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 (5350524bb654)

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
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set shiftwidth=2 tabstop=8 autoindent cindent expandtab: */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "TextOverflow.h"
#include <algorithm>

// Please maintain alphabetical order below
#include "nsBlockFrame.h"
#include "nsCaret.h"
#include "nsContentUtils.h"
#include "nsCSSAnonBoxes.h"
#include "nsFontMetrics.h"
#include "nsGfxScrollFrame.h"
#include "nsIScrollableFrame.h"
#include "nsLayoutUtils.h"
#include "nsPresContext.h"
#include "nsRect.h"
#include "nsRenderingContext.h"
#include "nsTextFrame.h"
#include "nsIFrameInlines.h"
#include "mozilla/ArrayUtils.h"
#include "mozilla/Likely.h"
#include "nsISelection.h"

namespace mozilla {
namespace css {

class LazyReferenceRenderingDrawTargetGetterFromFrame final :
    public gfxFontGroup::LazyReferenceDrawTargetGetter {
public:
  typedef mozilla::gfx::DrawTarget DrawTarget;

  explicit LazyReferenceRenderingDrawTargetGetterFromFrame(nsIFrame* aFrame)
    : mFrame(aFrame) {}
  virtual already_AddRefed<DrawTarget> GetRefDrawTarget() override
  {
    RefPtr<gfxContext> ctx =
      mFrame->PresContext()->PresShell()->CreateReferenceRenderingContext();
    RefPtr<DrawTarget> dt = ctx->GetDrawTarget();
    return dt.forget();
  }
private:
  nsIFrame* mFrame;
};

static gfxTextRun*
GetEllipsisTextRun(nsIFrame* aFrame)
{
  RefPtr<nsFontMetrics> fm =
    nsLayoutUtils::GetInflatedFontMetricsForFrame(aFrame);
  LazyReferenceRenderingDrawTargetGetterFromFrame lazyRefDrawTargetGetter(aFrame);
  return fm->GetThebesFontGroup()->GetEllipsisTextRun(
    aFrame->PresContext()->AppUnitsPerDevPixel(),
    nsLayoutUtils::GetTextRunOrientFlagsForStyle(aFrame->StyleContext()),
    lazyRefDrawTargetGetter);
}

static nsIFrame*
GetSelfOrNearestBlock(nsIFrame* aFrame)
{
  return nsLayoutUtils::GetAsBlock(aFrame) ? aFrame :
         nsLayoutUtils::FindNearestBlockAncestor(aFrame);
}

// Return true if the frame is an atomic inline-level element.
// It's not supposed to be called for block frames since we never
// process block descendants for text-overflow.
static bool
IsAtomicElement(nsIFrame* aFrame, const nsIAtom* aFrameType)
{
  NS_PRECONDITION(!nsLayoutUtils::GetAsBlock(aFrame) ||
                  !aFrame->IsBlockOutside(),
                  "unexpected block frame");
  NS_PRECONDITION(aFrameType != nsGkAtoms::placeholderFrame,
                  "unexpected placeholder frame");
  return !aFrame->IsFrameOfType(nsIFrame::eLineParticipant);
}

static bool
IsFullyClipped(nsTextFrame* aFrame, nscoord aLeft, nscoord aRight,
               nscoord* aSnappedLeft, nscoord* aSnappedRight)
{
  *aSnappedLeft = aLeft;
  *aSnappedRight = aRight;
  if (aLeft <= 0 && aRight <= 0) {
    return false;
  }
  return !aFrame->MeasureCharClippedText(aLeft, aRight,
                                         aSnappedLeft, aSnappedRight);
}

static bool
IsInlineAxisOverflowVisible(nsIFrame* aFrame)
{
  NS_PRECONDITION(nsLayoutUtils::GetAsBlock(aFrame) != nullptr,
                  "expected a block frame");

  nsIFrame* f = aFrame;
  while (f && f->StyleContext()->GetPseudo() &&
         f->GetType() != nsGkAtoms::scrollFrame) {
    f = f->GetParent();
  }
  if (!f) {
    return true;
  }
  auto overflow = aFrame->GetWritingMode().IsVertical() ?
    f->StyleDisplay()->mOverflowY : f->StyleDisplay()->mOverflowX;
  return overflow == NS_STYLE_OVERFLOW_VISIBLE;
}

