gecko-dev/layout/style/nsMediaFeatures.h

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/* vim: set shiftwidth=4 tabstop=8 autoindent cindent expandtab: */
/* ***** 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 nsMediaFeatures.
*
* The Initial Developer of the Original Code is the Mozilla Foundation.
* Portions created by the Initial Developer are Copyright (C) 2008
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* L. David Baron <dbaron@dbaron.org>, Mozilla Corporation (original author)
*
* Alternatively, the contents of this file may be used under the terms of
* either 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 ***** */
/* the features that media queries can test */
#ifndef nsMediaFeatures_h_
#define nsMediaFeatures_h_
#include "nscore.h"
class nsIAtom;
class nsPresContext;
class nsCSSValue;
struct nsMediaFeature;
typedef nsresult
(* nsMediaFeatureValueGetter)(nsPresContext* aPresContext,
const nsMediaFeature* aFeature,
nsCSSValue& aResult);
struct nsMediaFeature {
nsIAtom **mName; // extra indirection to point to nsGkAtoms members
enum RangeType { eMinMaxAllowed, eMinMaxNotAllowed };
RangeType mRangeType;
enum ValueType {
// All value types allow eCSSUnit_Null to indicate that no value
// was given (in addition to the types listed below).
eLength, // values are such that nsCSSValue::IsLengthUnit() is true
eInteger, // values are eCSSUnit_Integer
eBoolInteger,// values are eCSSUnit_Integer (0, -0, or 1 only)
eIntRatio, // values are eCSSUnit_Array of two eCSSUnit_Integer
eResolution, // values are in eCSSUnit_Inch (for dpi) or
// eCSSUnit_Centimeter (for dpcm)
eEnumerated // values are eCSSUnit_Enumerated (uses keyword table)
// Note that a number of pieces of code (both for parsing and
// for matching of valueless expressions) assume that all numeric
// value types cannot be negative. The parsing code also does
// not allow zeros in eIntRatio types.
};
ValueType mValueType;
union {
// In static arrays, it's the first member that's initialized. We
// need that to be void* so we can initialize both other types.
// This member should never be accessed by name.
const void* mInitializer_;
// If mValueType == eEnumerated: const PRInt32*: keyword table in
// the same format as the keyword tables in nsCSSProps.
const PRInt32* mKeywordTable;
// If mGetter == GetSystemMetric (which implies mValueType ==
// eBoolInteger): nsIAtom * const *, for the system metric.
nsIAtom * const * mMetric;
} mData;
// A function that returns the current value for this feature for a
// given presentation. If it returns eCSSUnit_Null, the feature is
// not present.
nsMediaFeatureValueGetter mGetter;
};
class nsMediaFeatures {
public:
// Terminated with an entry whose mName is null.
static const nsMediaFeature features[];
};
#endif /* !defined(nsMediaFeatures_h_) */