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Bug 1782597 Part 2 - Use null to indicate page value equal to the auto value for CSS named pages r=dholbert

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This applies both to the individual mStartPageValue and mEndPageValue fields
of the nsIFrame::PageValues struct, and for the nsIFrame::PageValuesProperty
being null to indicate both mStartPageValue and mEndPageValue are auto.

Fetching this is handled by nsIFrame::GetStartPageValue and
nsIFrame::GetEndPageValue, which also ensure the use of first-in-flow frames.

Differential Revision: https://phabricator.services.mozilla.com/D157873
This commit is contained in:
Emily McDonough
2022-10-05 22:07:47 +00:00
parent eb0252b850
commit 68042c67af
3 changed files with 140 additions and 61 deletions
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149
layout/base/nsCSSFrameConstructor.cpp
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@@ -1413,6 +1413,11 @@ nsCSSFrameConstructor::AutoFrameConstructionPageName::
"Page name should not have been set");
return;
}
#ifdef DEBUG
MOZ_ASSERT(!aFrame->mWasVisitedByAutoFrameConstructionPageName,
"Frame should only have been visited once");
aFrame->mWasVisitedByAutoFrameConstructionPageName = true;
#endif
EnsureAutoPageName(aState, aFrame->GetParent());
mNameToRestore = aState.mAutoPageNameValue;
@@ -1421,20 +1426,6 @@ nsCSSFrameConstructor::AutoFrameConstructionPageName::
"Page name should have been found by EnsureAutoPageName");
MaybeApplyPageName(aState, aFrame->StylePage()->mPage);
aFrame->SetAutoPageValue(aState.mAutoPageNameValue);
// Ensure that the PageValuesProperty field has been created.
// Before layout.css.named_pages.enabled is prefed on by default, we should
// investigate making this property optional, and have a missing property
// indicate a default root page-name or an auto page-name.
//
// When we make this property optional, we should add a debug-only flag on
// nsIFrame to indicate it was visited by this logic, as currently we assert
// the existence of this property to validate that.
nsIFrame::PageValues* pageValues =
aFrame->GetProperty(nsIFrame::PageValuesProperty());
if (!pageValues) {
pageValues = new nsIFrame::PageValues();
aFrame->AddProperty(nsIFrame::PageValuesProperty(), pageValues);
}
}
nsCSSFrameConstructor::AutoFrameConstructionPageName::
@@ -9367,6 +9358,51 @@ static bool FrameHasOnlyPlaceholderNextSiblings(const nsIFrame* aFrame) {
return !nextSibling;
}
static void SetPageValues(nsIFrame* const aFrame,
const nsAtom* const aAutoValue,
const nsAtom* const aStartValue,
const nsAtom* const aEndValue) {
MOZ_ASSERT(aAutoValue, "Auto page value should never be null");
MOZ_ASSERT(aStartValue || aEndValue, "Should not have called with no values");
nsIFrame::PageValues* pageValues =
aFrame->GetProperty(nsIFrame::PageValuesProperty());
if (aStartValue) {
if (aStartValue == aAutoValue) {
// If the page value struct already exists, set the start value to null
// to indicate the auto value.
if (pageValues) {
pageValues->mStartPageValue = nullptr;
}
} else {
// The start value is not auto, so we need to store it, creating the
// page values struct if it does not already exist.
if (!pageValues) {
pageValues = new nsIFrame::PageValues();
aFrame->SetProperty(nsIFrame::PageValuesProperty(), pageValues);
}
pageValues->mStartPageValue = aStartValue;
}
}
if (aEndValue) {
if (aEndValue == aAutoValue) {
// If the page value struct already exists, set the end value to null
// to indicate the auto value.
if (pageValues) {
pageValues->mEndPageValue = nullptr;
}
} else {
// The end value is not auto, so we need to store it, creating the
// page values struct if it does not already exist.
if (!pageValues) {
pageValues = new nsIFrame::PageValues();
aFrame->SetProperty(nsIFrame::PageValuesProperty(), pageValues);
}
pageValues->mEndPageValue = aEndValue;
}
}
}
inline void nsCSSFrameConstructor::ConstructFramesFromItemList(
nsFrameConstructorState& aState, FrameConstructionItemList& aItems,
nsContainerFrame* aParentFrame, bool aParentIsWrapperAnonBox,
@@ -9450,6 +9486,15 @@ inline void nsCSSFrameConstructor::ConstructFramesFromItemList(
// Set the start/end page values while iterating the frame list, to walk
// up the frame tree only once after iterating the frame list.
// This also avoids extra property lookups on these frames.
MOZ_ASSERT(aState.mAutoPageNameValue == aParentFrame->GetAutoPageValue(),
"aState.mAutoPageNameValue should have been equivalent to "
"the auto value stored on our parent frame.");
// Even though we store null for page values that equal the "auto" resolved
// value on frames, we always want startPageValue/endPageValue to be the
