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nsAccessNode.cpp

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is mozilla.org code.
 *
 * The Initial Developer of the Original Code is
 * Netscape Communications Corporation.
 * Portions created by the Initial Developer are Copyright (C) 2003
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *   Original Author: Aaron Leventhal (aaronl@netscape.com)
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either of the GNU General Public License Version 2 or later (the "GPL"),
 * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the MPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the MPL, the GPL or the LGPL.
 *
 * ***** END LICENSE BLOCK ***** */

#include "nsAccessNode.h"
#include "nsIAccessible.h"
#include "nsAccessibilityAtoms.h"
#include "nsHashtable.h"
#include "nsIAccessibilityService.h"
#include "nsIAccessibleDocument.h"
#include "nsPIAccessibleDocument.h"
#include "nsIDocShell.h"
#include "nsIDocShellTreeItem.h"
#include "nsIDocument.h"
#include "nsIDOMCSSStyleDeclaration.h"
#include "nsIDOMDocument.h"
#include "nsIDOMElement.h"
#include "nsIDOMNSHTMLElement.h"
#include "nsIDOMViewCSS.h"
#include "nsIDOMWindow.h"
#include "nsIInterfaceRequestorUtils.h"
#include "nsIFrame.h"
#include "nsIPrefService.h"
#include "nsIPrefBranch.h"
#include "nsPresContext.h"
#include "nsIPresShell.h"
#include "nsIServiceManager.h"
#include "nsIStringBundle.h"
#include "nsITimer.h"

/* For documentation of the accessibility architecture, 
 * see http://lxr.mozilla.org/seamonkey/source/accessible/accessible-docs.html
 */

nsIStringBundle *nsAccessNode::gStringBundle = 0;
nsIStringBundle *nsAccessNode::gKeyStringBundle = 0;
nsITimer *nsAccessNode::gDoCommandTimer = 0;
nsIDOMNode *nsAccessNode::gLastFocusedNode = 0;
PRBool nsAccessNode::gIsAccessibilityActive = PR_FALSE;
PRBool nsAccessNode::gIsCacheDisabled = PR_FALSE;
nsInterfaceHashtable<nsVoidHashKey, nsIAccessNode> nsAccessNode::gGlobalDocAccessibleCache;

/*
 * Class nsAccessNode
 */

//-----------------------------------------------------
// construction 
//-----------------------------------------------------
NS_IMPL_ISUPPORTS2(nsAccessNode, nsIAccessNode, nsPIAccessNode)

nsAccessNode::nsAccessNode(nsIDOMNode *aNode, nsIWeakReference* aShell): 
  mDOMNode(aNode), mWeakShell(aShell), mRefCnt(0)
{
#ifdef DEBUG
  mIsInitialized = PR_FALSE;
#endif
}

//-----------------------------------------------------
// destruction
//-----------------------------------------------------
nsAccessNode::~nsAccessNode()
{
  if (mWeakShell) {
    Shutdown();  // Otherwise virtual Shutdown() methods could get fired twice
  }
}

NS_IMETHODIMP nsAccessNode::Init()
{
  // We have to put this here, instead of constructor, otherwise
  // we don't have the virtual GetUniqueID() method for the hash key.
  // We need that for accessibles that don't have DOM nodes

