293 lines
10 KiB
C++
Executable File
293 lines
10 KiB
C++
Executable File
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* ***** BEGIN LICENSE BLOCK *****
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* Version: MPL 1.1/GPL 2.0/LGPL 2.1
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*
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* The contents of this file are subject to the Mozilla Public License Version
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* 1.1 (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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* http://www.mozilla.org/MPL/
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*
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* Software distributed under the License is distributed on an "AS IS" basis,
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* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
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* for the specific language governing rights and limitations under the
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* License.
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*
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* The Original Code is mozilla.org code.
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*
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* The Initial Developer of the Original Code is
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* Netscape Communications Corporation.
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* Portions created by the Initial Developer are Copyright (C) 2003
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* the Initial Developer. All Rights Reserved.
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*
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* Contributor(s):
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* Original Author: Aaron Leventhal (aaronl@netscape.com)
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*
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* Alternatively, the contents of this file may be used under the terms of
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* either of the GNU General Public License Version 2 or later (the "GPL"),
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* or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
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* in which case the provisions of the GPL or the LGPL are applicable instead
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* of those above. If you wish to allow use of your version of this file only
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* under the terms of either the GPL or the LGPL, and not to allow others to
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* use your version of this file under the terms of the MPL, indicate your
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* decision by deleting the provisions above and replace them with the notice
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* and other provisions required by the GPL or the LGPL. If you do not delete
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* the provisions above, a recipient may use your version of this file under
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* the terms of any one of the MPL, the GPL or the LGPL.
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*
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* ***** END LICENSE BLOCK ***** */
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#include "nsAccessibleTreeWalker.h"
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#include "nsAccessibilityAtoms.h"
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#include "nsAccessNode.h"
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#include "nsIServiceManager.h"
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#include "nsIContent.h"
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#include "nsIDOMXULElement.h"
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#include "nsIPresShell.h"
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#include "nsIFrame.h"
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#include "nsWeakReference.h"
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nsAccessibleTreeWalker::nsAccessibleTreeWalker(nsIWeakReference* aPresShell, nsIDOMNode* aNode, PRBool aWalkAnonContent):
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mWeakShell(aPresShell),
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mAccService(do_GetService("@mozilla.org/accessibilityService;1")),
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mWalkAnonContent(aWalkAnonContent)
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{
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mState.domNode = aNode;
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mState.prevState = nsnull;
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mState.siblingIndex = eSiblingsUninitialized;
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mState.siblingList = nsnull;
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mState.isHidden = false;
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mState.frame = nsnull;
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MOZ_COUNT_CTOR(nsAccessibleTreeWalker);
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}
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nsAccessibleTreeWalker::~nsAccessibleTreeWalker()
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{
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// Clear state stack from memory
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while (NS_SUCCEEDED(PopState()))
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/* do nothing */ ;
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MOZ_COUNT_DTOR(nsAccessibleTreeWalker);
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}
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void nsAccessibleTreeWalker::GetKids(nsIDOMNode *aParentNode)
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{
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nsCOMPtr<nsIContent> parentContent(do_QueryInterface(aParentNode));
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if (!parentContent || !parentContent->IsNodeOfType(nsINode::eHTML)) {
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mState.frame = nsnull; // Don't walk frames in non-HTML content, just walk the DOM.
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}
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PushState();
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UpdateFrame(PR_TRUE);
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// Walk frames? UpdateFrame() sets this when it sees anonymous frames
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if (mState.siblingIndex == eSiblingsWalkFrames) {
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return;
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}
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// Walk anonymous content? Not currently used for HTML -- anonymous content there uses frame walking
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mState.siblingIndex = 0; // Indicates our index into the sibling list
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if (parentContent) {
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if (mWalkAnonContent) {
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// Walk anonymous content
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nsIDocument* doc = parentContent->GetOwnerDoc();
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if (doc) {
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// returns null if no anon nodes
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doc->GetXBLChildNodesFor(parentContent,
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getter_AddRefs(mState.siblingList));
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}
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}
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if (!mState.siblingList) {
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// Walk normal DOM. Just use nsIContent -- it doesn't require
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// the mallocs that GetChildNodes() needs
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//aParentNode->GetChildNodes(getter_AddRefs(mState.siblingList));
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mState.parentContent = parentContent;
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mState.domNode = do_QueryInterface(parentContent->GetChildAt(0 /* 0 == mState.siblingIndex */));
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return;
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}
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}
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else {
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// We're on document node, that's why we could not QI to nsIContent.
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// So, use nsIDOMNodeList method to walk content.
