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

Untracked file

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
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=2 sw=2 et tw=78: */
/* ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is mozilla.org code.
 *
 * The Initial Developer of the Original Code is
 * Netscape Communications Corporation.
 * Portions created by the Initial Developer are Copyright (C) 1998
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *   Pierre Phaneuf <pp@ludusdesign.com>
 *   Mats Palmgren <mats.palmgren@bredband.net>
 *
 * 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 ***** */

/* the caret is the text cursor used, e.g., when editing */

#include "nsCOMPtr.h"

#include "nsITimer.h"

#include "nsIComponentManager.h"
#include "nsIServiceManager.h"
#include "nsFrameSelection.h"
#include "nsIFrame.h"
#include "nsIScrollableFrame.h"
#include "nsIDOMNode.h"
#include "nsIDOMRange.h"
#include "nsIFontMetrics.h"
#include "nsISelection.h"
#include "nsISelectionPrivate.h"
#include "nsIDOMCharacterData.h"
#include "nsIContent.h"
#include "nsIPresShell.h"
#include "nsIRenderingContext.h"
#include "nsIDeviceContext.h"
#include "nsIView.h"
#include "nsIScrollableView.h"
#include "nsIViewManager.h"
#include "nsPresContext.h"
#include "nsILookAndFeel.h"
#include "nsBlockFrame.h"
#include "nsISelectionController.h"
#include "nsDisplayList.h"
#include "nsCaret.h"
#include "nsTextFrame.h"
#include "nsXULPopupManager.h"
#include "nsMenuPopupFrame.h"
#include "nsTextFragment.h"

// The bidi indicator hangs off the caret to one side, to show which
// direction the typing is in. It needs to be at least 2x2 to avoid looking like 
// an insignificant dot
static const PRInt32 kMinBidiIndicatorPixels = 2;

#ifdef IBMBIDI
#include "nsIBidiKeyboard.h"
#include "nsContentUtils.h"
#endif //IBMBIDI

//-----------------------------------------------------------------------------

nsCaret::nsCaret()
: mPresShell(nsnull)
, mBlinkRate(500)
, mVisible(PR_FALSE)
, mDrawn(PR_FALSE)
, mReadOnly(PR_FALSE)
, mShowDuringSelection(PR_FALSE)
, mLastContentOffset(0)
, mLastHint(nsFrameSelection::HINTLEFT)
, mIgnoreUserModify(PR_TRUE)
#ifdef IBMBIDI
, mLastBidiLevel(0)
, mKeyboardRTL(PR_FALSE)
#endif
{
}

//-----------------------------------------------------------------------------
nsCaret::~nsCaret()
{
  KillTimer();
}

//-----------------------------------------------------------------------------
NS_IMETHODIMP nsCaret::Init(nsIPresShell *inPresShell)
{
  NS_ENSURE_ARG(inPresShell);
  
  mPresShell = do_GetWeakReference(inPresShell);    // the presshell owns us, so no addref
  NS_ASSERTION(mPresShell, "Hey, pres shell should support weak refs");

  // get nsILookAndFeel from the pres context, which has one cached.
  nsILookAndFeel *lookAndFeel = nsnull;
  nsPresContext *presContext = inPresShell->GetPresContext();
  
  // XXX we should just do this nsILookAndFeel consultation every time
  // we need these values.
  mCaretWidthCSSPx = 1;
  if (presContext && (lookAndFeel = presContext->LookAndFeel())) {
    PRInt32 tempInt;
    if (NS_SUCCEEDED(lookAndFeel->GetMetric(nsILookAndFeel::eMetric_CaretWidth, tempInt)))
      mCaretWidthCSSPx = (nscoord)tempInt;
    if (NS_SUCCEEDED(lookAndFeel->GetMetric(nsILookAndFeel::eMetric_CaretBlinkTime, tempInt)))
      mBlinkRate = (PRUint32)tempInt;
    if (NS_SUCCEEDED(lookAndFeel->GetMetric(nsILookAndFeel::eMetric_ShowCaretDuringSelection, tempInt)))
      mShowDuringSelection = tempInt ? PR_TRUE : PR_FALSE;
  }
  
  // get the selection from the pres shell, and set ourselves up as a selection
  // listener

  nsCOMPtr<nsISelectionController> selCon = do_QueryReferent(mPresShell);
  if (!selCon)
    return NS_ERROR_FAILURE;

  nsCOMPtr<nsISelection> domSelection;
  nsresult rv = selCon->GetSelection(nsISelectionController::SELECTION_NORMAL,
                                     getter_AddRefs(domSelection));
  if (NS_FAILED(rv))
    return rv;
  if (!domSelection)
    return NS_ERROR_FAILURE;

  nsCOMPtr<nsISelectionPrivate> privateSelection = do_QueryInterface(domSelection);
  if (privateSelection)
    privateSelection->AddSelectionListener(this);
  mDomSelectionWeak = do_GetWeakReference(domSelection);
  
  // set up the blink timer
  if (mVisible)
  {
    rv = StartBlinking();
    if (NS_FAILED(rv))
      return rv;
  }

  return NS_OK;
}

static PRBool
DrawCJKCaret(nsIFrame* aFrame, PRInt32 aOffset)
{
  nsIContent* content = aFrame->GetContent();
  const nsTextFragment* frag = content->GetText();
  if (!frag)
    return PR_FALSE;
  if (aOffset < 0 || aOffset >= frag->GetLength())
    return PR_FALSE;
  PRUnichar ch = frag->CharAt(aOffset);
  return 0x2e80 <= ch && ch <= 0xd7ff;
}

nsCaret::Metrics nsCaret::ComputeMetrics(nsIFrame* aFrame, PRInt32 aOffset)
{
  // Compute nominal sizes in appunits
  nscoord caretWidth = nsPresContext::CSSPixelsToAppUnits(mCaretWidthCSSPx);
  if (DrawCJKCaret(aFrame, aOffset)) {
    caretWidth += nsPresContext::CSSPixelsToAppUnits(1);
  }
  nscoord bidiIndicatorSize = nsPresContext::CSSPixelsToAppUnits(kMinBidiIndicatorPixels);
  bidiIndicatorSize = PR_MAX(caretWidth, bidiIndicatorSize);

  // Round them to device pixels. Always round down, except that anything
  // between 0 and 1 goes up to 1 so we don't let the caret disappear.
  PRUint32 tpp = aFrame->PresContext()->AppUnitsPerDevPixel();
  Metrics result;
  result.mCaretWidth = NS_ROUND_BORDER_TO_PIXELS(caretWidth, tpp);
  result.mBidiIndicatorSize = NS_ROUND_BORDER_TO_PIXELS(bidiIndicatorSize, tpp);
  return result;
}

//-----------------------------------------------------------------------------
NS_IMETHODIMP nsCaret::Terminate()
{
  // this doesn't erase the caret if it's drawn. Should it? We might not have
  // a good drawing environment during teardown.
  
