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 (920bcf17a9e1)

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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342 1343 1344 1345 1346 1347 1348 1349 1350 1351 1352 1353 1354 1355 1356 1357 1358 1359 1360 1361 1362 1363 1364 1365 1366 1367 1368 1369 1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 1411 1412 1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424 1425 1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448 1449 1450 1451 1452 1453 1454 1455 1456 1457 1458 1459 1460 1461 1462 1463 1464 1465 1466 1467 1468 1469 1470 1471 1472 1473 1474 1475 1476 1477 1478 1479 1480 1481 1482 1483 1484 1485 1486 1487 1488 1489 1490 1491 1492 1493 1494 1495 1496 1497 1498 1499 1500 1501 1502 1503 1504 1505 1506 1507 1508 1509 1510 1511 1512 1513 1514 1515 1516 1517 1518 1519 1520 1521 1522 1523 1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534 1535 1536 1537 1538 1539 1540 1541 1542 1543 1544 1545 1546 1547 1548 1549 1550 1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 1561 1562 1563 1564 1565 1566 1567 1568 1569 1570 1571 1572 1573 1574 1575 1576 1577 1578 1579 1580 1581 1582 1583 1584 1585 1586 1587 1588 1589 1590 1591 1592 1593 1594 1595 1596 1597 1598 1599 1600 1601 1602 1603 1604 1605 1606 1607 1608 1609 1610 1611 1612 1613 1614 1615 1616 1617 1618 1619 1620 1621 1622 1623 1624 1625 1626 1627 1628 1629 1630 1631 1632 1633 1634 1635 1636 1637 1638 1639 1640 1641 1642 1643 1644 1645 1646 1647 1648 1649 1650 1651 1652 1653 1654 1655 1656 1657 1658 1659 1660 1661 1662 1663 1664 1665 1666 1667 1668 1669 1670 1671 1672 1673 1674 1675 1676 1677 1678 1679 1680 1681 1682 1683 1684 1685 1686 1687 1688 1689 1690 1691 1692 1693 1694 1695 1696 1697 1698 1699 1700 1701 1702 1703 1704 1705 1706 1707 1708 1709 1710 1711 1712 1713 1714 1715 1716 1717 1718 1719 1720 1721 1722 1723 1724 1725 1726 1727 1728 1729 1730 1731 1732 1733 1734 1735 1736 1737 1738 1739 1740 1741 1742 1743 1744 1745 1746 1747 1748 1749 1750 1751 1752 1753 1754 1755 1756 1757 1758 1759 1760 1761 1762 1763 1764 1765 1766 1767 1768 1769 1770 1771 1772 1773 1774 1775 1776 1777 1778 1779 1780 1781 1782 1783 1784 1785 1786 1787 1788 1789 1790 1791 1792 1793 1794 1795 1796 1797 1798 1799 1800 1801 1802 1803 1804 1805 1806 1807 1808 1809 1810 1811 1812 1813 1814 1815 1816 1817 1818 1819 1820 1821 1822 1823 1824 1825 1826 1827 1828 1829 1830 1831 1832 1833 1834 1835 1836 1837 1838 1839 1840 1841 1842 1843 1844 1845 1846 1847 1848 1849 1850 1851 1852 1853 1854 1855 1856 1857 1858 1859 1860 1861 1862 1863 1864 1865 1866 1867 1868 1869 1870 1871 1872 1873 1874 1875 1876 1877 1878 1879 1880 1881 1882 1883 1884 1885 1886 1887 1888 1889 1890 1891 1892 1893 1894 1895 1896 1897 1898 1899 1900 1901 1902 1903 1904 1905 1906 1907 1908 1909 1910 1911 1912 1913 1914 1915 1916 1917 1918 1919 1920 1921 1922 1923 1924 1925 1926 1927 1928 1929 1930 1931 1932 1933 1934 1935 1936 1937 1938 1939 1940 1941 1942 1943 1944 1945 1946 1947 1948 1949 1950 1951 1952 1953 1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030 2031 2032 2033 2034 2035 2036 2037 2038 2039 2040 2041 2042 2043 2044 2045 2046 2047 2048 2049 2050 2051 2052 2053 2054 2055 2056 2057 2058 2059 2060 2061 2062 2063 2064 2065 2066 2067 2068 2069 2070 2071 2072 2073 2074 2075 2076 2077 2078 2079 2080 2081 2082 2083 2084 2085 2086 2087 2088 2089 2090 2091 2092 2093 2094 2095 2096 2097 2098 2099 2100 2101 2102 2103 2104 2105 2106 2107 2108 2109 2110 2111 2112 2113 2114 2115 2116 2117 2118 2119 2120 2121 2122 2123 2124 2125 2126 2127 2128 2129 2130 2131 2132 2133 2134 2135 2136 2137 2138 2139 2140 2141 2142 2143 2144 2145 2146 2147 2148 2149 2150 2151 2152 2153 2154 2155 2156 2157 2158 2159 2160 2161 2162 2163 2164 2165 2166 2167 2168 2169 2170 2171 2172 2173 2174 2175 2176 2177 2178 2179 2180 2181 2182 2183 2184 2185 2186 2187 2188 2189 2190 2191 2192 2193 2194 2195 2196 2197 2198 2199 2200 2201 2202 2203 2204 2205 2206 2207 2208 2209 2210 2211 2212 2213 2214 2215 2216 2217 2218 2219 2220 2221 2222 2223 2224 2225 2226 2227 2228 2229 2230 2231 2232 2233 2234 2235 2236 2237 2238 2239 2240 2241 2242 2243 2244 2245 2246 2247 2248 2249 2250 2251 2252 2253 2254 2255 2256 2257 2258 2259 2260 2261 2262 2263 2264 2265 2266 2267 2268 2269 2270 2271 2272 2273 2274 2275 2276 2277 2278 2279 2280 2281 2282 2283 2284 2285 2286 2287 2288 2289 2290 2291 2292 2293 2294 2295 2296 2297 2298 2299 2300
/* -*- 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 Communicator client code.
 *
 * The Initial Developer of the Original Code is
 * Netscape Communications Corporation.
 * Portions created by the Initial Developer are Copyright (C) 1998
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *
 * 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 ***** */

/* struct containing the input to nsIFrame::Reflow */

#include "nsCOMPtr.h"
#include "nsStyleConsts.h"
#include "nsCSSAnonBoxes.h"
#include "nsFrame.h"
#include "nsIContent.h"
#include "nsGkAtoms.h"
#include "nsPresContext.h"
#include "nsIPresShell.h"
#include "nsIDeviceContext.h"
#include "nsIRenderingContext.h"
#include "nsIFontMetrics.h"
#include "nsBlockFrame.h"
#include "nsLineBox.h"
#include "nsImageFrame.h"
#include "nsTableFrame.h"
#include "nsTableCellFrame.h"
#include "nsIServiceManager.h"
#include "nsIPercentHeightObserver.h"
#include "nsContentUtils.h"
#include "nsLayoutUtils.h"
#ifdef IBMBIDI
#include "nsBidiUtils.h"
#endif

#ifdef NS_DEBUG
#undef NOISY_VERTICAL_ALIGN
#else
#undef NOISY_VERTICAL_ALIGN
#endif

// Prefs-driven control for |text-decoration: blink|
static PRPackedBool sPrefIsLoaded = PR_FALSE;
static PRPackedBool sBlinkIsAllowed = PR_TRUE;

enum eNormalLineHeightControl {
  eUninitialized = -1,
  eNoExternalLeading = 0,   // does not include external leading 
  eIncludeExternalLeading,  // use whatever value font vendor provides
  eCompensateLeading        // compensate leading if leading provided by font vendor is not enough
};

static eNormalLineHeightControl sNormalLineHeightControl = eUninitialized;

// Initialize a <b>root</b> reflow state with a rendering context to
// use for measuring things.
nsHTMLReflowState::nsHTMLReflowState(nsPresContext*       aPresContext,
                                     nsIFrame*            aFrame,
                                     nsIRenderingContext* aRenderingContext,
                                     const nsSize&        aAvailableSpace)
  : nsCSSOffsetState(aFrame, aRenderingContext)
  , mBlockDelta(0)
  , mReflowDepth(0)
{
  NS_PRECONDITION(aPresContext, "no pres context");
  NS_PRECONDITION(aRenderingContext, "no rendering context");
  NS_PRECONDITION(aFrame, "no frame");
  parentReflowState = nsnull;
  availableWidth = aAvailableSpace.width;
  availableHeight = aAvailableSpace.height;
  mFloatManager = nsnull;
  mLineLayout = nsnull;
  mFlags.mSpecialHeightReflow = PR_FALSE;
  mFlags.mIsTopOfPage = PR_FALSE;
  mFlags.mTableIsSplittable = PR_FALSE;
  mFlags.mNextInFlowUntouched = PR_FALSE;
  mFlags.mAssumingHScrollbar = mFlags.mAssumingVScrollbar = PR_FALSE;
  mFlags.mHasClearance = PR_FALSE;
  mFlags.mHeightDependsOnAncestorCell = PR_FALSE;
  mDiscoveredClearance = nsnull;
  mPercentHeightObserver = nsnull;
  Init(aPresContext);
}

static PRBool CheckNextInFlowParenthood(nsIFrame* aFrame, nsIFrame* aParent)
{
  nsIFrame* frameNext = aFrame->GetNextInFlow();
  nsIFrame* parentNext = aParent->GetNextInFlow();
  return frameNext && parentNext && frameNext->GetParent() == parentNext;
}

// Initialize a reflow state for a child frames reflow. Some state
// is copied from the parent reflow state; the remaining state is
// computed.
nsHTMLReflowState::nsHTMLReflowState(nsPresContext*           aPresContext,
                                     const nsHTMLReflowState& aParentReflowState,
                                     nsIFrame*                aFrame,
                                     const nsSize&            aAvailableSpace,
                                     nscoord                  aContainingBlockWidth,
                                     nscoord                  aContainingBlockHeight,
                                     PRBool                   aInit)
  : nsCSSOffsetState(aFrame, aParentReflowState.rendContext)
  , mBlockDelta(0)
  , mReflowDepth(aParentReflowState.mReflowDepth + 1)
  , mFlags(aParentReflowState.mFlags)
{
  NS_PRECONDITION(aPresContext, "no pres context");
  NS_PRECONDITION(aFrame, "no frame");
  NS_PRECONDITION((aContainingBlockWidth == -1) ==
                    (aContainingBlockHeight == -1),
                  "cb width and height should only be non-default together");
  NS_PRECONDITION(aInit == PR_TRUE || aInit == PR_FALSE,
                  "aInit out of range for PRBool");
  NS_PRECONDITION(!mFlags.mSpecialHeightReflow ||
                  !NS_SUBTREE_DIRTY(aFrame),
                  "frame should be clean when getting special height reflow");

  parentReflowState = &aParentReflowState;

  // If the parent is dirty, then the child is as well.
  // XXX Are the other cases where the parent reflows a child a second
  // time, as a resize?
  if (!mFlags.mSpecialHeightReflow)
    frame->AddStateBits(parentReflowState->frame->GetStateBits() &
                        NS_FRAME_IS_DIRTY);

  availableWidth = aAvailableSpace.width;
  availableHeight = aAvailableSpace.height;

  mFloatManager = aParentReflowState.mFloatManager;
  if (frame->IsFrameOfType(nsIFrame::eLineParticipant))
    mLineLayout = aParentReflowState.mLineLayout;
  else
    mLineLayout = nsnull;
  mFlags.mIsTopOfPage = aParentReflowState.mFlags.mIsTopOfPage;
  mFlags.mNextInFlowUntouched = aParentReflowState.mFlags.mNextInFlowUntouched &&
    CheckNextInFlowParenthood(aFrame, aParentReflowState.frame);
  mFlags.mAssumingHScrollbar = mFlags.mAssumingVScrollbar = PR_FALSE;
  mFlags.mHasClearance = PR_FALSE;
  mDiscoveredClearance = nsnull;
  mPercentHeightObserver = (aParentReflowState.mPercentHeightObserver && 
                            aParentReflowState.mPercentHeightObserver->NeedsToObserve(*this)) 
                           ? aParentReflowState.mPercentHeightObserver : nsnull;

  if (aInit) {
    Init(aPresContext, aContainingBlockWidth, aContainingBlockHeight);
  }
}

inline nscoord
nsCSSOffsetState::ComputeWidthValue(nscoord aContainingBlockWidth,
                                    nscoord aContentEdgeToBoxSizing,
                                    nscoord aBoxSizingToMarginEdge,
                                    const nsStyleCoord& aCoord)
{
  return nsLayoutUtils::ComputeWidthValue(rendContext, frame,
                                          aContainingBlockWidth,
                                          aContentEdgeToBoxSizing,
                                          aBoxSizingToMarginEdge,
                                          aCoord);
}

nscoord
nsCSSOffsetState::ComputeWidthValue(nscoord aContainingBlockWidth,
                                    PRUint8 aBoxSizing,
                                    const nsStyleCoord& aCoord)
{
  nscoord inside = 0, outside = mComputedBorderPadding.LeftRight() +
                                mComputedMargin.LeftRight();
  switch (aBoxSizing) {
    case NS_STYLE_BOX_SIZING_BORDER:
      inside = mComputedBorderPadding.LeftRight();
      break;
    case NS_STYLE_BOX_SIZING_PADDING:
      inside = mComputedPadding.LeftRight();
      break;
  }
  outside -= inside;

  return ComputeWidthValue(aContainingBlockWidth, inside,
                           outside, aCoord);
}

void
nsHTMLReflowState::SetComputedWidth(nscoord aComputedWidth)
{
  NS_ASSERTION(frame, "Must have a frame!");
  // It'd be nice to assert that |frame| is not in reflow, but this fails for
  // two reasons:
  //
  // 1) Viewport frames reset the computed width on a copy of their reflow
  //    state when reflowing fixed-pos kids.  In that case we actually don't
  //    want to mess with the resize flags, because comparing the frame's rect
  //    to the munged computed width is pointless.
  // 2) nsFrame::BoxReflow creates a reflow state for its parent.  This reflow
  //    state is not used to reflow the parent, but just as a parent for the
  //    frame's own reflow state.  So given a nsBoxFrame inside some non-XUL
  //    (like a text control, for example), we'll end up creating a reflow
  //    state for the parent while the parent is reflowing.