  NS_ASSERTION(!mIsInitialized, "Initialized twice!");
  nsCOMPtr<nsIAccessibleDocument> docAccessible(GetDocAccessible());
  if (!docAccessible) {
    // No doc accessible yet for this node's document. 
    // There was probably an accessible event fired before the 
    // current document was ever asked for by the assistive technology.
    // Create a doc accessible so we can cache this node
    nsCOMPtr<nsIPresShell> presShell(do_QueryReferent(mWeakShell));
    if (presShell) {
      nsCOMPtr<nsIDOMNode> docNode(do_QueryInterface(presShell->GetDocument()));
      if (docNode) {
        nsCOMPtr<nsIAccessibilityService> accService = 
          do_GetService("@mozilla.org/accessibilityService;1");
        NS_ASSERTION(accService, "No accessibility service");
        if (accService) {
          nsCOMPtr<nsIAccessible> accessible;
          accService->GetAccessibleInShell(docNode, presShell, 
            getter_AddRefs(accessible));
          docAccessible = do_QueryInterface(accessible);
        }
      }
    }
    NS_ASSERTION(docAccessible, "Cannot cache new nsAccessNode");
    if (!docAccessible) {
      return NS_ERROR_FAILURE;
    }
  }
  void* uniqueID;
  GetUniqueID(&uniqueID);
  nsCOMPtr<nsPIAccessibleDocument> privateDocAccessible =
    do_QueryInterface(docAccessible);
  NS_ASSERTION(privateDocAccessible, "No private docaccessible for docaccessible");
  privateDocAccessible->CacheAccessNode(uniqueID, this);
#ifdef DEBUG
  mIsInitialized = PR_TRUE;
#endif

  return NS_OK;
}


NS_IMETHODIMP nsAccessNode::Shutdown()
{
  mDOMNode = nsnull;
  mWeakShell = nsnull;

  return NS_OK;
}

NS_IMETHODIMP nsAccessNode::GetUniqueID(void **aUniqueID)
{
  *aUniqueID = NS_STATIC_CAST(void*, mDOMNode);
  return NS_OK;
}

NS_IMETHODIMP nsAccessNode::GetOwnerWindow(void **aWindow)
{
  nsCOMPtr<nsIAccessibleDocument> docAccessible(GetDocAccessible());
  NS_ASSERTION(docAccessible, "No root accessible pointer back, Init() not called.");
  return docAccessible->GetWindowHandle(aWindow);
}

void nsAccessNode::InitXPAccessibility()
{
  if (gIsAccessibilityActive) {
    return;
  }

  nsCOMPtr<nsIStringBundleService> stringBundleService =
    do_GetService(NS_STRINGBUNDLE_CONTRACTID);
  if (stringBundleService) {
    // Static variables are released in ShutdownAllXPAccessibility();
    stringBundleService->CreateBundle(ACCESSIBLE_BUNDLE_URL, 
                                      &gStringBundle);
    stringBundleService->CreateBundle(PLATFORM_KEYS_BUNDLE_URL, 
                                      &gKeyStringBundle);
  }

  nsAccessibilityAtoms::AddRefAtoms();

  gGlobalDocAccessibleCache.Init(4);

  nsCOMPtr<nsIPrefBranch> prefBranch(do_GetService(NS_PREFSERVICE_CONTRACTID));
  if (prefBranch) {
    prefBranch->GetBoolPref("accessibility.disablecache", &gIsCacheDisabled);
  }

  gIsAccessibilityActive = PR_TRUE;
}

void nsAccessNode::ShutdownXPAccessibility()
{
  // Called by nsAccessibilityService::Shutdown()
  // which happens when xpcom is shutting down
  // at exit of program

  if (!gIsAccessibilityActive) {
    return;
  }
  NS_IF_RELEASE(gStringBundle);
  NS_IF_RELEASE(gKeyStringBundle);
  NS_IF_RELEASE(gDoCommandTimer);
  NS_IF_RELEASE(gLastFocusedNode);

  ClearCache(gGlobalDocAccessibleCache);

  gIsAccessibilityActive = PR_FALSE;
}

already_AddRefed<nsIPresShell> nsAccessNode::GetPresShell()
{
  nsIPresShell *presShell = nsnull;
  if (mWeakShell)
    CallQueryReferent(mWeakShell.get(), &presShell);
  if (!presShell) {
    if (mWeakShell) {
      // If our pres shell has died, but we're still holding onto
      // a weak reference, our accessibles are no longer relevant
      // and should be shut down
      Shutdown();
    }
    return nsnull;
  }
  return presShell;
}

nsPresContext* nsAccessNode::GetPresContext()
{
  nsCOMPtr<nsIPresShell> presShell(GetPresShell());
  if (!presShell) {
    return nsnull;
  }
  return presShell->GetPresContext();
}

