layout/generic/nsImageMap.cpp

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

/* code for HTML client-side image maps */

#include "nsImageMap.h"

#include "mozilla/dom/Element.h"
#include "mozilla/dom/Event.h"  // for nsIDOMEvent::InternalDOMEvent()
#include "mozilla/dom/HTMLAreaElement.h"
#include "mozilla/gfx/PathHelpers.h"
#include "mozilla/UniquePtr.h"
#include "nsString.h"
#include "nsReadableUtils.h"
#include "nsPresContext.h"
#include "nsNameSpaceManager.h"
#include "nsGkAtoms.h"
#include "nsImageFrame.h"
#include "nsCoord.h"
#include "nsIContentInlines.h"
#include "nsIScriptError.h"
#include "nsIStringBundle.h"
#include "nsContentUtils.h"
#include "ImageLayers.h"

#ifdef ACCESSIBILITY
#include "nsAccessibilityService.h"
#endif

using namespace mozilla;
using namespace mozilla::gfx;
using namespace mozilla::dom;

class Area {
 public:
  explicit Area(HTMLAreaElement* aArea);
  virtual ~Area();

  virtual void ParseCoords(const nsAString& aSpec);

  virtual bool IsInside(nscoord x, nscoord y) const = 0;
  virtual void Draw(nsIFrame* aFrame, DrawTarget& aDrawTarget,
                    const ColorPattern& aColor,
                    const StrokeOptions& aStrokeOptions) = 0;
  virtual void GetRect(nsIFrame* aFrame, nsRect& aRect) = 0;

  void HasFocus(bool aHasFocus);

  RefPtr<HTMLAreaElement> mArea;
  UniquePtr<nscoord[]> mCoords;
  int32_t mNumCoords;
  bool mHasFocus;
};

Area::Area(HTMLAreaElement* aArea) : mArea(aArea) {
  MOZ_COUNT_CTOR(Area);
  MOZ_ASSERT(mArea, "How did that happen?");
  mNumCoords = 0;
  mHasFocus = false;
}

Area::~Area() { MOZ_COUNT_DTOR(Area); }

#include <stdlib.h>

inline bool is_space(char c) {
  return (c == ' ' || c == '\f' || c == '\n' || c == '\r' || c == '\t' ||
          c == '\v');
}

static void logMessage(nsIContent* aContent, const nsAString& aCoordsSpec,
                       int32_t aFlags, const char* aMessageName) {
  nsIDocument* doc = aContent->OwnerDoc();

  nsContentUtils::ReportToConsole(
      aFlags, NS_LITERAL_CSTRING("Layout: ImageMap"), doc,
      nsContentUtils::eLAYOUT_PROPERTIES, aMessageName, nullptr, /* params */
      0, /* params length */
      nullptr,
      PromiseFlatString(NS_LITERAL_STRING("coords=\"") + aCoordsSpec +
                        NS_LITERAL_STRING("\""))); /* source line */
}

void Area::ParseCoords(const nsAString& aSpec) {
  char* cp = ToNewCString(aSpec);
  if (cp) {
    char* tptr;
    char* n_str;
    int32_t i, cnt;

    /*
     * Nothing in an empty list
     */
    mNumCoords = 0;
    mCoords = nullptr;
    if (*cp == '\0') {
      free(cp);
      return;
    }

    /*
     * Skip beginning whitespace, all whitespace is empty list.
     */
    n_str = cp;
    while (is_space(*n_str)) {
      n_str++;
    }
    if (*n_str == '\0') {
      free(cp);
      return;
    }

    /*
     * Make a pass where any two numbers separated by just whitespace
     * are given a comma separator.  Count entries while passing.
     */
    cnt = 0;
    while (*n_str != '\0') {
      bool has_comma;

      /*
       * Skip to a separator
       */
      tptr = n_str;
      while (!is_space(*tptr) && *tptr != ',' && *tptr != '\0') {
        tptr++;
      }
      n_str = tptr;

      /*
       * If no more entries, break out here
       */
      if (*n_str == '\0') {
        break;
      }

