accessible/ipc/RemoteAccessible.h

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=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 #ifndef mozilla_a11y_RemoteAccessible_h
   8 #define mozilla_a11y_RemoteAccessible_h
   9
  10 #include "mozilla/a11y/Accessible.h"
  11 #include "mozilla/a11y/CacheConstants.h"
  12 #include "mozilla/a11y/HyperTextAccessibleBase.h"
  13 #include "mozilla/a11y/Role.h"
  14 #include "AccAttributes.h"
  15 #include "nsIAccessibleText.h"
  16 #include "nsIAccessibleTypes.h"
  17 #include "nsTArray.h"
  18 #include "nsRect.h"
  19 #include "LocalAccessible.h"
  20
  21 namespace mozilla {
  22 namespace a11y {
  23
  24 class Attribute;
  25 class DocAccessibleParent;
  26 class RemoteAccessible;
  27 enum class RelationType;
  28
  29 /**
  30  * The class for an accessibility tree node that originated in the parent
  31  * process.
  32  */
  33 class RemoteAccessible : public Accessible, public HyperTextAccessibleBase {
  34  public:
  35   virtual ~RemoteAccessible() {
  36     MOZ_ASSERT(!mWrapper);
  37     MOZ_COUNT_DTOR(RemoteAccessible);
  38   }
  39
  40   virtual bool IsRemote() const override { return true; }
  41
  42   void AddChildAt(uint32_t aIdx, RemoteAccessible* aChild) {
  43     mChildren.InsertElementAt(aIdx, aChild);
  44     if (IsHyperText()) {
  45       InvalidateCachedHyperTextOffsets();
  46     }
  47   }
  48
  49   virtual uint32_t ChildCount() const override { return mChildren.Length(); }
  50   RemoteAccessible* RemoteChildAt(uint32_t aIdx) const {
  51     return mChildren.SafeElementAt(aIdx);
  52   }
  53   RemoteAccessible* RemoteFirstChild() const {
  54     return mChildren.Length() ? mChildren[0] : nullptr;
  55   }
  56   RemoteAccessible* RemoteLastChild() const {
  57     return mChildren.Length() ? mChildren[mChildren.Length() - 1] : nullptr;
  58   }
  59   RemoteAccessible* RemotePrevSibling() const {
  60     if (IsDoc()) {
  61       // The normal code path doesn't work for documents because the parent
  62       // might be a local OuterDoc, but IndexInParent() will return 1.
  63       // A document is always a single child of an OuterDoc anyway.
  64       return nullptr;
  65     }
  66     int32_t idx = IndexInParent();
  67     if (idx == -1) {
  68       return nullptr;  // No parent.
  69     }
  70     return idx > 0 ? RemoteParent()->mChildren[idx - 1] : nullptr;
  71   }
  72   RemoteAccessible* RemoteNextSibling() const {
  73     if (IsDoc()) {
  74       // The normal code path doesn't work for documents because the parent
  75       // might be a local OuterDoc, but IndexInParent() will return 1.
  76       // A document is always a single child of an OuterDoc anyway.
  77       return nullptr;
  78     }
  79     int32_t idx = IndexInParent();
  80     if (idx == -1) {
  81       return nullptr;  // No parent.
  82     }
  83     MOZ_ASSERT(idx >= 0);
  84     size_t newIdx = idx + 1;
  85     return newIdx < RemoteParent()->mChildren.Length()
  86                ? RemoteParent()->mChildren[newIdx]
  87                : nullptr;
  88   }
  89
  90   // Accessible hierarchy method overrides
  91
  92   virtual Accessible* Parent() const override { return RemoteParent(); }
  93
  94   virtual Accessible* ChildAt(uint32_t aIndex) const override {
  95     return RemoteChildAt(aIndex);
  96   }
  97
  98   virtual Accessible* NextSibling() const override {
  99     return RemoteNextSibling();
 100   }
 101
 102   virtual Accessible* PrevSibling() const override {
 103     return RemotePrevSibling();
 104   }
 105
 106   // XXX evaluate if this is fast enough.
