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3353a9c0e3
The values in the boolean context depend on its feature. For examples, in the case of prefers-reduced-motion 'no-preference' means false and 'reduced' mean true in the boolean context, whereas in the case of prefers-contrast 'no-preference' means false and other two values, 'high' and 'low' means true in the boolean context. To support it we introduce a child struct of nsCSSKTableEntry that has an additional field representing the value in the boolean context and use it when we have no specified value in the media feature (i.e. in the boolean context). MozReview-Commit-ID: 79HiW8l5ous
125 lines
4.5 KiB
C++
125 lines
4.5 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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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 features that media queries can test */
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#ifndef nsMediaFeatures_h_
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#define nsMediaFeatures_h_
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#include <stdint.h>
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class nsAtom;
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class nsIDocument;
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struct nsCSSKTableEntry;
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class nsCSSValue;
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class nsStaticAtom;
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struct nsCSSKeywordAndBoolTableEntry : public nsCSSKTableEntry {
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constexpr nsCSSKeywordAndBoolTableEntry(nsCSSKeyword aKeyword, int16_t aValue)
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: nsCSSKTableEntry(aKeyword, aValue)
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, mValueInBooleanContext(true)
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{
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}
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template<typename T,
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typename = typename std::enable_if<std::is_enum<T>::value>::type>
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constexpr nsCSSKeywordAndBoolTableEntry(
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nsCSSKeyword aKeyword,
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T aValue,
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bool aValueInBooleanContext)
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: nsCSSKTableEntry(aKeyword, aValue)
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, mValueInBooleanContext(aValueInBooleanContext)
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{
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}
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bool mValueInBooleanContext;
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};
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struct nsMediaFeature;
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typedef void (*nsMediaFeatureValueGetter)(nsIDocument* aDocument,
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const nsMediaFeature* aFeature,
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nsCSSValue& aResult);
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struct nsMediaFeature
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{
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nsStaticAtom** mName; // extra indirection to point to nsGkAtoms members
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enum RangeType { eMinMaxAllowed, eMinMaxNotAllowed };
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RangeType mRangeType;
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enum ValueType {
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// All value types allow eCSSUnit_Null to indicate that no value
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// was given (in addition to the types listed below).
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eLength, // values are eCSSUnit_Pixel
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eInteger, // values are eCSSUnit_Integer
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eFloat, // values are eCSSUnit_Number
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eBoolInteger, // values are eCSSUnit_Integer (0, -0, or 1 only)
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eIntRatio, // values are eCSSUnit_Array of two eCSSUnit_Integer
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eResolution, // values are in eCSSUnit_Inch (for dpi),
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// eCSSUnit_Pixel (for dppx), or
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// eCSSUnit_Centimeter (for dpcm)
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eEnumerated, // values are eCSSUnit_Enumerated (uses keyword table)
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eBoolEnumerated, // values are eCSSUnit_Enumerated (uses keyword and boolean
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// pair table)
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eIdent // values are eCSSUnit_Ident
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// Note that a number of pieces of code (both for parsing and
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// for matching of valueless expressions) assume that all numeric
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// value types cannot be negative. The parsing code also does
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// not allow zeros in eIntRatio types.
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};
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ValueType mValueType;
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enum RequirementFlags : uint8_t {
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// Bitfield of requirements that must be satisfied in order for this
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// media feature to be active.
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eNoRequirements = 0,
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eHasWebkitPrefix = 1 << 0, // Feature name must start w/ "-webkit-", even
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// before any "min-"/"max-" qualifier.
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// Feature is only supported if the pref
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// "layout.css.prefixes.device-pixel-ratio-webkit" is enabled.
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// (Should only be used for -webkit-device-pixel-ratio.)
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eWebkitDevicePixelRatioPrefEnabled = 1 << 1,
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// Feature is only usable from UA sheets and chrome:// urls.
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eUserAgentAndChromeOnly = 1 << 2,
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};
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uint8_t mReqFlags;
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union {
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// In static arrays, it's the first member that's initialized. We
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// need that to be void* so we can initialize both other types.
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// This member should never be accessed by name.
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const void* mInitializer_;
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// If mValueType == eEnumerated: const int32_t*: keyword table in
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// the same format as the keyword tables in nsCSSProps.
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const nsCSSKTableEntry* mKeywordTable;
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// If mValueType == eBoolEnumerated: similar to the above but having a
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// boolean field representing the value in Boolean context.
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const nsCSSKeywordAndBoolTableEntry* mKeywordAndBoolTable;
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// If mGetter == GetSystemMetric (which implies mValueType ==
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// eBoolInteger): nsAtom * const *, for the system metric.
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nsAtom * const * mMetric;
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} mData;
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// A function that returns the current value for this feature for a
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// given presentation. If it returns eCSSUnit_Null, the feature is
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// not present.
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nsMediaFeatureValueGetter mGetter;
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};
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class nsMediaFeatures
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{
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public:
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static void InitSystemMetrics();
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static void FreeSystemMetrics();
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static void Shutdown();
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// Terminated with an entry whose mName is null.
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static const nsMediaFeature features[];
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};
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#endif /* !defined(nsMediaFeatures_h_) */
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