layout/style/nsCSSProps.cpp

   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 /*
   8  * methods for dealing with CSS properties and tables of the keyword
   9  * values they accept
  10  */
  11
  12 #include "nsCSSProps.h"
  13
  14 #include "mozilla/ArrayUtils.h"
  15 #include "mozilla/Casting.h"
  16
  17 #include "gfxPlatform.h"
  18 #include "nsLayoutUtils.h"
  19 #include "nsIWidget.h"
  20 #include "nsStyleConsts.h"  // For system widget appearance types
  21
  22 #include "mozilla/dom/Animation.h"
  23 #include "mozilla/dom/AnimationEffectBinding.h"  // for PlaybackDirection
  24 #include "mozilla/gfx/gfxVars.h"                 // for UseWebRender
  25 #include "mozilla/gfx/gfxVarReceiver.h"
  26 #include "mozilla/LookAndFeel.h"  // for system colors
  27
  28 #include "nsString.h"
  29 #include "nsStaticNameTable.h"
  30
  31 #include "mozilla/Preferences.h"
  32 #include "mozilla/StaticPrefs_layout.h"
  33 #include "mozilla/StaticPtr.h"
  34
  35 using namespace mozilla;
  36
  37 static int32_t gPropertyTableRefCount;
  38 static StaticAutoPtr<nsStaticCaseInsensitiveNameTable> gFontDescTable;
  39 static StaticAutoPtr<nsStaticCaseInsensitiveNameTable> gCounterDescTable;
  40 static StaticAutoPtr<nsTHashMap<nsCStringHashKey, nsCSSPropertyID>>
  41     gPropertyIDLNameTable;
  42
  43 static constexpr const char* const kCSSRawFontDescs[] = {
  44 #define CSS_FONT_DESC(name_, method_) #name_,
  45 #include "nsCSSFontDescList.h"
  46 #undef CSS_FONT_DESC
  47 };
  48
  49 static constexpr const char* const kCSSRawCounterDescs[] = {
  50 #define CSS_COUNTER_DESC(name_, method_) #name_,
  51 #include "nsCSSCounterDescList.h"
  52 #undef CSS_COUNTER_DESC
  53 };
  54
  55 static constexpr CSSPropFlags kFlagsTable[eCSSProperty_COUNT_with_aliases] = {
  56 #define CSS_PROP_LONGHAND(name_, id_, method_, flags_, ...) flags_,
  57 #define CSS_PROP_SHORTHAND(name_, id_, method_, flags_, ...) flags_,
  58 #define CSS_PROP_ALIAS(name_, aliasid_, id_, method_, flags_, ...) flags_,
  59 #include "mozilla/ServoCSSPropList.h"
  60 #undef CSS_PROP_ALIAS
  61 #undef CSS_PROP_SHORTHAND
  62 #undef CSS_PROP_LONGHAND
  63 };
  64
  65 static nsStaticCaseInsensitiveNameTable* CreateStaticTable(
  66     const char* const aRawTable[], int32_t aLength) {
  67   auto table = new nsStaticCaseInsensitiveNameTable(aRawTable, aLength);
  68 #ifdef DEBUG
  69   // Partially verify the entries.