 107   virtual int32_t IndexInParent() const override {
 108     RemoteAccessible* parent = RemoteParent();
 109     if (!parent) {
 110       return -1;
 111     }
 112     return parent->mChildren.IndexOf(
 113         static_cast<const RemoteAccessible*>(this));
 114   }
 115   virtual uint32_t EmbeddedChildCount() override;
 116   virtual int32_t IndexOfEmbeddedChild(Accessible* aChild) override;
 117   virtual Accessible* EmbeddedChildAt(uint32_t aChildIdx) override;
 118
 119   void Shutdown();
 120
 121   void SetChildDoc(DocAccessibleParent* aChildDoc);
 122   void ClearChildDoc(DocAccessibleParent* aChildDoc);
 123
 124   /**
 125    * Remove The given child.
 126    */
 127   void RemoveChild(RemoteAccessible* aChild) {
 128     mChildren.RemoveElement(aChild);
 129     if (IsHyperText()) {
 130       InvalidateCachedHyperTextOffsets();
 131     }
 132   }
 133
 134   /**
 135    * Return the proxy for the parent of the wrapped accessible.
 136    */
 137   RemoteAccessible* RemoteParent() const;
 138
 139   LocalAccessible* OuterDocOfRemoteBrowser() const;
 140
 141   /**
 142    * Get the role of the accessible we're proxying.
 143    */
 144   virtual role Role() const override { return mRole; }
 145
 146   /**
 147    * Return true if this is an embedded object.
 148    */
 149   bool IsEmbeddedObject() const { return !IsText(); }
 150
 151   virtual bool IsLink() const override {
 152     if (IsHTMLLink()) {
 153       // XXX: HTML links always return true for IsLink.
 154       return true;
 155     }
 156
 157     if (IsText()) {
 158       return false;
 159     }
 160
 161     if (Accessible* parent = Parent()) {
 162       return parent->IsHyperText();
 163     }
 164
 165     return false;
 166   }
 167
 168   virtual bool HasNumericValue() const override {
 169     // XXX: We combine the aria and native "has numeric value" field
 170     // when we serialize the local accessible into eNumericValue.
 171     return HasGenericType(eNumericValue);
 172   }
 173
 174   // Methods that potentially access a cache.
 175
 176   virtual ENameValueFlag Name(nsString& aName) const override;
 177   virtual void Description(nsString& aDescription) const override;
 178   virtual void Value(nsString& aValue) const override;
 179
 180   virtual double CurValue() const override;
 181   virtual double MinValue() const override;
 182   virtual double MaxValue() const override;
 183   virtual double Step() const override;
 184   virtual bool SetCurValue(double aValue) override;
 185
 186   virtual Accessible* ChildAtPoint(
 187       int32_t aX, int32_t aY,
 188       LocalAccessible::EWhichChildAtPoint aWhichChild) override;
 189
 190   virtual LayoutDeviceIntRect Bounds() const override;
 191
 192   virtual nsRect BoundsInAppUnits() const override;
 193
 194   virtual Relation RelationByType(RelationType aType) const override;
 195
 196   virtual uint64_t State() override;
 197
 198   virtual already_AddRefed<AccAttributes> Attributes() override;
 199
 200   virtual nsAtom* TagName() const override;
 201
 202   virtual already_AddRefed<nsAtom> InputType() const override;
 203
 204   virtual already_AddRefed<nsAtom> DisplayStyle() const override;
 205
 206   virtual float Opacity() const override;
 207
 208   virtual void LiveRegionAttributes(nsAString* aLive, nsAString* aRelevant,
 209                                     Maybe<bool>* aAtomic,
 210                                     nsAString* aBusy) const override;
 211
 212   virtual Maybe<bool> ARIASelected() const override;
 213
 214   virtual uint8_t ActionCount() const override;
 215
 216   virtual void ActionNameAt(uint8_t aIndex, nsAString& aName) override;
 217
 218   virtual bool DoAction(uint8_t aIndex) const override;
 219
 220   virtual KeyBinding AccessKey() const override;
 221
 222   virtual void SelectionRanges(nsTArray<TextRange>* aRanges) const override;
 223
 224   MOZ_CAN_RUN_SCRIPT_BOUNDARY virtual bool RemoveFromSelection(