  NS_PRECONDITION(aComputedWidth >= 0, "Invalid computed width");
  if (mComputedWidth != aComputedWidth) {
    mComputedWidth = aComputedWidth;
    if (frame->GetType() != nsGkAtoms::viewportFrame) { // Or check GetParent()?
      InitResizeFlags(frame->PresContext());
    }
  }
}

void
nsHTMLReflowState::SetComputedHeight(nscoord aComputedHeight)
{
  NS_ASSERTION(frame, "Must have a frame!");
  // It'd be nice to assert that |frame| is not in reflow, but this fails
  // because:
  //
  //    nsFrame::BoxReflow creates a reflow state for its parent.  This reflow
  //    state is not used to reflow the parent, but just as a parent for the
  //    frame's own reflow state.  So given a nsBoxFrame inside some non-XUL
  //    (like a text control, for example), we'll end up creating a reflow
  //    state for the parent while the parent is reflowing.

  NS_PRECONDITION(aComputedHeight >= 0, "Invalid computed height");
  if (mComputedHeight != aComputedHeight) {
    mComputedHeight = aComputedHeight;
    InitResizeFlags(frame->PresContext());
  }
}

void
nsHTMLReflowState::Init(nsPresContext* aPresContext,
                        nscoord         aContainingBlockWidth,
                        nscoord         aContainingBlockHeight,
                        const nsMargin* aBorder,
                        const nsMargin* aPadding)
{
  NS_ASSERTION(availableWidth != NS_UNCONSTRAINEDSIZE,
               "shouldn't use unconstrained widths anymore");

  mStylePosition = frame->GetStylePosition();
  mStyleDisplay = frame->GetStyleDisplay();
  mStyleVisibility = frame->GetStyleVisibility();
  mStyleBorder = frame->GetStyleBorder();
  mStyleMargin = frame->GetStyleMargin();
  mStylePadding = frame->GetStylePadding();
  mStyleText = frame->GetStyleText();

  InitFrameType();
  InitCBReflowState();

  InitConstraints(aPresContext, aContainingBlockWidth, aContainingBlockHeight, aBorder, aPadding);

  InitResizeFlags(aPresContext);

  NS_ASSERTION((mFrameType == NS_CSS_FRAME_TYPE_INLINE &&
                !frame->IsFrameOfType(nsIFrame::eReplaced)) ||
               frame->GetType() == nsGkAtoms::textFrame ||
               mComputedWidth != NS_UNCONSTRAINEDSIZE,
               "shouldn't use unconstrained widths anymore");
}

void nsHTMLReflowState::InitCBReflowState()
{
  if (!parentReflowState) {
    mCBReflowState = nsnull;
    return;
  }

  if (parentReflowState->frame->IsContainingBlock() ||
      // Absolutely positioned frames should always be kids of the frames that
      // determine their containing block
      (NS_FRAME_GET_TYPE(mFrameType) == NS_CSS_FRAME_TYPE_ABSOLUTE)) {
    // a block inside a table cell needs to use the table cell
    if (parentReflowState->parentReflowState &&
        IS_TABLE_CELL(parentReflowState->parentReflowState->frame->GetType())) {
      mCBReflowState = parentReflowState->parentReflowState;
    } else {
      mCBReflowState = parentReflowState;
    }
      
    return;
  }
  
  mCBReflowState = parentReflowState->mCBReflowState;
}

/* Check whether CalcQuirkContainingBlockHeight would stop on the
 * given reflow state, using its block as a height.  (essentially 
 * returns false for any case in which CalcQuirkContainingBlockHeight 
 * has a "continue" in its main loop.)
 *
 * XXX Maybe refactor CalcQuirkContainingBlockHeight so it uses 
 * this function as well
 */
static PRBool
IsQuirkContainingBlockHeight(const nsHTMLReflowState* rs) 
{
  nsIAtom* frameType = rs->frame->GetType();
  if (nsGkAtoms::blockFrame == frameType ||
      nsGkAtoms::areaFrame == frameType ||
      nsGkAtoms::scrollFrame == frameType) {
    // Note: This next condition could change due to a style change,
    // but that would cause a style reflow anyway, which means we're ok.
    if (NS_AUTOHEIGHT == rs->ComputedHeight()) {
      if (!rs->frame->GetStyleDisplay()->IsAbsolutelyPositioned()) {
        return PR_FALSE;
      }
    }
  }
  return PR_TRUE;
}


void
nsHTMLReflowState::InitResizeFlags(nsPresContext* aPresContext)
{
  mFlags.mHResize = !(frame->GetStateBits() & NS_FRAME_IS_DIRTY) &&
                    frame->GetSize().width !=
                      mComputedWidth + mComputedBorderPadding.LeftRight();

  // XXX Should we really need to null check mCBReflowState?  (We do for
  // at least nsBoxFrame).
  if (IS_TABLE_CELL(frame->GetType()) &&
      (mFlags.mSpecialHeightReflow ||
       (frame->GetFirstInFlow()->GetStateBits() &
         NS_TABLE_CELL_HAD_SPECIAL_REFLOW)) &&
      (frame->GetStateBits() & NS_FRAME_CONTAINS_RELATIVE_HEIGHT)) {
    // Need to set the bit on the cell so that
    // mCBReflowState->mFlags.mVResize is set correctly below when
    // reflowing descendant.
    mFlags.mVResize = PR_TRUE;
  } else if (mCBReflowState && !frame->IsContainingBlock()) {
    // XXX Is this problematic for relatively positioned inlines acting
    // as containing block for absolutely positioned elements?
    mFlags.mVResize = mCBReflowState->mFlags.mVResize;
  } else if (mComputedHeight == NS_AUTOHEIGHT) {
    if (eCompatibility_NavQuirks == aPresContext->CompatibilityMode() &&
        mCBReflowState) {
      mFlags.mVResize = mCBReflowState->mFlags.mVResize;
    } else {
      mFlags.mVResize = mFlags.mHResize || NS_SUBTREE_DIRTY(frame); 
    }
  } else {
    // not 'auto' height
    mFlags.mVResize = frame->GetSize().height !=
                        mComputedHeight + mComputedBorderPadding.TopBottom();
  }

  PRBool dependsOnCBHeight =
    mStylePosition->mHeight.GetUnit() == eStyleUnit_Percent ||
    mStylePosition->mMinHeight.GetUnit() == eStyleUnit_Percent ||
    mStylePosition->mMaxHeight.GetUnit() == eStyleUnit_Percent ||
    mStylePosition->mOffset.GetTopUnit() == eStyleUnit_Percent ||
    mStylePosition->mOffset.GetBottomUnit() != eStyleUnit_Auto ||
    frame->IsBoxFrame() ||
    (mStylePosition->mHeight.GetUnit() == eStyleUnit_Auto &&
     frame->GetIntrinsicSize().height.GetUnit() == eStyleUnit_Percent);

  if (mStyleText->mLineHeight.GetUnit() == eStyleUnit_Enumerated) {
    NS_ASSERTION(mStyleText->mLineHeight.GetIntValue() ==
                 NS_STYLE_LINE_HEIGHT_BLOCK_HEIGHT,
                 "bad line-height value");

    // line-height depends on block height
    frame->AddStateBits(NS_FRAME_CONTAINS_RELATIVE_HEIGHT);
    // but only on containing blocks if this frame is not a suitable block
    dependsOnCBHeight |= !frame->IsContainingBlock();
  }

  // If we're the descendant of a table cell that performs special height
  // reflows and we could be the child that requires them, always set
  // the vertical resize in case this is the first pass before the
  // special height reflow.  However, don't do this if it actually is
  // the special height reflow, since in that case it will already be
  // set correctly above if we need it set.
  if (!mFlags.mVResize && mCBReflowState &&
      (IS_TABLE_CELL(mCBReflowState->frame->GetType()) || 
       mCBReflowState->mFlags.mHeightDependsOnAncestorCell) &&
      !mCBReflowState->mFlags.mSpecialHeightReflow && 
      dependsOnCBHeight) {
    mFlags.mVResize = PR_TRUE;
    mFlags.mHeightDependsOnAncestorCell = PR_TRUE;
  }

  // Set NS_FRAME_CONTAINS_RELATIVE_HEIGHT if it's needed.

  // It would be nice to check that |mComputedHeight != NS_AUTOHEIGHT|
  // &&ed with the percentage height check.  However, this doesn't get
  // along with table special height reflows, since a special height
  // reflow (a quirk that makes such percentage heights work on children
  // of table cells) can cause not just a single percentage height to
  // become fixed, but an entire descendant chain of percentage heights
  // to become fixed.
  if (dependsOnCBHeight && mCBReflowState) {
    const nsHTMLReflowState *rs = this;
    PRBool hitCBReflowState = PR_FALSE;
    do {
      rs = rs->parentReflowState;
      if (!rs) {
        break;
      }
        
      if (rs->frame->GetStateBits() & NS_FRAME_CONTAINS_RELATIVE_HEIGHT)
        break; // no need to go further
      rs->frame->AddStateBits(NS_FRAME_CONTAINS_RELATIVE_HEIGHT);
      
      // Keep track of whether we've hit the containing block, because
      // we need to go at least that far.
      if (rs == mCBReflowState) {
        hitCBReflowState = PR_TRUE;
      }

    } while (!hitCBReflowState ||
             (eCompatibility_NavQuirks == aPresContext->CompatibilityMode() &&
              !IsQuirkContainingBlockHeight(rs)));
    // Note: We actually don't need to set the
    // NS_FRAME_CONTAINS_RELATIVE_HEIGHT bit for the cases
    // where we hit the early break statements in
    // CalcQuirkContainingBlockHeight. But it doesn't hurt
    // us to set the bit in these cases.
    