      /*
       * Skip to the end of the separator, noting if we have a
       * comma.
       */
      has_comma = false;
      while (is_space(*tptr) || *tptr == ',') {
        if (*tptr == ',') {
          if (!has_comma) {
            has_comma = true;
          } else {
            break;
          }
        }
        tptr++;
      }
      /*
       * If this was trailing whitespace we skipped, we are done.
       */
      if ((*tptr == '\0') && !has_comma) {
        break;
      }
      /*
       * Else if the separator is all whitespace, and this is not the
       * end of the string, add a comma to the separator.
       */
      else if (!has_comma) {
        *n_str = ',';
      }

      /*
       * count the entry skipped.
       */
      cnt++;

      n_str = tptr;
    }
    /*
     * count the last entry in the list.
     */
    cnt++;

    /*
     * Allocate space for the coordinate array.
     */
    UniquePtr<nscoord[]> value_list = MakeUnique<nscoord[]>(cnt);
    if (!value_list) {
      free(cp);
      return;
    }

    /*
     * Second pass to copy integer values into list.
     */
    tptr = cp;
    for (i = 0; i < cnt; i++) {
      char* ptr;

      ptr = strchr(tptr, ',');
      if (ptr) {
        *ptr = '\0';
      }
      /*
       * Strip whitespace in front of number because I don't
       * trust atoi to do it on all platforms.
       */
      while (is_space(*tptr)) {
        tptr++;
      }
      if (*tptr == '\0') {
        value_list[i] = 0;
      } else {
        value_list[i] = (nscoord)::atoi(tptr);
      }
      if (ptr) {
        *ptr = ',';
        tptr = ptr + 1;
      }
    }

    mNumCoords = cnt;
    mCoords = Move(value_list);

    free(cp);
  }
}

void Area::HasFocus(bool aHasFocus) { mHasFocus = aHasFocus; }

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

class DefaultArea : public Area {
 public:
  explicit DefaultArea(HTMLAreaElement* aArea);

  virtual bool IsInside(nscoord x, nscoord y) const override;
  virtual void Draw(nsIFrame* aFrame, DrawTarget& aDrawTarget,
                    const ColorPattern& aColor,
                    const StrokeOptions& aStrokeOptions) override;
  virtual void GetRect(nsIFrame* aFrame, nsRect& aRect) override;
};

DefaultArea::DefaultArea(HTMLAreaElement* aArea) : Area(aArea) {}

bool DefaultArea::IsInside(nscoord x, nscoord y) const { return true; }

void DefaultArea::Draw(nsIFrame* aFrame, DrawTarget& aDrawTarget,
                       const ColorPattern& aColor,
                       const StrokeOptions& aStrokeOptions) {
  if (mHasFocus) {
    nsRect r(nsPoint(0, 0), aFrame->GetSize());
    const nscoord kOnePixel = nsPresContext::CSSPixelsToAppUnits(1);
    r.width -= kOnePixel;
    r.height -= kOnePixel;
    Rect rect = ToRect(nsLayoutUtils::RectToGfxRect(
        r, aFrame->PresContext()->AppUnitsPerDevPixel()));
    StrokeSnappedEdgesOfRect(rect, aDrawTarget, aColor, aStrokeOptions);
  }
}

void DefaultArea::GetRect(nsIFrame* aFrame, nsRect& aRect) {
  aRect = aFrame->GetRect();
  aRect.MoveTo(0, 0);
}

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

class RectArea : public Area {
 public:
  explicit RectArea(HTMLAreaElement* aArea);

  virtual void ParseCoords(const nsAString& aSpec) override;
  virtual bool IsInside(nscoord x, nscoord y) const override;
  virtual void Draw(nsIFrame* aFrame, DrawTarget& aDrawTarget,
                    const ColorPattern& aColor,
                    const StrokeOptions& aStrokeOptions) override;
  virtual void GetRect(nsIFrame* aFrame, nsRect& aRect) override;
};