 225       int32_t aSelectionNum) override;
 226
 227   virtual Maybe<int32_t> GetIntARIAAttr(nsAtom* aAttrName) const override;
 228
 229   virtual void Language(nsAString& aLocale) override;
 230
 231   //////////////////////////////////////////////////////////////////////////////
 232   // EditableTextAccessible
 233
 234   MOZ_CAN_RUN_SCRIPT_BOUNDARY virtual void ReplaceText(
 235       const nsAString& aText) override;
 236   MOZ_CAN_RUN_SCRIPT_BOUNDARY virtual void InsertText(
 237       const nsAString& aText, int32_t aPosition) override;
 238   MOZ_CAN_RUN_SCRIPT_BOUNDARY virtual void CopyText(int32_t aStartPos,
 239                                                     int32_t aEndPos) override;
 240   MOZ_CAN_RUN_SCRIPT_BOUNDARY virtual void CutText(int32_t aStartPos,
 241                                                    int32_t aEndPos) override;
 242   MOZ_CAN_RUN_SCRIPT_BOUNDARY virtual void DeleteText(int32_t aStartPos,
 243                                                       int32_t aEndPos) override;
 244   MOZ_CAN_RUN_SCRIPT virtual void PasteText(int32_t aPosition) override;
 245
 246   //////////////////////////////////////////////////////////////////////////////
 247   // SelectAccessible
 248
 249   virtual void SelectedItems(nsTArray<Accessible*>* aItems) override;
 250
 251   virtual uint32_t SelectedItemCount() override;
 252
 253   virtual Accessible* GetSelectedItem(uint32_t aIndex) override;
 254
 255   virtual bool IsItemSelected(uint32_t aIndex) override;
 256
 257   virtual bool AddItemToSelection(uint32_t aIndex) override;
 258
 259   virtual bool RemoveItemFromSelection(uint32_t aIndex) override;
 260
 261   virtual bool SelectAll() override;
 262
 263   virtual bool UnselectAll() override;
 264
 265   virtual void TakeSelection() override;
 266
 267   virtual void SetSelected(bool aSelect) override;
 268
 269   // Methods that interact with content.
 270
 271   virtual void TakeFocus() const override;
 272   virtual void ScrollTo(uint32_t aHow) const override;
 273   virtual void SetCaretOffset(int32_t aOffset) override;
 274
 275   /**
 276    * Allow the platform to store a pointers worth of data on us.
 277    */
 278   uintptr_t GetWrapper() const { return mWrapper; }
 279   void SetWrapper(uintptr_t aWrapper) { mWrapper = aWrapper; }
 280
 281   virtual uint64_t ID() const override { return mID; }
 282
 283   /**
 284    * Return the document containing this proxy, or the proxy itself if it is a
 285    * document.
 286    */
 287   DocAccessibleParent* Document() const { return mDoc; }
 288
 289   DocAccessibleParent* AsDoc() const { return IsDoc() ? mDoc : nullptr; }
 290
 291   void ApplyCache(CacheUpdateType aUpdateType, AccAttributes* aFields);
 292
 293   void UpdateStateCache(uint64_t aState, bool aEnabled) {
 294     if (aState & kRemoteCalculatedStates) {
 295       return;
 296     }
 297     uint64_t state = 0;
 298     if (mCachedFields) {
 299       if (auto oldState =
 300               mCachedFields->GetAttribute<uint64_t>(CacheKey::State)) {
 301         state = *oldState;
 302       }
 303     } else {
 304       mCachedFields = new AccAttributes();
 305     }
 306     if (aEnabled) {
 307       state |= aState;
 308     } else {
 309       state &= ~aState;
 310     }
 311     mCachedFields->SetAttribute(CacheKey::State, state);
 312   }
 313
 314   void InvalidateGroupInfo();
 315
 316   virtual void AppendTextTo(nsAString& aText, uint32_t aStartOffset = 0,
 317                             uint32_t aLength = UINT32_MAX) override;
 318
 319   virtual bool TableIsProbablyForLayout();
 320
 321   /**
 322    * Iterates through each atom in kRelationTypeAtoms, checking to see
 323    * if it is present in aFields. If it is present (or if aFields contains
 324    * a DeleteEntry() for this atom) and mCachedFields is initialized,
 325    * fetches the old rel targets and removes their existing reverse relations
 326    * stored in mReverseRelations.
