fune/layout/style/nsCSSProps.cpp

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

/*
 * methods for dealing with CSS properties and tables of the keyword
 * values they accept
 */

#include "nsCSSProps.h"

#include "mozilla/ArrayUtils.h"
#include "mozilla/Casting.h"

#include "gfxPlatform.h"
#include "nsLayoutUtils.h"
#include "nsIWidget.h"
#include "nsStyleConsts.h"  // For system widget appearance types

#include "mozilla/dom/Animation.h"
#include "mozilla/dom/AnimationEffectBinding.h"  // for PlaybackDirection
#include "mozilla/gfx/gfxVars.h"                 // for UseWebRender
#include "mozilla/gfx/gfxVarReceiver.h"
#include "mozilla/LookAndFeel.h"  // for system colors

#include "nsString.h"
#include "nsStaticNameTable.h"

#include "mozilla/Preferences.h"
#include "mozilla/StaticPrefs_layout.h"
#include "mozilla/StaticPtr.h"

using namespace mozilla;

static int32_t gPropertyTableRefCount;
static StaticAutoPtr<nsStaticCaseInsensitiveNameTable> gFontDescTable;
static StaticAutoPtr<nsStaticCaseInsensitiveNameTable> gCounterDescTable;
static StaticAutoPtr<nsTHashMap<nsCStringHashKey, nsCSSPropertyID>>
    gPropertyIDLNameTable;

static constexpr const char* const kCSSRawFontDescs[] = {
#define CSS_FONT_DESC(name_, method_) #name_,
#include "nsCSSFontDescList.h"
#undef CSS_FONT_DESC
};

static constexpr const char* const kCSSRawCounterDescs[] = {
#define CSS_COUNTER_DESC(name_, method_) #name_,
#include "nsCSSCounterDescList.h"
#undef CSS_COUNTER_DESC
};

static constexpr CSSPropFlags kFlagsTable[eCSSProperty_COUNT_with_aliases] = {
#define CSS_PROP_LONGHAND(name_, id_, method_, flags_, ...) flags_,
#define CSS_PROP_SHORTHAND(name_, id_, method_, flags_, ...) flags_,
#define CSS_PROP_ALIAS(name_, aliasid_, id_, method_, flags_, ...) flags_,
#include "mozilla/ServoCSSPropList.h"
#undef CSS_PROP_ALIAS
#undef CSS_PROP_SHORTHAND
#undef CSS_PROP_LONGHAND
};

static nsStaticCaseInsensitiveNameTable* CreateStaticTable(
    const char* const aRawTable[], int32_t aLength) {
  auto table = new nsStaticCaseInsensitiveNameTable(aRawTable, aLength);
#ifdef DEBUG
  // Partially verify the entries.
  for (int32_t index = 0; index < aLength; ++index) {
    nsAutoCString temp(aRawTable[index]);
    MOZ_ASSERT(-1 == temp.FindChar('_'),
               "underscore char in case insensitive name table");
  }
#endif
  return table;
}

void nsCSSProps::RecomputeEnabledState(const char* aPref, void*) {
  MOZ_RELEASE_ASSERT(NS_IsMainThread());
  DebugOnly<bool> foundPref = false;
  for (const PropertyPref* pref = kPropertyPrefTable;
       pref->mPropID != eCSSProperty_UNKNOWN; pref++) {
    if (!aPref || !strcmp(aPref, pref->mPref)) {
      foundPref = true;
#ifdef FUZZING
      gPropertyEnabled[pref->mPropID] = true;
#else
      gPropertyEnabled[pref->mPropID] = Preferences::GetBool(pref->mPref);
      if (pref->mPropID == eCSSProperty_backdrop_filter) {
        gPropertyEnabled[pref->mPropID] &=
            gfx::gfxVars::GetAllowBackdropFilterOrDefault();
      }
#endif
    }
  }
  MOZ_ASSERT(foundPref);
}

void nsCSSProps::AddRefTable(void) {
  if (0 == gPropertyTableRefCount++) {
    MOZ_ASSERT(!gFontDescTable, "pre existing array!");
    MOZ_ASSERT(!gCounterDescTable, "pre existing array!");
    MOZ_ASSERT(!gPropertyIDLNameTable, "pre existing array!");

    gFontDescTable = CreateStaticTable(kCSSRawFontDescs, eCSSFontDesc_COUNT);
    gCounterDescTable =
        CreateStaticTable(kCSSRawCounterDescs, eCSSCounterDesc_COUNT);

    gPropertyIDLNameTable = new nsTHashMap<nsCStringHashKey, nsCSSPropertyID>;
    for (nsCSSPropertyID p = nsCSSPropertyID(0);
         size_t(p) < ArrayLength(kIDLNameTable); p = nsCSSPropertyID(p + 1)) {
      if (kIDLNameTable[p]) {
        gPropertyIDLNameTable->InsertOrUpdate(
            nsDependentCString(kIDLNameTable[p]), p);
      }
    }

    static bool prefObserversInited = false;
    if (!prefObserversInited) {
      prefObserversInited = true;
      for (const PropertyPref* pref = kPropertyPrefTable;
           pref->mPropID != eCSSProperty_UNKNOWN; pref++) {
        // https://bugzilla.mozilla.org/show_bug.cgi?id=1472523
        // We need to use nsCString instead of substring because the preference
        // callback code stores them. Using AssignLiteral prevents any
        // unnecessary allocations.
        nsCString prefName;
        prefName.AssignLiteral(pref->mPref, strlen(pref->mPref));
        Preferences::RegisterCallback(nsCSSProps::RecomputeEnabledState,
                                      prefName);
      }
      RecomputeEnabledState(/* aPrefName = */ nullptr);
    }
  }
}

void nsCSSProps::ReleaseTable(void) {
  if (0 == --gPropertyTableRefCount) {
    gFontDescTable = nullptr;
    gCounterDescTable = nullptr;
    gPropertyIDLNameTable = nullptr;
  }
}