static void
ClipMarker(const nsRect&                          aContentArea,
           const nsRect&                          aMarkerRect,
           DisplayListClipState::AutoSaveRestore& aClipState)
{
  nscoord rightOverflow = aMarkerRect.XMost() - aContentArea.XMost();
  nsRect markerRect = aMarkerRect;
  if (rightOverflow > 0) {
    // Marker overflows on the right side (content width < marker width).
    markerRect.width -= rightOverflow;
    aClipState.ClipContentDescendants(markerRect);
  } else {
    nscoord leftOverflow = aContentArea.x - aMarkerRect.x;
    if (leftOverflow > 0) {
      // Marker overflows on the left side
      markerRect.width -= leftOverflow;
      markerRect.x += leftOverflow;
      aClipState.ClipContentDescendants(markerRect);
    }
  }
}

static void
InflateIStart(WritingMode aWM, LogicalRect* aRect, nscoord aDelta)
{
  nscoord iend = aRect->IEnd(aWM);
  aRect->IStart(aWM) -= aDelta;
  aRect->ISize(aWM) = std::max(iend - aRect->IStart(aWM), 0);
}

static void
InflateIEnd(WritingMode aWM, LogicalRect* aRect, nscoord aDelta)
{
  aRect->ISize(aWM) = std::max(aRect->ISize(aWM) + aDelta, 0);
}

static bool
IsFrameDescendantOfAny(nsIFrame* aChild,
                       const TextOverflow::FrameHashtable& aSetOfFrames,
                       nsIFrame* aCommonAncestor)
{
  for (nsIFrame* f = aChild; f && f != aCommonAncestor;
       f = nsLayoutUtils::GetCrossDocParentFrame(f)) {
    if (aSetOfFrames.GetEntry(f)) {
      return true;
    }
  }
  return false;
}

class nsDisplayTextOverflowMarker : public nsDisplayItem
{
public:
  nsDisplayTextOverflowMarker(nsDisplayListBuilder* aBuilder, nsIFrame* aFrame,
                              const nsRect& aRect, nscoord aAscent,
                              const nsStyleTextOverflowSide* aStyle,
                              uint32_t aIndex)
    : nsDisplayItem(aBuilder, aFrame), mRect(aRect),
      mStyle(aStyle), mAscent(aAscent), mIndex(aIndex) {
    MOZ_COUNT_CTOR(nsDisplayTextOverflowMarker);
  }
#ifdef NS_BUILD_REFCNT_LOGGING
  virtual ~nsDisplayTextOverflowMarker() {
    MOZ_COUNT_DTOR(nsDisplayTextOverflowMarker);
  }
#endif
  virtual nsRect GetBounds(nsDisplayListBuilder* aBuilder,
                           bool* aSnap) override {
    *aSnap = false;
    nsRect shadowRect =
      nsLayoutUtils::GetTextShadowRectsUnion(mRect, mFrame);
    return mRect.Union(shadowRect);
  }

  virtual nsRect GetComponentAlphaBounds(nsDisplayListBuilder* aBuilder) override
  {
    if (gfxPlatform::GetPlatform()->RespectsFontStyleSmoothing()) {
      // On OS X, web authors can turn off subpixel text rendering using the
      // CSS property -moz-osx-font-smoothing. If they do that, we don't need
      // to use component alpha layers for the affected text.
      if (mFrame->StyleFont()->mFont.smoothing == NS_FONT_SMOOTHING_GRAYSCALE) {
        return nsRect();
      }
    }
    bool snap;
    return GetBounds(aBuilder, &snap);
  }

  virtual void Paint(nsDisplayListBuilder* aBuilder,
                     nsRenderingContext* aCtx) override;

  virtual uint32_t GetPerFrameKey() override { 
    return (mIndex << nsDisplayItem::TYPE_BITS) | nsDisplayItem::GetPerFrameKey(); 
  }
  void PaintTextToContext(nsRenderingContext* aCtx,
                          nsPoint aOffsetFromRect);
  NS_DISPLAY_DECL_NAME("TextOverflow", TYPE_TEXT_OVERFLOW)
private:
  nsRect          mRect;   // in reference frame coordinates
  const nsStyleTextOverflowSide* mStyle;
  nscoord         mAscent; // baseline for the marker text in mRect
  uint32_t        mIndex;
};

static void
PaintTextShadowCallback(nsRenderingContext* aCtx,
                        nsPoint aShadowOffset,
                        const nscolor& aShadowColor,
                        void* aData)
{
  reinterpret_cast<nsDisplayTextOverflowMarker*>(aData)->
           PaintTextToContext(aCtx, aShadowOffset);
}

void
nsDisplayTextOverflowMarker::Paint(nsDisplayListBuilder* aBuilder,
                                   nsRenderingContext*   aCtx)
{
  nscolor foregroundColor = nsLayoutUtils::
    GetColor(mFrame, eCSSProperty__webkit_text_fill_color);

