Consider multicol container in paginated context when setting mIsTopOfPage bit.

aethanyc · moz-wptsync-bot · commit b09d34ff0340 · 2023-05-25T13:00:43.000+01:00
A top-level multicol in a paginated context can be fragmented. We should use the same logic to set the `mIsTopOfPage` bit as if the multicol is a nested one. WARNING: loading the testcase without this patch can trap Firefox in an infinite loop. Differential Revision: https://phabricator.services.mozilla.com/D177578 bugzilla-url: https://bugzilla.mozilla.org/show_bug.cgi?id=1831829 gecko-commit: 1620189277fc5ccc3e0afdf9ddba9de9794491e4 gecko-reviewers: emilio
diff --git a/css/css-break/break-inside-avoid-multicol-001-print-ref.html b/css/css-break/break-inside-avoid-multicol-001-print-ref.html
@@ -0,0 +1,32 @@
+<!DOCTYPE html>
+<html>
+  <meta charset="utf-8">
+  <title>CSS Fragmentation Reference: Print a multi-column container containing break-inside:avoid elements</title>
+  <link rel="author" title="Ting-Yu Lin" href="mailto:tlin@mozilla.com">
+  <link rel="author" title="Mozilla" href="https://www.mozilla.org/">
+
+  <style>
+  @page {
+    size: 5in 3in;
+    margin: 0.5in;
+  }
+  body {
+    margin: 0;
+  }
+  div {
+    width: 100%;
+    height: 1in;
+    background: green;
+  }
+  </style>
+
+  <article>
+    <!-- page 1 -->
+    <div style="width: 100%"></div>
+    <div style="width:50%"></div>
+
+    <!-- page 2 -->
+    <div style="width: 100%"></div>
+    <div style="width: 50%"></div>
+  </article>
+</html>
diff --git a/css/css-break/break-inside-avoid-multicol-001-print.html b/css/css-break/break-inside-avoid-multicol-001-print.html
@@ -0,0 +1,38 @@
+<!DOCTYPE html>
+<html>
+  <meta charset="utf-8">
+  <title>CSS Fragmentation Test: Print a multi-column container containing break-inside:avoid elements</title>
+  <link rel="author" title="Ting-Yu Lin" href="mailto:tlin@mozilla.com">
+  <link rel="author" title="Mozilla" href="https://www.mozilla.org/">
+  <link rel="help" href="https://drafts.csswg.org/css-break-3/#break-within">
+  <link rel="help" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1831829">
+  <link rel="match" href="break-inside-avoid-multicol-001-print-ref.html">
+
+  <style>
+  @page {
+    size: 5in 3in;
+    margin: 0.5in;
+  }
+  body {
+    margin: 0;
+  }
+  article {
+    column-count: 2;
+    column-gap: 0;
+  }
+  article > div {
+    width: 100%;
+    height: 3in;
+    background: green;
+    break-inside: avoid;
+  }
+  </style>
+
+  <article>
+    <!-- page 1 -->
+    <div></div>
+
+    <!-- page 2 -->
+    <div></div>
+  </article>
+</html>