RectArea::RectArea(HTMLAreaElement* aArea) : Area(aArea) {}

void RectArea::ParseCoords(const nsAString& aSpec) {
  Area::ParseCoords(aSpec);

  bool saneRect = true;
  int32_t flag = nsIScriptError::warningFlag;
  if (mNumCoords >= 4) {
    if (mCoords[0] > mCoords[2]) {
      // x-coords in reversed order
      nscoord x = mCoords[2];
      mCoords[2] = mCoords[0];
      mCoords[0] = x;
      saneRect = false;
    }

    if (mCoords[1] > mCoords[3]) {
      // y-coords in reversed order
      nscoord y = mCoords[3];
      mCoords[3] = mCoords[1];
      mCoords[1] = y;
      saneRect = false;
    }

    if (mNumCoords > 4) {
      // Someone missed the concept of a rect here
      saneRect = false;
    }
  } else {
    saneRect = false;
    flag = nsIScriptError::errorFlag;
  }

  if (!saneRect) {
    logMessage(mArea, aSpec, flag, "ImageMapRectBoundsError");
  }
}

bool RectArea::IsInside(nscoord x, nscoord y) const {
  if (mNumCoords >= 4) {  // Note: > is for nav compatibility
    nscoord x1 = mCoords[0];
    nscoord y1 = mCoords[1];
    nscoord x2 = mCoords[2];
    nscoord y2 = mCoords[3];
    NS_ASSERTION(x1 <= x2 && y1 <= y2,
                 "Someone screwed up RectArea::ParseCoords");
    if ((x >= x1) && (x <= x2) && (y >= y1) && (y <= y2)) {
      return true;
    }
  }
  return false;
}

void RectArea::Draw(nsIFrame* aFrame, DrawTarget& aDrawTarget,
                    const ColorPattern& aColor,
                    const StrokeOptions& aStrokeOptions) {
  if (mHasFocus) {
    if (mNumCoords >= 4) {
      nscoord x1 = nsPresContext::CSSPixelsToAppUnits(mCoords[0]);
      nscoord y1 = nsPresContext::CSSPixelsToAppUnits(mCoords[1]);
      nscoord x2 = nsPresContext::CSSPixelsToAppUnits(mCoords[2]);
      nscoord y2 = nsPresContext::CSSPixelsToAppUnits(mCoords[3]);
      NS_ASSERTION(x1 <= x2 && y1 <= y2,
                   "Someone screwed up RectArea::ParseCoords");
      nsRect r(x1, y1, x2 - x1, y2 - y1);
      Rect rect = ToRect(nsLayoutUtils::RectToGfxRect(
          r, aFrame->PresContext()->AppUnitsPerDevPixel()));
      StrokeSnappedEdgesOfRect(rect, aDrawTarget, aColor, aStrokeOptions);
    }
  }
}

void RectArea::GetRect(nsIFrame* aFrame, nsRect& aRect) {
  if (mNumCoords >= 4) {
    nscoord x1 = nsPresContext::CSSPixelsToAppUnits(mCoords[0]);
    nscoord y1 = nsPresContext::CSSPixelsToAppUnits(mCoords[1]);
    nscoord x2 = nsPresContext::CSSPixelsToAppUnits(mCoords[2]);
    nscoord y2 = nsPresContext::CSSPixelsToAppUnits(mCoords[3]);
    NS_ASSERTION(x1 <= x2 && y1 <= y2,
                 "Someone screwed up RectArea::ParseCoords");

    aRect.SetRect(x1, y1, x2, y2);
  }
}

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

class PolyArea : public Area {
 public:
  explicit PolyArea(HTMLAreaElement* aArea);

  virtual void ParseCoords(const nsAString& aSpec) override;
  virtual bool IsInside(nscoord x, nscoord y) const override;
  virtual void Draw(nsIFrame* aFrame, DrawTarget& aDrawTarget,
                    const ColorPattern& aColor,
                    const StrokeOptions& aStrokeOptions) override;
  virtual void GetRect(nsIFrame* aFrame, nsRect& aRect) override;
};