  // Paint the text-shadows for the overflow marker
  nsLayoutUtils::PaintTextShadow(mFrame, aCtx, mRect, mVisibleRect,
                                 foregroundColor, PaintTextShadowCallback,
                                 (void*)this);
  aCtx->ThebesContext()->SetColor(gfx::Color::FromABGR(foregroundColor));
  PaintTextToContext(aCtx, nsPoint(0, 0));
}

void
nsDisplayTextOverflowMarker::PaintTextToContext(nsRenderingContext* aCtx,
                                                nsPoint aOffsetFromRect)
{
  WritingMode wm = mFrame->GetWritingMode();
  nsPoint pt(mRect.x, mRect.y);
  if (wm.IsVertical()) {
    if (wm.IsVerticalLR()) {
      pt.x = NSToCoordFloor(nsLayoutUtils::GetSnappedBaselineX(
        mFrame, aCtx->ThebesContext(), pt.x, mAscent));
    } else {
      pt.x = NSToCoordFloor(nsLayoutUtils::GetSnappedBaselineX(
        mFrame, aCtx->ThebesContext(), pt.x + mRect.width, -mAscent));
    }
  } else {
    pt.y = NSToCoordFloor(nsLayoutUtils::GetSnappedBaselineY(
      mFrame, aCtx->ThebesContext(), pt.y, mAscent));
  }
  pt += aOffsetFromRect;

  if (mStyle->mType == NS_STYLE_TEXT_OVERFLOW_ELLIPSIS) {
    gfxTextRun* textRun = GetEllipsisTextRun(mFrame);
    if (textRun) {
      NS_ASSERTION(!textRun->IsRightToLeft(),
                   "Ellipsis textruns should always be LTR!");
      gfxPoint gfxPt(pt.x, pt.y);
      textRun->Draw(gfxTextRun::Range(textRun), gfxPt,
                    gfxTextRun::DrawParams(aCtx->ThebesContext()));
    }
  } else {
    RefPtr<nsFontMetrics> fm =
      nsLayoutUtils::GetInflatedFontMetricsForFrame(mFrame);
    nsLayoutUtils::DrawString(mFrame, *fm, aCtx, mStyle->mString.get(),
                              mStyle->mString.Length(), pt);
  }
}

TextOverflow::TextOverflow(nsDisplayListBuilder* aBuilder,
                           nsIFrame* aBlockFrame)
  : mContentArea(aBlockFrame->GetWritingMode(),
                 aBlockFrame->GetContentRectRelativeToSelf(),
                 aBlockFrame->GetSize())
  , mBuilder(aBuilder)
  , mBlock(aBlockFrame)
  , mScrollableFrame(nsLayoutUtils::GetScrollableFrameFor(aBlockFrame))
  , mBlockSize(aBlockFrame->GetSize())
  , mBlockWM(aBlockFrame->GetWritingMode())
  , mAdjustForPixelSnapping(false)
{
#ifdef MOZ_XUL
  if (!mScrollableFrame) {
    nsIAtom* pseudoType = aBlockFrame->StyleContext()->GetPseudo();
    if (pseudoType == nsCSSAnonBoxes::mozXULAnonymousBlock) {
      mScrollableFrame =
        nsLayoutUtils::GetScrollableFrameFor(aBlockFrame->GetParent());
      // nsXULScrollFrame::ClampAndSetBounds rounds to nearest pixels
      // for RTL blocks (also for overflow:hidden), so we need to move
      // the edges 1px outward in ExamineLineFrames to avoid triggering
      // a text-overflow marker in this case.
      mAdjustForPixelSnapping = !mBlockWM.IsBidiLTR();
    }
  }
#endif
  mCanHaveInlineAxisScrollbar = false;
  if (mScrollableFrame) {
    auto scrollbarStyle = mBlockWM.IsVertical() ?
      mScrollableFrame->GetScrollbarStyles().mVertical :
      mScrollableFrame->GetScrollbarStyles().mHorizontal;
    mCanHaveInlineAxisScrollbar = scrollbarStyle != NS_STYLE_OVERFLOW_HIDDEN;
    if (!mAdjustForPixelSnapping) {
      // Scrolling to the end position can leave some text still overflowing due
      // to pixel snapping behaviour in our scrolling code.
      mAdjustForPixelSnapping = mCanHaveInlineAxisScrollbar;
    }
    // Use a null containerSize to convert a vector from logical to physical.
    const nsSize nullContainerSize;
    mContentArea.MoveBy(mBlockWM,
                        LogicalPoint(mBlockWM,
                                     mScrollableFrame->GetScrollPosition(),
                                     nullContainerSize));
    nsIFrame* scrollFrame = do_QueryFrame(mScrollableFrame);
    scrollFrame->AddStateBits(NS_SCROLLFRAME_INVALIDATE_CONTENTS_ON_SCROLL);
  }
  uint8_t direction = aBlockFrame->StyleVisibility()->mDirection;
  const nsStyleTextReset* style = aBlockFrame->StyleTextReset();
  if (mBlockWM.IsBidiLTR()) {
    mIStart.Init(style->mTextOverflow.GetLeft(direction));
    mIEnd.Init(style->mTextOverflow.GetRight(direction));
  } else {
    mIStart.Init(style->mTextOverflow.GetRight(direction));
    mIEnd.Init(style->mTextOverflow.GetLeft(direction));
  }
  // The left/right marker string is setup in ExamineLineFrames when a line
  // has overflow on that side.
}

