gecko/layout/style/nsIMediaList.h

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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
*
* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is mozilla.org code.
*
* The Initial Developer of the Original Code is
* Boris Zbarsky <bzbarsky@mit.edu>.
* Portions created by the Initial Developer are Copyright (C) 2001
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* L. David Baron <dbaron@dbaron.org>, Mozilla Corporation
*
* Alternatively, the contents of this file may be used under the terms of
* either of the GNU General Public License Version 2 or later (the "GPL"),
* or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
/*
* representation of media lists used when linking to style sheets or by
* @media rules
*/
#ifndef nsIMediaList_h_
#define nsIMediaList_h_
#include "nsIDOMMediaList.h"
#include "nsTArray.h"
#include "nsIAtom.h"
#include "nsCSSValue.h"
class nsPresContext;
class nsCSSStyleSheet;
class nsAString;
struct nsMediaFeature;
struct nsMediaExpression {
enum Range { eMin, eMax, eEqual };
const nsMediaFeature *mFeature;
Range mRange;
nsCSSValue mValue;
// aActualValue must be obtained from mFeature->mGetter
PRBool Matches(nsPresContext* aPresContext,
const nsCSSValue& aActualValue) const;
};
/**
* 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:
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,
PRBool aExpressionMatches);
PRBool Matches(nsPresContext* aPresContext) const;
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;
PRBool mExpressionMatches;
};
struct FeatureEntry {
const nsMediaFeature *mFeature;
nsTArray<ExpressionEntry> mExpressions;
};
nsCOMPtr<nsIAtom> mMedium;
nsTArray<FeatureEntry> mFeatureCache;
};
class nsMediaQuery {
public:
nsMediaQuery()
: mNegated(PR_FALSE)
, mHasOnly(PR_FALSE)
, mTypeOmitted(PR_FALSE)
, mHadUnknownExpression(PR_FALSE)
{
}
private:
// for Clone only
nsMediaQuery(const nsMediaQuery& aOther)
: mNegated(aOther.mNegated)
, mHasOnly(aOther.mHasOnly)
, mTypeOmitted(aOther.mTypeOmitted)
, mHadUnknownExpression(aOther.mHadUnknownExpression)
, mMediaType(aOther.mMediaType)
// Clone checks the result of this deep copy for allocation failure
, mExpressions(aOther.mExpressions)
{
}
public:
void SetNegated() { mNegated = PR_TRUE; }
void SetHasOnly() { mHasOnly = PR_TRUE; }
void SetTypeOmitted() { mTypeOmitted = PR_TRUE; }
void SetHadUnknownExpression() { mHadUnknownExpression = PR_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?
PRBool Matches(nsPresContext* aPresContext,
nsMediaQueryResultCacheKey& aKey) const;
private:
PRPackedBool mNegated;
PRPackedBool mHasOnly; // only needed for serialization
PRPackedBool mTypeOmitted; // only needed for serialization
PRPackedBool mHadUnknownExpression;
nsCOMPtr<nsIAtom> mMediaType;
nsTArray<nsMediaExpression> mExpressions;
};
class nsMediaList : public nsIDOMMediaList {
public:
nsMediaList();
NS_DECL_ISUPPORTS
NS_DECL_NSIDOMMEDIALIST
nsresult GetText(nsAString& aMediaText);
nsresult SetText(const nsAString& aMediaText);
PRBool Matches(nsPresContext* aPresContext,
nsMediaQueryResultCacheKey& aKey);
nsresult SetStyleSheet(nsCSSStyleSheet* aSheet);
nsresult AppendQuery(nsAutoPtr<nsMediaQuery>& aQuery) {
// Takes ownership of aQuery (if it succeeds)
if (!mArray.AppendElement(aQuery.get())) {
return NS_ERROR_OUT_OF_MEMORY;
}
aQuery.forget();
return NS_OK;
}
nsresult Clone(nsMediaList** aResult);
PRInt32 Count() { return mArray.Length(); }
nsMediaQuery* MediumAt(PRInt32 aIndex) { return mArray[aIndex]; }
void Clear() { mArray.Clear(); mIsEmpty = PR_TRUE; }
// a media list with no items may not represent the lack of a media
// list; it could represent the empty string or something with parser
// errors, which means that the media list should never match
void SetNonEmpty() { mIsEmpty = PR_FALSE; }
protected:
~nsMediaList();
nsresult Delete(const nsAString & aOldMedium);
nsresult Append(const nsAString & aOldMedium);
nsTArray<nsAutoPtr<nsMediaQuery> > mArray;
PRBool mIsEmpty;
// not refcounted; sheet will let us know when it goes away
// mStyleSheet is the sheet that needs to be dirtied when this medialist
// changes
nsCSSStyleSheet* mStyleSheet;
};
#endif /* !defined(nsIMediaList_h_) */