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+/* -*- 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/. */
+
+/* the interface (to internal code) for retrieving computed style data */
+
+#ifndef _ComputedStyle_h_
+#define _ComputedStyle_h_
+
+#include "mozilla/Assertions.h"
+#include "mozilla/CachedInheritingStyles.h"
+#include "mozilla/Maybe.h"
+#include "mozilla/PseudoStyleType.h"
+#include "mozilla/ServoComputedData.h"
+#include "mozilla/ServoStyleConsts.h"
+#include "nsCSSPseudoElements.h"
+#include "nsColor.h"
+
+#include "nsStyleStructFwd.h"
+
+enum nsChangeHint : uint32_t;
+class nsWindowSizes;
+
+#define STYLE_STRUCT(name_) struct nsStyle##name_;
+#include "nsStyleStructList.h"
+#undef STYLE_STRUCT
+
+extern "C" {
+void Gecko_ComputedStyle_Destroy(mozilla::ComputedStyle*);
+}
+
+namespace mozilla {
+
+enum class StylePointerEvents : uint8_t;
+enum class StyleUserSelect : uint8_t;
+
+namespace dom {
+class Document;
+}
+
+/**
+ * A ComputedStyle represents the computed style data for an element.
+ *
+ * The computed style data are stored in a set of reference counted structs
+ * (see nsStyleStruct.h) that are stored directly on the ComputedStyle.
+ *
+ * Style structs are immutable once they have been produced, so when any change
+ * is made that needs a restyle, we create a new ComputedStyle.
+ *
+ * ComputedStyles are reference counted. References are generally held by:
+ *
+ * 1. nsIFrame::mComputedStyle, for every frame
+ * 2. Element::mServoData, for every element not inside a display:none subtree
+ * 3. nsComputedDOMStyle, when created for elements in display:none subtrees
+ * 4. media_queries::Device, which holds the initial value of every property
+ */
+
+class ComputedStyle {
+ using Flag = StyleComputedValueFlags;
+
+ const StyleComputedValueFlags& Flags() const { return mSource.flags; }
+
+ public:
+ ComputedStyle(PseudoStyleType aPseudoType,
+ ServoComputedDataForgotten aComputedValues);
+
+ // Returns the computed (not resolved) value of the given property.
+ void GetComputedPropertyValue(nsCSSPropertyID aId, nsACString& aOut) const {
+ Servo_GetComputedValue(this, aId, &aOut);
+ }
+
+ // Return the ComputedStyle whose style data should be used for the R,
+ // G, and B components of color, background-color, and border-*-color
+ // if RelevantLinkIsVisited().
+ //
+ // GetPseudo() and GetPseudoType() on this ComputedStyle return the
+ // same as on |this|, and its depth in the tree (number of GetParent()
+ // calls until null is returned) is the same as |this|, since its
+ // parent is either |this|'s parent or |this|'s parent's
+ // style-if-visited.
+ //
+ // Structs on this context should never be examined without also
+ // examining the corresponding struct on |this|. Doing so will likely
+ // both (1) lead to a privacy leak and (2) lead to dynamic change bugs
+ // related to the Peek code in ComputedStyle::CalcStyleDifference.
+ const ComputedStyle* GetStyleIfVisited() const {
+ return mSource.visited_style;
+ }
+
+ bool IsLazilyCascadedPseudoElement() const {
+ return IsPseudoElement() &&
+ !nsCSSPseudoElements::IsEagerlyCascadedInServo(GetPseudoType());
+ }
+
+ PseudoStyleType GetPseudoType() const { return mPseudoType; }
+
+ bool IsPseudoElement() const {
+ return PseudoStyle::IsPseudoElement(mPseudoType);
+ }
+
+ bool IsInheritingAnonBox() const {
+ return PseudoStyle::IsInheritingAnonBox(mPseudoType);
+ }
+
+ bool IsNonInheritingAnonBox() const {
+ return PseudoStyle::IsNonInheritingAnonBox(mPseudoType);
+ }
+
+ bool IsWrapperAnonBox() const {
+ return PseudoStyle::IsWrapperAnonBox(mPseudoType);
+ }
+
+ bool IsAnonBox() const { return PseudoStyle::IsAnonBox(mPseudoType); }
+
+ bool IsPseudoOrAnonBox() const {
+ return mPseudoType != PseudoStyleType::NotPseudo;
+ }
+
+ // Whether there are author-specified rules for border or background
+ // properties.
+ // Only returns something meaningful if the appearance property is not `none`.
+ bool HasAuthorSpecifiedBorderOrBackground() const {
+ return bool(Flags() & Flag::HAS_AUTHOR_SPECIFIED_BORDER_BACKGROUND);
+ }
+
+ // Does this ComputedStyle or any of its ancestors have text
+ // decoration lines?