  KillTimer();
  mBlinkTimer = nsnull;

  // unregiser ourselves as a selection listener
  nsCOMPtr<nsISelection> domSelection = do_QueryReferent(mDomSelectionWeak);
  nsCOMPtr<nsISelectionPrivate> privateSelection(do_QueryInterface(domSelection));
  if (privateSelection)
    privateSelection->RemoveSelectionListener(this);
  mDomSelectionWeak = nsnull;
  mPresShell = nsnull;

  mLastContent = nsnull;
  
  return NS_OK;
}


//-----------------------------------------------------------------------------
NS_IMPL_ISUPPORTS2(nsCaret, nsICaret, nsISelectionListener)

//-----------------------------------------------------------------------------
NS_IMETHODIMP nsCaret::GetCaretDOMSelection(nsISelection **aDOMSel)
{
  nsCOMPtr<nsISelection> sel(do_QueryReferent(mDomSelectionWeak));
  
  NS_IF_ADDREF(*aDOMSel = sel);

  return NS_OK;
}


//-----------------------------------------------------------------------------
NS_IMETHODIMP nsCaret::SetCaretDOMSelection(nsISelection *aDOMSel)
{
  NS_ENSURE_ARG_POINTER(aDOMSel);
  mDomSelectionWeak = do_GetWeakReference(aDOMSel);   // weak reference to pres shell
  if (mVisible)
  {
    // Stop the caret from blinking in its previous location.
    StopBlinking();
    // Start the caret blinking in the new location.
    StartBlinking();
  }
  return NS_OK;
}


//-----------------------------------------------------------------------------
NS_IMETHODIMP nsCaret::SetCaretVisible(PRBool inMakeVisible)
{
  mVisible = inMakeVisible;
  nsresult  err = NS_OK;
  if (mVisible) {
    err = StartBlinking();
    SetIgnoreUserModify(PR_TRUE);
  } else {
    err = StopBlinking();
    SetIgnoreUserModify(PR_FALSE);
  }

  return err;
}


//-----------------------------------------------------------------------------
NS_IMETHODIMP nsCaret::GetCaretVisible(PRBool *outMakeVisible)
{
  NS_ENSURE_ARG_POINTER(outMakeVisible);
  *outMakeVisible = (mVisible && MustDrawCaret(PR_TRUE));
  return NS_OK;
}


//-----------------------------------------------------------------------------
NS_IMETHODIMP nsCaret::SetCaretReadOnly(PRBool inMakeReadonly)
{
  mReadOnly = inMakeReadonly;
  return NS_OK;
}


//-----------------------------------------------------------------------------
NS_IMETHODIMP nsCaret::GetCaretCoordinates(EViewCoordinates aRelativeToType,
                                           nsISelection *aDOMSel,
                                           nsRect *outCoordinates,
                                           PRBool *outIsCollapsed,
                                           nsIView **outView)
{
  if (!mPresShell)
    return NS_ERROR_NOT_INITIALIZED;
  if (!outCoordinates || !outIsCollapsed)
    return NS_ERROR_NULL_POINTER;

  nsCOMPtr<nsISelection> domSelection = aDOMSel;

  if (outView)
    *outView = nsnull;

  // fill in defaults for failure
  outCoordinates->x = -1;
  outCoordinates->y = -1;
  outCoordinates->width = -1;
  outCoordinates->height = -1;
  *outIsCollapsed = PR_FALSE;
  
  nsresult err = domSelection->GetIsCollapsed(outIsCollapsed);
  if (NS_FAILED(err)) 
    return err;
    
  nsCOMPtr<nsIDOMNode>  focusNode;
  
  err = domSelection->GetFocusNode(getter_AddRefs(focusNode));
  if (NS_FAILED(err))
    return err;
  if (!focusNode)
    return NS_ERROR_FAILURE;
  
  PRInt32 focusOffset;
  err = domSelection->GetFocusOffset(&focusOffset);
  if (NS_FAILED(err))
    return err;
    
  nsCOMPtr<nsIContent> contentNode = do_QueryInterface(focusNode);
  if (!contentNode)
    return NS_ERROR_FAILURE;

  // find the frame that contains the content node that has focus
  nsIFrame*       theFrame = nsnull;
  PRInt32         theFrameOffset = 0;

  nsCOMPtr<nsFrameSelection> frameSelection = GetFrameSelection();
  if (!frameSelection)
    return NS_ERROR_FAILURE;
  PRUint8 bidiLevel = frameSelection->GetCaretBidiLevel();
  
  err = GetCaretFrameForNodeOffset(contentNode, focusOffset,
                                   frameSelection->GetHint(), bidiLevel,
                                   &theFrame, &theFrameOffset);
  if (NS_FAILED(err) || !theFrame)
    return err;
  
  nsPoint   viewOffset(0, 0);
  nsIView   *drawingView;     // views are not refcounted

  GetViewForRendering(theFrame, aRelativeToType, viewOffset, &drawingView, outView);
  if (!drawingView)
    return NS_ERROR_UNEXPECTED;
 
  nsPoint   framePos(0, 0);
  err = theFrame->GetPointFromOffset(theFrameOffset, &framePos);
  if (NS_FAILED(err))
    return err;

