DXR is a code search and navigation tool aimed at making sense of large projects. It supports full-text and regex searches as well as structural queries.

Header

Mercurial (c68fe15a81fc)

VCS Links

Line Code
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this file,
 * You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "TableAccessible.h"

#include "Accessible-inl.h"
#include "AccIterator.h"

#include "nsTableCellFrame.h"
#include "nsTableWrapperFrame.h"
#include "TableCellAccessible.h"

using namespace mozilla;
using namespace mozilla::a11y;

bool TableAccessible::IsProbablyLayoutTable() {
  // Implement a heuristic to determine if table is most likely used for layout.

  // XXX do we want to look for rowspan or colspan, especialy that span all but
  // a couple cells  at the beginning or end of a row/col, and especially when
  // they occur at the edge of a table?

  // XXX For now debugging descriptions are always on via SHOW_LAYOUT_HEURISTIC
  // This will allow release trunk builds to be used by testers to refine
  // the algorithm. Integrate it into Logging.
  // Change to |#define SHOW_LAYOUT_HEURISTIC DEBUG| before final release
#ifdef SHOW_LAYOUT_HEURISTIC
#  define RETURN_LAYOUT_ANSWER(isLayout, heuristic)                          \
    {                                                                        \
      mLayoutHeuristic = isLayout                                            \
                             ? NS_LITERAL_STRING("layout table: " heuristic) \
                             : NS_LITERAL_STRING("data table: " heuristic);  \
      return isLayout;                                                       \
    }
#else
#  define RETURN_LAYOUT_ANSWER(isLayout, heuristic) \
    { return isLayout; }
#endif

  Accessible* thisacc = AsAccessible();

  MOZ_ASSERT(!thisacc->IsDefunct(), "Table accessible should not be defunct");

  // Need to see all elements while document is being edited.
  if (thisacc->Document()->State() & states::EDITABLE) {
    RETURN_LAYOUT_ANSWER(false, "In editable document");
  }

  // Check to see if an ARIA role overrides the role from native markup,
  // but for which we still expose table semantics (treegrid, for example).
  if (thisacc->HasARIARole()) {
    RETURN_LAYOUT_ANSWER(false, "Has role attribute");
  }

  dom::Element* el = thisacc->Elm();
  if (el->IsMathMLElement(nsGkAtoms::mtable_)) {
    RETURN_LAYOUT_ANSWER(false, "MathML matrix");
  }

  MOZ_ASSERT(el->IsHTMLElement(nsGkAtoms::table),
             "Table should not be built by CSS display:table style");

  // Check if datatable attribute has "0" value.
  if (el->AttrValueIs(kNameSpaceID_None, nsGkAtoms::datatable,
                      NS_LITERAL_STRING("0"), eCaseMatters)) {
    RETURN_LAYOUT_ANSWER(true, "Has datatable = 0 attribute, it's for layout");
  }

  // Check for legitimate data table attributes.
  if (el->Element::HasNonEmptyAttr(nsGkAtoms::summary)) {
    RETURN_LAYOUT_ANSWER(false, "Has summary -- legitimate table structures");
  }

  // Check for legitimate data table elements.
  Accessible* caption = thisacc->FirstChild();
  if (caption && caption->IsHTMLCaption() && caption->HasChildren()) {
    RETURN_LAYOUT_ANSWER(false,
                         "Not empty caption -- legitimate table structures");
  }

  for (nsIContent* childElm = el->GetFirstChild(); childElm;
       childElm = childElm->GetNextSibling()) {
    if (!childElm->IsHTMLElement()) continue;

    if (childElm->IsAnyOfHTMLElements(nsGkAtoms::col, nsGkAtoms::colgroup,
                                      nsGkAtoms::tfoot, nsGkAtoms::thead)) {
      RETURN_LAYOUT_ANSWER(
          false,
          "Has col, colgroup, tfoot or thead -- legitimate table structures");
    }