/* static */
bool nsCSSProps::IsCustomPropertyName(const nsACString& aProperty) {
  return aProperty.Length() >= CSS_CUSTOM_NAME_PREFIX_LENGTH &&
         StringBeginsWith(aProperty, "--"_ns);
}

nsCSSPropertyID nsCSSProps::LookupPropertyByIDLName(
    const nsACString& aPropertyIDLName, EnabledState aEnabled) {
  MOZ_ASSERT(gPropertyIDLNameTable, "no lookup table, needs addref");
  nsCSSPropertyID res;
  if (!gPropertyIDLNameTable->Get(aPropertyIDLName, &res)) {
    return eCSSProperty_UNKNOWN;
  }
  MOZ_ASSERT(res < eCSSProperty_COUNT);
  if (!IsEnabled(res, aEnabled)) {
    return eCSSProperty_UNKNOWN;
  }
  return res;
}

nsCSSFontDesc nsCSSProps::LookupFontDesc(const nsACString& aFontDesc) {
  MOZ_ASSERT(gFontDescTable, "no lookup table, needs addref");
  nsCSSFontDesc which = nsCSSFontDesc(gFontDescTable->Lookup(aFontDesc));

  if (which == eCSSFontDesc_Display &&
      !StaticPrefs::layout_css_font_display_enabled()) {
    which = eCSSFontDesc_UNKNOWN;
  }
  return which;
}

static constexpr auto sDescNullStr = ""_ns;

const nsCString& nsCSSProps::GetStringValue(nsCSSFontDesc aFontDescID) {
  MOZ_ASSERT(gFontDescTable, "no lookup table, needs addref");
  if (gFontDescTable) {
    return gFontDescTable->GetStringValue(int32_t(aFontDescID));
  }
  return sDescNullStr;
}

const nsCString& nsCSSProps::GetStringValue(nsCSSCounterDesc aCounterDescID) {
  MOZ_ASSERT(gCounterDescTable, "no lookup table, needs addref");
  if (gCounterDescTable) {
    return gCounterDescTable->GetStringValue(int32_t(aCounterDescID));
  }
  return sDescNullStr;
}

bool nsCSSProps::PropHasFlags(nsCSSPropertyID aProperty, Flags aFlags) {
  MOZ_ASSERT(0 <= aProperty && aProperty < eCSSProperty_COUNT_with_aliases,
             "out of range");
  return (kFlagsTable[aProperty] & aFlags) == aFlags;
}

/* static */
bool nsCSSProps::gPropertyEnabled[eCSSProperty_COUNT_with_aliases] = {
// If the property has any "ENABLED_IN" flag set, it is disabled by
// default. Note that, if a property has pref, whatever its default
// value is, it will later be changed in nsCSSProps::AddRefTable().
// If the property has "ENABLED_IN" flags but doesn't have a pref,
// it is an internal property which is disabled elsewhere.
#define IS_ENABLED_BY_DEFAULT(flags_) \
  (!((flags_) & (CSSPropFlags::EnabledMask | CSSPropFlags::Inaccessible)))

#define CSS_PROP_LONGHAND(name_, id_, method_, flags_, ...) \
  IS_ENABLED_BY_DEFAULT(flags_),
#define CSS_PROP_SHORTHAND(name_, id_, method_, flags_, ...) \
  IS_ENABLED_BY_DEFAULT(flags_),
#define CSS_PROP_ALIAS(name_, aliasid_, id_, method_, flags_, ...) \
  IS_ENABLED_BY_DEFAULT(flags_),
#include "mozilla/ServoCSSPropList.h"
#undef CSS_PROP_ALIAS
#undef CSS_PROP_SHORTHAND
#undef CSS_PROP_LONGHAND

#undef IS_ENABLED_BY_DEFAULT
};

/**
 * A singleton class to register as a receiver for gfxVars.
 * Updates the state of backdrop-filter's pref if the gfx
 * backdrop filter var changes state.
 */
class nsCSSPropsGfxVarReceiver final : public gfx::gfxVarReceiver {
  constexpr nsCSSPropsGfxVarReceiver() = default;

  // Backdrop filter's last known enabled state.
  static bool sLastKnownAllowBackdropFilter;
  static nsCSSPropsGfxVarReceiver sInstance;

 public:
  static gfx::gfxVarReceiver& GetInstance() { return sInstance; }

  void OnVarChanged(const gfx::GfxVarUpdate&) override {
    bool enabled = gfx::gfxVars::AllowBackdropFilter();
    if (sLastKnownAllowBackdropFilter != enabled) {
      sLastKnownAllowBackdropFilter = enabled;
      nsCSSProps::RecomputeEnabledState(
          StaticPrefs::GetPrefName_layout_css_backdrop_filter_enabled());
    }
  }
};

/* static */
nsCSSPropsGfxVarReceiver nsCSSPropsGfxVarReceiver::sInstance =
    nsCSSPropsGfxVarReceiver();

/* static */
bool nsCSSPropsGfxVarReceiver::sLastKnownAllowBackdropFilter = true;

/* static */
gfx::gfxVarReceiver& nsCSSProps::GfxVarReceiver() {
  return nsCSSPropsGfxVarReceiver::GetInstance();
}

#include "nsCSSPropsGenerated.inc"