  }
  if (frame->GetStateBits() & NS_FRAME_IS_DIRTY) {
    // If we're reflowing everything, then we'll find out if we need
    // to re-set this.
    frame->RemoveStateBits(NS_FRAME_CONTAINS_RELATIVE_HEIGHT);
  }
}

/* static */
nscoord
nsHTMLReflowState::GetContainingBlockContentWidth(const nsHTMLReflowState* aReflowState)
{
  const nsHTMLReflowState* rs = aReflowState->mCBReflowState;
  if (!rs)
    return 0;
  return rs->mComputedWidth;
}

/* static */
nsIFrame*
nsHTMLReflowState::GetContainingBlockFor(const nsIFrame* aFrame)
{
  NS_PRECONDITION(aFrame, "Must have frame to work with");
  nsIFrame* container = aFrame->GetParent();
  if (aFrame->GetStyleDisplay()->IsAbsolutelyPositioned()) {
    // Absolutely positioned frames are just kids of their containing
    // blocks (which may happen to be inlines).
    return container;
  }
  while (container && !container->IsContainingBlock()) {
    container = container->GetParent();
  }
  return container;
}

void
nsHTMLReflowState::InitFrameType()
{
  const nsStyleDisplay *disp = mStyleDisplay;
  nsCSSFrameType frameType;

  // Section 9.7 of the CSS2 spec indicates that absolute position
  // takes precedence over float which takes precedence over display.
  // Make sure the frame was actually moved out of the flow, and don't
  // just assume what the style says
  // XXXldb nsRuleNode::ComputeDisplayData should take care of this, right?
  if (frame->GetStateBits() & NS_FRAME_OUT_OF_FLOW) {
    if (disp->IsAbsolutelyPositioned()) {
      frameType = NS_CSS_FRAME_TYPE_ABSOLUTE;
      //XXXfr hack for making frames behave properly when in overflow container lists
      //      see bug 154892; need to revisit later
      if (frame->GetPrevInFlow())
        frameType = NS_CSS_FRAME_TYPE_BLOCK;
    }
    else if (NS_STYLE_FLOAT_NONE != disp->mFloats) {
      frameType = NS_CSS_FRAME_TYPE_FLOATING;
    } else {
      NS_ASSERTION(disp->mDisplay == NS_STYLE_DISPLAY_POPUP,
                   "unknown out of flow frame type");
      frameType = NS_CSS_FRAME_TYPE_UNKNOWN;
    }
  }
  else {
    switch (disp->mDisplay) {
    case NS_STYLE_DISPLAY_BLOCK:
    case NS_STYLE_DISPLAY_LIST_ITEM:
    case NS_STYLE_DISPLAY_TABLE:
    case NS_STYLE_DISPLAY_TABLE_CAPTION:
      frameType = NS_CSS_FRAME_TYPE_BLOCK;
      break;

    case NS_STYLE_DISPLAY_INLINE:
    case NS_STYLE_DISPLAY_INLINE_BLOCK:
    case NS_STYLE_DISPLAY_MARKER:
    case NS_STYLE_DISPLAY_INLINE_TABLE:
    case NS_STYLE_DISPLAY_INLINE_BOX:
    case NS_STYLE_DISPLAY_INLINE_GRID:
    case NS_STYLE_DISPLAY_INLINE_STACK:
      frameType = NS_CSS_FRAME_TYPE_INLINE;
      break;

    case NS_STYLE_DISPLAY_RUN_IN:
    case NS_STYLE_DISPLAY_COMPACT:
      // XXX need to look ahead at the frame's sibling
      frameType = NS_CSS_FRAME_TYPE_BLOCK;
      break;

    case NS_STYLE_DISPLAY_TABLE_CELL:
    case NS_STYLE_DISPLAY_TABLE_ROW_GROUP:
    case NS_STYLE_DISPLAY_TABLE_COLUMN:
    case NS_STYLE_DISPLAY_TABLE_COLUMN_GROUP:
    case NS_STYLE_DISPLAY_TABLE_HEADER_GROUP:
    case NS_STYLE_DISPLAY_TABLE_FOOTER_GROUP:
    case NS_STYLE_DISPLAY_TABLE_ROW:
      frameType = NS_CSS_FRAME_TYPE_INTERNAL_TABLE;
      break;

    case NS_STYLE_DISPLAY_NONE:
    default:
      frameType = NS_CSS_FRAME_TYPE_UNKNOWN;
      break;
    }
  }

  // See if the frame is replaced
  if (frame->IsFrameOfType(nsIFrame::eReplacedContainsBlock)) {
    frameType = NS_FRAME_REPLACED_CONTAINS_BLOCK(frameType);
  } else if (frame->IsFrameOfType(nsIFrame::eReplaced)) {
    frameType = NS_FRAME_REPLACED(frameType);
  }

  mFrameType = frameType;
}

static void
nsPointDtor(void *aFrame, nsIAtom *aPropertyName,
            void *aPropertyValue, void *aDtorData)
{
  nsPoint *point = static_cast<nsPoint*>(aPropertyValue);
  delete point;
}

void
nsHTMLReflowState::ComputeRelativeOffsets(const nsHTMLReflowState* cbrs,
                                          nscoord aContainingBlockWidth,
                                          nscoord aContainingBlockHeight,
                                          nsPresContext* aPresContext)
{
  // Compute the 'left' and 'right' values. 'Left' moves the boxes to the right,
  // and 'right' moves the boxes to the left. The computed values are always:
  // left=-right
  PRBool  leftIsAuto = eStyleUnit_Auto == mStylePosition->mOffset.GetLeftUnit();
  PRBool  rightIsAuto = eStyleUnit_Auto == mStylePosition->mOffset.GetRightUnit();

  // Check for percentage based values and an unconstrained containing
  // block width. Treat them like 'auto'
  if (NS_UNCONSTRAINEDSIZE == aContainingBlockWidth) {
    if (eStyleUnit_Percent == mStylePosition->mOffset.GetLeftUnit()) {
      leftIsAuto = PR_TRUE;
    }
    if (eStyleUnit_Percent == mStylePosition->mOffset.GetRightUnit()) {
      rightIsAuto = PR_TRUE;
    }
  }

  // If neither 'left' not 'right' are auto, then we're over-constrained and
  // we ignore one of them
  if (!leftIsAuto && !rightIsAuto) {
    if (mCBReflowState &&
        NS_STYLE_DIRECTION_RTL == mCBReflowState->mStyleVisibility->mDirection) {
      leftIsAuto = PR_TRUE;
    } else {
      rightIsAuto = PR_TRUE;
    }
  }

  if (leftIsAuto) {
    if (rightIsAuto) {
      // If both are 'auto' (their initial values), the computed values are 0
      mComputedOffsets.left = mComputedOffsets.right = 0;
    } else {
      // 'Right' isn't 'auto' so compute its value
      mComputedOffsets.right = nsLayoutUtils::
        ComputeWidthDependentValue(aContainingBlockWidth,
                                   mStylePosition->mOffset.GetRight());

      // Computed value for 'left' is minus the value of 'right'
      mComputedOffsets.left = -mComputedOffsets.right;
    }

  } else {
    NS_ASSERTION(rightIsAuto, "unexpected specified constraint");
    
    // 'Left' isn't 'auto' so compute its value
    mComputedOffsets.left = nsLayoutUtils::
      ComputeWidthDependentValue(aContainingBlockWidth,
                                 mStylePosition->mOffset.GetLeft());

    // Computed value for 'right' is minus the value of 'left'
    mComputedOffsets.right = -mComputedOffsets.left;
  }

  // Compute the 'top' and 'bottom' values. The 'top' and 'bottom' properties
  // move relatively positioned elements up and down. They also must be each 
  // other's negative
  PRBool  topIsAuto = eStyleUnit_Auto == mStylePosition->mOffset.GetTopUnit();
  PRBool  bottomIsAuto = eStyleUnit_Auto == mStylePosition->mOffset.GetBottomUnit();

  // Check for percentage based values and a containing block height that
  // depends on the content height. Treat them like 'auto'
  if (NS_AUTOHEIGHT == aContainingBlockHeight) {
    if (eStyleUnit_Percent == mStylePosition->mOffset.GetTopUnit()) {
      topIsAuto = PR_TRUE;
    }
    if (eStyleUnit_Percent == mStylePosition->mOffset.GetBottomUnit()) {
      bottomIsAuto = PR_TRUE;
    }
  }

  // If neither is 'auto', 'bottom' is ignored
  if (!topIsAuto && !bottomIsAuto) {
    bottomIsAuto = PR_TRUE;
  }

  if (topIsAuto) {
    if (bottomIsAuto) {
      // If both are 'auto' (their initial values), the computed values are 0
      mComputedOffsets.top = mComputedOffsets.bottom = 0;
    } else {
      // 'Bottom' isn't 'auto' so compute its value
      mComputedOffsets.bottom = nsLayoutUtils::
        ComputeHeightDependentValue(aContainingBlockHeight,
                                    mStylePosition->mOffset.GetBottom());
      
      // Computed value for 'top' is minus the value of 'bottom'
      mComputedOffsets.top = -mComputedOffsets.bottom;
    }

  } else {
    NS_ASSERTION(bottomIsAuto, "unexpected specified constraint");
    
    // 'Top' isn't 'auto' so compute its value
    mComputedOffsets.top = nsLayoutUtils::
      ComputeHeightDependentValue(aContainingBlockHeight,
                                  mStylePosition->mOffset.GetTop());

    // Computed value for 'bottom' is minus the value of 'top'
    mComputedOffsets.bottom = -mComputedOffsets.top;
  }

  // Store the offset
  nsPropertyTable* propTable = aPresContext->PropertyTable();
  nsPoint* offsets = static_cast<nsPoint*>
                                (propTable->GetProperty(frame, nsGkAtoms::computedOffsetProperty));
  if (offsets)
    offsets->MoveTo(mComputedOffsets.left, mComputedOffsets.top);
  else {
    offsets = new nsPoint(mComputedOffsets.left, mComputedOffsets.top);
    if (offsets)
      propTable->SetProperty(frame, nsGkAtoms::computedOffsetProperty,
                              offsets, nsPointDtor, nsnull);
  }
}

inline PRBool
IsAnonBlockPseudo(nsIAtom *aPseudo)
{
  return aPseudo == nsCSSAnonBoxes::mozAnonymousBlock ||
         aPseudo == nsCSSAnonBoxes::mozAnonymousPositionedBlock;
}

nsIFrame*
nsHTMLReflowState::GetHypotheticalBoxContainer(nsIFrame* aFrame,
                                               nscoord& aCBLeftEdge,
                                               nscoord& aCBWidth)
{
  do {
    aFrame = aFrame->GetParent();
    NS_ASSERTION(aFrame, "Must find containing block somewhere");
  } while (!(aFrame->IsContainingBlock() ||
             (aFrame->IsFrameOfType(nsIFrame::eBlockFrame) &&
              IsAnonBlockPseudo(aFrame->GetStyleContext()->GetPseudoType()))));

  NS_ASSERTION(aFrame != frame, "How did that happen?");

  /* Now aFrame is the containing block we want */

  /* Check whether the containing block is currently being reflown.
     If so, use the info from the reflow state. */
  const nsHTMLReflowState* state;
  if (aFrame->GetStateBits() & NS_FRAME_IN_REFLOW) {
    for (state = parentReflowState; state && state->frame != aFrame;
         state = state->parentReflowState) {
      /* do nothing */
    }
  } else {
    state = nsnull;
  }
  
  if (state) {
    aCBLeftEdge = state->mComputedBorderPadding.left;
    aCBWidth = state->mComputedWidth;
  } else {
    /* Didn't find a reflow state for aFrame.  Just compute the information we
       want, on the assumption that aFrame already knows its size.  This really
       ought to be true by now. */
    NS_ASSERTION(!(aFrame->GetStateBits() & NS_FRAME_IN_REFLOW),
                 "aFrame shouldn't be in reflow; we'll lie if it is");
    nsMargin borderPadding = aFrame->GetUsedBorderAndPadding();
    aCBLeftEdge = borderPadding.left;
    aCBWidth = aFrame->GetSize().width - borderPadding.LeftRight();
  }

  return aFrame;
}

static nsIFrame*
GetNearestContainingBlock(nsIFrame *aFrame)
{
  nsIFrame *cb = aFrame;
  do {
    cb = cb->GetParent();
  } while (!cb->IsContainingBlock());
  return cb;
}

// When determining the hypothetical box that would have been if the element
// had been in the flow we may not be able to exactly determine both the left
// and right edges. For example, if the element is a non-replaced inline-level
// element we would have to reflow it in order to determine it desired width.
// In that case depending on the progression direction either the left or
// right edge would be marked as not being exact
struct nsHypotheticalBox {
  // offsets from left edge of containing block (which is a padding edge)
  nscoord       mLeft, mRight;
  // offset from top edge of containing block (which is a padding edge)
  nscoord       mTop;
#ifdef DEBUG
  PRPackedBool  mLeftIsExact, mRightIsExact;
#endif

  nsHypotheticalBox() {
#ifdef DEBUG
    mLeftIsExact = mRightIsExact = PR_FALSE;
#endif
  }
};
      
static PRBool
GetIntrinsicSizeFor(nsIFrame* aFrame, nsSize& aIntrinsicSize)
{
  // See if it is an image frame
  PRBool    result = PR_FALSE;

  // Currently the only type of replaced frame that we can get the intrinsic
  // size for is an image frame
  // XXX We should add back the GetReflowMetrics() function and one of the
  // things should be the intrinsic size...
  if (aFrame->GetType() == nsGkAtoms::imageFrame) {
    nsImageFrame* imageFrame = (nsImageFrame*)aFrame;

    imageFrame->GetIntrinsicImageSize(aIntrinsicSize);
    result = (aIntrinsicSize != nsSize(0, 0));
  }
  return result;
}

/**
 * aInsideBoxSizing returns the part of the horizontal padding, border,
 * and margin that goes inside the edge given by -moz-box-sizing;
 * aOutsideBoxSizing returns the rest.
 */
void
nsHTMLReflowState::CalculateHorizBorderPaddingMargin(
                       nscoord aContainingBlockWidth,
                       nscoord* aInsideBoxSizing,
                       nscoord* aOutsideBoxSizing)
{
  const nsMargin& border = mStyleBorder->GetActualBorder();
  nsMargin padding, margin;

