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3483fb3f51
Set the MOZ_DEBUG_RESTYLE environment variable and every restyle will have detailed logging printed to stderr. By default, restyles for animations are not logged; you can include them by also setting MOZ_DEBUG_RESTYLE_ANIMATIONS. If you wish to limit restyle logging to a particular change, you can call nsPresContext::StartRestyleLogging() and nsPresContext::StopRestyleLogging() at appropriate points. (You might want to add a couple of helper methods temporarily on nsIDocument and then expose them to your page with Web IDL to make them easier to call.) You do not need to have set MOZ_DEBUG_RESTYLE for this to work.
506 lines
21 KiB
C++
506 lines
21 KiB
C++
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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/* the interface (to internal code) for retrieving computed style data */
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#ifndef _nsStyleContext_h_
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#define _nsStyleContext_h_
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#include "nsRuleNode.h"
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#include "nsCSSPseudoElements.h"
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class nsIAtom;
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class nsPresContext;
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/**
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* An nsStyleContext represents the computed style data for an element.
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* The computed style data are stored in a set of structs (see
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* nsStyleStruct.h) that are cached either on the style context or in
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* the rule tree (see nsRuleNode.h for a description of this caching and
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* how the cached structs are shared).
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*
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* Since the data in |nsIStyleRule|s and |nsRuleNode|s are immutable
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* (with a few exceptions, like system color changes), the data in an
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* nsStyleContext are also immutable (with the additional exception of
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* GetUniqueStyleData). When style data change,
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* nsFrameManager::ReResolveStyleContext creates a new style context.
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*
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* Style contexts are reference counted. References are generally held
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* by:
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* 1. the |nsIFrame|s that are using the style context and
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* 2. any *child* style contexts (this might be the reverse of
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* expectation, but it makes sense in this case)
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* Style contexts participate in the mark phase of rule node garbage
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* collection.
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*/
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class nsStyleContext MOZ_FINAL
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{
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public:
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/**
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* Create a new style context.
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* @param aParent The parent of a style context is used for CSS
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* inheritance. When the element or pseudo-element
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* this style context represents the style data of
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* inherits a CSS property, the value comes from the
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* parent style context. This means style context
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* parentage must match the definitions of inheritance
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* in the CSS specification.
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* @param aPseudoTag The pseudo-element or anonymous box for which
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* this style context represents style. Null if
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* this style context is for a normal DOM element.
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* @param aPseudoType Must match aPseudoTag.
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* @param aRuleNode A rule node representing the ordered sequence of
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* rules that any element, pseudo-element, or
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* anonymous box that this style context is for
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* matches. See |nsRuleNode| and |nsIStyleRule|.
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* @param aSkipParentDisplayBasedStyleFixup
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* If set, this flag indicates that we should skip
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* the chunk of ApplyStyleFixups() that applies to
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* special cases where a child element's style may
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* need to be modified based on its parent's display
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* value.
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*/
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nsStyleContext(nsStyleContext* aParent, nsIAtom* aPseudoTag,
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nsCSSPseudoElements::Type aPseudoType,
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nsRuleNode* aRuleNode,
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bool aSkipParentDisplayBasedStyleFixup);
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void* operator new(size_t sz, nsPresContext* aPresContext) CPP_THROW_NEW;
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void Destroy();
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nsrefcnt AddRef() {
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if (mRefCnt == UINT32_MAX) {
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NS_WARNING("refcount overflow, leaking object");
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return mRefCnt;
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}
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++mRefCnt;
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NS_LOG_ADDREF(this, mRefCnt, "nsStyleContext", sizeof(nsStyleContext));
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return mRefCnt;
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}
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nsrefcnt Release() {
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if (mRefCnt == UINT32_MAX) {
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NS_WARNING("refcount overflow, leaking object");
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return mRefCnt;
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}
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--mRefCnt;
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NS_LOG_RELEASE(this, mRefCnt, "nsStyleContext");
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if (mRefCnt == 0) {
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Destroy();
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return 0;
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}
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return mRefCnt;
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}
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bool HasSingleReference() const {
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NS_ASSERTION(mRefCnt != 0,
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"do not call HasSingleReference on a newly created "
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"nsStyleContext with no references yet");
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return mRefCnt == 1;
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}
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nsPresContext* PresContext() const { return mRuleNode->PresContext(); }
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nsStyleContext* GetParent() const { return mParent; }
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nsIAtom* GetPseudo() const { return mPseudoTag; }
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nsCSSPseudoElements::Type GetPseudoType() const {
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return static_cast<nsCSSPseudoElements::Type>(mBits >>
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NS_STYLE_CONTEXT_TYPE_SHIFT);
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}
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// Find, if it already exists *and is easily findable* (i.e., near the
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// start of the child list), a style context whose:
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// * GetPseudo() matches aPseudoTag
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// * RuleNode() matches aRules
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// * !GetStyleIfVisited() == !aRulesIfVisited, and, if they're
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// non-null, GetStyleIfVisited()->RuleNode() == aRulesIfVisited
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// * RelevantLinkVisited() == aRelevantLinkVisited
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already_AddRefed<nsStyleContext>
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FindChildWithRules(const nsIAtom* aPseudoTag, nsRuleNode* aRules,
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nsRuleNode* aRulesIfVisited,
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bool aRelevantLinkVisited);
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// Does this style context or any of its ancestors have text
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// decoration lines?
