gecko-dev/layout/style/nsMediaList.h

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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
*
* 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/. */
/*
* representation of media lists used when linking to style sheets or by
* @media rules
*/
#ifndef nsMediaList_h_
#define nsMediaList_h_
#include "nsAutoPtr.h"
#include "nsIDOMMediaList.h"
#include "nsTArray.h"
#include "nsIAtom.h"
#include "nsCSSValue.h"
#include "nsWrapperCache.h"
#include "mozilla/Attributes.h"
#include "mozilla/ErrorResult.h"
class nsPresContext;
class nsAString;
struct nsMediaFeature;
namespace mozilla {
class StyleSheet;
namespace css {
class DocumentRule;
} // namespace css
} // namespace mozilla
struct nsMediaExpression {
enum Range { eMin, eMax, eEqual };
const nsMediaFeature *mFeature;
Range mRange;
nsCSSValue mValue;
// aActualValue must be obtained from mFeature->mGetter
bool Matches(nsPresContext* aPresContext,
const nsCSSValue& aActualValue) const;
bool operator==(const nsMediaExpression& aOther) const {
return mFeature == aOther.mFeature && // pointer equality fine (atom-like)
mRange == aOther.mRange &&
mValue == aOther.mValue;
}
bool operator!=(const nsMediaExpression& aOther) const {
return !(*this == aOther);
}
};
/**
* An nsMediaQueryResultCacheKey records what feature/value combinations
* a set of media query results are valid for. This allows the caller
* to quickly learn whether a prior result of media query evaluation is
* still valid (e.g., due to a window size change) without rerunning all
* of the evaluation and rebuilding the list of rules.
*
* This object may not be used after any media rules in any of the
* sheets it was given to have been modified. However, this is
* generally not a problem since ClearRuleCascades is called on the
* sheet whenever this happens, and these objects are stored inside the
* rule cascades. (FIXME: We're not actually doing this all the time.)
*
* The implementation could be further optimized in the future to store
* ranges (combinations of less-than, less-than-or-equal, greater-than,
* greater-than-or-equal, equal, not-equal, present, not-present) for
* each feature rather than simply storing the list of expressions.
* However, this requires combining any such ranges.
*/
class nsMediaQueryResultCacheKey {
public:
explicit nsMediaQueryResultCacheKey(nsIAtom* aMedium)
: mMedium(aMedium)
{}
/**
* Record that aExpression was tested while building the cached set
* that this cache key is for, and that aExpressionMatches was whether
* it matched.
*/
void AddExpression(const nsMediaExpression* aExpression,
bool aExpressionMatches);
bool Matches(nsPresContext* aPresContext) const;
bool HasFeatureConditions() const {
return !mFeatureCache.IsEmpty();
}
/**
* An operator== that implements list equality, which isn't quite as
* good as set equality, but catches the trivial equality cases.
*/
bool operator==(const nsMediaQueryResultCacheKey& aOther) const {
return mMedium == aOther.mMedium &&
mFeatureCache == aOther.mFeatureCache;
}
bool operator!=(const nsMediaQueryResultCacheKey& aOther) const {
return !(*this == aOther);
}
private:
struct ExpressionEntry {
// FIXME: if we were better at maintaining invariants about clearing
// rule cascades when media lists change, this could be a |const
// nsMediaExpression*| instead.
nsMediaExpression mExpression;
bool mExpressionMatches;
bool operator==(const ExpressionEntry& aOther) const {
return mExpression == aOther.mExpression &&
mExpressionMatches == aOther.mExpressionMatches;
}
bool operator!=(const ExpressionEntry& aOther) const {
return !(*this == aOther);
}
};
struct FeatureEntry {
const nsMediaFeature *mFeature;
InfallibleTArray<ExpressionEntry> mExpressions;
bool operator==(const FeatureEntry& aOther) const {
return mFeature == aOther.mFeature &&
mExpressions == aOther.mExpressions;
}
bool operator!=(const FeatureEntry& aOther) const {
return !(*this == aOther);
}
};
nsCOMPtr<nsIAtom> mMedium;
nsTArray<FeatureEntry> mFeatureCache;
};
/**
* nsDocumentRuleResultCacheKey is analagous to nsMediaQueryResultCacheKey
* and stores the result of matching the @-moz-document rules from a set
* of style sheets. nsCSSRuleProcessor builds up an
* nsDocumentRuleResultCacheKey as it visits the @-moz-document rules
* while building its RuleCascadeData.
*
* Rather than represent the result using a list of both the matching and
* non-matching rules, we just store the matched rules. The assumption is
* that in situations where we have a large number of rules -- such as the
* thousands added by AdBlock Plus -- that only a small number will be
* matched. Thus to check if the nsDocumentRuleResultCacheKey matches a
* given nsPresContext, we also need the entire list of @-moz-document
* rules to know which rules must not match.