/* static */ TextOverflow*
TextOverflow::WillProcessLines(nsDisplayListBuilder*   aBuilder,
                               nsIFrame*               aBlockFrame)
{
  if (!CanHaveTextOverflow(aBuilder, aBlockFrame)) {
    return nullptr;
  }
  nsIScrollableFrame* scrollableFrame = nsLayoutUtils::GetScrollableFrameFor(aBlockFrame);
  if (scrollableFrame && scrollableFrame->IsTransformingByAPZ()) {
    // If the APZ is actively scrolling this, don't bother with markers.
    return nullptr;
  }
  return new TextOverflow(aBuilder, aBlockFrame);
}

void
TextOverflow::ExamineFrameSubtree(nsIFrame*       aFrame,
                                  const LogicalRect& aContentArea,
                                  const LogicalRect& aInsideMarkersArea,
                                  FrameHashtable* aFramesToHide,
                                  AlignmentEdges* aAlignmentEdges,
                                  bool*           aFoundVisibleTextOrAtomic,
                                  InnerClipEdges* aClippedMarkerEdges)
{
  const nsIAtom* frameType = aFrame->GetType();
  if (frameType == nsGkAtoms::brFrame ||
      frameType == nsGkAtoms::placeholderFrame) {
    return;
  }
  const bool isAtomic = IsAtomicElement(aFrame, frameType);
  if (aFrame->StyleVisibility()->IsVisible()) {
    LogicalRect childRect =
      GetLogicalScrollableOverflowRectRelativeToBlock(aFrame);
    bool overflowIStart =
      childRect.IStart(mBlockWM) < aContentArea.IStart(mBlockWM);
    bool overflowIEnd =
      childRect.IEnd(mBlockWM) > aContentArea.IEnd(mBlockWM);
    if (overflowIStart) {
      mIStart.mHasOverflow = true;
    }
    if (overflowIEnd) {
      mIEnd.mHasOverflow = true;
    }
    if (isAtomic && ((mIStart.mActive && overflowIStart) ||
                     (mIEnd.mActive && overflowIEnd))) {
      aFramesToHide->PutEntry(aFrame);
    } else if (isAtomic || frameType == nsGkAtoms::textFrame) {
      AnalyzeMarkerEdges(aFrame, frameType, aInsideMarkersArea,
                         aFramesToHide, aAlignmentEdges,
                         aFoundVisibleTextOrAtomic,
                         aClippedMarkerEdges);
    }
  }
  if (isAtomic) {
    return;
  }

  for (nsIFrame* child : aFrame->PrincipalChildList()) {
    ExamineFrameSubtree(child, aContentArea, aInsideMarkersArea,
                        aFramesToHide, aAlignmentEdges,
                        aFoundVisibleTextOrAtomic,
                        aClippedMarkerEdges);
  }
}

void
TextOverflow::AnalyzeMarkerEdges(nsIFrame*       aFrame,
                                 const nsIAtom*  aFrameType,
                                 const LogicalRect& aInsideMarkersArea,
                                 FrameHashtable* aFramesToHide,
                                 AlignmentEdges* aAlignmentEdges,
                                 bool*           aFoundVisibleTextOrAtomic,
                                 InnerClipEdges* aClippedMarkerEdges)
{
  LogicalRect borderRect(mBlockWM,
                         nsRect(aFrame->GetOffsetTo(mBlock),
                                aFrame->GetSize()),
                         mBlockSize);
  nscoord istartOverlap = std::max(
    aInsideMarkersArea.IStart(mBlockWM) - borderRect.IStart(mBlockWM), 0);
  nscoord iendOverlap = std::max(
    borderRect.IEnd(mBlockWM) - aInsideMarkersArea.IEnd(mBlockWM), 0);
  bool insideIStartEdge =
    aInsideMarkersArea.IStart(mBlockWM) <= borderRect.IEnd(mBlockWM);
  bool insideIEndEdge =
    borderRect.IStart(mBlockWM) <= aInsideMarkersArea.IEnd(mBlockWM);

