[LayoutNG] Hit test floats in the same pseudo-stacking context.

We gave up when entering a new formatting context. But we should only stop when entering a child that's painted atomically. Bug: 1043787 Change-Id: I83bd88237311aa7edde00e5a3814a555cd56f112 Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2044210Reviewed-by: Ian Kilpatrick <ikilpatrick@chromium.org> Reviewed-by: Koji Ishii <kojii@chromium.org> Commit-Queue: Morten Stenshorne <mstensho@chromium.org> Cr-Commit-Position: refs/heads/master@{#739425}

[LayoutNG] Hit test floats in the same pseudo-stacking context.
We gave up when entering a new formatting context. But we should only stop when entering a child that's painted atomically. Bug: 1043787 Change-Id: I83bd88237311aa7edde00e5a3814a555cd56f112 Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2044210Reviewed-by: Ian Kilpatrick <ikilpatrick@chromium.org> Reviewed-by: Koji Ishii <kojii@chromium.org> Commit-Queue: Morten Stenshorne <mstensho@chromium.org> Cr-Commit-Position: refs/heads/master@{#739425}
eeb3f7df · Morten Stenshorne · Commit Bot · 0d129bfe · eeb3f7df · eeb3f7df
Commit eeb3f7df authored Feb 07, 2020 by Morten Stenshorne Committed by Commit Bot Feb 07, 2020
2 changed files
--- a/third_party/blink/renderer/core/paint/ng/ng_box_fragment_painter.cc
+++ b/third_party/blink/renderer/core/paint/ng/ng_box_fragment_painter.cc
@@ -2118,7 +2118,7 @@ bool NGBoxFragmentPainter::HitTestFloatingChildren(
      continue;
    }
-    if (child_fragment.IsBlockFormattingContextRoot())
+    if (child_fragment.IsPaintedAtomically())
      continue;
    if (const auto* child_container =

--- a/third_party/blink/web_tests/external/wpt/css/CSS2/floats/hit-test-floats-004.html
+++ b/third_party/blink/web_tests/external/wpt/css/CSS2/floats/hit-test-floats-004.html
+<!DOCTYPE html>
+<link rel="author" title="Morten Stenshorne" href="mailto:mstensho@chromium.org">
+<link rel="help" href="https://www.w3.org/TR/CSS22/visuren.html#floats">
+<link rel="help" href="https://www.w3.org/TR/CSS22/zindex.html">
+<div id="error" style="overflow:hidden; width:100px; height:100px;"></div>
+<div style="margin-top:-100px; overflow:hidden; width:100px; height:100px;">
+  <div id="target" style="float:left; width:100px; height:100px;"></div>
+</div>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script>
+  test(()=> {
+      var elm = document.elementFromPoint(50, 50);
+      assert_equals(elm.id, "target");
+  }, "Miss float below something else");
+</script>