1 files changed, 268 insertions, 0 deletions
diff --git a/layout/generic/nsSplittableFrame.cpp b/layout/generic/nsSplittableFrame.cpp
new file mode 100644
index 0000000000..99f9b7f16a
--- /dev/null
+++ b/layout/generic/nsSplittableFrame.cpp
@@ -0,0 +1,268 @@
+/* -*- 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/. */
+
+/*
+ * base class for rendering objects that can be split across lines,
+ * columns, or pages
+ */
+
+#include "nsSplittableFrame.h"
+#include "nsContainerFrame.h"
+#include "nsFieldSetFrame.h"
+#include "nsIFrameInlines.h"
+
+using namespace mozilla;
+
+void nsSplittableFrame::Init(nsIContent* aContent, nsContainerFrame* aParent,
+                             nsIFrame* aPrevInFlow) {
+  if (aPrevInFlow) {
+    // Hook the frame into the flow
+    SetPrevInFlow(aPrevInFlow);
+    aPrevInFlow->SetNextInFlow(this);
+  }
+  nsIFrame::Init(aContent, aParent, aPrevInFlow);
+}
+
+void nsSplittableFrame::DestroyFrom(nsIFrame* aDestructRoot,
+                                    PostDestroyData& aPostDestroyData) {
+  // Disconnect from the flow list
+  if (mPrevContinuation || mNextContinuation) {
+    RemoveFromFlow(this);
+  }
+
+  // Let the base class destroy the frame
+  nsIFrame::DestroyFrom(aDestructRoot, aPostDestroyData);
+}
+
+nsIFrame* nsSplittableFrame::GetPrevContinuation() const {
+  return mPrevContinuation;
+}
+
+void nsSplittableFrame::SetPrevContinuation(nsIFrame* aFrame) {
+  NS_ASSERTION(!aFrame || Type() == aFrame->Type(),
+               "setting a prev continuation with incorrect type!");
+  NS_ASSERTION(!IsInPrevContinuationChain(aFrame, this),
+               "creating a loop in continuation chain!");
+  mPrevContinuation = aFrame;
+  RemoveStateBits(NS_FRAME_IS_FLUID_CONTINUATION);
+}
+
+nsIFrame* nsSplittableFrame::GetNextContinuation() const {
+  return mNextContinuation;
+}
+
+void nsSplittableFrame::SetNextContinuation(nsIFrame* aFrame) {
+  NS_ASSERTION(!aFrame || Type() == aFrame->Type(),
+               "setting a next continuation with incorrect type!");
+  NS_ASSERTION(!IsInNextContinuationChain(aFrame, this),
+               "creating a loop in continuation chain!");
+  mNextContinuation = aFrame;
+  if (aFrame) aFrame->RemoveStateBits(NS_FRAME_IS_FLUID_CONTINUATION);
+}
+
+nsIFrame* nsSplittableFrame::FirstContinuation() const {
+  nsSplittableFrame* firstContinuation = const_cast<nsSplittableFrame*>(this);
+  while (firstContinuation->mPrevContinuation) {
+    firstContinuation =
+        static_cast<nsSplittableFrame*>(firstContinuation->mPrevContinuation);
+  }
+  MOZ_ASSERT(firstContinuation, "post-condition failed");
+  return firstContinuation;
+}
+
+nsIFrame* nsSplittableFrame::LastContinuation() const {
+  nsSplittableFrame* lastContinuation = const_cast<nsSplittableFrame*>(this);
+  while (lastContinuation->mNextContinuation) {
+    lastContinuation =
+        static_cast<nsSplittableFrame*>(lastContinuation->mNextContinuation);
+  }
+  MOZ_ASSERT(lastContinuation, "post-condition failed");
+  return lastContinuation;
+}
+
+#ifdef DEBUG
+bool nsSplittableFrame::IsInPrevContinuationChain(nsIFrame* aFrame1,
+                                                  nsIFrame* aFrame2) {
+  int32_t iterations = 0;
+  while (aFrame1 && iterations < 10) {
+    // Bail out after 10 iterations so we don't bog down debug builds too much
+    if (aFrame1 == aFrame2) return true;
+    aFrame1 = aFrame1->GetPrevContinuation();
+    ++iterations;
+  }
+  return false;
+}
+
+bool nsSplittableFrame::IsInNextContinuationChain(nsIFrame* aFrame1,
+                                                  nsIFrame* aFrame2) {
+  int32_t iterations = 0;
+  while (aFrame1 && iterations < 10) {
+    // Bail out after 10 iterations so we don't bog down debug builds too much
+    if (aFrame1 == aFrame2) return true;
+    aFrame1 = aFrame1->GetNextContinuation();
+    ++iterations;
+  }
+  return false;
+}
+#endif
+
+nsIFrame* nsSplittableFrame::GetPrevInFlow() const {
+  return HasAnyStateBits(NS_FRAME_IS_FLUID_CONTINUATION) ? mPrevContinuation
+                                                         : nullptr;
+}
+
+void nsSplittableFrame::SetPrevInFlow(nsIFrame* aFrame) {
+  NS_ASSERTION(!aFrame || Type() == aFrame->Type(),
+               "setting a prev in flow with incorrect type!");
+  NS_ASSERTION(!IsInPrevContinuationChain(aFrame, this),
+               "creating a loop in continuation chain!");
+  mPrevContinuation = aFrame;
+  AddStateBits(NS_FRAME_IS_FLUID_CONTINUATION);
+}
+
+nsIFrame* nsSplittableFrame::GetNextInFlow() const {
+  return mNextContinuation && mNextContinuation->HasAnyStateBits(
+                                  NS_FRAME_IS_FLUID_CONTINUATION)
