C++ HyperTextAccessible::GetChildAtOffset方法代码示例

Accessible*
nsAccessiblePivot::AdjustStartPosition(Accessible* aAccessible,
                                       RuleCache& aCache,
                                       uint16_t* aFilterResult,
                                       nsresult* aResult)
{
  Accessible* matched = aAccessible;
  *aResult = aCache.ApplyFilter(aAccessible, aFilterResult);

  if (aAccessible != mRoot && aAccessible != mModalRoot) {
    for (Accessible* temp = aAccessible->Parent();
         temp && temp != mRoot && temp != mModalRoot; temp = temp->Parent()) {
      uint16_t filtered = nsIAccessibleTraversalRule::FILTER_IGNORE;
      *aResult = aCache.ApplyFilter(temp, &filtered);
      NS_ENSURE_SUCCESS(*aResult, nullptr);
      if (filtered & nsIAccessibleTraversalRule::FILTER_IGNORE_SUBTREE) {
        *aFilterResult = filtered;
        matched = temp;
      }
    }
  }

  if (aAccessible == mPosition && mStartOffset != -1 && mEndOffset != -1) {
    HyperTextAccessible* text = aAccessible->AsHyperText();
    if (text) {
      matched = text->GetChildAtOffset(mStartOffset);
    }
  }

  return matched;
}

NS_IMETHODIMP
nsAccessiblePivot::MovePreviousByText(TextBoundaryType aBoundary, bool* aResult)
{
  NS_ENSURE_ARG(aResult);

  *aResult = false;

  int32_t tempStart = mStartOffset, tempEnd = mEndOffset;
  Accessible* tempPosition = mPosition;
  Accessible* root = GetActiveRoot();
  while (true) {
    Accessible* curPosition = tempPosition;
    HyperTextAccessible* text;
    // Find the nearest text node using a reverse preorder traversal starting
    // from the current node.
    if (!(text = tempPosition->AsHyperText())) {
      text = SearchForText(tempPosition, true);
      if (!text)
        return NS_OK;
      if (text != curPosition)
        tempStart = tempEnd = -1;
      tempPosition = text;
    }

    // If the search led to the parent of the node we started on (e.g. when
    // starting on a text leaf), start the text movement from the end of that
    // node, otherwise we just default to 0.
    if (tempStart == -1) {
      if (tempPosition != curPosition)
        tempStart = text == curPosition->Parent() ?
                    text->GetChildOffset(curPosition) : text->CharacterCount();
      else
        tempStart = 0;
    }

    // If there's no more text on the current node, try to find the previous
    // text node; if there isn't one, bail out.
    if (tempStart == 0) {
      if (tempPosition == root)
        return NS_OK;

      // If we're currently sitting on a link, try move to either the previous
      // sibling or the parent, whichever is closer to the current end
      // offset. Otherwise, do a forward search for the next node to land on
      // (we don't do this in the first case because we don't want to go to the
      // subtree).
      Accessible* sibling = tempPosition->PrevSibling();
      if (tempPosition->IsLink()) {
        if (sibling && sibling->IsLink()) {
          HyperTextAccessible* siblingText = sibling->AsHyperText();
          tempStart = tempEnd = siblingText ?
                                siblingText->CharacterCount() : -1;
          tempPosition = sibling;
        } else {
          tempStart = tempPosition->StartOffset();
          tempEnd = tempPosition->EndOffset();
          tempPosition = tempPosition->Parent();
        }
      } else {
        HyperTextAccessible* tempText = SearchForText(tempPosition, true);
        if (!tempText)
          return NS_OK;
        tempPosition = tempText;
        tempStart = tempEnd = tempText->CharacterCount();
      }
      continue;
    }

    AccessibleTextBoundary startBoundary, endBoundary;
    switch (aBoundary) {
      case CHAR_BOUNDARY:
        startBoundary = nsIAccessibleText::BOUNDARY_CHAR;
        endBoundary = nsIAccessibleText::BOUNDARY_CHAR;
        break;
      case WORD_BOUNDARY:
        startBoundary = nsIAccessibleText::BOUNDARY_WORD_START;
        endBoundary = nsIAccessibleText::BOUNDARY_WORD_END;
        break;
      default:
        return NS_ERROR_INVALID_ARG;
    }

    nsAutoString unusedText;
    int32_t newStart = 0, newEnd = 0, currentStart = tempStart, potentialEnd = 0;
    text->TextBeforeOffset(tempStart, startBoundary, &newStart, &newEnd, unusedText);
    if (newStart < tempStart)
      tempStart = newEnd >= currentStart ? newStart : newEnd;
    else // XXX: In certain odd cases newStart is equal to tempStart
      text->TextBeforeOffset(tempStart - 1, startBoundary, &newStart,
                             &tempStart, unusedText);
    text->TextAtOffset(tempStart, endBoundary, &newStart, &potentialEnd,
                       unusedText);
    tempEnd = potentialEnd < tempEnd ? potentialEnd : currentStart;

    // The offset range we've obtained might have embedded characters in it,
    // limit the range to the start of the last occurrence of an embedded
    // character.
    Accessible* childAtOffset = nullptr;
    for (int32_t i = tempEnd - 1; i >= tempStart; i--) {
      childAtOffset = text->GetChildAtOffset(i);
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