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bool HasTextDecorationLines() const
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{ return !!(mBits & NS_STYLE_HAS_TEXT_DECORATION_LINES); }
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// Does this style context represent the style for a pseudo-element or
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// inherit data from such a style context? Whether this returns true
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// is equivalent to whether it or any of its ancestors returns
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// non-null for GetPseudo.
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bool HasPseudoElementData() const
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{ return !!(mBits & NS_STYLE_HAS_PSEUDO_ELEMENT_DATA); }
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// Is the only link whose visitedness is allowed to influence the
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// style of the node this style context is for (which is that element
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// or its nearest ancestor that is a link) visited?
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bool RelevantLinkVisited() const
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{ return !!(mBits & NS_STYLE_RELEVANT_LINK_VISITED); }
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// Is this a style context for a link?
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bool IsLinkContext() const {
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return
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GetStyleIfVisited() && GetStyleIfVisited()->GetParent() == GetParent();
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}
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// Is this style context the GetStyleIfVisited() for some other style
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// context?
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bool IsStyleIfVisited() const
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{ return !!(mBits & NS_STYLE_IS_STYLE_IF_VISITED); }
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// Tells this style context that it should return true from
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// IsStyleIfVisited.
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void SetIsStyleIfVisited()
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{ mBits |= NS_STYLE_IS_STYLE_IF_VISITED; }
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// Return the style context whose style data should be used for the R,
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// G, and B components of color, background-color, and border-*-color
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// if RelevantLinkIsVisited().
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//
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// GetPseudo() and GetPseudoType() on this style context return the
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// same as on |this|, and its depth in the tree (number of GetParent()
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// calls until null is returned) is the same as |this|, since its
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// parent is either |this|'s parent or |this|'s parent's
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// style-if-visited.
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//
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// Structs on this context should never be examined without also
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// examining the corresponding struct on |this|. Doing so will likely
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// both (1) lead to a privacy leak and (2) lead to dynamic change bugs
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// related to the Peek code in nsStyleContext::CalcStyleDifference.
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nsStyleContext* GetStyleIfVisited() const
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{ return mStyleIfVisited; }
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// To be called only from nsStyleSet.
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void SetStyleIfVisited(already_AddRefed<nsStyleContext> aStyleIfVisited)
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{
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NS_ABORT_IF_FALSE(!IsStyleIfVisited(), "this context is not visited data");
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NS_ASSERTION(!mStyleIfVisited, "should only be set once");
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mStyleIfVisited = aStyleIfVisited;
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NS_ABORT_IF_FALSE(mStyleIfVisited->IsStyleIfVisited(),
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"other context is visited data");
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NS_ABORT_IF_FALSE(!mStyleIfVisited->GetStyleIfVisited(),
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"other context does not have visited data");
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NS_ASSERTION(GetStyleIfVisited()->GetPseudo() == GetPseudo(),
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"pseudo tag mismatch");
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if (GetParent() && GetParent()->GetStyleIfVisited()) {
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NS_ASSERTION(GetStyleIfVisited()->GetParent() ==
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GetParent()->GetStyleIfVisited() ||
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GetStyleIfVisited()->GetParent() == GetParent(),
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"parent mismatch");
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} else {
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NS_ASSERTION(GetStyleIfVisited()->GetParent() == GetParent(),
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"parent mismatch");
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}
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}
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// Does this style context, or any of its descendants, have any style values
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// that were computed based on this style context's grandparent style context
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// or any of the grandparent's ancestors?