  // we don't need drawingView anymore so reuse that; reset viewOffset values for our purposes
  if (aRelativeToType == eClosestViewCoordinates)
  {
    theFrame->GetOffsetFromView(viewOffset, &drawingView);
    if (outView)
      *outView = drawingView;
  }
  // now add the frame offset to the view offset, and we're done
  viewOffset += framePos;
  outCoordinates->x = viewOffset.x;
  outCoordinates->y = viewOffset.y;
  outCoordinates->height = theFrame->GetSize().height;
  outCoordinates->width = ComputeMetrics(theFrame, theFrameOffset).mCaretWidth;
  
  return NS_OK;
}

void nsCaret::DrawCaretAfterBriefDelay()
{
  // Make sure readonly caret gets drawn again if it needs to be
  if (!mBlinkTimer) {
    nsresult  err;
    mBlinkTimer = do_CreateInstance("@mozilla.org/timer;1", &err);    
    if (NS_FAILED(err))
      return;
  }    

  mBlinkTimer->InitWithFuncCallback(CaretBlinkCallback, this, 0,
                                    nsITimer::TYPE_ONE_SHOT);
}

NS_IMETHODIMP nsCaret::EraseCaret()
{
  if (mDrawn) {
    DrawCaret(PR_TRUE);
    if (mReadOnly && mBlinkRate) {
      // If readonly we don't have a blink timer set, so caret won't
      // be redrawn automatically. We need to force the caret to get
      // redrawn right after the paint
      DrawCaretAfterBriefDelay();
    }
  }

  return NS_OK;
}

NS_IMETHODIMP nsCaret::SetVisibilityDuringSelection(PRBool aVisibility) 
{
  mShowDuringSelection = aVisibility;
  return NS_OK;
}

NS_IMETHODIMP nsCaret::DrawAtPosition(nsIDOMNode* aNode, PRInt32 aOffset)
{
  NS_ENSURE_ARG(aNode);

  PRUint8 bidiLevel;
  nsCOMPtr<nsFrameSelection> frameSelection = GetFrameSelection();
  if (!frameSelection)
    return NS_ERROR_FAILURE;
  bidiLevel = frameSelection->GetCaretBidiLevel();

  // DrawAtPosition is used by consumers who want us to stay drawn where they
  // tell us. Setting mBlinkRate to 0 tells us to not set a timer to erase
  // ourselves, our consumer will take care of that.
  mBlinkRate = 0;

  // XXX we need to do more work here to get the correct hint.
  nsresult rv = DrawAtPositionWithHint(aNode, aOffset,
                                       nsFrameSelection::HINTLEFT,
                                       bidiLevel, PR_TRUE)
    ?  NS_OK : NS_ERROR_FAILURE;
  ToggleDrawnStatus();
  return rv;
}

nsIFrame * nsCaret::GetCaretFrame()
{
  // Return null if we're not drawn to prevent anybody from trying to draw us.
  if (!mDrawn)
    return nsnull;

  // Recompute the frame that we're supposed to draw in to guarantee that
  // we're not going to try to draw into a stale (dead) frame.
  PRInt32 unused;
  nsIFrame *frame = nsnull;
  nsresult rv = GetCaretFrameForNodeOffset(mLastContent, mLastContentOffset,
                                           mLastHint, mLastBidiLevel, &frame,
                                           &unused);
  if (NS_FAILED(rv))
    return nsnull;

  return frame;
}

void nsCaret::InvalidateOutsideCaret()
{
  nsIFrame *frame = GetCaretFrame();

  // Only invalidate if we are not fully contained by our frame's rect.
  if (frame && !frame->GetOverflowRect().Contains(GetCaretRect()))
    InvalidateRects(mCaretRect, GetHookRect(), frame);
}

void nsCaret::UpdateCaretPosition()
{
  // We'll recalculate anyway if we're not drawn right now.
  if (!mDrawn)
    return;

  // A trick! Make the DrawCaret code recalculate the caret's current
  // position.
  mDrawn = PR_FALSE;
  DrawCaret(PR_FALSE);
}

void nsCaret::PaintCaret(nsDisplayListBuilder *aBuilder,
                         nsIRenderingContext *aCtx,
                         const nsPoint &aOffset,
                         nscolor aColor)
{
  NS_ASSERTION(mDrawn, "The caret shouldn't be drawing");

  aCtx->SetColor(aColor);
  aCtx->FillRect(mCaretRect + aOffset);
  if (!GetHookRect().IsEmpty())
    aCtx->FillRect(GetHookRect() + aOffset);
}


//-----------------------------------------------------------------------------
NS_IMETHODIMP nsCaret::NotifySelectionChanged(nsIDOMDocument *, nsISelection *aDomSel, PRInt16 aReason)
{
  if (aReason & nsISelectionListener::MOUSEUP_REASON)//this wont do
    return NS_OK;

  nsCOMPtr<nsISelection> domSel(do_QueryReferent(mDomSelectionWeak));

  // The same caret is shared amongst the document and any text widgets it
  // may contain. This means that the caret could get notifications from
  // multiple selections.
  //
  // If this notification is for a selection that is not the one the
  // the caret is currently interested in (mDomSelectionWeak), then there
  // is nothing to do!

  if (domSel != aDomSel)
    return NS_OK;

  if (mVisible)
  {
    // Stop the caret from blinking in its previous location.
    StopBlinking();

    // Start the caret blinking in the new location.
    StartBlinking();
  }

  return NS_OK;
}


//-----------------------------------------------------------------------------
void nsCaret::KillTimer()
{
  if (mBlinkTimer)
  {
    mBlinkTimer->Cancel();
  }
}


//-----------------------------------------------------------------------------
nsresult nsCaret::PrimeTimer()
{
  // set up the blink timer
  if (!mReadOnly && mBlinkRate > 0)
  {
    if (!mBlinkTimer) {
      nsresult  err;
      mBlinkTimer = do_CreateInstance("@mozilla.org/timer;1", &err);    
      if (NS_FAILED(err))
        return err;
    }    

    mBlinkTimer->InitWithFuncCallback(CaretBlinkCallback, this, mBlinkRate,
                                      nsITimer::TYPE_REPEATING_SLACK);
  }

  return NS_OK;
}


//-----------------------------------------------------------------------------
nsresult nsCaret::StartBlinking()
{
  if (mReadOnly) {
    // Make sure the one draw command we use for a readonly caret isn't
    // done until the selection is set
    DrawCaretAfterBriefDelay();
    return NS_OK;
  }
  PrimeTimer();