PolyArea::PolyArea(HTMLAreaElement* aArea) : Area(aArea) {}

void PolyArea::ParseCoords(const nsAString& aSpec) {
  Area::ParseCoords(aSpec);

  if (mNumCoords >= 2) {
    if (mNumCoords & 1U) {
      logMessage(mArea, aSpec, nsIScriptError::warningFlag,
                 "ImageMapPolyOddNumberOfCoords");
    }
  } else {
    logMessage(mArea, aSpec, nsIScriptError::errorFlag,
               "ImageMapPolyWrongNumberOfCoords");
  }
}

bool PolyArea::IsInside(nscoord x, nscoord y) const {
  if (mNumCoords >= 6) {
    int32_t intersects = 0;
    nscoord wherex = x;
    nscoord wherey = y;
    int32_t totalv = mNumCoords / 2;
    int32_t totalc = totalv * 2;
    nscoord xval = mCoords[totalc - 2];
    nscoord yval = mCoords[totalc - 1];
    int32_t end = totalc;
    int32_t pointer = 1;

    if ((yval >= wherey) != (mCoords[pointer] >= wherey)) {
      if ((xval >= wherex) == (mCoords[0] >= wherex)) {
        intersects += (xval >= wherex) ? 1 : 0;
      } else {
        intersects += ((xval - (yval - wherey) * (mCoords[0] - xval) /
                                   (mCoords[pointer] - yval)) >= wherex)
                          ? 1
                          : 0;
      }
    }

    // XXX I wonder what this is doing; this is a translation of ptinpoly.c
    while (pointer < end) {
      yval = mCoords[pointer];
      pointer += 2;
      if (yval >= wherey) {
        while ((pointer < end) && (mCoords[pointer] >= wherey)) pointer += 2;
        if (pointer >= end) break;
        if ((mCoords[pointer - 3] >= wherex) ==
            (mCoords[pointer - 1] >= wherex)) {
          intersects += (mCoords[pointer - 3] >= wherex) ? 1 : 0;
        } else {
          intersects +=
              ((mCoords[pointer - 3] -
                (mCoords[pointer - 2] - wherey) *
                    (mCoords[pointer - 1] - mCoords[pointer - 3]) /
                    (mCoords[pointer] - mCoords[pointer - 2])) >= wherex)
                  ? 1
                  : 0;
        }
      } else {
        while ((pointer < end) && (mCoords[pointer] < wherey)) pointer += 2;
        if (pointer >= end) break;
        if ((mCoords[pointer - 3] >= wherex) ==
            (mCoords[pointer - 1] >= wherex)) {
          intersects += (mCoords[pointer - 3] >= wherex) ? 1 : 0;
        } else {
          intersects +=
              ((mCoords[pointer - 3] -
                (mCoords[pointer - 2] - wherey) *
                    (mCoords[pointer - 1] - mCoords[pointer - 3]) /
                    (mCoords[pointer] - mCoords[pointer - 2])) >= wherex)
                  ? 1
                  : 0;
        }
      }
    }
    if ((intersects & 1) != 0) {
      return true;
    }
  }
  return false;
}

void PolyArea::Draw(nsIFrame* aFrame, DrawTarget& aDrawTarget,
                    const ColorPattern& aColor,
                    const StrokeOptions& aStrokeOptions) {
  if (mHasFocus) {
    if (mNumCoords >= 6) {
      // Where possible, we want all horizontal and vertical lines to align on
      // pixel rows or columns, and to start at pixel boundaries so that one
      // pixel dashing neatly sits on pixels to give us neat lines. To achieve
      // that we draw each line segment as a separate path, snapping it to
      // device pixels if applicable.
      nsPresContext* pc = aFrame->PresContext();
      Point p1(pc->CSSPixelsToDevPixels(mCoords[0]),
               pc->CSSPixelsToDevPixels(mCoords[1]));
      Point p2, p1snapped, p2snapped;
      for (int32_t i = 2; i < mNumCoords; i += 2) {
        p2.x = pc->CSSPixelsToDevPixels(mCoords[i]);
        p2.y = pc->CSSPixelsToDevPixels(mCoords[i + 1]);
        p1snapped = p1;
        p2snapped = p2;
        SnapLineToDevicePixelsForStroking(p1snapped, p2snapped, aDrawTarget,
                                          aStrokeOptions.mLineWidth);
        aDrawTarget.StrokeLine(p1snapped, p2snapped, aColor, aStrokeOptions);
        p1 = p2;
      }
      p2.x = pc->CSSPixelsToDevPixels(mCoords[0]);
      p2.y = pc->CSSPixelsToDevPixels(mCoords[1]);
      p1snapped = p1;
      p2snapped = p2;
      SnapLineToDevicePixelsForStroking(p1snapped, p2snapped, aDrawTarget,
                                        aStrokeOptions.mLineWidth);
      aDrawTarget.StrokeLine(p1snapped, p2snapped, aColor, aStrokeOptions);
    }
  }
}