  if (istartOverlap > 0) {
    aClippedMarkerEdges->AccumulateIStart(mBlockWM, borderRect);
    if (!mIStart.mActive) {
      istartOverlap = 0;
    }
  }
  if (iendOverlap > 0) {
    aClippedMarkerEdges->AccumulateIEnd(mBlockWM, borderRect);
    if (!mIEnd.mActive) {
      iendOverlap = 0;
    }
  }

  if ((istartOverlap > 0 && insideIStartEdge) ||
      (iendOverlap > 0 && insideIEndEdge)) {
    if (aFrameType == nsGkAtoms::textFrame) {
      if (aInsideMarkersArea.IStart(mBlockWM) <
          aInsideMarkersArea.IEnd(mBlockWM)) {
        // a clipped text frame and there is some room between the markers
        nscoord snappedIStart, snappedIEnd;
        auto textFrame = static_cast<nsTextFrame*>(aFrame);
        bool isFullyClipped = mBlockWM.IsBidiLTR() ?
          IsFullyClipped(textFrame, istartOverlap, iendOverlap,
                         &snappedIStart, &snappedIEnd) :
          IsFullyClipped(textFrame, iendOverlap, istartOverlap,
                         &snappedIEnd, &snappedIStart);
        if (!isFullyClipped) {
          LogicalRect snappedRect = borderRect;
          if (istartOverlap > 0) {
            snappedRect.IStart(mBlockWM) += snappedIStart;
            snappedRect.ISize(mBlockWM) -= snappedIStart;
          }
          if (iendOverlap > 0) {
            snappedRect.ISize(mBlockWM) -= snappedIEnd;
          }
          aAlignmentEdges->Accumulate(mBlockWM, snappedRect);
          *aFoundVisibleTextOrAtomic = true;
        }
      }
    } else {
      aFramesToHide->PutEntry(aFrame);
    }
  } else if (!insideIStartEdge || !insideIEndEdge) {
    // frame is outside
    if (IsAtomicElement(aFrame, aFrameType)) {
      aFramesToHide->PutEntry(aFrame);
    }
  } else {
    // frame is inside
    aAlignmentEdges->Accumulate(mBlockWM, borderRect);
    *aFoundVisibleTextOrAtomic = true;
  }
}

void
TextOverflow::ExamineLineFrames(nsLineBox*      aLine,
                                FrameHashtable* aFramesToHide,
                                AlignmentEdges* aAlignmentEdges)
{
  // No ellipsing for 'clip' style.
  bool suppressIStart = mIStart.mStyle->mType == NS_STYLE_TEXT_OVERFLOW_CLIP;
  bool suppressIEnd = mIEnd.mStyle->mType == NS_STYLE_TEXT_OVERFLOW_CLIP;
  if (mCanHaveInlineAxisScrollbar) {
    LogicalPoint pos(mBlockWM, mScrollableFrame->GetScrollPosition(),
                     mBlockSize);
    LogicalRect scrollRange(mBlockWM, mScrollableFrame->GetScrollRange(),
                            mBlockSize);
    // No ellipsing when nothing to scroll to on that side (this includes
    // overflow:auto that doesn't trigger a horizontal scrollbar).
    if (pos.I(mBlockWM) <= scrollRange.IStart(mBlockWM)) {
      suppressIStart = true;
    }
    if (pos.I(mBlockWM) >= scrollRange.IEnd(mBlockWM)) {
      suppressIEnd = true;
    }
  }

  LogicalRect contentArea = mContentArea;
  const nscoord scrollAdjust = mAdjustForPixelSnapping ?
    mBlock->PresContext()->AppUnitsPerDevPixel() : 0;
  InflateIStart(mBlockWM, &contentArea, scrollAdjust);
  InflateIEnd(mBlockWM, &contentArea, scrollAdjust);
  LogicalRect lineRect(mBlockWM, aLine->GetScrollableOverflowArea(),
                       mBlockSize);
  const bool istartOverflow =
    !suppressIStart && lineRect.IStart(mBlockWM) < contentArea.IStart(mBlockWM);
  const bool iendOverflow =
    !suppressIEnd && lineRect.IEnd(mBlockWM) > contentArea.IEnd(mBlockWM);
  if (!istartOverflow && !iendOverflow) {
    // The line does not overflow on a side we should ellipsize.
    return;
  }

  int pass = 0;
  bool retryEmptyLine = true;
  bool guessIStart = istartOverflow;
  bool guessIEnd = iendOverflow;
  mIStart.mActive = istartOverflow;
  mIEnd.mActive = iendOverflow;
  bool clippedIStartMarker = false;
  bool clippedIEndMarker = false;
  do {
    // Setup marker strings as needed.
    if (guessIStart) {
      mIStart.SetupString(mBlock);
    }
    if (guessIEnd) {
      mIEnd.SetupString(mBlock);
    }
    