*/
class nsDocumentRuleResultCacheKey
{
public:
#ifdef DEBUG
nsDocumentRuleResultCacheKey()
: mFinalized(false) {}
#endif
bool AddMatchingRule(mozilla::css::DocumentRule* aRule);
bool Matches(nsPresContext* aPresContext,
const nsTArray<mozilla::css::DocumentRule*>& aRules) const;
bool operator==(const nsDocumentRuleResultCacheKey& aOther) const {
MOZ_ASSERT(mFinalized);
MOZ_ASSERT(aOther.mFinalized);
return mMatchingRules == aOther.mMatchingRules;
}
bool operator!=(const nsDocumentRuleResultCacheKey& aOther) const {
return !(*this == aOther);
}
void Swap(nsDocumentRuleResultCacheKey& aOther) {
mMatchingRules.SwapElements(aOther.mMatchingRules);
#ifdef DEBUG
std::swap(mFinalized, aOther.mFinalized);
#endif
}
void Finalize();
#ifdef DEBUG
void List(FILE* aOut = stdout, int32_t aIndex = 0) const;
#endif
size_t SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const;
private:
nsTArray<mozilla::css::DocumentRule*> mMatchingRules;
#ifdef DEBUG
bool mFinalized;
#endif
};
class nsMediaQuery {
public:
nsMediaQuery()
: mNegated(false)
, mHasOnly(false)
, mTypeOmitted(false)
, mHadUnknownExpression(false)
{
}
private:
// for Clone only
nsMediaQuery(const nsMediaQuery& aOther)
: mNegated(aOther.mNegated)
, mHasOnly(aOther.mHasOnly)
, mTypeOmitted(aOther.mTypeOmitted)
, mHadUnknownExpression(aOther.mHadUnknownExpression)
, mMediaType(aOther.mMediaType)
, mExpressions(aOther.mExpressions)
{
MOZ_ASSERT(mExpressions.Length() == aOther.mExpressions.Length());
}
public:
void SetNegated() { mNegated = true; }
void SetHasOnly() { mHasOnly = true; }
void SetTypeOmitted() { mTypeOmitted = true; }
void SetHadUnknownExpression() { mHadUnknownExpression = true; }
void SetType(nsIAtom* aMediaType) {
NS_ASSERTION(aMediaType,
"expected non-null");
mMediaType = aMediaType;
}
// Return a new nsMediaExpression in the array for the caller to fill
// in. The caller must either fill it in completely, or call
// SetHadUnknownExpression on this nsMediaQuery.
// Returns null on out-of-memory.
nsMediaExpression* NewExpression() { return mExpressions.AppendElement(); }
void AppendToString(nsAString& aString) const;
nsMediaQuery* Clone() const;
// Does this query apply to the presentation?
// If |aKey| is non-null, add cache information to it.
bool Matches(nsPresContext* aPresContext,
nsMediaQueryResultCacheKey* aKey) const;
private:
bool mNegated;
bool mHasOnly; // only needed for serialization
bool mTypeOmitted; // only needed for serialization
bool mHadUnknownExpression;
nsCOMPtr<nsIAtom> mMediaType;
nsTArray<nsMediaExpression> mExpressions;
};
class nsMediaList final : public nsIDOMMediaList
, public nsWrapperCache
{
public:
typedef mozilla::ErrorResult ErrorResult;
nsMediaList();
virtual JSObject*
WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto) override;
nsISupports* GetParentObject() const
{
return nullptr;
}
NS_DECL_CYCLE_COLLECTING_ISUPPORTS
NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(nsMediaList)
NS_DECL_NSIDOMMEDIALIST
void GetText(nsAString& aMediaText);
void SetText(const nsAString& aMediaText);
// Does this query apply to the presentation?
// If |aKey| is non-null, add cache information to it.
bool Matches(nsPresContext* aPresContext,
nsMediaQueryResultCacheKey* aKey);
void SetStyleSheet(mozilla::StyleSheet* aSheet);
void AppendQuery(nsAutoPtr<nsMediaQuery>& aQuery) {
// Takes ownership of aQuery
mArray.AppendElement(aQuery.forget());
}
already_AddRefed<nsMediaList> Clone();
nsMediaQuery* MediumAt(int32_t aIndex) { return mArray[aIndex]; }
void Clear() { mArray.Clear(); }
// WebIDL
// XPCOM GetMediaText and SetMediaText are fine.
uint32_t Length() { return mArray.Length(); }
void IndexedGetter(uint32_t aIndex, bool& aFound, nsAString& aReturn);
// XPCOM Item is fine.
void DeleteMedium(const nsAString& aMedium, ErrorResult& aRv)
{
aRv = DeleteMedium(aMedium);
}
void AppendMedium(const nsAString& aMedium, ErrorResult& aRv)
{
aRv = AppendMedium(aMedium);
}
protected:
~nsMediaList();
nsresult Delete(const nsAString & aOldMedium);
nsresult Append(const nsAString & aOldMedium);
InfallibleTArray<nsAutoPtr<nsMediaQuery> > mArray;
// not refcounted; sheet will let us know when it goes away
// mStyleSheet is the sheet that needs to be dirtied when this medialist
// changes
mozilla::StyleSheet* mStyleSheet;
};
#endif /* !defined(nsMediaList_h_) */