1 files changed, 57 insertions, 0 deletions
diff --git a/devtools/client/shared/components/VisibilityHandler.js b/devtools/client/shared/components/VisibilityHandler.js
new file mode 100644
index 0000000000..be1f3c5f93
--- /dev/null
+++ b/devtools/client/shared/components/VisibilityHandler.js
@@ -0,0 +1,57 @@
+/* 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 http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+/**
+ * Helper class to disable panel rendering when it is in background.
+ *
+ * Toolbox code hides the iframes when switching to another panel
+ * and triggers `visibilitychange` events.
+ *
+ * See devtools/client/framework/toolbox.js:setIframeVisible().
+ */
+
+const {
+  Component,
+} = require("resource://devtools/client/shared/vendor/react.js");
+const PropTypes = require("resource://devtools/client/shared/vendor/react-prop-types.js");
+
+class VisibilityHandler extends Component {
+  static get propTypes() {
+    return {
+      children: PropTypes.element.isRequired,
+    };
+  }
+
+  constructor(props) {
+    super(props);
+
+    this.onVisibilityChange = this.onVisibilityChange.bind(this);
+  }
+
+  componentDidMount() {
+    document.addEventListener("visibilitychange", this.onVisibilityChange);
+  }
+
+  shouldComponentUpdate() {
+    return document.visibilityState == "visible";
+  }
+
+  componentWillUnmount() {
+    document.removeEventListener("visibilitychange", this.onVisibilityChange);
+  }
+
+  onVisibilityChange() {
+    if (document.visibilityState == "visible") {
+      this.forceUpdate();
+    }
+  }
+
+  render() {
+    return this.props.children;
+  }
+}
+
+module.exports = VisibilityHandler;