 327    * Returns an array of bools where the ith array entry corresponds
 328    * to whether or not the rel at the ith entry of kRelationTypeAtoms
 329    * requires a post-processing update.
 330    */
 331   nsTArray<bool> PreProcessRelations(AccAttributes* aFields);
 332
 333   /**
 334    * Takes in the array returned from PreProcessRelations.
 335    * For each entry requiring an update, fetches the new relation
 336    * targets stored in mCachedFields and appropriately
 337    * updates their reverse relations in mReverseRelations.
 338    */
 339   void PostProcessRelations(const nsTArray<bool>& aToUpdate);
 340
 341   /**
 342    * This method is called during shutdown, before we clear our
 343    * reverse rel map from the document's mReverseRelations cache.
 344    * Here, we traverse our reverse relations, removing our ID from
 345    * the corresponding forward relation's target list. This ensures
 346    * the stored forward relations do not reference defunct accessibles.
 347    */
 348   void PruneRelationsOnShutdown();
 349
 350   uint32_t GetCachedTextLength();
 351   Maybe<const nsTArray<int32_t>&> GetCachedTextLines();
 352   nsRect GetCachedCharRect(int32_t aOffset);
 353   RefPtr<const AccAttributes> GetCachedTextAttributes();
 354   RefPtr<const AccAttributes> GetCachedARIAAttributes() const;
 355
 356   nsString GetCachedHTMLNameAttribute() const;
 357
 358   virtual HyperTextAccessibleBase* AsHyperTextBase() override {
 359     return IsHyperText() ? static_cast<HyperTextAccessibleBase*>(this)
 360                          : nullptr;
 361   }
 362
 363   virtual TableAccessible* AsTable() override;
 364   virtual TableCellAccessible* AsTableCell() override;
 365
 366   virtual void DOMNodeID(nsString& aID) const override;
 367
 368   virtual void ScrollToPoint(uint32_t aScrollType, int32_t aX,
 369                              int32_t aY) override;
 370
 371 #if !defined(XP_WIN)
 372   void Announce(const nsString& aAnnouncement, uint16_t aPriority);
 373 #endif  // !defined(XP_WIN)
 374
 375   // HyperTextAccessibleBase
 376   virtual already_AddRefed<AccAttributes> DefaultTextAttributes() override;
 377
 378   virtual void ScrollSubstringToPoint(int32_t aStartOffset, int32_t aEndOffset,
 379                                       uint32_t aCoordinateType, int32_t aX,
 380                                       int32_t aY) override;
 381
 382   /**
 383    * Invalidate cached HyperText offsets. This should be called whenever a
 384    * child is added or removed or the text of a text leaf child is changed.
 385    * Although GetChildOffset can either fully or partially invalidate the
 386    * offsets cache, calculating which offset to invalidate is not worthwhile
 387    * because a client might not even query offsets. This is in contrast to
 388    * LocalAccessible, where the offsets are always needed to fire text change
 389    * events. For RemoteAccessible, it's cheaper overall to just rebuild the
 390    * offsets cache when a client next needs it.