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bool UsesGrandancestorStyle() const
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{ return !!(mBits & NS_STYLE_USES_GRANDANCESTOR_STYLE); }
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// Is this style context shared with a sibling or cousin?
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// (See nsStyleSet::GetContext.)
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bool IsShared() const
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{ return !!(mBits & NS_STYLE_IS_SHARED); }
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// Does this style context have any children that return true for
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// UsesGrandancestorStyle()?
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bool HasChildThatUsesGrandancestorStyle() const;
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// Tell this style context to cache aStruct as the struct for aSID
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void SetStyle(nsStyleStructID aSID, void* aStruct);
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// Setters for inherit structs only, since rulenode only sets those eagerly.
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#define STYLE_STRUCT_INHERITED(name_, checkdata_cb_) \
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void SetStyle##name_ (nsStyle##name_ * aStruct) { \
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void *& slot = \
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mCachedInheritedData.mStyleStructs[eStyleStruct_##name_]; \
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NS_ASSERTION(!slot || \
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(mBits & \
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nsCachedStyleData::GetBitForSID(eStyleStruct_##name_)), \
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"Going to leak styledata"); \
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slot = aStruct; \
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}
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#define STYLE_STRUCT_RESET(name_, checkdata_cb_) /* nothing */
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#include "nsStyleStructList.h"
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#undef STYLE_STRUCT_RESET
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#undef STYLE_STRUCT_INHERITED
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/**
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* Returns whether this style context and aOther both have the same
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* cached style struct pointer for a given style struct.
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*/
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bool HasSameCachedStyleData(nsStyleContext* aOther, nsStyleStructID aSID);
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/**
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* Returns whether this style context has cached, inherited style data for a
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* given style struct.
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*/
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bool HasCachedInheritedStyleData(nsStyleStructID aSID)
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{ return mBits & nsCachedStyleData::GetBitForSID(aSID); }
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nsRuleNode* RuleNode() { return mRuleNode; }
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void AddStyleBit(const uint64_t& aBit) { mBits |= aBit; }
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/*
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* Mark this style context's rule node (and its ancestors) to prevent
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* it from being garbage collected.
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*/
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void Mark();
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/*
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* Get the style data for a style struct. This is the most important
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* member function of nsIStyleContext. It fills in a const pointer
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* to a style data struct that is appropriate for the style context's
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* frame. This struct may be shared with other contexts (either in
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* the rule tree or the style context tree), so it should not be
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* modified.
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*
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* This function will NOT return null (even when out of memory) when
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* given a valid style struct ID, so the result does not need to be
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* null-checked.
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*
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* The typesafe functions below are preferred to the use of this
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* function, both because they're easier to read and because they're
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* faster.
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*/
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const void* NS_FASTCALL StyleData(nsStyleStructID aSID);
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/**
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* Define typesafe getter functions for each style struct by
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* preprocessing the list of style structs. These functions are the
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* preferred way to get style data. The macro creates functions like:
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* const nsStyleBorder* StyleBorder();
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* const nsStyleColor* StyleColor();
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*/
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#define STYLE_STRUCT(name_, checkdata_cb_) \
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const nsStyle##name_ * Style##name_() { \
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return DoGetStyle##name_(true); \
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}
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#include "nsStyleStructList.h"
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#undef STYLE_STRUCT
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/**
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* PeekStyle* is like GetStyle* but doesn't trigger style
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* computation if the data is not cached on either the style context
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* or the rule node.
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*
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* Perhaps this shouldn't be a public nsStyleContext API.
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*/
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#define STYLE_STRUCT(name_, checkdata_cb_) \
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const nsStyle##name_ * PeekStyle##name_() { \
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return DoGetStyle##name_(false); \
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}
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#include "nsStyleStructList.h"
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#undef STYLE_STRUCT
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void* GetUniqueStyleData(const nsStyleStructID& aSID);
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/**
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* Compute the style changes needed during restyling when this style
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* context is being replaced by aOther. (This is nonsymmetric since
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* we optimize by skipping comparison for styles that have never been
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* requested.)