already_AddRefed<nsIAccessibleDocument> nsAccessNode::GetDocAccessible()
{
  return GetDocAccessibleFor(mWeakShell); // Addref'd
}

nsIFrame* nsAccessNode::GetFrame()
{
  nsCOMPtr<nsIPresShell> shell(do_QueryReferent(mWeakShell));
  if (!shell) 
    return nsnull;  

  nsIFrame* frame;
  nsCOMPtr<nsIContent> content(do_QueryInterface(mDOMNode));
  while (content) {
    shell->GetPrimaryFrameFor(content, &frame);
    if (frame) {
      return frame;
    }
    nsCOMPtr<nsIContent> tempContent = content->GetParent();
    content = tempContent;
  }

  return nsnull;
}

NS_IMETHODIMP
nsAccessNode::GetDOMNode(nsIDOMNode **aNode)
{
  NS_IF_ADDREF(*aNode = mDOMNode);
  return NS_OK;
}

NS_IMETHODIMP
nsAccessNode::GetNumChildren(PRInt32 *aNumChildren)
{
  nsCOMPtr<nsIContent> content(do_QueryInterface(mDOMNode));

  if (!content) {
    *aNumChildren = 0;

    return NS_ERROR_NULL_POINTER;
  }

  *aNumChildren = content->GetChildCount();

  return NS_OK;
}

NS_IMETHODIMP
nsAccessNode::GetAccessibleDocument(nsIAccessibleDocument **aDocAccessible)
{
  *aDocAccessible = GetDocAccessibleFor(mWeakShell).get();
  return NS_OK;
}

NS_IMETHODIMP
nsAccessNode::GetInnerHTML(nsAString& aInnerHTML)
{
  aInnerHTML.Truncate();

  nsCOMPtr<nsIDOMNSHTMLElement> domNSElement(do_QueryInterface(mDOMNode));
  NS_ENSURE_TRUE(domNSElement, NS_ERROR_NULL_POINTER);

  return domNSElement->GetInnerHTML(aInnerHTML);
}

nsresult
nsAccessNode::MakeAccessNode(nsIDOMNode *aNode, nsIAccessNode **aAccessNode)
{
  nsCOMPtr<nsIAccessibilityService> accService = 
    do_GetService("@mozilla.org/accessibilityService;1");
  NS_ENSURE_TRUE(accService, NS_ERROR_FAILURE);

  nsCOMPtr<nsIAccessNode> accessNode;
  accService->GetCachedAccessNode(aNode, mWeakShell, getter_AddRefs(accessNode));

  if (!accessNode) {
    nsCOMPtr<nsIAccessible> accessible;
    accService->GetAccessibleInWeakShell(aNode, mWeakShell, 
                                         getter_AddRefs(accessible));
    
    accessNode = do_QueryInterface(accessible);
  }

  if (accessNode) {
    NS_ADDREF(*aAccessNode = accessNode);
    return NS_OK;
  }

  nsAccessNode *newAccessNode = new nsAccessNode(aNode, mWeakShell);
  if (!newAccessNode) {
    return NS_ERROR_OUT_OF_MEMORY;
  }

  NS_ADDREF(*aAccessNode = newAccessNode);
  newAccessNode->Init();

  return NS_OK;
}

NS_IMETHODIMP
nsAccessNode::GetFirstChildNode(nsIAccessNode **aAccessNode)
{
  NS_ENSURE_TRUE(mDOMNode, NS_ERROR_NULL_POINTER);

  nsCOMPtr<nsIDOMNode> domNode;
  mDOMNode->GetFirstChild(getter_AddRefs(domNode));
  NS_ENSURE_TRUE(domNode, NS_ERROR_NULL_POINTER);

  return MakeAccessNode(domNode, aAccessNode);
}

NS_IMETHODIMP
nsAccessNode::GetLastChildNode(nsIAccessNode **aAccessNode)
{
  NS_ENSURE_TRUE(mDOMNode, NS_ERROR_NULL_POINTER);

  nsCOMPtr<nsIDOMNode> domNode;
  mDOMNode->GetLastChild(getter_AddRefs(domNode));
  NS_ENSURE_TRUE(domNode, NS_ERROR_NULL_POINTER);

