1 files changed, 62 insertions, 0 deletions
diff --git a/layout/xul/nsStackFrame.cpp b/layout/xul/nsStackFrame.cpp
new file mode 100644
index 0000000000..64dbb40128
--- /dev/null
+++ b/layout/xul/nsStackFrame.cpp
@@ -0,0 +1,62 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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/. */
+
+//
+// Eric Vaughan
+// Netscape Communications
+//
+// See documentation in associated header file
+//
+
+#include "nsStackFrame.h"
+
+#include "mozilla/ComputedStyle.h"
+#include "mozilla/PresShell.h"
+#include "nsIContent.h"
+#include "nsCOMPtr.h"
+#include "nsHTMLParts.h"
+#include "nsCSSRendering.h"
+#include "nsBoxLayoutState.h"
+#include "nsStackLayout.h"
+#include "nsDisplayList.h"
+
+using namespace mozilla;
+
+nsIFrame* NS_NewStackFrame(PresShell* aPresShell, ComputedStyle* aStyle) {
+  return new (aPresShell) nsStackFrame(aStyle, aPresShell->GetPresContext());
+}
+
+NS_IMPL_FRAMEARENA_HELPERS(nsStackFrame)
+
+nsStackFrame::nsStackFrame(ComputedStyle* aStyle, nsPresContext* aPresContext)
+    : nsBoxFrame(aStyle, aPresContext, kClassID) {
+  nsCOMPtr<nsBoxLayout> layout;
+  NS_NewStackLayout(layout);
+  SetXULLayoutManager(layout);
+}
+
+// REVIEW: The old code put everything in the background layer. To be more
+// consistent with the way other frames work, I'm putting everything in the
+// Content() (i.e., foreground) layer (see nsIFrame::BuildDisplayListForChild,
+// the case for stacking context but non-positioned, non-floating frames).
+// This could easily be changed back by hacking
+// nsBoxFrame::BuildDisplayListInternal a bit more.
+void nsStackFrame::BuildDisplayListForChildren(nsDisplayListBuilder* aBuilder,
+                                               const nsDisplayListSet& aLists) {
+  // BuildDisplayListForChild puts stacking contexts into the
+  // PositionedDescendants list. So we need to map that list to
+  // aLists.Content(). This is an easy way to do that.
+  nsDisplayList* content = aLists.Content();
+  nsDisplayListSet kidLists(content, content, content, content, content,
+                            content);
+  nsIFrame* kid = mFrames.FirstChild();
+  while (kid) {
+    // Force each child into its own true stacking context.
+    BuildDisplayListForChild(aBuilder, kid, kidLists,
+                             DisplayChildFlag::ForceStackingContext);
+    kid = kid->GetNextSibling();
+  }
+}