+             ? mNextContinuation
+             : nullptr;
+}
+
+void nsSplittableFrame::SetNextInFlow(nsIFrame* aFrame) {
+  NS_ASSERTION(!aFrame || Type() == aFrame->Type(),
+               "setting a next in flow with incorrect type!");
+  NS_ASSERTION(!IsInNextContinuationChain(aFrame, this),
+               "creating a loop in continuation chain!");
+  mNextContinuation = aFrame;
+  if (aFrame) aFrame->AddStateBits(NS_FRAME_IS_FLUID_CONTINUATION);
+}
+
+nsIFrame* nsSplittableFrame::FirstInFlow() const {
+  nsSplittableFrame* firstInFlow = const_cast<nsSplittableFrame*>(this);
+  while (nsIFrame* prev = firstInFlow->GetPrevInFlow()) {
+    firstInFlow = static_cast<nsSplittableFrame*>(prev);
+  }
+  MOZ_ASSERT(firstInFlow, "post-condition failed");
+  return firstInFlow;
+}
+
+nsIFrame* nsSplittableFrame::LastInFlow() const {
+  nsSplittableFrame* lastInFlow = const_cast<nsSplittableFrame*>(this);
+  while (nsIFrame* next = lastInFlow->GetNextInFlow()) {
+    lastInFlow = static_cast<nsSplittableFrame*>(next);
+  }
+  MOZ_ASSERT(lastInFlow, "post-condition failed");
+  return lastInFlow;
+}
+
+// Remove this frame from the flow. Connects prev in flow and next in flow
+void nsSplittableFrame::RemoveFromFlow(nsIFrame* aFrame) {
+  nsIFrame* prevContinuation = aFrame->GetPrevContinuation();
+  nsIFrame* nextContinuation = aFrame->GetNextContinuation();
+
+  // The new continuation is fluid only if the continuation on both sides
+  // of the removed frame was fluid
+  if (aFrame->GetPrevInFlow() && aFrame->GetNextInFlow()) {
+    if (prevContinuation) {
+      prevContinuation->SetNextInFlow(nextContinuation);
+    }
+    if (nextContinuation) {
+      nextContinuation->SetPrevInFlow(prevContinuation);
+    }
+  } else {
+    if (prevContinuation) {
+      prevContinuation->SetNextContinuation(nextContinuation);
+    }
+    if (nextContinuation) {
+      nextContinuation->SetPrevContinuation(prevContinuation);
+    }
+  }
+
+  aFrame->SetPrevInFlow(nullptr);
+  aFrame->SetNextInFlow(nullptr);
+}
+
+NS_DECLARE_FRAME_PROPERTY_SMALL_VALUE(ConsumedBSizeProperty, nscoord);
+
+nscoord nsSplittableFrame::CalcAndCacheConsumedBSize() {
+  nsIFrame* prev = GetPrevContinuation();
+  if (!prev) {
+    return 0;
+  }
+  const auto wm = GetWritingMode();
+  nscoord bSize = 0;
+  for (; prev; prev = prev->GetPrevContinuation()) {
+    bSize += prev->ContentSize(wm).BSize(wm);
+    bool found = false;
+    nscoord consumed = prev->GetProperty(ConsumedBSizeProperty(), &found);
+    if (found) {
+      bSize += consumed;
+      break;
+    }
+    MOZ_ASSERT(!prev->GetPrevContinuation(),
+               "Property should always be set on prev continuation if not "
+               "the first continuation");
+  }
+  SetProperty(ConsumedBSizeProperty(), bSize);
+  return bSize;
+}
+
+nscoord nsSplittableFrame::GetEffectiveComputedBSize(
+    const ReflowInput& aReflowInput, nscoord aConsumedBSize) const {
+  nscoord bSize = aReflowInput.ComputedBSize();
+  if (bSize == NS_UNCONSTRAINEDSIZE) {
+    return NS_UNCONSTRAINEDSIZE;
+  }
+
+  bSize -= aConsumedBSize;
+
+  // nsFieldSetFrame's inner frames are special since some of their content-box
+  // BSize may be consumed by positioning it below the legend.  So we always
+  // report zero for true overflow containers here.
+  // XXXmats: hmm, can we fix this so that the sizes actually adds up instead?
+  if (IsTrueOverflowContainer() &&
+      Style()->GetPseudoType() == PseudoStyleType::fieldsetContent) {
+    for (nsFieldSetFrame* fieldset = do_QueryFrame(GetParent()); fieldset;
+         fieldset = static_cast<nsFieldSetFrame*>(fieldset->GetPrevInFlow())) {
+      bSize -= fieldset->LegendSpace();
+    }
+  }
+
+  // We may have stretched the frame beyond its computed height. Oh well.
+  return std::max(0, bSize);
+}
+
+LogicalSides nsSplittableFrame::GetBlockLevelLogicalSkipSides(
+    bool aAfterReflow) const {
+  LogicalSides skip(mWritingMode);
+  if (MOZ_UNLIKELY(IsTrueOverflowContainer())) {
+    skip |= eLogicalSideBitsBBoth;
+    return skip;
+  }
+
+  if (MOZ_UNLIKELY(StyleBorder()->mBoxDecorationBreak ==
+                   StyleBoxDecorationBreak::Clone)) {
+    return skip;
+  }
+
+  if (GetPrevContinuation()) {
+    skip |= eLogicalSideBitsBStart;
+  }
+
+  // Always skip block-end side if we have a *later* sibling across column-span
+  // split.
+  if (HasColumnSpanSiblings()) {
+    skip |= eLogicalSideBitsBEnd;
+  }
+
+  if (aAfterReflow) {
+    nsIFrame* nif = GetNextContinuation();
+    if (nif && !nif->IsTrueOverflowContainer()) {
+      skip |= eLogicalSideBitsBEnd;
+    }
+  }
+
+  return skip;
+}