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*
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* This method returns a change hint (see nsChangeHint.h). All change
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* hints apply to the frame and its later continuations or ib-split
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* siblings. Most (all of those except the "NotHandledForDescendants"
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* hints) also apply to all descendants. The caller must pass in any
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* non-inherited hints that resulted from the parent style context's
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* style change. The caller *may* pass more hints than needed, but
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* must not pass less than needed; therefore if the caller doesn't
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* know, the caller should pass
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* nsChangeHint_Hints_NotHandledForDescendants.
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*
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* aEqualStructs must not be null. Into it will be stored a bitfield
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* representing which structs were compared to be non-equal.
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*/
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nsChangeHint CalcStyleDifference(nsStyleContext* aOther,
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nsChangeHint aParentHintsNotHandledForDescendants,
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uint32_t* aEqualStructs);
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/**
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* Get a color that depends on link-visitedness using this and
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* this->GetStyleIfVisited().
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*
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* aProperty must be a color-valued property that StyleAnimationValue
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* knows how to extract. It must also be a property that we know to
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* do change handling for in nsStyleContext::CalcDifference.
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*
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* Note that if aProperty is eCSSProperty_border_*_color, this
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* function handles -moz-use-text-color.
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*/
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nscolor GetVisitedDependentColor(nsCSSProperty aProperty);
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/**
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* aColors should be a two element array of nscolor in which the first
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* color is the unvisited color and the second is the visited color.
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*
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* Combine the R, G, and B components of whichever of aColors should
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* be used based on aLinkIsVisited with the A component of aColors[0].
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*/
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static nscolor CombineVisitedColors(nscolor *aColors,
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bool aLinkIsVisited);
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/**
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* Start the background image loads for this style context.
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*/
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void StartBackgroundImageLoads() {
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// Just get our background struct; that should do the trick
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StyleBackground();
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}
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/**
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* Moves this style context to a new parent.
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*
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* This function violates style context tree immutability, and
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* is a very low-level function and should only be used after verifying
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* many conditions that make it safe to call.
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*/
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void MoveTo(nsStyleContext* aNewParent);
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/**
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* Swaps owned style struct pointers between this and aNewContext, on
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* the assumption that aNewContext is the new style context for a frame
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* and this is the old one. aStructs indicates which structs to consider
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* swapping; only those which are owned in both this and aNewContext
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* will be swapped.
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*
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* Additionally, if there are identical struct pointers for one of the
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* structs indicated by aStructs, and it is not an owned struct on this,
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* then the cached struct slot on this will be set to null. If the struct
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* has been swapped on an ancestor, this style context (being the old one)
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* will be left caching the struct pointer on the new ancestor, despite
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* inheriting from the old ancestor. This is not normally a problem, as
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* this style context will usually be destroyed by being released at the
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* end of ElementRestyler::Restyle; but for style contexts held on to outside
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* of the frame, we need to clear out the cached pointer so that if we need
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* it again we'll re-fetch it from the new ancestor.
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*/
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void SwapStyleData(nsStyleContext* aNewContext, uint32_t aStructs);
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/**
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* On each descendant of this style context, clears out any cached inherited
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* structs indicated in aStructs.
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*/
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void ClearCachedInheritedStyleDataOnDescendants(uint32_t aStructs);
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#ifdef DEBUG
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void List(FILE* out, int32_t aIndent);
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static void AssertStyleStructMaxDifferenceValid();
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static const char* StructName(nsStyleStructID aSID);
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#endif
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private:
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// Private destructor, to discourage deletion outside of Release():
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~nsStyleContext();
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void AddChild(nsStyleContext* aChild);
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void RemoveChild(nsStyleContext* aChild);
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void ApplyStyleFixups(bool aSkipParentDisplayBasedStyleFixup);
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// Helper function for HasChildThatUsesGrandancestorStyle.
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static bool ListContainsStyleContextThatUsesGrandancestorStyle(
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const nsStyleContext* aHead);
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// Helper function that GetStyleData and GetUniqueStyleData use. Only
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// returns the structs we cache ourselves; never consults the ruletree.
