAutoRealm, JSContext};
 use js::jsval::UndefinedValue;
 use js::rust::HandleValue;
 use msg::constellation_msg::{PipelineId, TopLevelBrowsingContextId};
+use net_traits::image_cache::ImageCache;
 use net_traits::request::{CredentialsMode, Destination, ParserMetadata};
 use net_traits::request::{Referrer, RequestBuilder, RequestMode};
 use net_traits::IpcSend;
@@ -174,6 +175,8 @@ pub struct DedicatedWorkerGlobalScope {
     #[ignore_malloc_size_of = "Can't measure trait objects"]
     /// Sender to the parent thread.
     parent_sender: Box<ScriptChan + Send>,
+    #[ignore_malloc_size_of = "Arc"]
+    image_cache: Arc<ImageCache>,
 }
 
 impl WorkerEventLoopMethods for DedicatedWorkerGlobalScope {
@@ -225,6 +228,7 @@ impl DedicatedWorkerGlobalScope {
         timer_event_chan: IpcSender<TimerEvent>,
         timer_event_port: Receiver<(TrustedWorkerAddress, TimerEvent)>,
         closing: Arc<AtomicBool>,
+        image_cache: Arc<dyn ImageCache>,
     ) -> DedicatedWorkerGlobalScope {
         DedicatedWorkerGlobalScope {
             workerglobalscope: WorkerGlobalScope::new_inherited(
@@ -242,6 +246,7 @@ impl DedicatedWorkerGlobalScope {
             timer_event_port: timer_event_port,
             parent_sender: parent_sender,
             worker: DomRefCell::new(None),
+            image_cache: image_cache,
         }
     }
 
@@ -259,6 +264,7 @@ impl DedicatedWorkerGlobalScope {
         timer_event_chan: IpcSender<TimerEvent>,
         timer_event_port: Receiver<(TrustedWorkerAddress, TimerEvent)>,
         closing: Arc<AtomicBool>,
+        image_cache: Arc<dyn ImageCache>,
     ) -> DomRoot<DedicatedWorkerGlobalScope> {
         let cx = runtime.cx();
         let scope = Box::new(DedicatedWorkerGlobalScope::new_inherited(
@@ -274,6 +280,7 @@ impl DedicatedWorkerGlobalScope {
             timer_event_chan,
             timer_event_port,
             closing,
+            image_cache,
         ));
         unsafe { DedicatedWorkerGlobalScopeBinding::Wrap(cx, scope) }
     }
@@ -292,6 +299,7 @@ impl DedicatedWorkerGlobalScope {
         worker_name: String,
         worker_type: WorkerType,
         closing: Arc<AtomicBool>,
+        image_cache: Arc<dyn ImageCache>,
     ) {
         let serialized_worker_url = worker_url.to_string();
         let name = format!("WebWorker for {}", serialized_worker_url);
@@ -363,6 +371,7 @@ impl DedicatedWorkerGlobalScope {
                     timer_ipc_chan,
                     timer_rx,
                     closing,
+                    image_cache,
                 );
                 // FIXME(njn): workers currently don't have a unique ID suitable for using in reporter
                 // registration (#6631), so we instead use a random number and cross our fingers.
@@ -428,6 +437,10 @@ impl DedicatedWorkerGlobalScope {
             .expect("Thread spawning failed");
     }
 
+    pub fn image_cache(&self) -> Arc<dyn ImageCache> {
+        self.image_cache.clone()
+    }
+
     pub fn script_chan(&self) -> Box<dyn ScriptChan + Send> {
         Box::new(WorkerThreadWorkerChan {
             sender: self.own_sender.clone(),

components/script/dom/globalscope.rs

@@ -20,6 +20,7 @@ use crate::dom::errorevent::ErrorEvent;
 use crate::dom::event::{Event, EventBubbles, EventCancelable, EventStatus};
 use crate::dom::eventsource::EventSource;
 use crate::dom::eventtarget::EventTarget;
+use crate::dom::paintworkletglobalscope::PaintWorkletGlobalScope;
 use crate::dom::performance::Performance;
 use crate::dom::window::Window;
 use crate::dom::workerglobalscope::WorkerGlobalScope;
@@ -51,6 +52,7 @@ use js::rust::{get_object_class, CompileOptionsWrapper, ParentRuntime, Runtime};
 use js::rust::{HandleValue, MutableHandleValue};
 use js::{JSCLASS_IS_DOMJSCLASS, JSCLASS_IS_GLOBAL};
 use msg::constellation_msg::PipelineId;
+use net_traits::image_cache::ImageCache;
 use net_traits::{CoreResourceThread, IpcSend, ResourceThreads};
 use profile_traits::{mem as profile_mem, time as profile_time};
 use script_traits::{MsDuration, ScriptToConstellationChan, TimerEvent};
@@ -376,6 +378,19 @@ impl GlobalScope {
         &self.origin
     }
 
+    pub fn image_cache(&self) -> Arc<dyn ImageCache> {
+        if let Some(window) = self.downcast::<Window>() {
+            return window.image_cache();
+        }
+        if let Some(worker) = self.downcast::<DedicatedWorkerGlobalScope>() {
+            return worker.image_cache();
+        }
+        if let Some(worker) = self.downcast::<PaintWorkletGlobalScope>() {
+            return worker.image_cache();
+        }
+        unreachable!();
+    }
+
     /// Get the [base url](https://html.spec.whatwg.org/multipage/#api-base-url)
     /// for this global scope.
     pub fn api_base_url(&self) -> ServoUrl {

components/script/dom/offscreencanvas.rs

@@ -93,7 +93,12 @@ impl OffscreenCanvas {
             };
         }
         let size = self.get_size();
-        let context = OffscreenCanvasRenderingContext2D::new(&self.global(), self, size);
+        let context = OffscreenCanvasRenderingContext2D::new(
+            &self.global(),
+            self,
+            size,
+            self.placeholder.as_ref().map(|c| &**c),
+        );
         *self.context.borrow_mut() = Some(OffscreenCanvasContext::OffscreenContext2d(
             Dom::from_ref(&*context),
         ));