    if (childElm->IsHTMLElement(nsGkAtoms::tbody)) {
      for (nsIContent* rowElm = childElm->GetFirstChild(); rowElm;
           rowElm = rowElm->GetNextSibling()) {
        if (rowElm->IsHTMLElement(nsGkAtoms::tr)) {
          for (nsIContent* cellElm = rowElm->GetFirstChild(); cellElm;
               cellElm = cellElm->GetNextSibling()) {
            if (cellElm->IsHTMLElement()) {
              if (cellElm->NodeInfo()->Equals(nsGkAtoms::th)) {
                RETURN_LAYOUT_ANSWER(false,
                                     "Has th -- legitimate table structures");
              }

              if (cellElm->AsElement()->HasAttr(kNameSpaceID_None,
                                                nsGkAtoms::headers) ||
                  cellElm->AsElement()->HasAttr(kNameSpaceID_None,
                                                nsGkAtoms::scope) ||
                  cellElm->AsElement()->HasAttr(kNameSpaceID_None,
                                                nsGkAtoms::abbr)) {
                RETURN_LAYOUT_ANSWER(false,
                                     "Has headers, scope, or abbr attribute -- "
                                     "legitimate table structures");
              }

              Accessible* cell = thisacc->Document()->GetAccessible(cellElm);
              if (cell && cell->ChildCount() == 1 &&
                  cell->FirstChild()->IsAbbreviation()) {
                RETURN_LAYOUT_ANSWER(false,
                                     "has abbr -- legitimate table structures");
              }
            }
          }
        }
      }
    }
  }

  // Check for nested tables.
  nsCOMPtr<nsIHTMLCollection> nestedTables =
      el->GetElementsByTagName(NS_LITERAL_STRING("table"));
  if (nestedTables->Length() > 0) {
    RETURN_LAYOUT_ANSWER(true, "Has a nested table within it");
  }

  // If only 1 column or only 1 row, it's for layout.
  auto colCount = ColCount();
  if (colCount <= 1) {
    RETURN_LAYOUT_ANSWER(true, "Has only 1 column");
  }
  auto rowCount = RowCount();
  if (rowCount <= 1) {
    RETURN_LAYOUT_ANSWER(true, "Has only 1 row");
  }

  // Check for many columns.
  if (colCount >= 5) {
    RETURN_LAYOUT_ANSWER(false, ">=5 columns");
  }

  // Now we know there are 2-4 columns and 2 or more rows. Check to see if
  // there are visible borders on the cells.
  // XXX currently, we just check the first cell -- do we really need to do
  // more?
  nsTableWrapperFrame* tableFrame = do_QueryFrame(el->GetPrimaryFrame());
  if (!tableFrame) {
    RETURN_LAYOUT_ANSWER(false, "table with no frame!");
  }

  nsIFrame* cellFrame = tableFrame->GetCellFrameAt(0, 0);
  if (!cellFrame) {
    RETURN_LAYOUT_ANSWER(false, "table's first cell has no frame!");
  }

  nsMargin border;
  cellFrame->GetXULBorder(border);
  if (border.top && border.bottom && border.left && border.right) {
    RETURN_LAYOUT_ANSWER(false, "Has nonzero border-width on table cell");
  }

  // Rules for non-bordered tables with 2-4 columns and 2+ rows from here on
  // forward.

  // Check for styled background color across rows (alternating background
  // color is a common feature for data tables).
  auto childCount = thisacc->ChildCount();
  nscolor rowColor = 0;
  nscolor prevRowColor;
  for (auto childIdx = 0U; childIdx < childCount; childIdx++) {
    Accessible* child = thisacc->GetChildAt(childIdx);
    if (child->IsHTMLTableRow()) {
      prevRowColor = rowColor;
      nsIFrame* rowFrame = child->GetFrame();
      MOZ_ASSERT(rowFrame, "Table hierarchy got screwed up");
      if (!rowFrame) {
        RETURN_LAYOUT_ANSWER(false, "Unexpected table hierarchy");
      }

      rowColor = rowFrame->StyleBackground()->BackgroundColor(rowFrame);

      if (childIdx > 0 && prevRowColor != rowColor) {
        RETURN_LAYOUT_ANSWER(false,
                             "2 styles of row background color, non-bordered");
      }
    }
  }