    // If there is insufficient space for both markers then keep the one on the
    // end side per the block's 'direction'.
    nscoord istartMarkerISize = mIStart.mActive ? mIStart.mISize : 0;
    nscoord iendMarkerISize = mIEnd.mActive ? mIEnd.mISize : 0;
    if (istartMarkerISize && iendMarkerISize &&
        istartMarkerISize + iendMarkerISize > contentArea.ISize(mBlockWM)) {
      istartMarkerISize = 0;
    }

    // Calculate the area between the potential markers aligned at the
    // block's edge.
    LogicalRect insideMarkersArea = mContentArea;
    if (guessIStart) {
      InflateIStart(mBlockWM, &insideMarkersArea, -istartMarkerISize);
    }
    if (guessIEnd) {
      InflateIEnd(mBlockWM, &insideMarkersArea, -iendMarkerISize);
    }

    // Analyze the frames on aLine for the overflow situation at the content
    // edges and at the edges of the area between the markers.
    bool foundVisibleTextOrAtomic = false;
    int32_t n = aLine->GetChildCount();
    nsIFrame* child = aLine->mFirstChild;
    InnerClipEdges clippedMarkerEdges;
    for (; n-- > 0; child = child->GetNextSibling()) {
      ExamineFrameSubtree(child, contentArea, insideMarkersArea,
                          aFramesToHide, aAlignmentEdges,
                          &foundVisibleTextOrAtomic,
                          &clippedMarkerEdges);
    }
    if (!foundVisibleTextOrAtomic && retryEmptyLine) {
      aAlignmentEdges->mAssigned = false;
      aFramesToHide->Clear();
      pass = -1;
      if (mIStart.IsNeeded() && mIStart.mActive && !clippedIStartMarker) {
        if (clippedMarkerEdges.mAssignedIStart &&
            clippedMarkerEdges.mIStart > mContentArea.IStart(mBlockWM)) {
          mIStart.mISize =
            clippedMarkerEdges.mIStart - mContentArea.IStart(mBlockWM);
          NS_ASSERTION(mIStart.mISize < mIStart.mIntrinsicISize,
                      "clipping a marker should make it strictly smaller");
          clippedIStartMarker = true;
        } else {
          mIStart.mActive = guessIStart = false;
        }
        continue;
      }
      if (mIEnd.IsNeeded() && mIEnd.mActive && !clippedIEndMarker) {
        if (clippedMarkerEdges.mAssignedIEnd &&
            mContentArea.IEnd(mBlockWM) > clippedMarkerEdges.mIEnd) {
          mIEnd.mISize = mContentArea.IEnd(mBlockWM) - clippedMarkerEdges.mIEnd;
          NS_ASSERTION(mIEnd.mISize < mIEnd.mIntrinsicISize,
                      "clipping a marker should make it strictly smaller");
          clippedIEndMarker = true;
        } else {
          mIEnd.mActive = guessIEnd = false;
        }
        continue;
      }
      // The line simply has no visible content even without markers,
      // so examine the line again without suppressing markers.
      retryEmptyLine = false;
      mIStart.mISize = mIStart.mIntrinsicISize;
      mIStart.mActive = guessIStart = istartOverflow;
      mIEnd.mISize = mIEnd.mIntrinsicISize;
      mIEnd.mActive = guessIEnd = iendOverflow;
      continue;
    }
    if (guessIStart == (mIStart.mActive && mIStart.IsNeeded()) &&
        guessIEnd == (mIEnd.mActive && mIEnd.IsNeeded())) {
      break;
    } else {
      guessIStart = mIStart.mActive && mIStart.IsNeeded();
      guessIEnd = mIEnd.mActive && mIEnd.IsNeeded();
      mIStart.Reset();
      mIEnd.Reset();
      aFramesToHide->Clear();
    }
    NS_ASSERTION(pass == 0, "2nd pass should never guess wrong");
  } while (++pass != 2);
  if (!istartOverflow || !mIStart.mActive) {
    mIStart.Reset();
  }
  if (!iendOverflow || !mIEnd.mActive) {
    mIEnd.Reset();
  }
}

void
TextOverflow::ProcessLine(const nsDisplayListSet& aLists,
                          nsLineBox*              aLine)
{
  NS_ASSERTION(mIStart.mStyle->mType != NS_STYLE_TEXT_OVERFLOW_CLIP ||
               mIEnd.mStyle->mType != NS_STYLE_TEXT_OVERFLOW_CLIP,
               "TextOverflow with 'clip' for both sides");
  mIStart.Reset();
  mIStart.mActive = mIStart.mStyle->mType != NS_STYLE_TEXT_OVERFLOW_CLIP;
  mIEnd.Reset();
  mIEnd.mActive = mIEnd.mStyle->mType != NS_STYLE_TEXT_OVERFLOW_CLIP;