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inline const void* GetCachedStyleData(nsStyleStructID aSID);
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// Helper functions for GetStyle* and PeekStyle*
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#define STYLE_STRUCT_INHERITED(name_, checkdata_cb_) \
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const nsStyle##name_ * DoGetStyle##name_(bool aComputeData) { \
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const nsStyle##name_ * cachedData = \
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static_cast<nsStyle##name_*>( \
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mCachedInheritedData.mStyleStructs[eStyleStruct_##name_]); \
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if (cachedData) /* Have it cached already, yay */ \
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return cachedData; \
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/* Have the rulenode deal */ \
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return mRuleNode->GetStyle##name_(this, aComputeData); \
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}
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#define STYLE_STRUCT_RESET(name_, checkdata_cb_) \
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const nsStyle##name_ * DoGetStyle##name_(bool aComputeData) { \
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const nsStyle##name_ * cachedData = mCachedResetData \
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? static_cast<nsStyle##name_*>( \
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mCachedResetData->mStyleStructs[eStyleStruct_##name_]) \
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: nullptr; \
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if (cachedData) /* Have it cached already, yay */ \
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return cachedData; \
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/* Have the rulenode deal */ \
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return mRuleNode->GetStyle##name_(this, aComputeData); \
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}
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#include "nsStyleStructList.h"
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#undef STYLE_STRUCT_RESET
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#undef STYLE_STRUCT_INHERITED
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// Helper for ClearCachedInheritedStyleDataOnDescendants.
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void DoClearCachedInheritedStyleDataOnDescendants(uint32_t aStructs);
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#ifdef DEBUG
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void AssertStructsNotUsedElsewhere(nsStyleContext* aDestroyingContext,
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int32_t aLevels) const;
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#endif
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nsStyleContext* mParent; // STRONG
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// Children are kept in two circularly-linked lists. The list anchor
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// is not part of the list (null for empty), and we point to the first
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// child.
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// mEmptyChild for children whose rule node is the root rule node, and
|
|
// mChild for other children. The order of children is not
|
|
// meaningful.
|
|
nsStyleContext* mChild;
|
|
nsStyleContext* mEmptyChild;
|
|
nsStyleContext* mPrevSibling;
|
|
nsStyleContext* mNextSibling;
|
|
|
|
// Style to be used instead for the R, G, and B components of color,
|
|
// background-color, and border-*-color if the nearest ancestor link
|
|
// element is visited (see RelevantLinkVisited()).
|
|
nsRefPtr<nsStyleContext> mStyleIfVisited;
|
|
|
|
// If this style context is for a pseudo-element or anonymous box,
|
|
// the relevant atom.
|
|
nsCOMPtr<nsIAtom> mPseudoTag;
|
|
|
|
// The rule node is the node in the lexicographic tree of rule nodes
|
|
// (the "rule tree") that indicates which style rules are used to
|
|
// compute the style data, and in what cascading order. The least
|
|
// specific rule matched is the one whose rule node is a child of the
|
|
// root of the rule tree, and the most specific rule matched is the
|
|
// |mRule| member of |mRuleNode|.
|
|
nsRuleNode* const mRuleNode;
|
|
|
|
// mCachedInheritedData and mCachedResetData point to both structs that
|
|
// are owned by this style context and structs that are owned by one of
|
|
// this style context's ancestors (which are indirectly owned since this
|
|
// style context owns a reference to its parent). If the bit in |mBits|
|
|
// is set for a struct, that means that the pointer for that struct is
|
|
// owned by an ancestor or by mRuleNode rather than by this style context.
|
|
// Since style contexts typically have some inherited data but only sometimes
|
|
// have reset data, we always allocate the mCachedInheritedData, but only
|
|
// sometimes allocate the mCachedResetData.
|
|
nsResetStyleData* mCachedResetData; // Cached reset style data.
|
|
nsInheritedStyleData mCachedInheritedData; // Cached inherited style data
|
|
uint64_t mBits; // Which structs are inherited from the
|
|
// parent context or owned by mRuleNode.
|
|
uint32_t mRefCnt;
|
|
};
|
|
|
|
already_AddRefed<nsStyleContext>
|
|
NS_NewStyleContext(nsStyleContext* aParentContext,
|
|
nsIAtom* aPseudoTag,
|
|
nsCSSPseudoElements::Type aPseudoType,
|
|
nsRuleNode* aRuleNode,
|
|
bool aSkipParentDisplayBasedStyleFixup);
|
|
#endif
|