  70   for (int32_t index = 0; index < aLength; ++index) {
  71     nsAutoCString temp(aRawTable[index]);
  72     MOZ_ASSERT(-1 == temp.FindChar('_'),
  73                "underscore char in case insensitive name table");
  74   }
  75 #endif
  76   return table;
  77 }
  78
  79 void nsCSSProps::RecomputeEnabledState(const char* aPref, void*) {
  80   MOZ_RELEASE_ASSERT(NS_IsMainThread());
  81   DebugOnly<bool> foundPref = false;
  82   for (const PropertyPref* pref = kPropertyPrefTable;
  83        pref->mPropID != eCSSProperty_UNKNOWN; pref++) {
  84     if (!aPref || !strcmp(aPref, pref->mPref)) {
  85       foundPref = true;
  86 #ifdef FUZZING
  87       gPropertyEnabled[pref->mPropID] = true;
  88 #else
  89       gPropertyEnabled[pref->mPropID] = Preferences::GetBool(pref->mPref);
  90       if (pref->mPropID == eCSSProperty_backdrop_filter) {
  91         gPropertyEnabled[pref->mPropID] &=
  92             gfx::gfxVars::GetAllowBackdropFilterOrDefault();
  93       }
  94 #endif
  95     }
  96   }
  97   MOZ_ASSERT(foundPref);
  98 }
  99
 100 void nsCSSProps::AddRefTable(void) {
 101   if (0 == gPropertyTableRefCount++) {
 102     MOZ_ASSERT(!gFontDescTable, "pre existing array!");
 103     MOZ_ASSERT(!gCounterDescTable, "pre existing array!");
 104     MOZ_ASSERT(!gPropertyIDLNameTable, "pre existing array!");
 105
 106     gFontDescTable = CreateStaticTable(kCSSRawFontDescs, eCSSFontDesc_COUNT);
 107     gCounterDescTable =
 108         CreateStaticTable(kCSSRawCounterDescs, eCSSCounterDesc_COUNT);
 109
 110     gPropertyIDLNameTable = new nsTHashMap<nsCStringHashKey, nsCSSPropertyID>;
 111     for (nsCSSPropertyID p = nsCSSPropertyID(0);
 112          size_t(p) < ArrayLength(kIDLNameTable); p = nsCSSPropertyID(p + 1)) {
 113       if (kIDLNameTable[p]) {
 114         gPropertyIDLNameTable->InsertOrUpdate(
 115             nsDependentCString(kIDLNameTable[p]), p);
 116       }
 117     }
 118
 119     static bool prefObserversInited = false;
 120     if (!prefObserversInited) {
 121       prefObserversInited = true;
 122       for (const PropertyPref* pref = kPropertyPrefTable;
 123            pref->mPropID != eCSSProperty_UNKNOWN; pref++) {
 124         // https://bugzilla.mozilla.org/show_bug.cgi?id=1472523
 125         // We need to use nsCString instead of substring because the preference
 126         // callback code stores them. Using AssignLiteral prevents any
 127         // unnecessary allocations.
 128         nsCString prefName;
 129         prefName.AssignLiteral(pref->mPref, strlen(pref->mPref));
 130         Preferences::RegisterCallback(nsCSSProps::RecomputeEnabledState,
 131                                       prefName);
 132       }
 133       RecomputeEnabledState(/* aPrefName = */ nullptr);
 134     }
 135   }
 136 }
 137
 138 void nsCSSProps::ReleaseTable(void) {
 139   if (0 == --gPropertyTableRefCount) {
 140     gFontDescTable = nullptr;
 141     gCounterDescTable = nullptr;
 142     gPropertyIDLNameTable = nullptr;
 143   }
 144 }
 145
 146 /* static */
 147 bool nsCSSProps::IsCustomPropertyName(const nsACString& aProperty) {
 148   return aProperty.Length() >= CSS_CUSTOM_NAME_PREFIX_LENGTH &&
 149          StringBeginsWith(aProperty, "--"_ns);
 150 }
 151
 152 nsCSSPropertyID nsCSSProps::LookupPropertyByIDLName(
 153     const nsACString& aPropertyIDLName, EnabledState aEnabled) {
 154   MOZ_ASSERT(gPropertyIDLNameTable, "no lookup table, needs addref");
 155   nsCSSPropertyID res;
 156   if (!gPropertyIDLNameTable->Get(aPropertyIDLName, &res)) {
 157     return eCSSProperty_UNKNOWN;
 158   }
 159   MOZ_ASSERT(res < eCSSProperty_COUNT);
 160   if (!IsEnabled(res, aEnabled)) {
 161     return eCSSProperty_UNKNOWN;
 162   }
 163   return res;
 164 }
 165