// actual atoms reflecting the start/end values. This is because when we
// propagate the values up the frame tree, we will need to compare them to
// the auto value for each ancestor. This value might be different than the
// auto value for this frame.
const nsAtom* startPageValue = nullptr;
const nsAtom* endPageValue = nullptr;
for (nsIFrame* f : aFrameList) {
@@ -9484,21 +9529,29 @@ inline void nsCSSFrameConstructor::ConstructFramesFromItemList(
: aState.mAutoPageNameValue;
nsIFrame::PageValues* pageValues =
f->GetProperty(nsIFrame::PageValuesProperty());
if (!pageValues) {
pageValues = new nsIFrame::PageValues();
f->AddProperty(nsIFrame::PageValuesProperty(), pageValues);
}
MOZ_ASSERT(!pageValues->mStartPageValue == !pageValues->mEndPageValue,
"Both or neither mStartPageValue and mEndPageValue should "
"have been set");
if (!pageValues->mStartPageValue) {
pageValues->mStartPageValue = pageNameAtom;
pageValues->mEndPageValue = pageNameAtom;
// If this frame has any children, it will already have had its page
// values set at this point. However, if no page values have been set,
// we must ensure that the appropriate PageValuesProperty value has been
// set.
// If the page name is equal to the auto value, then PageValuesProperty
// should remain null to indicate that the start/end values are both
// equal to the auto value.
if (pageNameAtom != aState.mAutoPageNameValue && !pageValues) {
pageValues = new nsIFrame::PageValues{pageNameAtom, pageNameAtom};
f->SetProperty(nsIFrame::PageValuesProperty(), pageValues);
}
// We don't want to use GetStartPageValue() or GetEndPageValue(), as each
// requires a property lookup which we can avoid here.
if (!startPageValue) {
startPageValue = pageValues->mStartPageValue;
startPageValue = (pageValues && pageValues->mStartPageValue)
? pageValues->mStartPageValue.get()
: aState.mAutoPageNameValue;
}
endPageValue = pageValues->mEndPageValue;
endPageValue = (pageValues && pageValues->mEndPageValue)
? pageValues->mEndPageValue.get()
: aState.mAutoPageNameValue;
MOZ_ASSERT(startPageValue && endPageValue,
"Should have found start/end page value");
}
MOZ_ASSERT(!startPageValue == !endPageValue,
"Should have set both or neither page values");
@@ -9507,7 +9560,8 @@ inline void nsCSSFrameConstructor::ConstructFramesFromItemList(
// end page values.
// As we go, if we find that, for a frame, we are not contributing one of
// the start/end page values, then our subtree will not contribute this
// value from that frame onward.
// value from that frame onward. startPageValue/endPageValue are set to
// null to indicate this.
// Stop iterating when we are not contributing either start or end
// values, when we hit the root frame (no parent), or when we find a
// frame that is not a block frame.
@@ -9517,31 +9571,32 @@ inline void nsCSSFrameConstructor::ConstructFramesFromItemList(
ancestorFrame = ancestorFrame->GetParent()) {
MOZ_ASSERT(!ancestorFrame->GetPrevInFlow(),
"Should not have fragmentation yet");
nsIFrame::PageValues* const ancestorPageValues =
ancestorFrame->GetProperty(nsIFrame::PageValuesProperty());
if (!ancestorPageValues) {
break;
MOZ_ASSERT(ancestorFrame->mWasVisitedByAutoFrameConstructionPageName,
"Frame should have been visited by "
"AutoFrameConstructionPageName");
{
// Get what the auto value is, based on this frame's parent.
// For the root frame, `auto` resolves to the empty atom.
const nsContainerFrame* const parent = ancestorFrame->GetParent();
const nsAtom* const parentAuto = MOZ_LIKELY(parent)
? parent->GetAutoPageValue()
: nsGkAtoms::_empty;
SetPageValues(ancestorFrame, parentAuto, startPageValue,
endPageValue);
}
// Set start/end values if we are still contributing those values.
// Once we stop contributing start/end values, we know there is a
// sibling subtree that contributed that value to our shared parent
// instead of our starting frame's subtree. This means once
// startPageValue/endPageValue becomes null, it should stay null and
// we no longer need to check for siblings in that direction.
if (startPageValue) {
ancestorPageValues->mStartPageValue = startPageValue;
if (!FrameHasOnlyPlaceholderPrevSiblings(ancestorFrame)) {
startPageValue = nullptr;
}
// startPageValue/endPageValue becomes null, indicating that we are no
// longer contributing that page value, it should stay null and we no
// longer need to check for siblings in that direction.
if (startPageValue &&
!FrameHasOnlyPlaceholderPrevSiblings(ancestorFrame)) {
startPageValue = nullptr;
}
if (endPageValue) {
ancestorPageValues->mEndPageValue = endPageValue;
if (!FrameHasOnlyPlaceholderNextSiblings(ancestorFrame)) {
endPageValue = nullptr;
}
if (endPageValue &&
!FrameHasOnlyPlaceholderNextSiblings(ancestorFrame)) {
endPageValue = nullptr;
}
}
}