void PolyArea::GetRect(nsIFrame* aFrame, nsRect& aRect) {
  if (mNumCoords >= 6) {
    nscoord x1, x2, y1, y2, xtmp, ytmp;
    x1 = x2 = nsPresContext::CSSPixelsToAppUnits(mCoords[0]);
    y1 = y2 = nsPresContext::CSSPixelsToAppUnits(mCoords[1]);
    for (int32_t i = 2; i < mNumCoords; i += 2) {
      xtmp = nsPresContext::CSSPixelsToAppUnits(mCoords[i]);
      ytmp = nsPresContext::CSSPixelsToAppUnits(mCoords[i + 1]);
      x1 = x1 < xtmp ? x1 : xtmp;
      y1 = y1 < ytmp ? y1 : ytmp;
      x2 = x2 > xtmp ? x2 : xtmp;
      y2 = y2 > ytmp ? y2 : ytmp;
    }

    aRect.SetRect(x1, y1, x2, y2);
  }
}

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

class CircleArea : public Area {
 public:
  explicit CircleArea(HTMLAreaElement* aArea);

  virtual void ParseCoords(const nsAString& aSpec) override;
  virtual bool IsInside(nscoord x, nscoord y) const override;
  virtual void Draw(nsIFrame* aFrame, DrawTarget& aDrawTarget,
                    const ColorPattern& aColor,
                    const StrokeOptions& aStrokeOptions) override;
  virtual void GetRect(nsIFrame* aFrame, nsRect& aRect) override;
};

CircleArea::CircleArea(HTMLAreaElement* aArea) : Area(aArea) {}

void CircleArea::ParseCoords(const nsAString& aSpec) {
  Area::ParseCoords(aSpec);

  bool wrongNumberOfCoords = false;
  int32_t flag = nsIScriptError::warningFlag;
  if (mNumCoords >= 3) {
    if (mCoords[2] < 0) {
      logMessage(mArea, aSpec, nsIScriptError::errorFlag,
                 "ImageMapCircleNegativeRadius");
    }

    if (mNumCoords > 3) {
      wrongNumberOfCoords = true;
    }
  } else {
    wrongNumberOfCoords = true;
    flag = nsIScriptError::errorFlag;
  }

  if (wrongNumberOfCoords) {
    logMessage(mArea, aSpec, flag, "ImageMapCircleWrongNumberOfCoords");
  }
}

bool CircleArea::IsInside(nscoord x, nscoord y) const {
  // Note: > is for nav compatibility
  if (mNumCoords >= 3) {
    nscoord x1 = mCoords[0];
    nscoord y1 = mCoords[1];
    nscoord radius = mCoords[2];
    if (radius < 0) {
      return false;
    }
    nscoord dx = x1 - x;
    nscoord dy = y1 - y;
    nscoord dist = (dx * dx) + (dy * dy);
    if (dist <= (radius * radius)) {
      return true;
    }
  }
  return false;
}

void CircleArea::Draw(nsIFrame* aFrame, DrawTarget& aDrawTarget,
                      const ColorPattern& aColor,
                      const StrokeOptions& aStrokeOptions) {
  if (mHasFocus) {
    if (mNumCoords >= 3) {
      Point center(aFrame->PresContext()->CSSPixelsToDevPixels(mCoords[0]),
                   aFrame->PresContext()->CSSPixelsToDevPixels(mCoords[1]));
      Float diameter =
          2 * aFrame->PresContext()->CSSPixelsToDevPixels(mCoords[2]);
      if (diameter <= 0) {
        return;
      }
      RefPtr<PathBuilder> builder = aDrawTarget.CreatePathBuilder();
      AppendEllipseToPath(builder, center, Size(diameter, diameter));
      RefPtr<Path> circle = builder->Finish();
      aDrawTarget.Stroke(circle, aColor, aStrokeOptions);
    }
  }
}