 166 nsCSSFontDesc nsCSSProps::LookupFontDesc(const nsACString& aFontDesc) {
 167   MOZ_ASSERT(gFontDescTable, "no lookup table, needs addref");
 168   nsCSSFontDesc which = nsCSSFontDesc(gFontDescTable->Lookup(aFontDesc));
 169
 170   if (which == eCSSFontDesc_Display &&
 171       !StaticPrefs::layout_css_font_display_enabled()) {
 172     which = eCSSFontDesc_UNKNOWN;
 173   }
 174   return which;
 175 }
 176
 177 static constexpr auto sDescNullStr = ""_ns;
 178
 179 const nsCString& nsCSSProps::GetStringValue(nsCSSFontDesc aFontDescID) {
 180   MOZ_ASSERT(gFontDescTable, "no lookup table, needs addref");
 181   if (gFontDescTable) {
 182     return gFontDescTable->GetStringValue(int32_t(aFontDescID));
 183   }
 184   return sDescNullStr;
 185 }
 186
 187 const nsCString& nsCSSProps::GetStringValue(nsCSSCounterDesc aCounterDescID) {
 188   MOZ_ASSERT(gCounterDescTable, "no lookup table, needs addref");
 189   if (gCounterDescTable) {
 190     return gCounterDescTable->GetStringValue(int32_t(aCounterDescID));
 191   }
 192   return sDescNullStr;
 193 }
 194
 195 bool nsCSSProps::PropHasFlags(nsCSSPropertyID aProperty, Flags aFlags) {
 196   MOZ_ASSERT(0 <= aProperty && aProperty < eCSSProperty_COUNT_with_aliases,
 197              "out of range");
 198   return (kFlagsTable[aProperty] & aFlags) == aFlags;
 199 }
 200
 201 /* static */
 202 bool nsCSSProps::gPropertyEnabled[eCSSProperty_COUNT_with_aliases] = {
 203 // If the property has any "ENABLED_IN" flag set, it is disabled by
 204 // default. Note that, if a property has pref, whatever its default
 205 // value is, it will later be changed in nsCSSProps::AddRefTable().
 206 // If the property has "ENABLED_IN" flags but doesn't have a pref,
 207 // it is an internal property which is disabled elsewhere.
 208 #define IS_ENABLED_BY_DEFAULT(flags_) \
 209   (!((flags_) & (CSSPropFlags::EnabledMask | CSSPropFlags::Inaccessible)))
 210
 211 #define CSS_PROP_LONGHAND(name_, id_, method_, flags_, ...) \
 212   IS_ENABLED_BY_DEFAULT(flags_),
 213 #define CSS_PROP_SHORTHAND(name_, id_, method_, flags_, ...) \
 214   IS_ENABLED_BY_DEFAULT(flags_),
 215 #define CSS_PROP_ALIAS(name_, aliasid_, id_, method_, flags_, ...) \
 216   IS_ENABLED_BY_DEFAULT(flags_),
 217 #include "mozilla/ServoCSSPropList.h"
 218 #undef CSS_PROP_ALIAS
 219 #undef CSS_PROP_SHORTHAND
 220 #undef CSS_PROP_LONGHAND
 221
 222 #undef IS_ENABLED_BY_DEFAULT
 223 };
 224
 225 /**
 226  * A singleton class to register as a receiver for gfxVars.
 227  * Updates the state of backdrop-filter's pref if the gfx
 228  * backdrop filter var changes state.
 229  */
 230 class nsCSSPropsGfxVarReceiver final : public gfx::gfxVarReceiver {
 231   constexpr nsCSSPropsGfxVarReceiver() = default;
 232
 233   // Backdrop filter's last known enabled state.
 234   static bool sLastKnownAllowBackdropFilter;
 235   static nsCSSPropsGfxVarReceiver sInstance;
 236
 237  public:
 238   static gfx::gfxVarReceiver& GetInstance() { return sInstance; }
 239
 240   void OnVarChanged(const gfx::GfxVarUpdate&) override {
 241     bool enabled = gfx::gfxVars::AllowBackdropFilter();
 242     if (sLastKnownAllowBackdropFilter != enabled) {
 243       sLastKnownAllowBackdropFilter = enabled;
 244       nsCSSProps::RecomputeEnabledState(
 245           StaticPrefs::GetPrefName_layout_css_backdrop_filter_enabled());
 246     }
 247   }
 248 };
 249
 250 /* static */
 251 nsCSSPropsGfxVarReceiver nsCSSPropsGfxVarReceiver::sInstance =
 252     nsCSSPropsGfxVarReceiver();
 253
 254 /* static */
 255 bool nsCSSPropsGfxVarReceiver::sLastKnownAllowBackdropFilter = true;
 256
 257 /* static */
 258 gfx::gfxVarReceiver& nsCSSProps::GfxVarReceiver() {
 259   return nsCSSPropsGfxVarReceiver::GetInstance();
 260 }
 261
 262 #include "nsCSSPropsGenerated.inc"