 391    */
 392   void InvalidateCachedHyperTextOffsets() {
 393     if (mCachedFields) {
 394       mCachedFields->Remove(CacheKey::HyperTextOffsets);
 395     }
 396   }
 397
 398   size_t SizeOfIncludingThis(MallocSizeOf aMallocSizeOf);
 399   virtual size_t SizeOfExcludingThis(MallocSizeOf aMallocSizeOf);
 400
 401  protected:
 402   RemoteAccessible(uint64_t aID, DocAccessibleParent* aDoc, role aRole,
 403                    AccType aType, AccGenericType aGenericTypes,
 404                    uint8_t aRoleMapEntryIndex)
 405       : Accessible(aType, aGenericTypes, aRoleMapEntryIndex),
 406         mParent(kNoParent),
 407         mDoc(aDoc),
 408         mWrapper(0),
 409         mID(aID),
 410         mCachedFields(nullptr),
 411         mRole(aRole) {
 412     MOZ_COUNT_CTOR(RemoteAccessible);
 413   }
 414
 415   explicit RemoteAccessible(DocAccessibleParent* aThisAsDoc)
 416       : Accessible(),
 417         mParent(kNoParent),
 418         mDoc(aThisAsDoc),
 419         mWrapper(0),
 420         mID(0),
 421         mCachedFields(nullptr),
 422         mRole(roles::DOCUMENT) {
 423     mGenericTypes = eDocument | eHyperText;
 424     MOZ_COUNT_CTOR(RemoteAccessible);
 425   }
 426
 427  protected:
 428   void SetParent(RemoteAccessible* aParent);
 429   Maybe<nsRect> RetrieveCachedBounds() const;
 430   bool ApplyTransform(nsRect& aCumulativeBounds) const;
 431   bool ApplyScrollOffset(nsRect& aBounds) const;
 432   void ApplyCrossDocOffset(nsRect& aBounds) const;
 433   LayoutDeviceIntRect BoundsWithOffset(
 434       Maybe<nsRect> aOffset, bool aBoundsAreForHittesting = false) const;
 435   bool IsFixedPos() const;
 436   bool IsOverflowHidden() const;
 437
 438   /**
 439    * Returns true if an accessible's frame has no scrollable overflow, and
 440    * false otherwise.
 441    * Does not return true for partially clipped accessibles.
 442    */
 443   bool IsClipped() const;
 444
 445   /**
 446    * Checks if our hittesting match has any clipped children and, if so
 447    * descends it and subsequent TEXT_CONTAINERs in search of a text leaf.
 448    * We do this because some sites use clipping to hide text that is only
 449    * visible to a11y, while displaying a visual version of the same text on
 450    * the web page. We want a hittest of the visible text to resolve to the
 451    * hidden, a11y-only text node.
 452    */
 453   RemoteAccessible* DoFuzzyHittesting();
 454
 455   // This function is used exclusively for hit testing.
 456   bool ContainsPoint(int32_t aX, int32_t aY);
 457
 458   virtual void ARIAGroupPosition(int32_t* aLevel, int32_t* aSetSize,
 459                                  int32_t* aPosInSet) const override;
 460
 461   virtual AccGroupInfo* GetGroupInfo() const override;
 462
 463   virtual AccGroupInfo* GetOrCreateGroupInfo() override;
 464
 465   virtual void GetPositionAndSetSize(int32_t* aPosInSet,
 466                                      int32_t* aSetSize) override;
 467
 468   virtual bool HasPrimaryAction() const override;
 469
 470   nsAtom* GetPrimaryAction() const;
 471
 472   virtual nsTArray<int32_t>& GetCachedHyperTextOffsets() override;
 473
 474  private:
 475   uintptr_t mParent;
 476   static const uintptr_t kNoParent = UINTPTR_MAX;
 477
 478   friend DocAccessibleParent;
 479   friend TextLeafPoint;
 480   friend HyperTextAccessibleBase;
 481   friend class xpcAccessible;
 482   friend class CachedTableCellAccessible;
 483 #ifdef XP_WIN
 484   friend class sdnAccessible;
 485 #endif
 486
 487   nsTArray<RemoteAccessible*> mChildren;
 488   DocAccessibleParent* mDoc;
 489   uintptr_t mWrapper;
 490   uint64_t mID;
 491
 492  protected:
 493   virtual const Accessible* Acc() const override { return this; }
 494
 495   RefPtr<AccAttributes> mCachedFields;
 496
 497   // XXX DocAccessibleParent gets to change this to change the role of
 498   // documents.
 499   role mRole : 27;
 500 };
 501
 502 ////////////////////////////////////////////////////////////////////////////////
 503 // RemoteAccessible downcasting method
 504
 505 inline RemoteAccessible* Accessible::AsRemote() {
 506   return IsRemote() ? static_cast<RemoteAccessible*>(this) : nullptr;
 507 }
 508
 509 }  // namespace a11y
 510 }  // namespace mozilla
 511
 512 #endif