  FrameHashtable framesToHide(64);
  AlignmentEdges alignmentEdges;
  ExamineLineFrames(aLine, &framesToHide, &alignmentEdges);
  bool needIStart = mIStart.IsNeeded();
  bool needIEnd = mIEnd.IsNeeded();
  if (!needIStart && !needIEnd) {
    return;
  }
  NS_ASSERTION(mIStart.mStyle->mType != NS_STYLE_TEXT_OVERFLOW_CLIP ||
               !needIStart, "left marker for 'clip'");
  NS_ASSERTION(mIEnd.mStyle->mType != NS_STYLE_TEXT_OVERFLOW_CLIP ||
               !needIEnd, "right marker for 'clip'");

  // If there is insufficient space for both markers then keep the one on the
  // end side per the block's 'direction'.
  if (needIStart && needIEnd &&
      mIStart.mISize + mIEnd.mISize > mContentArea.ISize(mBlockWM)) {
    needIStart = false;
  }
  LogicalRect insideMarkersArea = mContentArea;
  if (needIStart) {
    InflateIStart(mBlockWM, &insideMarkersArea, -mIStart.mISize);
  }
  if (needIEnd) {
    InflateIEnd(mBlockWM, &insideMarkersArea, -mIEnd.mISize);
  }
  if (!mCanHaveInlineAxisScrollbar && alignmentEdges.mAssigned) {
    LogicalRect alignmentRect(mBlockWM, alignmentEdges.mIStart,
                              insideMarkersArea.BStart(mBlockWM),
                              alignmentEdges.ISize(), 1);
    insideMarkersArea.IntersectRect(insideMarkersArea, alignmentRect);
  }

  // Clip and remove display items as needed at the final marker edges.
  nsDisplayList* lists[] = { aLists.Content(), aLists.PositionedDescendants() };
  for (uint32_t i = 0; i < ArrayLength(lists); ++i) {
    PruneDisplayListContents(lists[i], framesToHide, insideMarkersArea);
  }
  CreateMarkers(aLine, needIStart, needIEnd, insideMarkersArea);
}

void
TextOverflow::PruneDisplayListContents(nsDisplayList* aList,
                                       const FrameHashtable& aFramesToHide,
                                       const LogicalRect& aInsideMarkersArea)
{
  nsDisplayList saved;
  nsDisplayItem* item;
  while ((item = aList->RemoveBottom())) {
    nsIFrame* itemFrame = item->Frame();
    if (IsFrameDescendantOfAny(itemFrame, aFramesToHide, mBlock)) {
      item->~nsDisplayItem();
      continue;
    }

    nsDisplayList* wrapper = item->GetSameCoordinateSystemChildren();
    if (wrapper) {
      if (!itemFrame || GetSelfOrNearestBlock(itemFrame) == mBlock) {
        PruneDisplayListContents(wrapper, aFramesToHide, aInsideMarkersArea);
      }
    }

    nsCharClipDisplayItem* charClip = itemFrame ? 
      nsCharClipDisplayItem::CheckCast(item) : nullptr;
    if (charClip && GetSelfOrNearestBlock(itemFrame) == mBlock) {
      LogicalRect rect =
        GetLogicalScrollableOverflowRectRelativeToBlock(itemFrame);
      if (mIStart.IsNeeded()) {
        nscoord istart =
          aInsideMarkersArea.IStart(mBlockWM) - rect.IStart(mBlockWM);
        if (istart > 0) {
          (mBlockWM.IsBidiLTR() ?
           charClip->mVisIStartEdge : charClip->mVisIEndEdge) = istart;
        }
      }
      if (mIEnd.IsNeeded()) {
        nscoord iend = rect.IEnd(mBlockWM) - aInsideMarkersArea.IEnd(mBlockWM);
        if (iend > 0) {
          (mBlockWM.IsBidiLTR() ?
           charClip->mVisIEndEdge : charClip->mVisIStartEdge) = iend;
        }
      }
    }

    saved.AppendToTop(item);
  }
  aList->AppendToTop(&saved);
}

/* static */ bool
TextOverflow::HasClippedOverflow(nsIFrame* aBlockFrame)
{
  const nsStyleTextReset* style = aBlockFrame->StyleTextReset();
  return style->mTextOverflow.mLeft.mType == NS_STYLE_TEXT_OVERFLOW_CLIP &&
         style->mTextOverflow.mRight.mType == NS_STYLE_TEXT_OVERFLOW_CLIP;
}