  // If we are currently drawn, then the second call to DrawCaret below will
  // actually erase the caret. That would cause the caret to spend an "off"
  // cycle before it appears, which is not really what we want. This first
  // call to DrawCaret makes sure that the first cycle after a call to
  // StartBlinking is an "on" cycle.
  if (mDrawn)
    DrawCaret(PR_TRUE);

  DrawCaret(PR_TRUE);    // draw it right away
  
  return NS_OK;
}


//-----------------------------------------------------------------------------
nsresult nsCaret::StopBlinking()
{
  if (mDrawn)     // erase the caret if necessary
    DrawCaret(PR_TRUE);

  NS_ASSERTION(!mDrawn, "Caret still drawn after StopBlinking().");
  KillTimer();

  return NS_OK;
}

PRBool
nsCaret::DrawAtPositionWithHint(nsIDOMNode*             aNode,
                                PRInt32                 aOffset,
                                nsFrameSelection::HINT  aFrameHint,
                                PRUint8                 aBidiLevel,
                                PRBool                  aInvalidate)
{
  nsCOMPtr<nsIContent> contentNode = do_QueryInterface(aNode);
  if (!contentNode)
    return PR_FALSE;

  nsIFrame* theFrame = nsnull;
  PRInt32   theFrameOffset = 0;

  nsresult rv = GetCaretFrameForNodeOffset(contentNode, aOffset, aFrameHint, aBidiLevel,
                                           &theFrame, &theFrameOffset);
  if (NS_FAILED(rv) || !theFrame)
    return PR_FALSE;

  // now we have a frame, check whether it's appropriate to show the caret here
  const nsStyleUserInterface* userinterface = theFrame->GetStyleUserInterface();
  if ((!mIgnoreUserModify &&
       userinterface->mUserModify == NS_STYLE_USER_MODIFY_READ_ONLY) ||
      (userinterface->mUserInput == NS_STYLE_USER_INPUT_NONE) ||
      (userinterface->mUserInput == NS_STYLE_USER_INPUT_DISABLED))
  {
    return PR_FALSE;
  }  

  if (!mDrawn)
  {
    // save stuff so we can figure out what frame we're in later.
    mLastContent = contentNode;
    mLastContentOffset = aOffset;
    mLastHint = aFrameHint;
    mLastBidiLevel = aBidiLevel;

    // If there has been a reflow, set the caret Bidi level to the level of the current frame
    if (aBidiLevel & BIDI_LEVEL_UNDEFINED) {
      nsCOMPtr<nsFrameSelection> frameSelection = GetFrameSelection();
      if (!frameSelection)
        return PR_FALSE;
      frameSelection->SetCaretBidiLevel(NS_GET_EMBEDDING_LEVEL(theFrame));
    }

    // Only update the caret's rect when we're not currently drawn.
    rv = UpdateCaretRects(theFrame, theFrameOffset);
    if (NS_FAILED(rv))
      return PR_FALSE;
  }

  if (aInvalidate)
    InvalidateRects(mCaretRect, mHookRect, theFrame);

  return PR_TRUE;
}

/**
 * Find the first frame in an in-order traversal of the frame subtree rooted
 * at aFrame which is either a text frame logically at the end of a line,
 * or which is aStopAtFrame. Return null if no such frame is found. We don't
 * descend into the children of non-eLineParticipant frames.
 */
static nsIFrame*
CheckForTrailingTextFrameRecursive(nsIFrame* aFrame, nsIFrame* aStopAtFrame)
{
  if (aFrame == aStopAtFrame ||
      ((aFrame->GetType() == nsGkAtoms::textFrame &&
       (static_cast<nsTextFrame*>(aFrame))->IsAtEndOfLine())))
    return aFrame;
  if (!aFrame->IsFrameOfType(nsIFrame::eLineParticipant))
    return nsnull;

  for (nsIFrame* f = aFrame->GetFirstChild(nsnull); f; f = f->GetNextSibling())
  {
    nsIFrame* r = CheckForTrailingTextFrameRecursive(f, aStopAtFrame);
    if (r)
      return r;
  }
  return nsnull;
}

static nsLineBox*
FindContainingLine(nsIFrame* aFrame)
{
  while (aFrame && aFrame->IsFrameOfType(nsIFrame::eLineParticipant))
  {
    nsIFrame* parent = aFrame->GetParent();
    nsBlockFrame* blockParent;
    if (NS_SUCCEEDED(parent->QueryInterface(kBlockFrameCID, (void**)&blockParent)))
    {
      PRBool isValid;
      nsBlockInFlowLineIterator iter(blockParent, aFrame, &isValid);
      return isValid ? iter.GetLine().get() : nsnull;
    }
    aFrame = parent;
  }
  return nsnull;
}

static void
AdjustCaretFrameForLineEnd(nsIFrame** aFrame, PRInt32* aOffset)
{
  nsLineBox* line = FindContainingLine(*aFrame);
  if (!line)
    return;
  PRInt32 count = line->GetChildCount();
  for (nsIFrame* f = line->mFirstChild; count > 0; --count, f = f->GetNextSibling())
  {
    nsIFrame* r = CheckForTrailingTextFrameRecursive(f, *aFrame);
    if (r == *aFrame)
      return;
    if (r)
    {
      *aFrame = r;
      NS_ASSERTION(r->GetType() == nsGkAtoms::textFrame, "Expected text frame");
      *aOffset = (static_cast<nsTextFrame*>(r))->GetContentEnd();
      return;
    }
  }
}

NS_IMETHODIMP 
nsCaret::GetCaretFrameForNodeOffset(nsIContent*             aContentNode,
                                    PRInt32                 aOffset,
                                    nsFrameSelection::HINT aFrameHint,
                                    PRUint8                 aBidiLevel,
                                    nsIFrame**              aReturnFrame,
                                    PRInt32*                aReturnOffset)
{

