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-rw-r--r--devtools/server/actors/resources/reflow.js63
1 files changed, 63 insertions, 0 deletions
diff --git a/devtools/server/actors/resources/reflow.js b/devtools/server/actors/resources/reflow.js
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+++ b/devtools/server/actors/resources/reflow.js
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+/* 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";
+
+const {
+ TYPES: { REFLOW },
+} = require("resource://devtools/server/actors/resources/index.js");
+const Targets = require("resource://devtools/server/actors/targets/index.js");
+
+const {
+ getLayoutChangesObserver,
+ releaseLayoutChangesObserver,
+} = require("resource://devtools/server/actors/reflow.js");
+
+class ReflowWatcher {
+ /**
+ * Start watching for reflows related to a given Target Actor.
+ *
+ * @param TargetActor targetActor
+ * The target actor from which we should observe reflows
+ * @param Object options
+ * Dictionary object with following attributes:
+ * - onAvailable: mandatory function
+ * This will be called for each resource.
+ */
+ async watch(targetActor, { onAvailable }) {
+ // Only track reflow for non-ParentProcess FRAME targets
+ if (
+ targetActor.targetType !== Targets.TYPES.FRAME ||
+ targetActor.typeName === "parentProcessTarget"
+ ) {
+ return;
+ }
+
+ this._targetActor = targetActor;
+
+ const onReflows = reflows => {
+ onAvailable([
+ {
+ resourceType: REFLOW,
+ reflows,
+ },
+ ]);
+ };
+
+ this._observer = getLayoutChangesObserver(targetActor);
+ this._offReflows = this._observer.on("reflows", onReflows);
+ this._observer.start();
+ }
+
+ destroy() {
+ releaseLayoutChangesObserver(this._targetActor);
+
+ if (this._offReflows) {
+ this._offReflows();
+ this._offReflows = null;
+ }
+ }
+}
+
+module.exports = ReflowWatcher;