Group calling: tell RingRTC about our rendered resolutions for perf

ts/util/hooks.ts

@@ -44,3 +44,25 @@ export const useBoundActions = <T extends ActionCreatorsMapObject>(
     return bindActionCreators(actions, dispatch);
   }, [actions, dispatch]);
 };
+
+export const usePageVisibility = (): boolean => {
+  const [result, setResult] = React.useState(!document.hidden);
+
+  React.useEffect(() => {
+    const onVisibilityChange = () => {
+      setResult(!document.hidden);
+    };
+
+    document.addEventListener('visibilitychange', onVisibilityChange, false);
+
+    return () => {
+      document.removeEventListener(
+        'visibilitychange',
+        onVisibilityChange,
+        false
+      );
+    };
+  }, []);
+
+  return result;
+};

ts/util/lint/exceptions.json

@@ -14427,7 +14427,7 @@
     "rule": "React-useRef",
     "path": "ts/components/CallingPip.tsx",
     "line": "  const localVideoRef = React.useRef(null);",
-    "lineNumber": 78,
+    "lineNumber": 80,
     "reasonCategory": "usageTrusted",
     "updated": "2020-10-26T19:12:24.410Z",
     "reasonDetail": "Used to get the local video element for rendering."

ts/util/ringrtc/nonRenderedRemoteParticipant.ts

@@ -0,0 +1,12 @@
+// Copyright 2020 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
+import type { GroupCallVideoRequest } from '../../types/Calling';
+
+export const nonRenderedRemoteParticipant = ({
+  demuxId,
+}: Readonly<{ demuxId: number }>): GroupCallVideoRequest => ({
+  demuxId,
+  width: 0,
+  height: 0,
+});