  //get frame selection and find out what frame to use...
  nsCOMPtr<nsIPresShell> presShell = do_QueryReferent(mPresShell);
  if (!presShell)
    return NS_ERROR_FAILURE;

  nsCOMPtr<nsFrameSelection> frameSelection = GetFrameSelection();
  if (!frameSelection)
    return NS_ERROR_FAILURE;

  nsIFrame* theFrame = nsnull;
  PRInt32   theFrameOffset = 0;

  theFrame = frameSelection->GetFrameForNodeOffset(aContentNode, aOffset,
                                                   aFrameHint, &theFrameOffset);
  if (!theFrame)
    return NS_ERROR_FAILURE;

  // if theFrame is after a text frame that's logically at the end of the line
  // (e.g. if theFrame is a <br> frame), then put the caret at the end of
  // that text frame instead. This way, the caret will be positioned as if
  // trailing whitespace was not trimmed.
  AdjustCaretFrameForLineEnd(&theFrame, &theFrameOffset);
  
  // Mamdouh : modification of the caret to work at rtl and ltr with Bidi
  //
  // Direction Style from this->GetStyleData()
  // now in (visibility->mDirection)
  // ------------------
  // NS_STYLE_DIRECTION_LTR : LTR or Default
  // NS_STYLE_DIRECTION_RTL
  // NS_STYLE_DIRECTION_INHERIT
  nsPresContext *presContext = presShell->GetPresContext();
  if (presContext && presContext->BidiEnabled())
  {
    // If there has been a reflow, take the caret Bidi level to be the level of the current frame
    if (aBidiLevel & BIDI_LEVEL_UNDEFINED)
      aBidiLevel = NS_GET_EMBEDDING_LEVEL(theFrame);

    PRInt32 start;
    PRInt32 end;
    nsIFrame* frameBefore;
    nsIFrame* frameAfter;
    PRUint8 levelBefore;     // Bidi level of the character before the caret
    PRUint8 levelAfter;      // Bidi level of the character after the caret

    theFrame->GetOffsets(start, end);
    if (start == 0 || end == 0 || start == theFrameOffset || end == theFrameOffset)
    {
      nsPrevNextBidiLevels levels = frameSelection->
        GetPrevNextBidiLevels(aContentNode, aOffset, PR_FALSE);
    
      /* Boundary condition, we need to know the Bidi levels of the characters before and after the caret */
      if (levels.mFrameBefore || levels.mFrameAfter)
      {
        frameBefore = levels.mFrameBefore;
        frameAfter = levels.mFrameAfter;
        levelBefore = levels.mLevelBefore;
        levelAfter = levels.mLevelAfter;

        if ((levelBefore != levelAfter) || (aBidiLevel != levelBefore))
        {
          aBidiLevel = PR_MAX(aBidiLevel, PR_MIN(levelBefore, levelAfter));                                  // rule c3
          aBidiLevel = PR_MIN(aBidiLevel, PR_MAX(levelBefore, levelAfter));                                  // rule c4
          if (aBidiLevel == levelBefore                                                                      // rule c1
              || aBidiLevel > levelBefore && aBidiLevel < levelAfter && !((aBidiLevel ^ levelBefore) & 1)    // rule c5
              || aBidiLevel < levelBefore && aBidiLevel > levelAfter && !((aBidiLevel ^ levelBefore) & 1))   // rule c9
          {
            if (theFrame != frameBefore)
            {
              if (frameBefore) // if there is a frameBefore, move into it
              {
                theFrame = frameBefore;
                theFrame->GetOffsets(start, end);
                theFrameOffset = end;
              }
              else 
              {
                // if there is no frameBefore, we must be at the beginning of the line
                // so we stay with the current frame.
                // Exception: when the first frame on the line has a different Bidi level from the paragraph level, there is no
                // real frame for the caret to be in. We have to find the visually first frame on the line.
                PRUint8 baseLevel = NS_GET_BASE_LEVEL(frameAfter);
                if (baseLevel != levelAfter)
                {
                  nsPeekOffsetStruct pos;
                  pos.SetData(eSelectBeginLine, eDirPrevious, 0, 0, PR_FALSE, PR_TRUE, PR_FALSE, PR_TRUE);
                  if (NS_SUCCEEDED(frameAfter->PeekOffset(&pos))) {
                    theFrame = pos.mResultFrame;
                    theFrameOffset = pos.mContentOffset;
                  }
                }
              }
            }
          }
          else if (aBidiLevel == levelAfter                                                                     // rule c2
                   || aBidiLevel > levelBefore && aBidiLevel < levelAfter && !((aBidiLevel ^ levelAfter) & 1)   // rule c6  
                   || aBidiLevel < levelBefore && aBidiLevel > levelAfter && !((aBidiLevel ^ levelAfter) & 1))  // rule c10
          {
            if (theFrame != frameAfter)
            {
              if (frameAfter)
              {
                // if there is a frameAfter, move into it
                theFrame = frameAfter;
                theFrame->GetOffsets(start, end);
                theFrameOffset = start;
              }
              else 
              {
                // if there is no frameAfter, we must be at the end of the line
                // so we stay with the current frame.
                // Exception: when the last frame on the line has a different Bidi level from the paragraph level, there is no
                // real frame for the caret to be in. We have to find the visually last frame on the line.
                PRUint8 baseLevel = NS_GET_BASE_LEVEL(frameBefore);
                if (baseLevel != levelBefore)
                {
                  nsPeekOffsetStruct pos;
                  pos.SetData(eSelectEndLine, eDirNext, 0, 0, PR_FALSE, PR_TRUE, PR_FALSE, PR_TRUE);
                  if (NS_SUCCEEDED(frameBefore->PeekOffset(&pos))) {
                    theFrame = pos.mResultFrame;
                    theFrameOffset = pos.mContentOffset;
                  }
                }
              }
            }
          }
          else if (aBidiLevel > levelBefore && aBidiLevel < levelAfter  // rule c7/8
                   && !((levelBefore ^ levelAfter) & 1)                 // before and after have the same parity
                   && ((aBidiLevel ^ levelAfter) & 1))                  // caret has different parity
          {
            if (NS_SUCCEEDED(frameSelection->GetFrameFromLevel(frameAfter, eDirNext, aBidiLevel, &theFrame)))
            {
              theFrame->GetOffsets(start, end);
              levelAfter = NS_GET_EMBEDDING_LEVEL(theFrame);
              if (aBidiLevel & 1) // c8: caret to the right of the rightmost character
                theFrameOffset = (levelAfter & 1) ? start : end;
              else               // c7: caret to the left of the leftmost character
                theFrameOffset = (levelAfter & 1) ? end : start;
            }
          }
          else if (aBidiLevel < levelBefore && aBidiLevel > levelAfter  // rule c11/12
                   && !((levelBefore ^ levelAfter) & 1)                 // before and after have the same parity
                   && ((aBidiLevel ^ levelAfter) & 1))                  // caret has different parity
          {
            if (NS_SUCCEEDED(frameSelection->GetFrameFromLevel(frameBefore, eDirPrevious, aBidiLevel, &theFrame)))
            {
              theFrame->GetOffsets(start, end);
              levelBefore = NS_GET_EMBEDDING_LEVEL(theFrame);
              if (aBidiLevel & 1) // c12: caret to the left of the leftmost character
                theFrameOffset = (levelBefore & 1) ? end : start;
              else               // c11: caret to the right of the rightmost character
                theFrameOffset = (levelBefore & 1) ? start : end;
            }
          }   
        }
      }
    }
  }
  *aReturnFrame = theFrame;
  *aReturnOffset = theFrameOffset;
  return NS_OK;
}