  // See if the style system can provide us the padding directly
  if (!mStylePadding->GetPadding(padding)) {
    // We have to compute the left and right values
    padding.left = nsLayoutUtils::
      ComputeWidthDependentValue(aContainingBlockWidth,
                                 mStylePadding->mPadding.GetLeft());
    padding.right = nsLayoutUtils::
      ComputeWidthDependentValue(aContainingBlockWidth,
                                 mStylePadding->mPadding.GetRight());
  }

  // See if the style system can provide us the margin directly
  if (!mStyleMargin->GetMargin(margin)) {
    // We have to compute the left and right values
    if (eStyleUnit_Auto == mStyleMargin->mMargin.GetLeftUnit()) {
      // XXX FIXME (or does CalculateBlockSideMargins do this?)
      margin.left = 0;  // just ignore
    } else {
      margin.left = nsLayoutUtils::
        ComputeWidthDependentValue(aContainingBlockWidth,
                                   mStyleMargin->mMargin.GetLeft());
    }
    if (eStyleUnit_Auto == mStyleMargin->mMargin.GetRightUnit()) {
      // XXX FIXME (or does CalculateBlockSideMargins do this?)
      margin.right = 0;  // just ignore
    } else {
      margin.right = nsLayoutUtils::
        ComputeWidthDependentValue(aContainingBlockWidth,
                                   mStyleMargin->mMargin.GetRight());
    }
  }

  nscoord outside =
    padding.LeftRight() + border.LeftRight() + margin.LeftRight();
  nscoord inside = 0;
  switch (mStylePosition->mBoxSizing) {
    case NS_STYLE_BOX_SIZING_BORDER:
      inside += border.LeftRight();
      // fall through
    case NS_STYLE_BOX_SIZING_PADDING:
      inside += padding.LeftRight();
  }
  outside -= inside;
  *aInsideBoxSizing = inside;
  *aOutsideBoxSizing = outside;
  return;
}

/**
 * Returns PR_TRUE iff a pre-order traversal of the normal child
 * frames rooted at aFrame finds no non-empty frame before aDescendant.
 */
static PRBool AreAllEarlierInFlowFramesEmpty(nsIFrame* aFrame,
  nsIFrame* aDescendant, PRBool* aFound) {
  if (aFrame == aDescendant) {
    *aFound = PR_TRUE;
    return PR_TRUE;
  }
  if (!aFrame->IsSelfEmpty()) {
    *aFound = PR_FALSE;
    return PR_FALSE;
  }
  for (nsIFrame* f = aFrame->GetFirstChild(nsnull); f; f = f->GetNextSibling()) {
    PRBool allEmpty = AreAllEarlierInFlowFramesEmpty(f, aDescendant, aFound);
    if (*aFound || !allEmpty) {
      return allEmpty;
    }
  }
  *aFound = PR_FALSE;
  return PR_TRUE;
}

// Calculate the hypothetical box that the element would have if it were in
// the flow. The values returned are relative to the padding edge of the
// absolute containing block
// aContainingBlock is the placeholder's containing block (XXX rename it?)
// cbrs->frame is the actual containing block
void
nsHTMLReflowState::CalculateHypotheticalBox(nsPresContext*    aPresContext,
                                            nsIFrame*         aPlaceholderFrame,
                                            nsIFrame*         aContainingBlock,
                                            nscoord           aBlockLeftContentEdge,
                                            nscoord           aBlockContentWidth,
                                            const nsHTMLReflowState* cbrs,
                                            nsHypotheticalBox& aHypotheticalBox)
{
  NS_ASSERTION(mStyleDisplay->mOriginalDisplay != NS_STYLE_DISPLAY_NONE,
               "mOriginalDisplay has not been properly initialized");
  
  // If it's a replaced element and it has a 'auto' value for 'width', see if we
  // can get the intrinsic size. This will allow us to exactly determine both the
  // left and right edges
  PRBool isAutoWidth = mStylePosition->mWidth.GetUnit() == eStyleUnit_Auto;
  nsSize      intrinsicSize;
  PRBool      knowIntrinsicSize = PR_FALSE;
  if (NS_FRAME_IS_REPLACED(mFrameType) && isAutoWidth) {
    // See if we can get the intrinsic size of the element
    knowIntrinsicSize = GetIntrinsicSizeFor(frame, intrinsicSize);
  }

  // See if we can calculate what the box width would have been if the
  // element had been in the flow
  nscoord boxWidth;
  PRBool  knowBoxWidth = PR_FALSE;
  if ((NS_STYLE_DISPLAY_INLINE == mStyleDisplay->mOriginalDisplay) &&
      !NS_FRAME_IS_REPLACED(mFrameType)) {
    // For non-replaced inline-level elements the 'width' property doesn't apply,
    // so we don't know what the width would have been without reflowing it

  } else {
    // It's either a replaced inline-level element or a block-level element

    // Determine the total amount of horizontal border/padding/margin that
    // the element would have had if it had been in the flow. Note that we
    // ignore any 'auto' and 'inherit' values
    nscoord insideBoxSizing, outsideBoxSizing;
    CalculateHorizBorderPaddingMargin(aBlockContentWidth,
                                      &insideBoxSizing, &outsideBoxSizing);

    if (NS_FRAME_IS_REPLACED(mFrameType) && isAutoWidth) {
      // It's a replaced element with an 'auto' width so the box width is
      // its intrinsic size plus any border/padding/margin
      if (knowIntrinsicSize) {
        boxWidth = intrinsicSize.width + outsideBoxSizing + insideBoxSizing;
        knowBoxWidth = PR_TRUE;
      }

    } else if (isAutoWidth) {
      // The box width is the containing block width
      boxWidth = aBlockContentWidth;
      knowBoxWidth = PR_TRUE;
    
    } else {
      // We need to compute it. It's important we do this, because if it's
      // percentage based this computed value may be different from the computed
      // value calculated using the absolute containing block width
      boxWidth = ComputeWidthValue(aBlockContentWidth,
                                   insideBoxSizing, outsideBoxSizing,
                                   mStylePosition->mWidth) + 
                 insideBoxSizing + outsideBoxSizing;
      knowBoxWidth = PR_TRUE;
    }
  }
  
  // Get the 'direction' of the block
  const nsStyleVisibility* blockVis = aContainingBlock->GetStyleVisibility();

  // Get the placeholder x-offset and y-offset in the coordinate
  // space of the block frame that contains it
  // XXXbz the placeholder is not fully reflown yet if our containing block is
  // relatively positioned...
  nsPoint placeholderOffset = aPlaceholderFrame->GetOffsetTo(aContainingBlock);

  // First, determine the hypothetical box's mTop
  nsBlockFrame* blockFrame = nsLayoutUtils::GetAsBlock(aContainingBlock);
  if (blockFrame) {
    PRBool isValid;
    nsBlockInFlowLineIterator iter(blockFrame, aPlaceholderFrame, &isValid);
    NS_ASSERTION(isValid, "Can't find placeholder!");
    NS_ASSERTION(iter.GetContainer() == blockFrame, "Found placeholder in wrong block!");
    nsBlockFrame::line_iterator lineBox = iter.GetLine();

    // How we determine the hypothetical box depends on whether the element
    // would have been inline-level or block-level
    if (NS_STYLE_DISPLAY_INLINE == mStyleDisplay->mOriginalDisplay) {
      // Use the top of the inline box which the placeholder lives in as the
      // hypothetical box's top.
      aHypotheticalBox.mTop = lineBox->mBounds.y;
    } else {
      // The element would have been block-level which means it would be below
      // the line containing the placeholder frame, unless all the frames
      // before it are empty.  In that case, it would have been just before
      // this line.      
      // XXXbz the line box is not fully reflown yet if our containing block is
      // relatively positioned...
      if (lineBox != iter.End()) {
        nsIFrame * firstFrame = lineBox->mFirstChild;
        PRBool found = PR_FALSE;
        PRBool allEmpty = PR_TRUE;
        while (firstFrame) { // See bug 223064
          allEmpty = AreAllEarlierInFlowFramesEmpty(firstFrame,
            aPlaceholderFrame, &found);
          if (found || !allEmpty)
            break;
          firstFrame = firstFrame->GetNextSibling();
        }
        NS_ASSERTION(firstFrame, "Couldn't find placeholder!");

        if (allEmpty) {
          // The top of the hypothetical box is the top of the line containing
          // the placeholder, since there is nothing in the line before our
          // placeholder except empty frames.
          aHypotheticalBox.mTop = lineBox->mBounds.y;
        } else {
          // The top of the hypothetical box is just below the line containing
          // the placeholder.
          aHypotheticalBox.mTop = lineBox->mBounds.YMost();
        }
      } else {
        // Just use the placeholder's y-offset
        aHypotheticalBox.mTop = placeholderOffset.y;
      }
    }
  } else {
    // The containing block is not a block, so it's probably something
    // like a XUL box, etc.
    // Just use the placeholder's y-offset
    aHypotheticalBox.mTop = placeholderOffset.y;
  }

  // Second, determine the hypothetical box's mLeft & mRight
  // To determine the left and right offsets we need to look at the block's 'direction'
  if (NS_STYLE_DIRECTION_LTR == blockVis->mDirection) {
    // How we determine the hypothetical box depends on whether the element
    // would have been inline-level or block-level
    if (NS_STYLE_DISPLAY_INLINE == mStyleDisplay->mOriginalDisplay) {
      // The placeholder represents the left edge of the hypothetical box
      aHypotheticalBox.mLeft = placeholderOffset.x;
    } else {
      aHypotheticalBox.mLeft = aBlockLeftContentEdge;
    }
#ifdef DEBUG
    aHypotheticalBox.mLeftIsExact = PR_TRUE;
#endif

    if (knowBoxWidth) {
      aHypotheticalBox.mRight = aHypotheticalBox.mLeft + boxWidth;
#ifdef DEBUG
      aHypotheticalBox.mRightIsExact = PR_TRUE;
#endif
    } else {
      // We can't compute the right edge because we don't know the desired
      // width. So instead use the right content edge of the block parent,
      // but remember it's not exact
      aHypotheticalBox.mRight = aBlockLeftContentEdge + aBlockContentWidth;
#ifdef DEBUG
      aHypotheticalBox.mRightIsExact = PR_FALSE;
#endif
    }

  } else {
    // The placeholder represents the right edge of the hypothetical box
    if (NS_STYLE_DISPLAY_INLINE == mStyleDisplay->mOriginalDisplay) {
      aHypotheticalBox.mRight = placeholderOffset.x;
    } else {
      aHypotheticalBox.mRight = aBlockLeftContentEdge + aBlockContentWidth;
    }
#ifdef DEBUG
    aHypotheticalBox.mRightIsExact = PR_TRUE;
#endif
    
    if (knowBoxWidth) {
      aHypotheticalBox.mLeft = aHypotheticalBox.mRight - boxWidth;
#ifdef DEBUG
      aHypotheticalBox.mLeftIsExact = PR_TRUE;
#endif
    } else {
      // We can't compute the left edge because we don't know the desired
      // width. So instead use the left content edge of the block parent,
      // but remember it's not exact
      aHypotheticalBox.mLeft = aBlockLeftContentEdge;
#ifdef DEBUG
      aHypotheticalBox.mLeftIsExact = PR_FALSE;
#endif
    }

  }

  // The current coordinate space is that of the nearest block to the placeholder.
  // Convert to the coordinate space of the absolute containing block
  // One weird thing here is that for fixed-positioned elements we want to do
  // the conversion incorrectly; specifically we want to ignore any scrolling
  // that may have happened;
  nsPoint cbOffset;
  if (mStyleDisplay->mPosition == NS_STYLE_POSITION_FIXED &&
      // Exclude cases inside -moz-transform where fixed is like absolute.
      nsLayoutUtils::IsReallyFixedPos(frame)) {
    // In this case, cbrs->frame will always be an ancestor of
    // aContainingBlock, so can just walk our way up the frame tree.
    // Make sure to not add positions of frames whose parent is a
    // scrollFrame, since we're doing fixed positioning, which assumes
    // everything is scrolled to (0,0).
    cbOffset.MoveTo(0, 0);
    do {
      NS_ASSERTION(aContainingBlock,
                   "Should hit cbrs->frame before we run off the frame tree!");
      cbOffset += aContainingBlock->GetPositionIgnoringScrolling();
      aContainingBlock = aContainingBlock->GetParent();
    } while (aContainingBlock != cbrs->frame);
  } else {
    // XXXldb We need to either ignore scrolling for the absolute
    // positioning case too (and take the incompatibility) or figure out
    // how to make these positioned elements actually *move* when we
    // scroll, and thus avoid the resulting incremental reflow bugs.
    cbOffset = aContainingBlock->GetOffsetTo(cbrs->frame);
  }
  aHypotheticalBox.mLeft += cbOffset.x;
  aHypotheticalBox.mTop += cbOffset.y;
  aHypotheticalBox.mRight += cbOffset.x;
  
