tor-browser

commit cb0e9ab3be4e5d8310155a978463a59f8c49493b
parent 39952d088a8c1a636a93469db97c52d4cdb1eeda
Author: Emilio Cobos Álvarez <emilio@crisal.io>
Date:   Wed,  1 Oct 2025 14:49:18 +0000

Bug 1991410 - Don't apply intersection root rect clip to targets inside popups. r=tnikkel,layout-reviewers

Since they don't get clipped by the viewport.

Differential Revision: https://phabricator.services.mozilla.com/D266983

Diffstat:
M
dom/base/DOMIntersectionObserver.cpp
 | 
7
++++---
M
toolkit/content/tests/chrome/window_largemenu.xhtml
 | 
32
+++++++++++++++++++++++++++++++-

2 files changed, 35 insertions(+), 4 deletions(-)
diff --git a/dom/base/DOMIntersectionObserver.cpp b/dom/base/DOMIntersectionObserver.cpp
@@ -556,9 +556,10 @@ static Maybe<nsRect> ComputeTheIntersection(
 
     intersectionRect = intersectionRectRelativeToRoot.EdgeInclusiveIntersection(
         *aRemoteDocumentVisibleRect);
-    if (intersectionRect.isNothing()) {
-      return Nothing();
-    }
+  } else if (aTarget->HasAnyStateBits(NS_FRAME_IN_POPUP)) {
+    // Popups don't get clipped to the viewport, so avoid applying the root
+    // intersection rect, see bug 1991410.
+    intersectionRect = Some(intersectionRectRelativeToRoot);
   } else {
     intersectionRect =
         intersectionRectRelativeToRoot.EdgeInclusiveIntersection(aRootBounds);
diff --git a/toolkit/content/tests/chrome/window_largemenu.xhtml b/toolkit/content/tests/chrome/window_largemenu.xhtml
@@ -93,13 +93,41 @@ async function nextTest()
   popup.openPopupAtScreen(100, y, false);
 }
 
+async function assertItemsOcclusionState(popup) {
+  info("Checking intersection state");
+  let items = popup.querySelectorAll("menuitem");
+  isnot(items.length, 0, "Should have items");
+  let {promise, resolve} = Promise.withResolvers();
+  let io = new IntersectionObserver(function(entries) {
+    resolve(entries)
+  });
+  for (let item of items) {
+    io.observe(item);
+  }
+  let entries = await promise;
+  io.disconnect();
+  is(entries.length, items.length, "Should have an entry per element");
+
+  let scrollbox = popup.scrollBox.scrollbox;
+  let scrollBoxRect = scrollbox.getBoundingClientRect();
+  let borderTop = parseFloat(getComputedStyle(scrollbox).borderTop);
+  let borderBottom = parseFloat(getComputedStyle(scrollbox).borderBottom);
+
+  for (let entry of entries) {
+    let itemRect = entry.boundingClientRect;
+    // Importantly, we don't consider the page's viewport.
+    let shouldIntersect = itemRect.bottom >= scrollBoxRect.top + borderTop && itemRect.top <= scrollBoxRect.bottom - borderBottom;
+    is(entry.isIntersecting, shouldIntersect, `${entry.target.outerHTML} intersection state matches`);
+  }
+}
+
 async function popupShown() {
   // This is needed for overflow events to run.
   await nextFrame();
   startTest();
 }
 
-function startTest()
+async function startTest()
 {
   if (gTests[gTestIndex] == "menu movement")
     return testPopupMovement();
@@ -114,6 +142,8 @@ function startTest()
   var scrollbox = popup.scrollBox.scrollbox;
   var expectedScrollPos = 0;
 
+  await assertItemsOcclusionState(popup);
+
   info(`${gTests[gTestIndex]}: ${JSON.stringify(rect)} | ${screen.width}x${screen.height} | ${gScreenY}`);
   if (gTestIndex == 0) {
     // the popup should be in the center of the screen