//-----------------------------------------------------------------------------
void nsCaret::GetViewForRendering(nsIFrame *caretFrame,
                                  EViewCoordinates coordType,
                                  nsPoint &viewOffset,
                                  nsIView **outRenderingView,
                                  nsIView **outRelativeView)
{
  if (!caretFrame || !outRenderingView)
    return;

  // XXX by Masayuki Nakano:
  // This code is not good. This is adhoc approach.
  // Our best approach is to use the event fired widget related view.
  // But if we do so, we need large change for editor and this.
  if (coordType == eIMECoordinates) {
#if defined(XP_MACOSX) || defined(XP_WIN)
   // #59405 and #313918, on Mac and Windows, the coordinate for IME need to be
   // root view related.
   coordType = eTopLevelWindowCoordinates; 
#else
   // #59405, on unix, the coordinate for IME need to be view
   // (nearest native window) related.
   coordType = eRenderingViewCoordinates; 
#endif
  }

  *outRenderingView = nsnull;
  if (outRelativeView)
    *outRelativeView = nsnull;
  
  NS_ASSERTION(caretFrame, "Should have a frame here");
 
  viewOffset.x = 0;
  viewOffset.y = 0;
  
  nsPoint withinViewOffset(0, 0);
  // get the offset of this frame from its parent view (walks up frame hierarchy)
  nsIView* theView = nsnull;
  caretFrame->GetOffsetFromView(withinViewOffset, &theView);
  if (!theView)
      return;

  if (outRelativeView && coordType == eClosestViewCoordinates)
    *outRelativeView = theView;

  // Note: views are not refcounted.
  nsIView* returnView = nsIView::GetViewFor(theView->GetNearestWidget(nsnull));
  
  // This gets uses the first view with a widget
  if (coordType == eRenderingViewCoordinates) {
    if (returnView) {
      // Now adjust the view offset for this view.
      withinViewOffset += theView->GetOffsetTo(returnView);
      
      // Account for the view's origin not lining up with the widget's
      // (bug 190290)
      withinViewOffset += returnView->GetPosition() -
                          returnView->GetBounds().TopLeft();
      viewOffset = withinViewOffset;

      if (outRelativeView)
        *outRelativeView = returnView;
    }
  }
  else {
    // window-relative coordinates. Done for us by the view.
    withinViewOffset += theView->GetOffsetTo(nsnull);
    viewOffset = withinViewOffset;

    // Get the relative view for top level window coordinates
    if (outRelativeView && coordType == eTopLevelWindowCoordinates) {
      nsCOMPtr<nsIPresShell> presShell = do_QueryReferent(mPresShell);
      if (presShell) {
        nsIViewManager* vm = presShell->GetViewManager();
        if (vm) {
          vm->GetRootView(*outRelativeView);
        }
      }
    }
  }

  *outRenderingView = returnView;
}

nsresult nsCaret::CheckCaretDrawingState() 
{
  // If the caret's drawn when it shouldn't be, erase it.
  if (mDrawn && (!mVisible || !MustDrawCaret(PR_TRUE)))
    EraseCaret();
  return NS_OK;
}

/*-----------------------------------------------------------------------------

  MustDrawCaret
  
  Find out if we need to do any caret drawing. This returns true if
  either:
  a) The caret has been drawn, and we need to erase it.
  b) The caret is not drawn, and the selection is collapsed.
  c) The caret is not hidden due to open XUL popups
     (see IsMenuPopupHidingCaret()).
  
----------------------------------------------------------------------------- */
PRBool nsCaret::MustDrawCaret(PRBool aIgnoreDrawnState)
{
  nsCOMPtr<nsIPresShell> presShell = do_QueryReferent(mPresShell);
  if (presShell) {
    PRBool isPaintingSuppressed;
    presShell->IsPaintingSuppressed(&isPaintingSuppressed);
    if (isPaintingSuppressed)
      return PR_FALSE;
  }

  if (!aIgnoreDrawnState && mDrawn)
    return PR_TRUE;

  nsCOMPtr<nsISelection> domSelection = do_QueryReferent(mDomSelectionWeak);
  if (!domSelection)
    return PR_FALSE;
  PRBool isCollapsed;

  if (NS_FAILED(domSelection->GetIsCollapsed(&isCollapsed)))
    return PR_FALSE;

  if (mShowDuringSelection)
    return PR_TRUE;      // show the caret even in selections

  if (IsMenuPopupHidingCaret())
    return PR_FALSE;

  return isCollapsed;
}

PRBool nsCaret::IsMenuPopupHidingCaret()
{
  // Check if there are open popups.
  nsXULPopupManager *popMgr = nsXULPopupManager::GetInstance();
  nsTArray<nsIFrame*> popups = popMgr->GetVisiblePopups();

  if (popups.Length() == 0)
    return PR_FALSE; // No popups, so caret can't be hidden by them.