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aParentNode->GetChildNodes(getter_AddRefs(mState.siblingList));
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if (!mState.siblingList) {
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return;
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}
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}
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mState.siblingList->Item(0 /* 0 == mState.siblingIndex */, getter_AddRefs(mState.domNode));
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}
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NS_IMETHODIMP nsAccessibleTreeWalker::PopState()
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{
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nsIFrame *frameParent = mState.frame? mState.frame->GetParent(): nsnull;
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if (mState.prevState) {
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WalkState *toBeDeleted = mState.prevState;
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mState = *mState.prevState; // deep copy
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mState.isHidden = PR_FALSE; // If we were in a child, the parent wasn't hidden
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if (!mState.frame) {
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mState.frame = frameParent;
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}
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delete toBeDeleted;
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return NS_OK;
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}
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ClearState();
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mState.frame = frameParent;
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mState.isHidden = PR_FALSE;
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return NS_ERROR_FAILURE;
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}
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void nsAccessibleTreeWalker::ClearState()
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{
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mState.siblingList = nsnull;
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mState.parentContent = nsnull;
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mState.accessible = nsnull;
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mState.domNode = nsnull;
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mState.siblingIndex = eSiblingsUninitialized;
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}
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NS_IMETHODIMP nsAccessibleTreeWalker::PushState()
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{
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// Duplicate mState and put right before end; reset mState; make mState the new end of the stack
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WalkState* nextToLastState= new WalkState();
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if (!nextToLastState)
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return NS_ERROR_OUT_OF_MEMORY;
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*nextToLastState = mState; // Deep copy - copy contents of struct to new state that will be added to end of our stack
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ClearState();
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mState.prevState = nextToLastState; // Link to previous state
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return NS_OK;
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}
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void nsAccessibleTreeWalker::GetNextDOMNode()
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{
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// Get next DOM node
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if (mState.parentContent) {
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mState.domNode = do_QueryInterface(mState.parentContent->GetChildAt(++mState.siblingIndex));
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}
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else if (mState.siblingIndex == eSiblingsWalkFrames) {
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if (mState.frame) {
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mState.domNode = do_QueryInterface(mState.frame->GetContent());
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} else {
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mState.domNode = nsnull;
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}
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}
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else {
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mState.siblingList->Item(++mState.siblingIndex, getter_AddRefs(mState.domNode));
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}
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}
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NS_IMETHODIMP nsAccessibleTreeWalker::GetNextSibling()
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{
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// Make sure mState.prevState and mState.siblingIndex are initialized so we can walk forward
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NS_ASSERTION(mState.prevState && mState.siblingIndex != eSiblingsUninitialized,
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"Error - GetNextSibling() only works after a GetFirstChild(), so we must have a prevState.");
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mState.accessible = nsnull;
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while (PR_TRUE) {
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// Get next frame
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UpdateFrame(PR_FALSE);
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GetNextDOMNode();
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if (!mState.domNode) { // Done with current siblings
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PopState(); // Use parent - go up in stack. Can always pop state because we have to start with a GetFirstChild().
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if (!mState.prevState) {
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mState.accessible = nsnull;
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break; // Back to original accessible that we did GetFirstChild() from
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}
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}
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else if ((mState.domNode != mState.prevState->domNode && GetAccessible()) ||
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NS_SUCCEEDED(GetFirstChild())) {
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return NS_OK; // if next is accessible, use it
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}
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}
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return NS_ERROR_FAILURE;
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}
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NS_IMETHODIMP nsAccessibleTreeWalker::GetFirstChild()
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{
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mState.accessible = nsnull;
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if (mState.isHidden || !mState.domNode) {
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return NS_ERROR_FAILURE;
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}
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nsCOMPtr<nsIDOMNode> parent(mState.domNode);
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GetKids(parent); // Side effects change our state (mState)
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// Recursive loop: depth first search for first accessible child
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while (mState.domNode) {
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if ((mState.domNode != parent && GetAccessible()) || NS_SUCCEEDED(GetFirstChild()))
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return NS_OK;
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UpdateFrame(PR_FALSE);
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GetNextDOMNode();
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}
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PopState(); // Return to previous state
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return NS_ERROR_FAILURE;
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}
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void nsAccessibleTreeWalker::UpdateFrame(PRBool aTryFirstChild)
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{
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if (!mState.frame) {
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return;
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}
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if (aTryFirstChild) {
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nsIContent *containerContent = mState.frame->GetContent();
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mState.frame = mState.frame->GetFirstChild(nsnull);
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// temporary workaround for Bug 359210. We never want to walk frames.
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// Aaron Leventhal will refix :before and :after content later without walking frames.
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#if 0
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if (mState.frame && mState.siblingIndex < 0) {
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// Container frames can contain generated content frames from
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// :before and :after style rules, so we walk their frame trees
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// instead of content trees
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// XXX Walking the frame tree doesn't get us Aural CSS nodes, e.g.
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// @media screen { display: none; }
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// Asking the style system might be better (with ProbePseudoStyleFor(),
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// except that we need to ask only for those display types that support
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// :before and :after (which roughly means non-replaced elements)
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// Here's some code to see if there is an :after rule for an element
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// nsRefPtr<nsStyleContext> pseudoContext;
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// nsStyleContext *styleContext = primaryFrame->GetStyleContext();
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// if (aContent) {
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// pseudoContext = presContext->StyleSet()->
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// ProbePseudoStyleFor(content, nsAccessibilityAtoms::after, aStyleContext);
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mState.domNode = do_QueryInterface(mState.frame->GetContent());
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mState.siblingIndex = eSiblingsWalkFrames;
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}
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#endif
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// Special case: <input type="file">
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// We should still need to walk frames inside the file control frame
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// This special case may turn into a more general rule after Firefox 3,
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// if HTML 5 controls use nsIAnonymousContentCreator
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if (containerContent->Tag() == nsAccessibilityAtoms::input &&
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containerContent->AttrValueIs(kNameSpaceID_None, nsAccessibilityAtoms::type,
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NS_LITERAL_STRING("file"), eIgnoreCase) &&
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mState.frame && mState.siblingIndex < 0) {
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mState.domNode = do_QueryInterface(mState.frame->GetContent());
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mState.siblingIndex = eSiblingsWalkFrames;
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}
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}
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else {
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mState.frame = mState.frame->GetNextSibling();
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}
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}
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/**
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* If the DOM node's frame has an accessible or the DOMNode
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* itself implements nsIAccessible return it.
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*/
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PRBool nsAccessibleTreeWalker::GetAccessible()
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{
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if (!mAccService) {
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return PR_FALSE;
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}
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mState.accessible = nsnull;
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nsCOMPtr<nsIPresShell> presShell(do_QueryReferent(mWeakShell));
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mAccService->GetAccessible(mState.domNode, presShell, mWeakShell,
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&mState.frame, &mState.isHidden,
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getter_AddRefs(mState.accessible));
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return mState.accessible ? PR_TRUE : PR_FALSE;
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}
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