  // The specified offsets are relative to the absolute containing block's
  // padding edge and our current values are relative to the border edge, so
  // translate.
  nsMargin border = cbrs->mComputedBorderPadding - cbrs->mComputedPadding;
  aHypotheticalBox.mLeft -= border.left;
  aHypotheticalBox.mRight -= border.left;
  aHypotheticalBox.mTop -= border.top;
}

void
nsHTMLReflowState::InitAbsoluteConstraints(nsPresContext* aPresContext,
                                           const nsHTMLReflowState* cbrs,
                                           nscoord containingBlockWidth,
                                           nscoord containingBlockHeight)
{
  NS_PRECONDITION(containingBlockHeight != NS_AUTOHEIGHT,
                  "containing block height must be constrained");

  // Get the placeholder frame
  nsIFrame*     placeholderFrame;

  aPresContext->PresShell()->GetPlaceholderFrameFor(frame, &placeholderFrame);
  NS_ASSERTION(nsnull != placeholderFrame, "no placeholder frame");

  // If both 'left' and 'right' are 'auto' or both 'top' and 'bottom' are
  // 'auto', then compute the hypothetical box of where the element would
  // have been if it had been in the flow
  nsHypotheticalBox hypotheticalBox;
  if (((eStyleUnit_Auto == mStylePosition->mOffset.GetLeftUnit()) &&
       (eStyleUnit_Auto == mStylePosition->mOffset.GetRightUnit())) ||
      ((eStyleUnit_Auto == mStylePosition->mOffset.GetTopUnit()) &&
       (eStyleUnit_Auto == mStylePosition->mOffset.GetBottomUnit()))) {
    // Find the nearest containing block frame to the placeholder frame,
    // and return its left edge and width.
    nscoord cbLeftEdge, cbWidth;
    nsIFrame* cbFrame = GetHypotheticalBoxContainer(placeholderFrame,
                                                    cbLeftEdge,
                                                    cbWidth);

    CalculateHypotheticalBox(aPresContext, placeholderFrame, cbFrame,
                             cbLeftEdge, cbWidth, cbrs, hypotheticalBox);
  }

  // Initialize the 'left' and 'right' computed offsets
  // XXX Handle new 'static-position' value...
  PRBool        leftIsAuto = PR_FALSE, rightIsAuto = PR_FALSE;
  if (eStyleUnit_Auto == mStylePosition->mOffset.GetLeftUnit()) {
    mComputedOffsets.left = 0;
    leftIsAuto = PR_TRUE;
  } else {
    mComputedOffsets.left = nsLayoutUtils::
      ComputeWidthDependentValue(containingBlockWidth,
                                 mStylePosition->mOffset.GetLeft());
  }
  if (eStyleUnit_Auto == mStylePosition->mOffset.GetRightUnit()) {
    mComputedOffsets.right = 0;
    rightIsAuto = PR_TRUE;
  } else {
    mComputedOffsets.right = nsLayoutUtils::
      ComputeWidthDependentValue(containingBlockWidth,
                                 mStylePosition->mOffset.GetRight());
  }

  // Use the horizontal component of the hypothetical box in the cases
  // where it's needed.
  if (leftIsAuto && rightIsAuto) {
    // Use the direction of the original ("static-position") containing block
    // to dictate whether 'left' or 'right' is treated like 'static-position'.
    if (NS_STYLE_DIRECTION_LTR == GetNearestContainingBlock(placeholderFrame)
                                    ->GetStyleVisibility()->mDirection) {
      NS_ASSERTION(hypotheticalBox.mLeftIsExact, "should always have "
                   "exact value on containing block's start side");
      mComputedOffsets.left = hypotheticalBox.mLeft;
      leftIsAuto = PR_FALSE;
    } else {
      NS_ASSERTION(hypotheticalBox.mRightIsExact, "should always have "
                   "exact value on containing block's start side");
      mComputedOffsets.right = containingBlockWidth - hypotheticalBox.mRight;
      rightIsAuto = PR_FALSE;
    }
  }

  // Initialize the 'top' and 'bottom' computed offsets
  PRBool      topIsAuto = PR_FALSE, bottomIsAuto = PR_FALSE;
  if (eStyleUnit_Auto == mStylePosition->mOffset.GetTopUnit()) {
    mComputedOffsets.top = 0;
    topIsAuto = PR_TRUE;
  } else {
    mComputedOffsets.top = nsLayoutUtils::
      ComputeHeightDependentValue(containingBlockHeight,
                                  mStylePosition->mOffset.GetTop());
  }
  if (eStyleUnit_Auto == mStylePosition->mOffset.GetBottomUnit()) {
    mComputedOffsets.bottom = 0;        
    bottomIsAuto = PR_TRUE;
  } else {
    mComputedOffsets.bottom = nsLayoutUtils::
      ComputeHeightDependentValue(containingBlockHeight,
                                  mStylePosition->mOffset.GetBottom());
  }

  if (topIsAuto && bottomIsAuto) {
    // Treat 'top' like 'static-position'
    mComputedOffsets.top = hypotheticalBox.mTop;
    topIsAuto = PR_FALSE;
  }

  PRBool widthIsAuto = eStyleUnit_Auto == mStylePosition->mWidth.GetUnit();
  PRBool heightIsAuto = eStyleUnit_Auto == mStylePosition->mHeight.GetUnit();

  PRBool shrinkWrap = leftIsAuto || rightIsAuto;
  nsSize size =
    frame->ComputeSize(rendContext,
                       nsSize(containingBlockWidth,
                              containingBlockHeight),
                       containingBlockWidth, // XXX or availableWidth?
                       nsSize(mComputedMargin.LeftRight() +
                                mComputedOffsets.LeftRight(),
                              mComputedMargin.TopBottom() +
                                mComputedOffsets.TopBottom()),
                       nsSize(mComputedBorderPadding.LeftRight() -
                                mComputedPadding.LeftRight(),
                              mComputedBorderPadding.TopBottom() -
                                mComputedPadding.TopBottom()),
                       nsSize(mComputedPadding.LeftRight(),
                              mComputedPadding.TopBottom()),
                       shrinkWrap);
  mComputedWidth = size.width;
  mComputedHeight = size.height;
  NS_ASSERTION(mComputedWidth >= 0, "Bogus width");
  NS_ASSERTION(mComputedHeight == NS_UNCONSTRAINEDSIZE ||
               mComputedHeight >= 0, "Bogus height");

  // XXX Now that we have ComputeSize, can we condense many of the
  // branches off of widthIsAuto?

  if (leftIsAuto) {
    // We know 'right' is not 'auto' anymore thanks to the hypothetical
    // box code above.
    // Solve for 'left'.
    if (widthIsAuto) {
      // XXXldb This, and the corresponding code in
      // nsAbsoluteContainingBlock.cpp, could probably go away now that
      // we always compute widths.
      mComputedOffsets.left = NS_AUTOOFFSET;
    } else {
      mComputedOffsets.left = containingBlockWidth - mComputedMargin.left -
        mComputedBorderPadding.left - mComputedWidth - mComputedBorderPadding.right - 
        mComputedMargin.right - mComputedOffsets.right;

    }
  } else if (rightIsAuto) {
    // We know 'left' is not 'auto' anymore thanks to the hypothetical
    // box code above.
    // Solve for 'right'.
    if (widthIsAuto) {
      // XXXldb This, and the corresponding code in
      // nsAbsoluteContainingBlock.cpp, could probably go away now that
      // we always compute widths.
      mComputedOffsets.right = NS_AUTOOFFSET;
    } else {
      mComputedOffsets.right = containingBlockWidth - mComputedOffsets.left -
        mComputedMargin.left - mComputedBorderPadding.left - mComputedWidth -
        mComputedBorderPadding.right - mComputedMargin.right;
    }
  } else {
    // Neither 'left' nor 'right' is 'auto'.  However, the width might
    // still not fill all the available space (even though we didn't
    // shrink-wrap) in case:
    //  * width was specified
    //  * we're dealing with a replaced element
    //  * width was constrained by min-width or max-width.

    nscoord availMarginSpace = containingBlockWidth -
                               mComputedOffsets.LeftRight() -
                               mComputedMargin.LeftRight() -
                               mComputedBorderPadding.LeftRight() -
                               mComputedWidth;
    PRBool marginLeftIsAuto =
      eStyleUnit_Auto == mStyleMargin->mMargin.GetLeftUnit();
    PRBool marginRightIsAuto =
      eStyleUnit_Auto == mStyleMargin->mMargin.GetRightUnit();

    if (availMarginSpace < 0 ||
        (!marginLeftIsAuto && !marginRightIsAuto)) {
      // We're over-constrained so use the direction of the containing block
      // to dictate which value to ignore.  (And note that the spec says to ignore
      // 'left' or 'right' rather than 'margin-left' or 'margin-right'.)
      if (cbrs &&
          NS_STYLE_DIRECTION_RTL == cbrs->mStyleVisibility->mDirection) {
        // Ignore the specified value for 'left'.
        mComputedOffsets.left += availMarginSpace;
      } else {
        // Ignore the specified value for 'right'.
        mComputedOffsets.right += availMarginSpace;
      }
    } else if (marginLeftIsAuto) {
      if (marginRightIsAuto) {
        // Both 'margin-left' and 'margin-right' are 'auto', so they get
        // equal values
        mComputedMargin.left = availMarginSpace / 2;
        mComputedMargin.right = availMarginSpace - mComputedMargin.left;
      } else {
        // Just 'margin-left' is 'auto'
        mComputedMargin.left = availMarginSpace;
      }
    } else {
      // Just 'margin-right' is 'auto'
      mComputedMargin.right = availMarginSpace;
    }
  }

  if (topIsAuto) {
    // solve for 'top'
    if (heightIsAuto) {
      mComputedOffsets.top = NS_AUTOOFFSET;
    } else {
      mComputedOffsets.top = containingBlockHeight - mComputedMargin.top -
        mComputedBorderPadding.top - mComputedHeight - mComputedBorderPadding.bottom - 
        mComputedMargin.bottom - mComputedOffsets.bottom;
    }
  } else if (bottomIsAuto) {
    // solve for 'bottom'
    if (heightIsAuto) {
      mComputedOffsets.bottom = NS_AUTOOFFSET;
    } else {
      mComputedOffsets.bottom = containingBlockHeight - mComputedOffsets.top -
        mComputedMargin.top - mComputedBorderPadding.top - mComputedHeight -
        mComputedBorderPadding.bottom - mComputedMargin.bottom;
    }
  } else {
    // Neither 'top' nor 'bottom' is 'auto'.
    nscoord autoHeight = containingBlockHeight -
                         mComputedOffsets.TopBottom() -
                         mComputedMargin.TopBottom() -
                         mComputedBorderPadding.TopBottom();
    if (autoHeight < 0) {
      autoHeight = 0;
    }

    if (mComputedHeight == NS_UNCONSTRAINEDSIZE) {
      // For non-replaced elements with 'height' auto, the 'height'
      // fills the remaining space.
      mComputedHeight = autoHeight;

      // XXX Do these need box-sizing adjustments?
      if (mComputedHeight > mComputedMaxHeight)
        mComputedHeight = mComputedMaxHeight;
      if (mComputedHeight < mComputedMinHeight)
        mComputedHeight = mComputedMinHeight;
    }

    // The height might still not fill all the available space in case:
    //  * height was specified
    //  * we're dealing with a replaced element
    //  * height was constrained by min-height or max-height.
    nscoord availMarginSpace = autoHeight - mComputedHeight;
    PRBool marginTopIsAuto =
      eStyleUnit_Auto == mStyleMargin->mMargin.GetTopUnit();
    PRBool marginBottomIsAuto =
      eStyleUnit_Auto == mStyleMargin->mMargin.GetBottomUnit();

    if (availMarginSpace < 0 || (!marginTopIsAuto && !marginBottomIsAuto)) {
      // We're over-constrained so ignore the specified value for
      // 'bottom'.  (And note that the spec says to ignore 'bottom'
      // rather than 'margin-bottom'.)
      mComputedOffsets.bottom += availMarginSpace;
    } else if (marginTopIsAuto) {
      if (marginBottomIsAuto) {
        // Both 'margin-top' and 'margin-bottom' are 'auto', so they get
        // equal values
        mComputedMargin.top = availMarginSpace / 2;
        mComputedMargin.bottom = availMarginSpace - mComputedMargin.top;
      } else {
        // Just 'margin-top' is 'auto'
        mComputedMargin.top = availMarginSpace - mComputedMargin.bottom;
      }
    } else {
      // Just 'margin-bottom' is 'auto'
      mComputedMargin.bottom = availMarginSpace - mComputedMargin.top;
    }
  }
}

nscoord 
GetVerticalMarginBorderPadding(const nsHTMLReflowState* aReflowState)
{
  nscoord result = 0;
  if (!aReflowState) return result;