+ // Differs from nsStyleTextReset::HasTextDecorationLines, which tests
+ // only the data for a single context.
+ bool HasTextDecorationLines() const {
+ return bool(Flags() & Flag::HAS_TEXT_DECORATION_LINES);
+ }
+
+ // Whether any line break inside should be suppressed? If this returns
+ // true, the line should not be broken inside, which means inlines act
+ // as if nowrap is set, <br> is suppressed, and blocks are inlinized.
+ // This bit is propogated to all children of line partitipants. It is
+ // currently used by ruby to make its content frames unbreakable.
+ // NOTE: for nsTextFrame, use nsTextFrame::ShouldSuppressLineBreak()
+ // instead of this method.
+ bool ShouldSuppressLineBreak() const {
+ return bool(Flags() & Flag::SHOULD_SUPPRESS_LINEBREAK);
+ }
+
+ // Is this horizontal-in-vertical (tate-chu-yoko) text? This flag is
+ // only set on ComputedStyles whose pseudo is nsCSSAnonBoxes::mozText().
+ bool IsTextCombined() const { return bool(Flags() & Flag::IS_TEXT_COMBINED); }
+
+ // Whether there's any font metric dependency coming directly from our style.
+ bool DependsOnSelfFontMetrics() const {
+ return bool(Flags() & Flag::DEPENDS_ON_SELF_FONT_METRICS);
+ }
+
+ // Whether there's any font metric dependency coming directly from our parent
+ // style.
+ bool DependsOnInheritedFontMetrics() const {
+ return bool(Flags() & Flag::DEPENDS_ON_INHERITED_FONT_METRICS);
+ }
+
+ // Does this ComputedStyle represent the style for a pseudo-element or
+ // inherit data from such a ComputedStyle? Whether this returns true
+ // is equivalent to whether it or any of its ancestors returns
+ // non-null for IsPseudoElement().
+ bool HasPseudoElementData() const {
+ return bool(Flags() & Flag::IS_IN_PSEUDO_ELEMENT_SUBTREE);
+ }
+
+ bool SelfOrAncestorHasContainStyle() const {
+ return bool(Flags() & Flag::SELF_OR_ANCESTOR_HAS_CONTAIN_STYLE);
+ }
+
+ // Is the only link whose visitedness is allowed to influence the
+ // style of the node this ComputedStyle is for (which is that element
+ // or its nearest ancestor that is a link) visited?
+ bool RelevantLinkVisited() const {
+ return bool(Flags() & Flag::IS_RELEVANT_LINK_VISITED);
+ }
+
+ // Whether this style is for the root element of the document.
+ bool IsRootElementStyle() const {
+ return bool(Flags() & Flag::IS_ROOT_ELEMENT_STYLE);
+ }
+
+ bool IsInOpacityZeroSubtree() const {
+ return bool(Flags() & Flag::IS_IN_OPACITY_ZERO_SUBTREE);
+ }
+
+ ComputedStyle* GetCachedInheritingAnonBoxStyle(
+ PseudoStyleType aPseudoType) const {
+ MOZ_ASSERT(PseudoStyle::IsInheritingAnonBox(aPseudoType));
+ return mCachedInheritingStyles.Lookup(aPseudoType);
+ }
+
+ void SetCachedInheritedAnonBoxStyle(ComputedStyle* aStyle) {
+ mCachedInheritingStyles.Insert(aStyle);
+ }
+
+ ComputedStyle* GetCachedLazyPseudoStyle(PseudoStyleType aPseudo) const;
+
+ void SetCachedLazyPseudoStyle(ComputedStyle* aStyle) {
+ MOZ_ASSERT(aStyle->IsPseudoElement());
+ MOZ_ASSERT(!GetCachedLazyPseudoStyle(aStyle->GetPseudoType()));
+ MOZ_ASSERT(aStyle->IsLazilyCascadedPseudoElement());
+
+ // Since we're caching lazy pseudo styles on the ComputedValues of the
+ // originating element, we can assume that we either have the same
+ // originating element, or that they were at least similar enough to share
+ // the same ComputedValues, which means that they would match the same
+ // pseudo rules. This allows us to avoid matching selectors and checking
+ // the rule node before deciding to share.
+ //
+ // The one place this optimization breaks is with pseudo-elements that
+ // support state (like :hover). So we just avoid sharing in those cases.