  return MakeAccessNode(domNode, aAccessNode);
}

NS_IMETHODIMP
nsAccessNode::GetParentNode(nsIAccessNode **aAccessNode)
{
  NS_ENSURE_TRUE(mDOMNode, NS_ERROR_NULL_POINTER);

  nsCOMPtr<nsIDOMNode> domNode;
  mDOMNode->GetParentNode(getter_AddRefs(domNode));
  NS_ENSURE_TRUE(domNode, NS_ERROR_NULL_POINTER);

  return MakeAccessNode(domNode, aAccessNode);
}

NS_IMETHODIMP
nsAccessNode::GetPreviousSiblingNode(nsIAccessNode **aAccessNode)
{
  NS_ENSURE_TRUE(mDOMNode, NS_ERROR_NULL_POINTER);

  nsCOMPtr<nsIDOMNode> domNode;
  mDOMNode->GetPreviousSibling(getter_AddRefs(domNode));
  NS_ENSURE_TRUE(domNode, NS_ERROR_NULL_POINTER);

  return MakeAccessNode(domNode, aAccessNode);
}

NS_IMETHODIMP
nsAccessNode::GetNextSiblingNode(nsIAccessNode **aAccessNode)
{
  NS_ENSURE_TRUE(mDOMNode, NS_ERROR_NULL_POINTER);

  nsCOMPtr<nsIDOMNode> domNode;
  mDOMNode->GetNextSibling(getter_AddRefs(domNode));
  NS_ENSURE_TRUE(domNode, NS_ERROR_NULL_POINTER);

  return MakeAccessNode(domNode, aAccessNode);
}

NS_IMETHODIMP
nsAccessNode::GetChildNodeAt(PRInt32 aChildNum, nsIAccessNode **aAccessNode)
{
  nsCOMPtr<nsIContent> content(do_QueryInterface(mDOMNode));
  NS_ENSURE_TRUE(content, NS_ERROR_NULL_POINTER);

  nsCOMPtr<nsIDOMNode> domNode =
    do_QueryInterface(content->GetChildAt(aChildNum));
  NS_ENSURE_TRUE(domNode, NS_ERROR_NULL_POINTER);

  return MakeAccessNode(domNode, aAccessNode);
}

NS_IMETHODIMP
nsAccessNode::GetComputedStyleValue(const nsAString& aPseudoElt, const nsAString& aPropertyName, nsAString& aValue)
{
  nsCOMPtr<nsIDOMElement> domElement(do_QueryInterface(mDOMNode));
  nsPresContext *presContext = GetPresContext();
  NS_ENSURE_TRUE(domElement && presContext, NS_ERROR_FAILURE);

  nsCOMPtr<nsISupports> container = presContext->GetContainer();
  nsCOMPtr<nsIDOMWindow> domWin(do_GetInterface(container));
  nsCOMPtr<nsIDOMViewCSS> viewCSS(do_QueryInterface(domWin));
  NS_ENSURE_TRUE(viewCSS, NS_ERROR_FAILURE);

  nsCOMPtr<nsIDOMCSSStyleDeclaration> styleDecl;
  viewCSS->GetComputedStyle(domElement, aPseudoElt, getter_AddRefs(styleDecl));
  NS_ENSURE_TRUE(styleDecl, NS_ERROR_FAILURE);
  
  return styleDecl->GetPropertyValue(aPropertyName, aValue);
}

/***************** Hashtable of nsIAccessNode's *****************/

already_AddRefed<nsIAccessibleDocument>
nsAccessNode::GetDocAccessibleFor(nsIWeakReference *aPresShell)
{
  nsIAccessibleDocument *docAccessible = nsnull;
  nsCOMPtr<nsIAccessNode> accessNode;
  gGlobalDocAccessibleCache.Get(NS_STATIC_CAST(void*, aPresShell), getter_AddRefs(accessNode));
  if (accessNode) {
    CallQueryInterface(accessNode, &docAccessible);
  }
  return docAccessible;
}
 