  // zero auto margins
  nsMargin margin = aReflowState->mComputedMargin;
  if (NS_AUTOMARGIN == margin.top) 
    margin.top = 0;
  if (NS_AUTOMARGIN == margin.bottom) 
    margin.bottom = 0;

  result += margin.top + margin.bottom;
  result += aReflowState->mComputedBorderPadding.top + 
            aReflowState->mComputedBorderPadding.bottom;

  return result;
}

/* Get the height based on the viewport of the containing block specified 
 * in aReflowState when the containing block has mComputedHeight == NS_AUTOHEIGHT
 * This will walk up the chain of containing blocks looking for a computed height
 * until it finds the canvas frame, or it encounters a frame that is not a block,
 * area, or scroll frame. This handles compatibility with IE (see bug 85016 and bug 219693)
 *
 *  When we encounter scrolledContent area frames, we skip over them, since they are guaranteed to not be useful for computing the containing block.
 *
 * See also IsQuirkContainingBlockHeight.
 */
static nscoord
CalcQuirkContainingBlockHeight(const nsHTMLReflowState* aCBReflowState)
{
  nsHTMLReflowState* firstAncestorRS = nsnull; // a candidate for html frame
  nsHTMLReflowState* secondAncestorRS = nsnull; // a candidate for body frame
  
  // initialize the default to NS_AUTOHEIGHT as this is the containings block
  // computed height when this function is called. It is possible that we 
  // don't alter this height especially if we are restricted to one level
  nscoord result = NS_AUTOHEIGHT; 
                             
  const nsHTMLReflowState* rs = aCBReflowState;
  for (; rs; rs = (nsHTMLReflowState *)(rs->parentReflowState)) { 
    nsIAtom* frameType = rs->frame->GetType();
    // if the ancestor is auto height then skip it and continue up if it 
    // is the first block/area frame and possibly the body/html
    if (nsGkAtoms::blockFrame == frameType ||
        nsGkAtoms::areaFrame == frameType ||
        nsGkAtoms::scrollFrame == frameType) {

      secondAncestorRS = firstAncestorRS;
      firstAncestorRS = (nsHTMLReflowState*)rs;

      // If the current frame we're looking at is positioned, we don't want to
      // go any further (see bug 221784).  The behavior we want here is: 1) If
      // not auto-height, use this as the percentage base.  2) If auto-height,
      // keep looking, unless the frame is positioned.
      if (NS_AUTOHEIGHT == rs->ComputedHeight()) {
        if (rs->frame->GetStyleDisplay()->IsAbsolutelyPositioned()) {
          break;
        } else {
          continue;
        }
      }
    }
    else if (nsGkAtoms::canvasFrame == frameType) {
      // Always continue on to the height calculation
    }
    else if (nsGkAtoms::pageContentFrame == frameType) {
      nsIFrame* prevInFlow = rs->frame->GetPrevInFlow();
      // only use the page content frame for a height basis if it is the first in flow
      if (prevInFlow) 
        break;
    }
    else {
      break;
    }

    // if the ancestor is the page content frame then the percent base is 
    // the avail height, otherwise it is the computed height
    result = (nsGkAtoms::pageContentFrame == frameType)
             ? rs->availableHeight : rs->ComputedHeight();
    // if unconstrained - don't sutract borders - would result in huge height
    if (NS_AUTOHEIGHT == result) return result;

    // if we got to the canvas or page content frame, then subtract out 
    // margin/border/padding for the BODY and HTML elements
    if ((nsGkAtoms::canvasFrame == frameType) || 
        (nsGkAtoms::pageContentFrame == frameType)) {

      result -= GetVerticalMarginBorderPadding(firstAncestorRS); 
      result -= GetVerticalMarginBorderPadding(secondAncestorRS); 

#ifdef DEBUG
      // make sure the first ancestor is the HTML and the second is the BODY
      if (firstAncestorRS) {
        nsIContent* frameContent = firstAncestorRS->frame->GetContent();
        if (frameContent) {
          nsIAtom *contentTag = frameContent->Tag();
          NS_ASSERTION(contentTag == nsGkAtoms::html, "First ancestor is not HTML");
        }
      }
      if (secondAncestorRS) {
        nsIContent* frameContent = secondAncestorRS->frame->GetContent();
        if (frameContent) {
          nsIAtom *contentTag = frameContent->Tag();
          NS_ASSERTION(contentTag == nsGkAtoms::body, "Second ancestor is not BODY");
        }
      }
#endif
      
    }
    // if we got to the html frame (a block child of the canvas) ...
    else if (nsGkAtoms::blockFrame == frameType &&
             nsGkAtoms::canvasFrame ==
               rs->parentReflowState->frame->GetType()) {
      // ... then subtract out margin/border/padding for the BODY element
      result -= GetVerticalMarginBorderPadding(secondAncestorRS);
    }
    break;
  }

  // Make sure not to return a negative height here!
  return PR_MAX(result, 0);
}
// Called by InitConstraints() to compute the containing block rectangle for
// the element. Handles the special logic for absolutely positioned elements
void
nsHTMLReflowState::ComputeContainingBlockRectangle(nsPresContext*          aPresContext,
                                                   const nsHTMLReflowState* aContainingBlockRS,
                                                   nscoord&                 aContainingBlockWidth,
                                                   nscoord&                 aContainingBlockHeight)
{
  // Unless the element is absolutely positioned, the containing block is
  // formed by the content edge of the nearest block-level ancestor
  aContainingBlockWidth = aContainingBlockRS->mComputedWidth;
  aContainingBlockHeight = aContainingBlockRS->mComputedHeight;
  
  if (NS_FRAME_GET_TYPE(mFrameType) == NS_CSS_FRAME_TYPE_ABSOLUTE) {
    // See if the ancestor is block-level or inline-level
    if (NS_FRAME_GET_TYPE(aContainingBlockRS->mFrameType) == NS_CSS_FRAME_TYPE_INLINE) {
      // Base our size on the actual size of the frame.  In cases when this is
      // completely bogus (eg initial reflow), this code shouldn't even be
      // called, since the code in nsPositionedInlineFrame::Reflow will pass in
      // the containing block dimensions to our constructor.
      // XXXbz we should be taking the in-flows into account too, but
      // that's very hard.
      nsMargin computedBorder = aContainingBlockRS->mComputedBorderPadding -
        aContainingBlockRS->mComputedPadding;
      aContainingBlockWidth = aContainingBlockRS->frame->GetRect().width -
        computedBorder.LeftRight();;
      NS_ASSERTION(aContainingBlockWidth >= 0,
                   "Negative containing block width!");
      aContainingBlockHeight = aContainingBlockRS->frame->GetRect().height -
        computedBorder.TopBottom();
      NS_ASSERTION(aContainingBlockHeight >= 0,
                   "Negative containing block height!");
    } else {
      // If the ancestor is block-level, the containing block is formed by the
      // padding edge of the ancestor
      aContainingBlockWidth += aContainingBlockRS->mComputedPadding.LeftRight();
      aContainingBlockHeight += aContainingBlockRS->mComputedPadding.TopBottom();
    }
  } else {
    // an element in quirks mode gets a containing block based on looking for a
    // parent with a non-auto height if the element has a percent height
    if (NS_AUTOHEIGHT == aContainingBlockHeight) {
      if (eCompatibility_NavQuirks == aPresContext->CompatibilityMode() &&
          mStylePosition->mHeight.GetUnit() == eStyleUnit_Percent) {
        aContainingBlockHeight = CalcQuirkContainingBlockHeight(aContainingBlockRS);
      }
    }
  }
}

// Prefs callback to pick up changes
static int
PrefsChanged(const char *aPrefName, void *instance)
{
  sBlinkIsAllowed =
    nsContentUtils::GetBoolPref("browser.blink_allowed", sBlinkIsAllowed);

  return 0; /* PREF_OK */
}

// Check to see if |text-decoration: blink| is allowed.  The first time
// called, register the callback and then force-load the pref.  After that,
// just use the cached value.
static PRBool BlinkIsAllowed(void)
{
  if (!sPrefIsLoaded) {
    // Set up a listener and check the initial value
    nsContentUtils::RegisterPrefCallback("browser.blink_allowed", PrefsChanged,
                                         nsnull);
    PrefsChanged(nsnull, nsnull);
    sPrefIsLoaded = PR_TRUE;
  }
  return sBlinkIsAllowed;
}

static eNormalLineHeightControl GetNormalLineHeightCalcControl(void)
{
  if (sNormalLineHeightControl == eUninitialized) {
    // browser.display.normal_lineheight_calc_control is not user
    // changeable, so no need to register callback for it.
    sNormalLineHeightControl =
      static_cast<eNormalLineHeightControl>
                 (nsContentUtils::GetIntPref("browser.display.normal_lineheight_calc_control", eNoExternalLeading));
  }
  return sNormalLineHeightControl;
}

static inline PRBool
IsSideCaption(nsIFrame* aFrame, const nsStyleDisplay* aStyleDisplay)
{
  if (aStyleDisplay->mDisplay != NS_STYLE_DISPLAY_TABLE_CAPTION)
    return PR_FALSE;
  PRUint8 captionSide = aFrame->GetStyleTableBorder()->mCaptionSide;
  return captionSide == NS_STYLE_CAPTION_SIDE_LEFT ||
         captionSide == NS_STYLE_CAPTION_SIDE_RIGHT;
}

// XXX refactor this code to have methods for each set of properties
// we are computing: width,height,line-height; margin; offsets

void
nsHTMLReflowState::InitConstraints(nsPresContext* aPresContext,
                                   nscoord         aContainingBlockWidth,
                                   nscoord         aContainingBlockHeight,
                                   const nsMargin* aBorder,
                                   const nsMargin* aPadding)
{
  // If this is the root frame, then set the computed width and
  // height equal to the available space
  if (nsnull == parentReflowState) {
    // XXXldb This doesn't mean what it used to!
    InitOffsets(aContainingBlockWidth, aBorder, aPadding);
    // Override mComputedMargin since reflow roots start from the
    // frame's boundary, which is inside the margin.
    mComputedMargin.SizeTo(0, 0, 0, 0);
    mComputedOffsets.SizeTo(0, 0, 0, 0);

    mComputedWidth = availableWidth - mComputedBorderPadding.LeftRight();
    if (mComputedWidth < 0)
      mComputedWidth = 0;
    if (availableHeight != NS_UNCONSTRAINEDSIZE) {
      mComputedHeight = availableHeight - mComputedBorderPadding.TopBottom();
      if (mComputedHeight < 0)
        mComputedHeight = 0;
    } else {
      mComputedHeight = NS_UNCONSTRAINEDSIZE;
    }

    mComputedMinWidth = mComputedMinHeight = 0;
    mComputedMaxWidth = mComputedMaxHeight = NS_UNCONSTRAINEDSIZE;
  } else {
    // Get the containing block reflow state
    const nsHTMLReflowState* cbrs = mCBReflowState;
    NS_ASSERTION(nsnull != cbrs, "no containing block");

    // If we weren't given a containing block width and height, then
    // compute one
    if (aContainingBlockWidth == -1) {
      ComputeContainingBlockRectangle(aPresContext, cbrs, aContainingBlockWidth, 
                                      aContainingBlockHeight);
    }

#if 0
    nsFrame::ListTag(stdout, frame); printf(": cb=");
    nsFrame::ListTag(stdout, cbrs->frame); printf(" size=%d,%d\n", aContainingBlockWidth, aContainingBlockHeight);
#endif

    // See if the containing block height is based on the size of its
    // content
    nsIAtom* fType;
    if (NS_AUTOHEIGHT == aContainingBlockHeight) {
      // See if the containing block is a cell frame which needs
      // to use the mComputedHeight of the cell instead of what the cell block passed in.
      // XXX It seems like this could lead to bugs with min-height and friends
      if (cbrs->parentReflowState) {
        fType = cbrs->frame->GetType();
        if (IS_TABLE_CELL(fType)) {
          // use the cell's computed height 
          aContainingBlockHeight = cbrs->mComputedHeight;
        }
      }
    }

    InitOffsets(aContainingBlockWidth, aBorder, aPadding);

    nsStyleUnit heightUnit = mStylePosition->mHeight.GetUnit();

