1 files changed, 47 insertions, 0 deletions
diff --git a/browser/components/screenshots/ScreenshotsHelperChild.sys.mjs b/browser/components/screenshots/ScreenshotsHelperChild.sys.mjs
new file mode 100644
index 0000000000..550c3fb13c
--- /dev/null
+++ b/browser/components/screenshots/ScreenshotsHelperChild.sys.mjs
@@ -0,0 +1,47 @@
+/* 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/. */
+
+import {
+  getBestRectForElement,
+  getElementFromPoint,
+} from "chrome://browser/content/screenshots/overlayHelpers.mjs";
+
+/**
+ * This class is used to get the dimensions of hovered elements within iframes.
+ * The main content process cannot get the dimensions of elements within
+ * iframes so a message will be send to this actor to get the dimensions of the
+ * element for a given point inside the iframe.
+ */
+export class ScreenshotsHelperChild extends JSWindowActorChild {
+  receiveMessage(message) {
+    if (message.name === "ScreenshotsHelper:GetElementRectFromPoint") {
+      return this.getBestElementRectFromPoint(message.data);
+    }
+    return null;
+  }
+
+  async getBestElementRectFromPoint(data) {
+    let { x, y } = data;
+
+    x -= this.contentWindow.mozInnerScreenX;
+    y -= this.contentWindow.mozInnerScreenY;
+
+    let { ele, rect } = await getElementFromPoint(x, y, this.document);
+
+    if (!rect) {
+      rect = getBestRectForElement(ele, this.document);
+    }
+
+    if (rect) {
+      rect = {
+        left: rect.left + this.contentWindow.mozInnerScreenX,
+        right: rect.right + this.contentWindow.mozInnerScreenX,
+        top: rect.top + this.contentWindow.mozInnerScreenY,
+        bottom: rect.bottom + this.contentWindow.mozInnerScreenY,
+      };
+    }
+
+    return rect;
+  }
+}