  // Get the selection focus content, that's where the caret would 
  // go if it was drawn.
  nsCOMPtr<nsIDOMNode> node;
  nsCOMPtr<nsISelection> domSelection = do_QueryReferent(mDomSelectionWeak);
  if (!domSelection)
    return PR_TRUE; // No selection/caret to draw.
  domSelection->GetFocusNode(getter_AddRefs(node));
  if (!node)
    return PR_TRUE; // No selection/caret to draw.
  nsCOMPtr<nsIContent> caretContent = do_QueryInterface(node);
  if (!caretContent)
    return PR_TRUE; // No selection/caret to draw.

  // If there's a menu popup open before the popup with
  // the caret, don't show the caret.
  for (PRUint32 i=0; i<popups.Length(); i++) {
    nsMenuPopupFrame* popupFrame = static_cast<nsMenuPopupFrame*>(popups[i]);
    nsIContent* popupContent = popupFrame->GetContent();

    if (nsContentUtils::ContentIsDescendantOf(caretContent, popupContent)) {
      // The caret is in this popup. There were no menu popups before this
      // popup, so don't hide the caret.
      return PR_FALSE;
    }

    if (popupFrame->PopupType() == ePopupTypeMenu && !popupFrame->IsContextMenu()) {
      // This is an open menu popup. It does not contain the caret (else we'd
      // have returned above). Even if the caret is in a subsequent popup,
      // or another document/frame, it should be hidden.
      return PR_TRUE;
    }
  }

  // There are no open menu popups, no need to hide the caret.
  return PR_FALSE;
}

/*-----------------------------------------------------------------------------

  DrawCaret
    
----------------------------------------------------------------------------- */

void nsCaret::DrawCaret(PRBool aInvalidate)
{
  // do we need to draw the caret at all?
  if (!MustDrawCaret(PR_FALSE))
    return;
  
  nsCOMPtr<nsIDOMNode> node;
  PRInt32 offset;
  nsFrameSelection::HINT hint;
  PRUint8 bidiLevel;

  if (!mDrawn)
  {
    nsCOMPtr<nsISelection> domSelection = do_QueryReferent(mDomSelectionWeak);
    nsCOMPtr<nsISelectionPrivate> privateSelection(do_QueryInterface(domSelection));
    if (!privateSelection) return;
    
    PRBool isCollapsed = PR_FALSE;
    domSelection->GetIsCollapsed(&isCollapsed);
    if (!mShowDuringSelection && !isCollapsed)
      return;

    PRBool hintRight;
    privateSelection->GetInterlinePosition(&hintRight);//translate hint.
    hint = hintRight ? nsFrameSelection::HINTRIGHT : nsFrameSelection::HINTLEFT;

    // get the node and offset, which is where we want the caret to draw
    domSelection->GetFocusNode(getter_AddRefs(node));
    if (!node)
      return;
    
    if (NS_FAILED(domSelection->GetFocusOffset(&offset)))
      return;

    nsCOMPtr<nsFrameSelection> frameSelection = GetFrameSelection();
    if (!frameSelection)
      return;
    bidiLevel = frameSelection->GetCaretBidiLevel();
  }
  else
  {
    if (!mLastContent)
    {
      mDrawn = PR_FALSE;
      return;
    }
    if (!mLastContent->IsInDoc())
    {
      mLastContent = nsnull;
      mDrawn = PR_FALSE;
      return;
    }
    node = do_QueryInterface(mLastContent);
    offset = mLastContentOffset;
    hint = mLastHint;
    bidiLevel = mLastBidiLevel;
  }

  DrawAtPositionWithHint(node, offset, hint, bidiLevel, aInvalidate);
  ToggleDrawnStatus();
}

nsresult nsCaret::UpdateCaretRects(nsIFrame* aFrame, PRInt32 aFrameOffset)
{
  NS_ASSERTION(aFrame, "Should have a frame here");

  nsRect frameRect = aFrame->GetRect();
  frameRect.x = 0;
  frameRect.y = 0;

  nsCOMPtr<nsIPresShell> presShell = do_QueryReferent(mPresShell);
  if (!presShell) return NS_ERROR_FAILURE;

  nsPresContext *presContext = presShell->GetPresContext();

  // if we got a zero-height frame, it's probably a BR frame at the end of a non-empty line
  // (see BRFrame::Reflow). In that case, figure out a height. We have to do this
  // after we've got an RC.
  if (frameRect.height == 0)
  {
    nsCOMPtr<nsIFontMetrics> fm;
    nsLayoutUtils::GetFontMetricsForFrame(aFrame, getter_AddRefs(fm));

    if (fm)
    {
      nscoord ascent, descent;
      fm->GetMaxAscent(ascent);
      fm->GetMaxDescent(descent);
      frameRect.height = ascent + descent;
      frameRect.y -= ascent; // BR frames sit on the baseline of the text, so we need to subtract
      // the ascent to account for the frame height.
    }
  }

  mCaretRect = frameRect;
  nsCOMPtr<nsISelection> domSelection = do_QueryReferent(mDomSelectionWeak);
  nsCOMPtr<nsISelectionPrivate> privateSelection = do_QueryInterface(domSelection);

  nsPoint framePos;

  // if cache in selection is available, apply it, else refresh it
  nsresult rv = privateSelection->GetCachedFrameOffset(aFrame, aFrameOffset,
                                                       framePos);
  if (NS_FAILED(rv))
  {
    mCaretRect.Empty();
    return rv;
  }

  mCaretRect += framePos;
  Metrics metrics = ComputeMetrics(aFrame, aFrameOffset);
  mCaretRect.width = metrics.mCaretWidth;

