1 files changed, 79 insertions, 0 deletions
diff --git a/layout/generic/nsBackdropFrame.cpp b/layout/generic/nsBackdropFrame.cpp
new file mode 100644
index 0000000000..20d3fcd368
--- /dev/null
+++ b/layout/generic/nsBackdropFrame.cpp
@@ -0,0 +1,79 @@
+/* -*- 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/. */
+
+/* rendering object for CSS "::backdrop" */
+
+#include "nsBackdropFrame.h"
+
+#include "mozilla/PresShell.h"
+#include "nsDisplayList.h"
+
+using namespace mozilla;
+
+NS_IMPL_FRAMEARENA_HELPERS(nsBackdropFrame)
+
+#ifdef DEBUG_FRAME_DUMP
+nsresult nsBackdropFrame::GetFrameName(nsAString& aResult) const {
+  return MakeFrameName(u"Backdrop"_ns, aResult);
+}
+#endif
+
+/* virtual */
+ComputedStyle* nsBackdropFrame::GetParentComputedStyle(
+    nsIFrame** aProviderFrame) const {
+  // Style context of backdrop pseudo-element does not inherit from
+  // any element, per the Fullscreen API spec.
+  *aProviderFrame = nullptr;
+  return nullptr;
+}
+
+/* virtual */
+void nsBackdropFrame::BuildDisplayList(nsDisplayListBuilder* aBuilder,
+                                       const nsDisplayListSet& aLists) {
+  DO_GLOBAL_REFLOW_COUNT_DSP("nsBackdropFrame");
+  // We want this frame to always be there even if its display value is
+  // none or contents so that we can respond to style change on it. To
+  // support those values, we skip painting ourselves in those cases.
+  auto display = StyleDisplay()->mDisplay;
+  if (display == mozilla::StyleDisplay::None ||
+      display == mozilla::StyleDisplay::Contents) {
+    return;
+  }
+
+  DisplayBorderBackgroundOutline(aBuilder, aLists);
+}
+
+/* virtual */
+LogicalSize nsBackdropFrame::ComputeAutoSize(
+    gfxContext* aRenderingContext, WritingMode aWM, const LogicalSize& aCBSize,
+    nscoord aAvailableISize, const LogicalSize& aMargin,
+    const LogicalSize& aBorderPadding, const StyleSizeOverrides& aSizeOverrides,
+    ComputeSizeFlags aFlags) {
+  // Note that this frame is a child of the viewport frame.
+  LogicalSize result(aWM, 0xdeadbeef, NS_UNCONSTRAINEDSIZE);
+  if (aFlags.contains(ComputeSizeFlag::ShrinkWrap)) {
+    result.ISize(aWM) = 0;
+  } else {
+    result.ISize(aWM) =
+        aAvailableISize - aMargin.ISize(aWM) - aBorderPadding.ISize(aWM);
+  }
+  return result;
+}
+
+/* virtual */
+void nsBackdropFrame::Reflow(nsPresContext* aPresContext,
+                             ReflowOutput& aDesiredSize,
+                             const ReflowInput& aReflowInput,
+                             nsReflowStatus& aStatus) {
+  MarkInReflow();
+  DO_GLOBAL_REFLOW_COUNT("nsBackdropFrame");
+  DISPLAY_REFLOW(aPresContext, this, aReflowInput, aDesiredSize, aStatus);
+  MOZ_ASSERT(aStatus.IsEmpty(), "Caller should pass a fresh reflow status!");
+
+  // Note that this frame is a child of the viewport frame.
+  WritingMode wm = aReflowInput.GetWritingMode();
+  aDesiredSize.SetSize(wm, aReflowInput.ComputedSizeWithBorderPadding(wm));
+}