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The Tor Browser
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MediaFeatureChange.h (3185B)

      1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
      2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
      3 /* This Source Code Form is subject to the terms of the Mozilla Public
      4 * License, v. 2.0. If a copy of the MPL was not distributed with this
      5 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
      6 
      7 /* A struct defining a media feature change. */
      8 
      9 #ifndef mozilla_MediaFeatureChange_h__
     10 #define mozilla_MediaFeatureChange_h__
     11 
     12 #include "mozilla/Attributes.h"
     13 #include "mozilla/ServoStyleConsts.h"
     14 #include "mozilla/TypedEnumBits.h"
     15 #include "nsChangeHint.h"
     16 
     17 namespace mozilla {
     18 
     19 enum class MediaFeatureChangeReason : uint8_t {
     20  // The viewport size the document has used has changed.
     21  //
     22  // This affects size media queries like min-width.
     23  ViewportChange = 1 << 0,
     24  // The effective text zoom has changed. This affects the meaning of em units,
     25  // and thus affects any media query that uses a Length.
     26  ZoomChange = 1 << 1,
     27  // The resolution has changed. This can affect device-pixel-ratio media
     28  // queries, for example.
     29  ResolutionChange = 1 << 2,
     30  // The medium has changed.
     31  MediumChange = 1 << 3,
     32  // The size-mode has changed.
     33  SizeModeChange = 1 << 4,
     34  // A system metric or multiple have changed. This affects all the media
     35  // features that expose the presence of a system metric directly.
     36  SystemMetricsChange = 1 << 5,
     37  // display-mode changed on the document, thus the display-mode media queries
     38  // may have changed.
     39  DisplayModeChange = 1 << 6,
     40  // A preference that affects media query results has changed. For
     41  // example, changes to document_color_use will affect
     42  // prefers-contrast.
     43  PreferenceChange = 1 << 7,
     44 };
     45 
     46 MOZ_MAKE_ENUM_CLASS_BITWISE_OPERATORS(MediaFeatureChangeReason)
     47 
     48 enum class MediaFeatureChangePropagation : uint8_t {
     49  JustThisDocument = 0,
     50  SubDocuments = 1 << 0,
     51  Images = 1 << 1,
     52  All = Images | SubDocuments,
     53 };
     54 
     55 MOZ_MAKE_ENUM_CLASS_BITWISE_OPERATORS(MediaFeatureChangePropagation)
     56 
     57 struct MediaFeatureChange {
     58  static const auto kAllChanges = static_cast<MediaFeatureChangeReason>(~0);
     59 
     60  RestyleHint mRestyleHint;
     61  nsChangeHint mChangeHint;
     62  MediaFeatureChangeReason mReason;
     63 
     64  MOZ_IMPLICIT MediaFeatureChange(MediaFeatureChangeReason aReason)
     65      : MediaFeatureChange(RestyleHint{0}, nsChangeHint(0), aReason) {}
     66 
     67  MediaFeatureChange(RestyleHint aRestyleHint, nsChangeHint aChangeHint,
     68                     MediaFeatureChangeReason aReason)
     69      : mRestyleHint(aRestyleHint),
     70        mChangeHint(aChangeHint),
     71        mReason(aReason) {}
     72 
     73  inline MediaFeatureChange& operator|=(const MediaFeatureChange& aOther) {
     74    mRestyleHint |= aOther.mRestyleHint;
     75    mChangeHint |= aOther.mChangeHint;
     76    mReason |= aOther.mReason;
     77    return *this;
     78  }
     79 
     80  static MediaFeatureChange ForPreferredColorSchemeOrForcedColorsChange() {
     81    // We need to restyle because not only media queries have changed, system
     82    // colors may as well via the prefers-color-scheme meta tag / effective
     83    // color-scheme property value.
     84    return {RestyleHint::RecascadeSubtree(), nsChangeHint(0),
     85            MediaFeatureChangeReason::SystemMetricsChange};
     86  }
     87 };
     88 
     89 }  // namespace mozilla
     90 
     91 #endif