    // Check for a percentage based height and a containing block height
    // that depends on the content height
    // XXX twiddling heightUnit doesn't help anymore
    if (eStyleUnit_Percent == heightUnit) {
      if (NS_AUTOHEIGHT == aContainingBlockHeight) {
        // this if clause enables %-height on replaced inline frames,
        // such as images.  See bug 54119.  The else clause "heightUnit = eStyleUnit_Auto;"
        // used to be called exclusively.
        if (NS_FRAME_REPLACED(NS_CSS_FRAME_TYPE_INLINE) == mFrameType ||
            NS_FRAME_REPLACED_CONTAINS_BLOCK(
                NS_CSS_FRAME_TYPE_INLINE) == mFrameType) {
          // Get the containing block reflow state
          NS_ASSERTION(nsnull != cbrs, "no containing block");
          // in quirks mode, get the cb height using the special quirk method
          if (eCompatibility_NavQuirks == aPresContext->CompatibilityMode()) {
            if (!IS_TABLE_CELL(fType)) {
              aContainingBlockHeight = CalcQuirkContainingBlockHeight(cbrs);
              if (aContainingBlockHeight == NS_AUTOHEIGHT) {
                heightUnit = eStyleUnit_Auto;
              }
            }
            else {
              heightUnit = eStyleUnit_Auto;
            }
          }
          // in standard mode, use the cb height.  if it's "auto", as will be the case
          // by default in BODY, use auto height as per CSS2 spec.
          else 
          {
            if (NS_AUTOHEIGHT != cbrs->mComputedHeight)
              aContainingBlockHeight = cbrs->mComputedHeight;
            else
              heightUnit = eStyleUnit_Auto;
          }
        }
        else {
          // default to interpreting the height like 'auto'
          heightUnit = eStyleUnit_Auto;
        }
      }
    }

    // Compute our offsets if the element is relatively positioned.  We need
    // the correct containing block width and height here, which is why we need
    // to do it after all the quirks-n-such above.
    if (NS_STYLE_POSITION_RELATIVE == mStyleDisplay->mPosition) {
      ComputeRelativeOffsets(cbrs, aContainingBlockWidth, aContainingBlockHeight, aPresContext);
    } else {
      // Initialize offsets to 0
      mComputedOffsets.SizeTo(0, 0, 0, 0);
    }

    // Calculate the computed values for min and max properties.  Note that
    // this MUST come after we've computed our border and padding.
    ComputeMinMaxValues(aContainingBlockWidth, aContainingBlockHeight, cbrs);

    // Calculate the computed width and height. This varies by frame type

    if (NS_CSS_FRAME_TYPE_INTERNAL_TABLE == mFrameType) {
      // Internal table elements. The rules vary depending on the type.
      // Calculate the computed width
      PRBool rowOrRowGroup = PR_FALSE;
      nsStyleUnit widthUnit = mStylePosition->mWidth.GetUnit();
      if ((NS_STYLE_DISPLAY_TABLE_ROW == mStyleDisplay->mDisplay) ||
          (NS_STYLE_DISPLAY_TABLE_ROW_GROUP == mStyleDisplay->mDisplay)) {
        // 'width' property doesn't apply to table rows and row groups
        widthUnit = eStyleUnit_Auto;
        rowOrRowGroup = PR_TRUE;
      }

      if (eStyleUnit_Auto == widthUnit) {
        mComputedWidth = availableWidth;

        if ((mComputedWidth != NS_UNCONSTRAINEDSIZE) && !rowOrRowGroup){
          // Internal table elements don't have margins. Only tables and
          // cells have border and padding
          mComputedWidth -= mComputedBorderPadding.left +
            mComputedBorderPadding.right;
          if (mComputedWidth < 0)
            mComputedWidth = 0;
        }
        NS_ASSERTION(mComputedWidth >= 0, "Bogus computed width");
      
      } else {
        NS_ASSERTION(widthUnit == mStylePosition->mWidth.GetUnit(),
                     "unexpected width unit change");
        mComputedWidth = ComputeWidthValue(aContainingBlockWidth,
                                           mStylePosition->mBoxSizing,
                                           mStylePosition->mWidth);
      }

      // Calculate the computed height
      if ((NS_STYLE_DISPLAY_TABLE_COLUMN == mStyleDisplay->mDisplay) ||
          (NS_STYLE_DISPLAY_TABLE_COLUMN_GROUP == mStyleDisplay->mDisplay)) {
        // 'height' property doesn't apply to table columns and column groups
        heightUnit = eStyleUnit_Auto;
      }
      if (eStyleUnit_Auto == heightUnit) {
        mComputedHeight = NS_AUTOHEIGHT;
      } else {
        NS_ASSERTION(heightUnit == mStylePosition->mHeight.GetUnit(),
                     "unexpected height unit change");
        mComputedHeight = nsLayoutUtils::
          ComputeHeightDependentValue(aContainingBlockHeight,
                                      mStylePosition->mHeight);
      }

      // Doesn't apply to table elements
      mComputedMinWidth = mComputedMinHeight = 0;
      mComputedMaxWidth = mComputedMaxHeight = NS_UNCONSTRAINEDSIZE;

    } else if (NS_FRAME_GET_TYPE(mFrameType) == NS_CSS_FRAME_TYPE_ABSOLUTE) {
      // XXX not sure if this belongs here or somewhere else - cwk
      InitAbsoluteConstraints(aPresContext, cbrs, aContainingBlockWidth,
                              aContainingBlockHeight);
    } else {
      PRBool isBlock =
        NS_CSS_FRAME_TYPE_BLOCK == NS_FRAME_GET_TYPE(mFrameType);
      nsSize size =
        frame->ComputeSize(rendContext,
                           nsSize(aContainingBlockWidth,
                                  aContainingBlockHeight),
                           availableWidth,
                           nsSize(mComputedMargin.LeftRight(),
                                  mComputedMargin.TopBottom()),
                           nsSize(mComputedBorderPadding.LeftRight() -
                                    mComputedPadding.LeftRight(),
                                  mComputedBorderPadding.TopBottom() -
                                    mComputedPadding.TopBottom()),
                           nsSize(mComputedPadding.LeftRight(),
                                  mComputedPadding.TopBottom()),
                           !isBlock);

      mComputedWidth = size.width;
      mComputedHeight = size.height;
      NS_ASSERTION(mComputedWidth >= 0, "Bogus width");
      NS_ASSERTION(mComputedHeight == NS_UNCONSTRAINEDSIZE ||
                   mComputedHeight >= 0, "Bogus height");

      if (isBlock && !IsSideCaption(frame, mStyleDisplay))
        CalculateBlockSideMargins(availableWidth, mComputedWidth);
    }
  }
  // Check for blinking text and permission to display it
  mFlags.mBlinks = (parentReflowState && parentReflowState->mFlags.mBlinks);
  if (!mFlags.mBlinks && BlinkIsAllowed()) {
    const nsStyleTextReset* st = frame->GetStyleTextReset();
    mFlags.mBlinks = 
      ((st->mTextDecoration & NS_STYLE_TEXT_DECORATION_BLINK) != 0);
  }
}

void
nsCSSOffsetState::InitOffsets(nscoord aContainingBlockWidth,
                              const nsMargin *aBorder,
                              const nsMargin *aPadding)
{
  // Compute margins from the specified margin style information. These
  // become the default computed values, and may be adjusted below
  // XXX fix to provide 0,0 for the top&bottom margins for
  // inline-non-replaced elements
  ComputeMargin(aContainingBlockWidth);

  const nsStyleDisplay *disp = frame->GetStyleDisplay();
  PRBool isThemed = frame->IsThemed(disp);
  nsPresContext *presContext = frame->PresContext();

  if (isThemed &&
      presContext->GetTheme()->GetWidgetPadding(presContext->DeviceContext(),
                                                frame, disp->mAppearance,
                                                &mComputedPadding)) {
    mComputedPadding.top = presContext->DevPixelsToAppUnits(mComputedPadding.top);
    mComputedPadding.right = presContext->DevPixelsToAppUnits(mComputedPadding.right);
    mComputedPadding.bottom = presContext->DevPixelsToAppUnits(mComputedPadding.bottom);
    mComputedPadding.left = presContext->DevPixelsToAppUnits(mComputedPadding.left);
  }
  else if (aPadding) { // padding is an input arg
    mComputedPadding.top    = aPadding->top;
    mComputedPadding.right  = aPadding->right;
    mComputedPadding.bottom = aPadding->bottom;
    mComputedPadding.left   = aPadding->left;
  }
  else {
    ComputePadding(aContainingBlockWidth);
  }

  if (isThemed) {
    presContext->GetTheme()->GetWidgetBorder(presContext->DeviceContext(),
                                             frame, disp->mAppearance,
                                             &mComputedBorderPadding);
    mComputedBorderPadding.top =
      presContext->DevPixelsToAppUnits(mComputedBorderPadding.top);
    mComputedBorderPadding.right =
      presContext->DevPixelsToAppUnits(mComputedBorderPadding.right);
    mComputedBorderPadding.bottom =
      presContext->DevPixelsToAppUnits(mComputedBorderPadding.bottom);
    mComputedBorderPadding.left =
      presContext->DevPixelsToAppUnits(mComputedBorderPadding.left);
  }
  else if (aBorder) {  // border is an input arg
    mComputedBorderPadding = *aBorder;
  }
  else {
    mComputedBorderPadding = frame->GetStyleBorder()->GetActualBorder();
  }
  mComputedBorderPadding += mComputedPadding;

  nsIAtom* frameType = frame->GetType();
  if (frameType == nsGkAtoms::tableFrame) {
    nsTableFrame *tableFrame = static_cast<nsTableFrame*>(frame);

    if (tableFrame->IsBorderCollapse()) {
      // border-collapsed tables don't use any of their padding, and
      // only part of their border.  We need to do this here before we
      // try to do anything like handling 'auto' widths,
      // '-moz-box-sizing', or 'auto' margins.
      mComputedPadding.SizeTo(0,0,0,0);
      mComputedBorderPadding = tableFrame->GetIncludedOuterBCBorder();
    }
  } else if (frameType == nsGkAtoms::scrollbarFrame) {
    // scrollbars may have had their width or height smashed to zero
    // by the associated scrollframe, in which case we must not report
    // any padding or border.
    nsSize size(frame->GetSize());
    if (size.width == 0 || size.height == 0) {
      mComputedPadding.left = 0;
      mComputedPadding.right = 0;
      mComputedBorderPadding.left = 0;
      mComputedBorderPadding.right = 0;
      mComputedPadding.top = 0;
      mComputedPadding.bottom = 0;
      mComputedBorderPadding.top = 0;
      mComputedBorderPadding.bottom = 0;
    }
  }
}

// This code enforces section 10.3.3 of the CSS2 spec for this formula:
//
// 'margin-left' + 'border-left-width' + 'padding-left' + 'width' +
//   'padding-right' + 'border-right-width' + 'margin-right'
//   = width of containing block 
//
// Note: the width unit is not auto when this is called
void
nsHTMLReflowState::CalculateBlockSideMargins(nscoord aAvailWidth,
                                             nscoord aComputedWidth)
{
  NS_ASSERTION(NS_UNCONSTRAINEDSIZE != aComputedWidth &&
               NS_UNCONSTRAINEDSIZE != aAvailWidth,
               "this shouldn't happen anymore");

  nscoord sum = mComputedMargin.left + mComputedBorderPadding.left +
    aComputedWidth + mComputedBorderPadding.right + mComputedMargin.right;
  if (sum == aAvailWidth)
    // The sum is already correct
    return;

  // Determine the left and right margin values. The width value
  // remains constant while we do this.

  // Calculate how much space is available for margins
  nscoord availMarginSpace = aAvailWidth - sum;

  // If the available margin space is negative, then don't follow the
  // usual overconstraint rules.
  if (availMarginSpace < 0) {
    if (mCBReflowState &&
        mCBReflowState->mStyleVisibility->mDirection == NS_STYLE_DIRECTION_RTL) {
      mComputedMargin.left += availMarginSpace;
    } else {
      mComputedMargin.right += availMarginSpace;
    }
    return;
  }

  // The css2 spec clearly defines how block elements should behave
  // in section 10.3.3.
  PRBool isAutoLeftMargin =
    eStyleUnit_Auto == mStyleMargin->mMargin.GetLeftUnit();
  PRBool isAutoRightMargin =
    eStyleUnit_Auto == mStyleMargin->mMargin.GetRightUnit();
  if (!isAutoLeftMargin && !isAutoRightMargin) {
    // Neither margin is 'auto' so we're over constrained. Use the
    // 'direction' property of the parent to tell which margin to
    // ignore
    // First check if there is an HTML alignment that we should honor
    const nsHTMLReflowState* prs = parentReflowState;
    if (frame->GetType() == nsGkAtoms::tableFrame) {
      NS_ASSERTION(prs->frame->GetType() == nsGkAtoms::tableOuterFrame,
                   "table not inside outer table");
      // Center the table within the outer table based on the alignment
      // of the outer table's parent.
      prs = prs->parentReflowState;
    }
    if (prs &&
        (prs->mStyleText->mTextAlign == NS_STYLE_TEXT_ALIGN_MOZ_LEFT ||
         prs->mStyleText->mTextAlign == NS_STYLE_TEXT_ALIGN_MOZ_CENTER ||
         prs->mStyleText->mTextAlign == NS_STYLE_TEXT_ALIGN_MOZ_RIGHT)) {
      isAutoLeftMargin =
        prs->mStyleText->mTextAlign != NS_STYLE_TEXT_ALIGN_MOZ_LEFT;
      isAutoRightMargin =
        prs->mStyleText->mTextAlign != NS_STYLE_TEXT_ALIGN_MOZ_RIGHT;
    }
    // Otherwise apply the CSS rules, and ignore one margin by forcing
    // it to 'auto', depending on 'direction'.
    else if (mCBReflowState &&
             NS_STYLE_DIRECTION_RTL == mCBReflowState->mStyleVisibility->mDirection) {
      isAutoLeftMargin = PR_TRUE;
    }
    else {
      isAutoRightMargin = PR_TRUE;
    }
  }

  // Logic which is common to blocks and tables
  // The computed margins need not be zero because the 'auto' could come from
  // overconstraint or from HTML alignment so values need to be accumulated

  if (isAutoLeftMargin) {
    if (isAutoRightMargin) {
      // Both margins are 'auto' so the computed addition should be equal
      nscoord forLeft = availMarginSpace / 2;
      mComputedMargin.left  += forLeft;
      mComputedMargin.right += availMarginSpace - forLeft;
    } else {
      mComputedMargin.left += availMarginSpace;
    }
  } else if (isAutoRightMargin) {
    mComputedMargin.right += availMarginSpace;
  }
}

#define NORMAL_LINE_HEIGHT_FACTOR 1.2f    // in term of emHeight 
// For "normal" we use the font's normal line height (em height + leading).
// If both internal leading and  external leading specified by font itself
// are zeros, we should compensate this by creating extra (external) leading 
// in eCompensateLeading mode. This is necessary because without this 
// compensation, normal line height might looks too tight. 