/* static */ bool
TextOverflow::CanHaveTextOverflow(nsDisplayListBuilder* aBuilder,
                                  nsIFrame*             aBlockFrame)
{
  // Nothing to do for text-overflow:clip or if 'overflow-x/y:visible' or if
  // we're just building items for event processing or frame visibility.
  if (HasClippedOverflow(aBlockFrame) ||
      IsInlineAxisOverflowVisible(aBlockFrame) ||
      aBuilder->IsForEventDelivery() ||
      aBuilder->IsForFrameVisibility()) {
    return false;
  }

  // Skip ComboboxControlFrame because it would clip the drop-down arrow.
  // Its anon block inherits 'text-overflow' and does what is expected.
  if (aBlockFrame->GetType() == nsGkAtoms::comboboxControlFrame) {
    return false;
  }

  // Inhibit the markers if a descendant content owns the caret.
  RefPtr<nsCaret> caret = aBlockFrame->PresContext()->PresShell()->GetCaret();
  if (caret && caret->IsVisible()) {
    nsCOMPtr<nsISelection> domSelection = caret->GetSelection();
    if (domSelection) {
      nsCOMPtr<nsIDOMNode> node;
      domSelection->GetFocusNode(getter_AddRefs(node));
      nsCOMPtr<nsIContent> content = do_QueryInterface(node);
      if (content && nsContentUtils::ContentIsDescendantOf(content,
                       aBlockFrame->GetContent())) {
        return false;
      }
    }
  }
  return true;
}

void
TextOverflow::CreateMarkers(const nsLineBox* aLine,
                            bool aCreateIStart, bool aCreateIEnd,
                            const mozilla::LogicalRect& aInsideMarkersArea)
{
  if (aCreateIStart) {
    DisplayListClipState::AutoSaveRestore clipState(mBuilder);

    LogicalRect markerLogicalRect(
      mBlockWM, aInsideMarkersArea.IStart(mBlockWM) - mIStart.mIntrinsicISize,
      aLine->BStart(), mIStart.mIntrinsicISize, aLine->BSize());
    nsPoint offset = mBuilder->ToReferenceFrame(mBlock);
    nsRect markerRect =
      markerLogicalRect.GetPhysicalRect(mBlockWM, mBlockSize) + offset;
    ClipMarker(mContentArea.GetPhysicalRect(mBlockWM, mBlockSize) + offset,
               markerRect, clipState);
    nsDisplayItem* marker = new (mBuilder)
      nsDisplayTextOverflowMarker(mBuilder, mBlock, markerRect,
                                  aLine->GetLogicalAscent(), mIStart.mStyle, 0);
    mMarkerList.AppendNewToTop(marker);
  }

  if (aCreateIEnd) {
    DisplayListClipState::AutoSaveRestore clipState(mBuilder);

    LogicalRect markerLogicalRect(
      mBlockWM, aInsideMarkersArea.IEnd(mBlockWM), aLine->BStart(),
      mIEnd.mIntrinsicISize, aLine->BSize());
    nsPoint offset = mBuilder->ToReferenceFrame(mBlock);
    nsRect markerRect =
      markerLogicalRect.GetPhysicalRect(mBlockWM, mBlockSize) + offset;
    ClipMarker(mContentArea.GetPhysicalRect(mBlockWM, mBlockSize) + offset,
               markerRect, clipState);
    nsDisplayItem* marker = new (mBuilder)
      nsDisplayTextOverflowMarker(mBuilder, mBlock, markerRect,
                                  aLine->GetLogicalAscent(), mIEnd.mStyle, 1);
    mMarkerList.AppendNewToTop(marker);
  }
}

void
TextOverflow::Marker::SetupString(nsIFrame* aFrame)
{
  if (mInitialized) {
    return;
  }

  if (mStyle->mType == NS_STYLE_TEXT_OVERFLOW_ELLIPSIS) {
    gfxTextRun* textRun = GetEllipsisTextRun(aFrame);
    if (textRun) {
      mISize = textRun->GetAdvanceWidth();
    } else {
      mISize = 0;
    }
  } else {
    nsRenderingContext rc(
      aFrame->PresContext()->PresShell()->CreateReferenceRenderingContext());
    RefPtr<nsFontMetrics> fm =
      nsLayoutUtils::GetInflatedFontMetricsForFrame(aFrame);
    mISize = nsLayoutUtils::AppUnitWidthOfStringBidi(mStyle->mString, aFrame,
                                                     *fm, rc);
  }
  mIntrinsicISize = mISize;
  mInitialized = true;
}

} // namespace css
} // namespace mozilla