already_AddRefed<nsIAccessibleDocument>
nsAccessNode::GetDocAccessibleFor(nsISupports *aContainer)
{
  nsCOMPtr<nsIDocShell> docShell(do_QueryInterface(aContainer));
  NS_ASSERTION(docShell, "This method currently only supports docshells");
  nsCOMPtr<nsIPresShell> presShell;
  docShell->GetPresShell(getter_AddRefs(presShell));
  nsCOMPtr<nsIWeakReference> weakShell(do_GetWeakReference(presShell));
  return weakShell ? GetDocAccessibleFor(weakShell) : nsnull;
}
 
already_AddRefed<nsIAccessibleDocument>
nsAccessNode::GetDocAccessibleFor(nsIDOMNode *aNode)
{
  nsCOMPtr<nsIPresShell> eventShell = GetPresShellFor(aNode);
  nsCOMPtr<nsIWeakReference> weakEventShell(do_GetWeakReference(eventShell));
  return weakEventShell? GetDocAccessibleFor(weakEventShell) : nsnull;
}

already_AddRefed<nsIPresShell>
nsAccessNode::GetPresShellFor(nsIDOMNode *aNode)
{
  nsCOMPtr<nsIDOMDocument> domDocument;
  aNode->GetOwnerDocument(getter_AddRefs(domDocument));
  nsCOMPtr<nsIDocument> doc(do_QueryInterface(domDocument));
  if (!doc) {   // This is necessary when the node is the document node
    doc = do_QueryInterface(aNode);
  }
  nsIPresShell *presShell = nsnull;
  if (doc) {
    presShell = doc->GetShellAt(0);
    NS_IF_ADDREF(presShell);
  }
  return presShell;
}


already_AddRefed<nsIDocShellTreeItem>
nsAccessNode::GetDocShellTreeItemFor(nsIDOMNode *aStartNode)
{
  nsCOMPtr<nsIDOMDocument> domDoc;
  aStartNode->GetOwnerDocument(getter_AddRefs(domDoc));
  nsCOMPtr<nsIDocument> doc(do_QueryInterface(domDoc));
  if (!doc) {
    doc = do_QueryInterface(aStartNode);
  }
  NS_ASSERTION(doc, "No document for node passed in");
  NS_ENSURE_TRUE(doc, nsnull);
  nsCOMPtr<nsISupports> container = doc->GetContainer();
  nsIDocShellTreeItem *docShellTreeItem = nsnull;
  if (container) {
    CallQueryInterface(container, &docShellTreeItem);
  }

  return docShellTreeItem;
}

void nsAccessNode::PutCacheEntry(nsInterfaceHashtable<nsVoidHashKey, nsIAccessNode> &aCache, 
                                 void* aUniqueID, 
                                 nsIAccessNode *aAccessNode)
{
#ifdef DEBUG
  nsCOMPtr<nsIAccessNode> oldAccessNode;
  GetCacheEntry(aCache, aUniqueID, getter_AddRefs(oldAccessNode));
  NS_ASSERTION(!oldAccessNode, "This cache entry shouldn't exist already");
#endif
  aCache.Put(aUniqueID, aAccessNode);
}

void nsAccessNode::GetCacheEntry(nsInterfaceHashtable<nsVoidHashKey, nsIAccessNode> &aCache, 
                                 void* aUniqueID, 
                                 nsIAccessNode **aAccessNode)
{
  aCache.Get(aUniqueID, aAccessNode);  // AddRefs for us
}

PLDHashOperator nsAccessNode::ClearCacheEntry(const void* aKey, nsCOMPtr<nsIAccessNode>& aAccessNode, void* aUserArg)
{
  nsCOMPtr<nsPIAccessNode> privateAccessNode(do_QueryInterface(aAccessNode));
  privateAccessNode->Shutdown();

  return PL_DHASH_REMOVE;
}

void nsAccessNode::ClearCache(nsInterfaceHashtable<nsVoidHashKey, nsIAccessNode> &aCache)
{
  aCache.Enumerate(ClearCacheEntry, nsnull);
}

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