+ if (nsCSSPseudoElements::PseudoElementSupportsUserActionState(
+ aStyle->GetPseudoType())) {
+ return;
+ }
+
+ mCachedInheritingStyles.Insert(aStyle);
+ }
+
+#define STYLE_STRUCT(name_) \
+ inline const nsStyle##name_* Style##name_() const MOZ_NONNULL_RETURN { \
+ return mSource.Style##name_(); \
+ }
+#include "nsStyleStructList.h"
+#undef STYLE_STRUCT
+
+ inline mozilla::StylePointerEvents PointerEvents() const;
+ inline mozilla::StyleUserSelect UserSelect() const;
+
+ /**
+ * Returns whether the element is a containing block for its absolutely
+ * positioned descendants.
+ * aContextFrame is the frame for which this is the style (or an old style).
+ */
+ inline bool IsAbsPosContainingBlock(const nsIFrame*) const;
+
+ /**
+ * Returns true when the element is a containing block for its fixed-pos
+ * descendants.
+ * aContextFrame is the frame for which this is the style (or an old style).
+ */
+ inline bool IsFixedPosContainingBlock(const nsIFrame*) const;
+
+ /**
+ * Tests for only the sub-parts of IsFixedPosContainingBlock that apply to:
+ * - nearly all frames, except those that are in SVG text subtrees.
+ * - frames that support CSS contain:layout and contain:paint and are not
+ * in SVG text subtrees.
+ * - frames that support CSS transforms and are not in SVG text subtrees.
+ *
+ * This should be used only when the caller has the style but not the
+ * frame (i.e., when calculating style changes).
+ */
+ inline bool IsFixedPosContainingBlockForNonSVGTextFrames() const;
+
+ /**
+ * Compute the style changes needed during restyling when this style
+ * context is being replaced by aNewContext. (This is nonsymmetric since
+ * we optimize by skipping comparison for styles that have never been
+ * requested.)
+ *
+ * This method returns a change hint (see nsChangeHint.h). All change
+ * hints apply to the frame and its later continuations or ib-split
+ * siblings. Most (all of those except the "NotHandledForDescendants"
+ * hints) also apply to all descendants.
+ *
+ * aEqualStructs must not be null. Into it will be stored a bitfield
+ * representing which structs were compared to be non-equal.
+ *
+ * CSS Variables are not compared here. Instead, the caller is responsible for
+ * that when needed (basically only for elements).
+ */
+ nsChangeHint CalcStyleDifference(const ComputedStyle& aNewContext,
+ uint32_t* aEqualStructs) const;
+
+#ifdef DEBUG
+ bool EqualForCachedAnonymousContentStyle(const ComputedStyle&) const;
+#endif
+
+#ifdef DEBUG
+ void DumpMatchedRules() const;
+#endif
+
+ /**
+ * Get a color that depends on link-visitedness using this and
+ * this->GetStyleIfVisited().
+ *
+ * @param aField A pointer to a member variable in a style struct.
+ * The member variable and its style struct must have
+ * been listed in nsCSSVisitedDependentPropList.h.
+ */
+ template <typename T, typename S>
+ nscolor GetVisitedDependentColor(T S::*aField) const;
+
+ /**
+ * aColors should be a two element array of nscolor in which the first
+ * color is the unvisited color and the second is the visited color.
+ *
+ * Combine the R, G, and B components of whichever of aColors should
+ * be used based on aLinkIsVisited with the A component of aColors[0].
+ */
+ static nscolor CombineVisitedColors(nscolor* aColors, bool aLinkIsVisited);
+
+ /**
+ * Start image loads for this style.
+ *
+ * The Document is used to get a hand on the image loader. The old style is a
+ * hack for bug 1439285.
+ */
+ inline void StartImageLoads(dom::Document&,
+ const ComputedStyle* aOldStyle = nullptr);
+
+#ifdef DEBUG
+ void List(FILE* out, int32_t aIndent);
+ static const char* StructName(StyleStructID aSID);
+ static Maybe<StyleStructID> LookupStruct(const nsACString& aName);
+#endif
+
+ // The |aCVsSize| outparam on this function is where the actual CVs size
+ // value is added. It's done that way because the callers know which value
+ // the size should be added to.
+ void AddSizeOfIncludingThis(nsWindowSizes& aSizes, size_t* aCVsSize) const;
+
+ StyleWritingMode WritingMode() const { return {mSource.WritingMode().mBits}; }
+
+ protected:
+ // Needs to be friend so that it can call the destructor without making it
+ // public.
+ friend void ::Gecko_ComputedStyle_Destroy(ComputedStyle*);
+
+ ~ComputedStyle() = default;
+
+ ServoComputedData mSource;
+
+ // A cache of anonymous box and lazy pseudo styles inheriting from this style.
+ CachedInheritingStyles mCachedInheritingStyles;
+
+ const PseudoStyleType mPseudoType;
+};
+
+} // namespace mozilla
+
+#endif