  // Check for many rows.
  const uint32_t kMaxLayoutRows = 20;
  if (rowCount > kMaxLayoutRows) {  // A ton of rows, this is probably for data
    RETURN_LAYOUT_ANSWER(false, ">= kMaxLayoutRows (20) and non-bordered");
  }

  // Check for very wide table.
  nsIFrame* documentFrame = thisacc->Document()->GetFrame();
  nsSize documentSize = documentFrame->GetSize();
  if (documentSize.width > 0) {
    nsSize tableSize = thisacc->GetFrame()->GetSize();
    int32_t percentageOfDocWidth = (100 * tableSize.width) / documentSize.width;
    if (percentageOfDocWidth > 95) {
      // 3-4 columns, no borders, not a lot of rows, and 95% of the doc's width
      // Probably for layout
      RETURN_LAYOUT_ANSWER(
          true, "<= 4 columns, table width is 95% of document width");
    }
  }

  // Two column rules.
  if (rowCount * colCount <= 10) {
    RETURN_LAYOUT_ANSWER(true, "2-4 columns, 10 cells or less, non-bordered");
  }

  static const nsLiteralString tags[] = {NS_LITERAL_STRING("embed"),
                                         NS_LITERAL_STRING("object"),
                                         NS_LITERAL_STRING("iframe")};
  for (auto& tag : tags) {
    nsCOMPtr<nsIHTMLCollection> descendants = el->GetElementsByTagName(tag);
    if (descendants->Length() > 0) {
      RETURN_LAYOUT_ANSWER(true,
                           "Has no borders, and has iframe, object or embed, "
                           "typical of advertisements");
    }
  }

  RETURN_LAYOUT_ANSWER(false,
                       "No layout factor strong enough, so will guess data");
}

Accessible* TableAccessible::RowAt(int32_t aRow) {
  int32_t rowIdx = aRow;

  AccIterator rowIter(this->AsAccessible(), filters::GetRow);

  Accessible* row = rowIter.Next();
  while (rowIdx != 0 && (row = rowIter.Next())) {
    rowIdx--;
  }

  return row;
}

Accessible* TableAccessible::CellInRowAt(Accessible* aRow, int32_t aColumn) {
  int32_t colIdx = aColumn;

  AccIterator cellIter(aRow, filters::GetCell);
  Accessible* cell = nullptr;

  while (colIdx >= 0 && (cell = cellIter.Next())) {
    MOZ_ASSERT(cell->IsTableCell(), "No table or grid cell!");
    colIdx -= cell->AsTableCell()->ColExtent();
  }

  return cell;
}

int32_t TableAccessible::ColIndexAt(uint32_t aCellIdx) {
  uint32_t colCount = ColCount();
  if (colCount < 1 || aCellIdx >= colCount * RowCount()) {
    return -1;  // Error: column count is 0 or index out of bounds.
  }

  return aCellIdx % colCount;
}

int32_t TableAccessible::RowIndexAt(uint32_t aCellIdx) {
  uint32_t colCount = ColCount();
  if (colCount < 1 || aCellIdx >= colCount * RowCount()) {
    return -1;  // Error: column count is 0 or index out of bounds.
  }

  return aCellIdx / colCount;
}

void TableAccessible::RowAndColIndicesAt(uint32_t aCellIdx, int32_t* aRowIdx,
                                         int32_t* aColIdx) {
  uint32_t colCount = ColCount();
  if (colCount < 1 || aCellIdx >= colCount * RowCount()) {
    *aRowIdx = -1;
    *aColIdx = -1;
    return;  // Error: column count is 0 or index out of bounds.
  }

  *aRowIdx = aCellIdx / colCount;
  *aColIdx = aCellIdx % colCount;
}