layout/style/MediaFeatureChange.h

   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 "nsChangeHint.h"
  13 #include "mozilla/Attributes.h"
  14 #include "mozilla/TypedEnumBits.h"
  15 #include "mozilla/ServoStyleConsts.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 ForPreferredColorSchemeChange() {
  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