1 files changed, 149 insertions, 0 deletions
diff --git a/layout/painting/DisplayListClipState.cpp b/layout/painting/DisplayListClipState.cpp
new file mode 100644
index 0000000000..8a87e2906b
--- /dev/null
+++ b/layout/painting/DisplayListClipState.cpp
@@ -0,0 +1,149 @@
+/* -*- 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/. */
+
+#include "DisplayListClipState.h"
+
+#include "nsDisplayList.h"
+
+namespace mozilla {
+
+const DisplayItemClipChain* DisplayListClipState::GetCurrentCombinedClipChain(
+    nsDisplayListBuilder* aBuilder) {
+  if (mCurrentCombinedClipChainIsValid) {
+    return mCurrentCombinedClipChain;
+  }
+  if (!mClipChainContentDescendants && !mClipChainContainingBlockDescendants) {
+    mCurrentCombinedClipChain = nullptr;
+    mCurrentCombinedClipChainIsValid = true;
+    return nullptr;
+  }
+
+  mCurrentCombinedClipChain = aBuilder->CreateClipChainIntersection(
+      mCurrentCombinedClipChain, mClipChainContentDescendants,
+      mClipChainContainingBlockDescendants);
+  mCurrentCombinedClipChainIsValid = true;
+  return mCurrentCombinedClipChain;
+}
+
+static void ApplyClip(nsDisplayListBuilder* aBuilder,
+                      const DisplayItemClipChain*& aClipToModify,
+                      const ActiveScrolledRoot* aASR,
+                      DisplayItemClipChain& aClipChainOnStack) {
+  aClipChainOnStack.mASR = aASR;
+  if (aClipToModify && aClipToModify->mASR == aASR) {
+    // Intersect with aClipToModify and replace the clip chain item.
+    aClipChainOnStack.mClip.IntersectWith(aClipToModify->mClip);
+    aClipChainOnStack.mParent = aClipToModify->mParent;
+    aClipToModify = &aClipChainOnStack;
+  } else if (!aClipToModify ||
+             ActiveScrolledRoot::IsAncestor(aClipToModify->mASR, aASR)) {
+    // Add a new clip chain item at the bottom.
+    aClipChainOnStack.mParent = aClipToModify;
+    aClipToModify = &aClipChainOnStack;
+  } else {
+    // We need to insert / intersect a DisplayItemClipChain in the middle of the
+    // aClipToModify chain. This is a very rare case.
+    // Find the common ancestor and have the builder create the
+    // DisplayItemClipChain intersection. This will create new
+    // DisplayItemClipChain objects for all descendants of ancestorSC and we
+    // will not hold on to a pointer to aClipChainOnStack.
+    const DisplayItemClipChain* ancestorSC = aClipToModify;
+    while (ancestorSC &&
+           ActiveScrolledRoot::IsAncestor(aASR, ancestorSC->mASR)) {
+      ancestorSC = ancestorSC->mParent;
+    }
+    ancestorSC = aBuilder->CopyWholeChain(ancestorSC);
+    aClipChainOnStack.mParent = nullptr;
+    aClipToModify = aBuilder->CreateClipChainIntersection(
+        ancestorSC, aClipToModify, &aClipChainOnStack);
+  }
+}
+
+void DisplayListClipState::ClipContainingBlockDescendants(
+    nsDisplayListBuilder* aBuilder, const nsRect& aRect, const nscoord* aRadii,
+    DisplayItemClipChain& aClipChainOnStack) {
+  if (aRadii) {
+    aClipChainOnStack.mClip.SetTo(aRect, aRadii);
+  } else {
+    aClipChainOnStack.mClip.SetTo(aRect);
+  }
+  const ActiveScrolledRoot* asr = aBuilder->CurrentActiveScrolledRoot();
+  ApplyClip(aBuilder, mClipChainContainingBlockDescendants, asr,
+            aClipChainOnStack);
+  InvalidateCurrentCombinedClipChain(asr);
+}
+
+void DisplayListClipState::ClipContentDescendants(
+    nsDisplayListBuilder* aBuilder, const nsRect& aRect, const nscoord* aRadii,
+    DisplayItemClipChain& aClipChainOnStack) {
+  if (aRadii) {
+    aClipChainOnStack.mClip.SetTo(aRect, aRadii);
+  } else {
+    aClipChainOnStack.mClip.SetTo(aRect);
+  }
+  const ActiveScrolledRoot* asr = aBuilder->CurrentActiveScrolledRoot();
+  ApplyClip(aBuilder, mClipChainContentDescendants, asr, aClipChainOnStack);
+  InvalidateCurrentCombinedClipChain(asr);
+}
+
+void DisplayListClipState::ClipContentDescendants(
+    nsDisplayListBuilder* aBuilder, const nsRect& aRect,
+    const nsRect& aRoundedRect, const nscoord* aRadii,
+    DisplayItemClipChain& aClipChainOnStack) {
+  if (aRadii) {
+    aClipChainOnStack.mClip.SetTo(aRect, aRoundedRect, aRadii);
+  } else {
+    nsRect intersect = aRect.Intersect(aRoundedRect);
+    aClipChainOnStack.mClip.SetTo(intersect);
+  }
+  const ActiveScrolledRoot* asr = aBuilder->CurrentActiveScrolledRoot();
+  ApplyClip(aBuilder, mClipChainContentDescendants, asr, aClipChainOnStack);
+  InvalidateCurrentCombinedClipChain(asr);
+}
+
+void DisplayListClipState::InvalidateCurrentCombinedClipChain(
+    const ActiveScrolledRoot* aInvalidateUpTo) {
+  mClippedToDisplayPort = false;
+  mCurrentCombinedClipChainIsValid = false;
+  while (mCurrentCombinedClipChain &&
+         ActiveScrolledRoot::IsAncestor(aInvalidateUpTo,
+                                        mCurrentCombinedClipChain->mASR)) {
+    mCurrentCombinedClipChain = mCurrentCombinedClipChain->mParent;
+  }
+}
+
+void DisplayListClipState::ClipContainingBlockDescendantsToContentBox(
+    nsDisplayListBuilder* aBuilder, nsIFrame* aFrame,
+    DisplayItemClipChain& aClipChainOnStack, uint32_t aFlags) {
+  nscoord radii[8];
+  bool hasBorderRadius = aFrame->GetContentBoxBorderRadii(radii);
+  if (!hasBorderRadius &&
+      (aFlags & ASSUME_DRAWING_RESTRICTED_TO_CONTENT_RECT)) {
+    return;
+  }
+
+  nsRect clipRect = aFrame->GetContentRectRelativeToSelf() +
+                    aBuilder->ToReferenceFrame(aFrame);
+  // If we have a border-radius, we have to clip our content to that
+  // radius.
+  ClipContainingBlockDescendants(
+      aBuilder, clipRect, hasBorderRadius ? radii : nullptr, aClipChainOnStack);
+}
+
+DisplayListClipState::AutoSaveRestore::AutoSaveRestore(
+    nsDisplayListBuilder* aBuilder)
+    : mBuilder(aBuilder),
+      mState(aBuilder->ClipState()),
+      mSavedState(aBuilder->ClipState())
+#ifdef DEBUG
+      ,
+      mClipUsed(false),
+      mRestored(false)
+#endif
+{
+}
+
+}  // namespace mozilla