// For risk management, we use preference to control the behavior, and 
// eNoExternalLeading is the old behavior.
static nscoord
GetNormalLineHeight(nsIFontMetrics* aFontMetrics)
{
  NS_PRECONDITION(nsnull != aFontMetrics, "no font metrics");

  nscoord normalLineHeight;

  nscoord externalLeading, internalLeading, emHeight;
  aFontMetrics->GetExternalLeading(externalLeading);
  aFontMetrics->GetInternalLeading(internalLeading);
  aFontMetrics->GetEmHeight(emHeight);
  switch (GetNormalLineHeightCalcControl()) {
  case eIncludeExternalLeading:
    normalLineHeight = emHeight+ internalLeading + externalLeading;
    break;
  case eCompensateLeading:
    if (!internalLeading && !externalLeading)
      normalLineHeight = NSToCoordRound(emHeight * NORMAL_LINE_HEIGHT_FACTOR);
    else
      normalLineHeight = emHeight+ internalLeading + externalLeading;
    break;
  default:
    //case eNoExternalLeading:
    normalLineHeight = emHeight + internalLeading;
  }
  return normalLineHeight;
}

static nscoord
ComputeLineHeight(nsStyleContext* aStyleContext,
                  nscoord aBlockHeight)
{
  const nsStyleCoord& lhCoord = aStyleContext->GetStyleText()->mLineHeight;

  if (lhCoord.GetUnit() == eStyleUnit_Coord)
    return lhCoord.GetCoordValue();

  if (lhCoord.GetUnit() == eStyleUnit_Factor)
    // For factor units the computed value of the line-height property 
    // is found by multiplying the factor by the font's computed size
    // (adjusted for min-size prefs and text zoom).
    return NSToCoordRound(lhCoord.GetFactorValue() *
                          aStyleContext->GetStyleFont()->mFont.size);

  NS_ASSERTION(lhCoord.GetUnit() == eStyleUnit_Normal ||
               lhCoord.GetUnit() == eStyleUnit_Enumerated,
               "bad line-height unit");
  
  if (lhCoord.GetUnit() == eStyleUnit_Enumerated) {
    NS_ASSERTION(lhCoord.GetIntValue() == NS_STYLE_LINE_HEIGHT_BLOCK_HEIGHT,
                 "bad line-height value");
    if (aBlockHeight != NS_AUTOHEIGHT)
      return aBlockHeight;
  }

  nsCOMPtr<nsIFontMetrics> fm;
  nsLayoutUtils::GetFontMetricsForStyleContext(aStyleContext,
                                               getter_AddRefs(fm));
  return GetNormalLineHeight(fm);
}

nscoord
nsHTMLReflowState::CalcLineHeight() const
{
  nscoord blockHeight =
    frame->IsContainingBlock() ? mComputedHeight :
    (mCBReflowState ? mCBReflowState->mComputedHeight : NS_AUTOHEIGHT);

  return CalcLineHeight(frame->GetStyleContext(), blockHeight);
}

/* static */ nscoord
nsHTMLReflowState::CalcLineHeight(nsStyleContext* aStyleContext,
                                  nscoord aBlockHeight)
{
  NS_PRECONDITION(aStyleContext, "Must have a style context");
  
  nscoord lineHeight = ComputeLineHeight(aStyleContext, aBlockHeight);

  NS_ASSERTION(lineHeight >= 0, "ComputeLineHeight screwed up");

  return lineHeight;
}

/* static */
void
nsCSSOffsetState::DestroyMarginFunc(void*    aFrame,
                                    nsIAtom* aPropertyName,
                                    void*    aPropertyValue,
                                    void*    aDtorData)
{
  delete static_cast<nsMargin*>(aPropertyValue);
}

void
nsCSSOffsetState::ComputeMargin(nscoord aContainingBlockWidth)
{
  // If style style can provide us the margin directly, then use it.
  const nsStyleMargin *styleMargin = frame->GetStyleMargin();
  if (!styleMargin->GetMargin(mComputedMargin)) {
    // We have to compute the value
    if (NS_UNCONSTRAINEDSIZE == aContainingBlockWidth) {
      mComputedMargin.left = 0;
      mComputedMargin.right = 0;

      if (eStyleUnit_Coord == styleMargin->mMargin.GetLeftUnit()) {
        mComputedMargin.left = styleMargin->mMargin.GetLeft().GetCoordValue();
      }
      if (eStyleUnit_Coord == styleMargin->mMargin.GetRightUnit()) {
        mComputedMargin.right = styleMargin->mMargin.GetRight().GetCoordValue();
      }

    } else {
      mComputedMargin.left = nsLayoutUtils::
        ComputeWidthDependentValue(aContainingBlockWidth,
                                   styleMargin->mMargin.GetLeft());
      mComputedMargin.right = nsLayoutUtils::
        ComputeWidthDependentValue(aContainingBlockWidth,
                                   styleMargin->mMargin.GetRight());
    }

    // According to the CSS2 spec, margin percentages are
    // calculated with respect to the *width* of the containing
    // block, even for margin-top and margin-bottom.
    // XXX This isn't true for page boxes, if we implement them.
    mComputedMargin.top = nsLayoutUtils::
      ComputeWidthDependentValue(aContainingBlockWidth,
                                 styleMargin->mMargin.GetTop());
    mComputedMargin.bottom = nsLayoutUtils::
      ComputeWidthDependentValue(aContainingBlockWidth,
                                 styleMargin->mMargin.GetBottom());

    // XXX We need to include 'auto' horizontal margins in this too!
    // ... but if we did that, we'd need to fix nsFrame::GetUsedMargin
    // to use it even when the margins are all zero (since sometimes
    // they get treated as auto)
    frame->SetProperty(nsGkAtoms::usedMarginProperty,
                       new nsMargin(mComputedMargin),
                       DestroyMarginFunc);
  }
}

void
nsCSSOffsetState::ComputePadding(nscoord aContainingBlockWidth)
{
  // If style can provide us the padding directly, then use it.
  const nsStylePadding *stylePadding = frame->GetStylePadding();
  if (!stylePadding->GetPadding(mComputedPadding)) {
    // We have to compute the value
    mComputedPadding.left = nsLayoutUtils::
      ComputeWidthDependentValue(aContainingBlockWidth,
                                 stylePadding->mPadding.GetLeft());
    mComputedPadding.right = nsLayoutUtils::
      ComputeWidthDependentValue(aContainingBlockWidth,
                                 stylePadding->mPadding.GetRight());

    // According to the CSS2 spec, percentages are calculated with respect to
    // containing block width for padding-top and padding-bottom
    mComputedPadding.top = nsLayoutUtils::
      ComputeWidthDependentValue(aContainingBlockWidth,
                                 stylePadding->mPadding.GetTop());
    mComputedPadding.bottom = nsLayoutUtils::
      ComputeWidthDependentValue(aContainingBlockWidth,
                                 stylePadding->mPadding.GetBottom());

    frame->SetProperty(nsGkAtoms::usedPaddingProperty,
                       new nsMargin(mComputedPadding),
                       DestroyMarginFunc);
  }
  // a table row/col group, row/col doesn't have padding
  // XXXldb Neither do border-collapse tables.
  nsIAtom* frameType = frame->GetType();
  if (nsGkAtoms::tableRowGroupFrame == frameType ||
      nsGkAtoms::tableColGroupFrame == frameType ||
      nsGkAtoms::tableRowFrame      == frameType ||
      nsGkAtoms::tableColFrame      == frameType) {
    mComputedPadding.top    = 0;
    mComputedPadding.right  = 0;
    mComputedPadding.bottom = 0;
    mComputedPadding.left   = 0;
  }
}

void
nsHTMLReflowState::ApplyMinMaxConstraints(nscoord* aFrameWidth,
                                          nscoord* aFrameHeight) const
{
  if (aFrameWidth) {
    if (NS_UNCONSTRAINEDSIZE != mComputedMaxWidth) {
      *aFrameWidth = PR_MIN(*aFrameWidth, mComputedMaxWidth);
    }
    *aFrameWidth = PR_MAX(*aFrameWidth, mComputedMinWidth);
  }

  if (aFrameHeight) {
    if (NS_UNCONSTRAINEDSIZE != mComputedMaxHeight) {
      *aFrameHeight = PR_MIN(*aFrameHeight, mComputedMaxHeight);
    }
    *aFrameHeight = PR_MAX(*aFrameHeight, mComputedMinHeight);
  }
}

void
nsHTMLReflowState::ComputeMinMaxValues(nscoord aContainingBlockWidth,
                                       nscoord aContainingBlockHeight,
                                       const nsHTMLReflowState* aContainingBlockRS)
{
  mComputedMinWidth = ComputeWidthValue(aContainingBlockWidth,
                                        mStylePosition->mBoxSizing,
                                        mStylePosition->mMinWidth);

  if (eStyleUnit_None == mStylePosition->mMaxWidth.GetUnit()) {
    // Specified value of 'none'
    mComputedMaxWidth = NS_UNCONSTRAINEDSIZE;  // no limit
  } else {
    mComputedMaxWidth = ComputeWidthValue(aContainingBlockWidth,
                                          mStylePosition->mBoxSizing,
                                          mStylePosition->mMaxWidth);
  }

  // If the computed value of 'min-width' is greater than the value of
  // 'max-width', 'max-width' is set to the value of 'min-width'
  if (mComputedMinWidth > mComputedMaxWidth) {
    mComputedMaxWidth = mComputedMinWidth;
  }

  // Check for percentage based values and a containing block height that
  // depends on the content height. Treat them like 'auto'
  if ((NS_AUTOHEIGHT == aContainingBlockHeight) &&
      (eStyleUnit_Percent == mStylePosition->mMinHeight.GetUnit())) {
    mComputedMinHeight = 0;
  } else {
    mComputedMinHeight = nsLayoutUtils::
      ComputeHeightDependentValue(aContainingBlockHeight,
                                  mStylePosition->mMinHeight);
  }
  nsStyleUnit maxHeightUnit = mStylePosition->mMaxHeight.GetUnit();
  if (eStyleUnit_None == maxHeightUnit) {
    // Specified value of 'none'
    mComputedMaxHeight = NS_UNCONSTRAINEDSIZE;  // no limit
  } else {
    // Check for percentage based values and a containing block height that
    // depends on the content height. Treat them like 'auto'
    if ((NS_AUTOHEIGHT == aContainingBlockHeight) && 
        (eStyleUnit_Percent == maxHeightUnit)) {
      mComputedMaxHeight = NS_UNCONSTRAINEDSIZE;
    } else {
      mComputedMaxHeight = nsLayoutUtils::
        ComputeHeightDependentValue(aContainingBlockHeight,
                                    mStylePosition->mMaxHeight);
    }
  }

  // If the computed value of 'min-height' is greater than the value of
  // 'max-height', 'max-height' is set to the value of 'min-height'
  if (mComputedMinHeight > mComputedMaxHeight) {
    mComputedMaxHeight = mComputedMinHeight;
  }
}

void
nsHTMLReflowState::SetTruncated(const nsHTMLReflowMetrics& aMetrics,
                                nsReflowStatus* aStatus) const
{
  if (availableHeight != NS_UNCONSTRAINEDSIZE &&
      availableHeight < aMetrics.height &&
      !mFlags.mIsTopOfPage) {
    *aStatus |= NS_FRAME_TRUNCATED;
  } else {
    *aStatus &= ~NS_FRAME_TRUNCATED;
  }
}