  // Clamp our position to be within our scroll frame. If we don't, then it
  // clips us, and we don't appear at all. See bug 335560.
  nsIFrame *scrollFrame =
    nsLayoutUtils::GetClosestFrameOfType(aFrame, nsGkAtoms::scrollFrame);
  if (scrollFrame)
  {
    // First, use the scrollFrame to get at the scrollable view that we're in.
    nsIScrollableFrame *scrollable;
    CallQueryInterface(scrollFrame, &scrollable);
    nsIScrollableView *scrollView = scrollable->GetScrollableView();
    nsIView *view;
    scrollView->GetScrolledView(view);

    // Compute the caret's coordinates in the enclosing view's coordinate
    // space. To do so, we need to correct for both the original frame's
    // offset from the scrollframe, and the scrollable view's offset from the
    // scrolled frame's view.
    nsPoint toScroll = aFrame->GetOffsetTo(scrollFrame) -
      view->GetOffsetTo(scrollFrame->GetView());
    nsRect caretInScroll = mCaretRect + toScroll;

    // Now see if thet caret extends beyond the view's bounds. If it does,
    // then snap it back, put it as close to the edge as it can.
    nscoord overflow = caretInScroll.XMost() - view->GetBounds().width;
    if (overflow > 0)
      mCaretRect.x -= overflow;
  }

  // on RTL frames the right edge of mCaretRect must be equal to framePos
  const nsStyleVisibility* vis = aFrame->GetStyleVisibility();
  if (NS_STYLE_DIRECTION_RTL == vis->mDirection)
    mCaretRect.x -= mCaretRect.width;

  return UpdateHookRect(presContext, metrics);
}

nsresult nsCaret::UpdateHookRect(nsPresContext* aPresContext,
                                 const Metrics& aMetrics)
{
  mHookRect.Empty();

#ifdef IBMBIDI
  // Simon -- make a hook to draw to the left or right of the caret to show keyboard language direction
  PRBool bidiEnabled;
  PRBool isCaretRTL=PR_FALSE;
  nsIBidiKeyboard* bidiKeyboard = nsContentUtils::GetBidiKeyboard();
  if (!bidiKeyboard || NS_FAILED(bidiKeyboard->IsLangRTL(&isCaretRTL)))
    // if bidiKeyboard->IsLangRTL() failed, there is no way to tell the
    // keyboard direction, or the user has no right-to-left keyboard
    // installed, so we  never draw the hook.
    return NS_OK;
  if (isCaretRTL)
  {
    bidiEnabled = PR_TRUE;
    aPresContext->SetBidiEnabled();
  }
  else
    bidiEnabled = aPresContext->BidiEnabled();
  if (bidiEnabled)
  {
    if (isCaretRTL != mKeyboardRTL)
    {
      /* if the caret bidi level and the keyboard language direction are not in
       * synch, the keyboard language must have been changed by the
       * user, and if the caret is in a boundary condition (between left-to-right and
       * right-to-left characters) it may have to change position to
       * reflect the location in which the next character typed will
       * appear. We will call |SelectionLanguageChange| and exit
       * without drawing the caret in the old position.
       */ 
      mKeyboardRTL = isCaretRTL;
      nsCOMPtr<nsISelection> domSelection = do_QueryReferent(mDomSelectionWeak);
      if (domSelection)
      {
        if (NS_SUCCEEDED(domSelection->SelectionLanguageChange(mKeyboardRTL)))
        {
          return NS_ERROR_FAILURE;
        }
      }
    }
    // If keyboard language is RTL, draw the hook on the left; if LTR, to the right
    // The height of the hook rectangle is the same as the width of the caret
    // rectangle.
    nscoord bidiIndicatorSize = aMetrics.mBidiIndicatorSize;
    mHookRect.SetRect(mCaretRect.x + ((isCaretRTL) ?
                      bidiIndicatorSize * -1 :
                      mCaretRect.width),
                      mCaretRect.y + bidiIndicatorSize,
                      bidiIndicatorSize,
                      mCaretRect.width);
  }
#endif //IBMBIDI

  return NS_OK;
}

// static
void nsCaret::InvalidateRects(const nsRect &aRect, const nsRect &aHook,
                              nsIFrame *aFrame)
{
  NS_ASSERTION(aFrame, "Must have a frame to invalidate");
  nsRect rect;
  rect.UnionRect(aRect, aHook);
  aFrame->Invalidate(rect, PR_FALSE);
}

//-----------------------------------------------------------------------------
/* static */
void nsCaret::CaretBlinkCallback(nsITimer *aTimer, void *aClosure)
{
  nsCaret   *theCaret = reinterpret_cast<nsCaret*>(aClosure);
  if (!theCaret) return;
  
  theCaret->DrawCaret(PR_TRUE);
}


//-----------------------------------------------------------------------------
already_AddRefed<nsFrameSelection>
nsCaret::GetFrameSelection()
{
  nsCOMPtr<nsISelectionPrivate> privateSelection(do_QueryReferent(mDomSelectionWeak));
  if (!privateSelection)
    return nsnull;
  nsFrameSelection* frameSelection = nsnull;
  privateSelection->GetFrameSelection(&frameSelection);
  return frameSelection;
}

void
nsCaret::SetIgnoreUserModify(PRBool aIgnoreUserModify)
{
  if (!aIgnoreUserModify && mIgnoreUserModify && mDrawn) {
    // We're turning off mIgnoreUserModify. If the caret's drawn
    // in a read-only node we must erase it, else the next call
    // to DrawCaret() won't erase the old caret, due to the new
    // mIgnoreUserModify value.
    nsIFrame *frame = GetCaretFrame();
    if (frame) {
      const nsStyleUserInterface* userinterface = frame->GetStyleUserInterface();
      if (userinterface->mUserModify == NS_STYLE_USER_MODIFY_READ_ONLY) {
        StopBlinking();
      }
    }
  }
  mIgnoreUserModify = aIgnoreUserModify;
}

//-----------------------------------------------------------------------------
nsresult NS_NewCaret(nsICaret** aInstancePtrResult)
{
  NS_PRECONDITION(aInstancePtrResult, "null ptr");
  
  nsCaret* caret = new nsCaret();
  if (nsnull == caret)
      return NS_ERROR_OUT_OF_MEMORY;
      
  return caret->QueryInterface(NS_GET_IID(nsICaret), (void**) aInstancePtrResult);
}