void CircleArea::GetRect(nsIFrame* aFrame, nsRect& aRect) {
  if (mNumCoords >= 3) {
    nscoord x1 = nsPresContext::CSSPixelsToAppUnits(mCoords[0]);
    nscoord y1 = nsPresContext::CSSPixelsToAppUnits(mCoords[1]);
    nscoord radius = nsPresContext::CSSPixelsToAppUnits(mCoords[2]);
    if (radius < 0) {
      return;
    }

    aRect.SetRect(x1 - radius, y1 - radius, x1 + radius, y1 + radius);
  }
}

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

nsImageMap::nsImageMap() : mImageFrame(nullptr), mConsiderWholeSubtree(false) {}

nsImageMap::~nsImageMap() {
  NS_ASSERTION(mAreas.Length() == 0, "Destroy was not called");
}

NS_IMPL_ISUPPORTS(nsImageMap, nsIMutationObserver, nsIDOMEventListener)

nsresult nsImageMap::GetBoundsForAreaContent(nsIContent* aContent,
                                             nsRect& aBounds) {
  NS_ENSURE_TRUE(aContent && mImageFrame, NS_ERROR_INVALID_ARG);

  // Find the Area struct associated with this content node, and return bounds
  for (auto& area : mAreas) {
    if (area->mArea == aContent) {
      aBounds = nsRect();
      area->GetRect(mImageFrame, aBounds);
      return NS_OK;
    }
  }
  return NS_ERROR_FAILURE;
}

void nsImageMap::AreaRemoved(HTMLAreaElement* aArea) {
  if (aArea->IsInUncomposedDoc()) {
    NS_ASSERTION(aArea->GetPrimaryFrame() == mImageFrame,
                 "Unexpected primary frame");

    aArea->SetPrimaryFrame(nullptr);
  }

  aArea->RemoveSystemEventListener(NS_LITERAL_STRING("focus"), this, false);
  aArea->RemoveSystemEventListener(NS_LITERAL_STRING("blur"), this, false);
}

void nsImageMap::FreeAreas() {
  for (UniquePtr<Area>& area : mAreas) {
    AreaRemoved(area->mArea);
  }

  mAreas.Clear();
}

void nsImageMap::Init(nsImageFrame* aImageFrame, nsIContent* aMap) {
  MOZ_ASSERT(aMap);
  MOZ_ASSERT(aImageFrame);

  mImageFrame = aImageFrame;
  mMap = aMap;
  mMap->AddMutationObserver(this);

  // "Compile" the areas in the map into faster access versions
  UpdateAreas();
}

void nsImageMap::SearchForAreas(nsIContent* aParent) {
  // Look for <area> elements.
  for (nsIContent* child = aParent->GetFirstChild(); child;
       child = child->GetNextSibling()) {
    if (auto* area = HTMLAreaElement::FromContent(child)) {
      AddArea(area);

      // Continue to next child. This stops mConsiderWholeSubtree from
      // getting set. It also makes us ignore children of <area>s which
      // is consistent with how we react to dynamic insertion of such
      // children.
      continue;
    }

    if (child->IsElement()) {
      mConsiderWholeSubtree = true;
      SearchForAreas(child);
    }
  }
}

void nsImageMap::UpdateAreas() {
  // Get rid of old area data
  FreeAreas();

  mConsiderWholeSubtree = false;
  SearchForAreas(mMap);

#ifdef ACCESSIBILITY
  if (nsAccessibilityService* accService = GetAccService()) {
    accService->UpdateImageMap(mImageFrame);
  }
#endif
}

void nsImageMap::AddArea(HTMLAreaElement* aArea) {
  static Element::AttrValuesArray strings[] = {
      &nsGkAtoms::rect,     &nsGkAtoms::rectangle,
      &nsGkAtoms::circle,   &nsGkAtoms::circ,
      &nsGkAtoms::_default, &nsGkAtoms::poly,
      &nsGkAtoms::polygon,  nullptr};

  UniquePtr<Area> area;
  switch (aArea->FindAttrValueIn(kNameSpaceID_None, nsGkAtoms::shape, strings,
                                 eIgnoreCase)) {
    case Element::ATTR_VALUE_NO_MATCH:
    case Element::ATTR_MISSING:
    case 0:
    case 1:
      area = MakeUnique<RectArea>(aArea);
      break;
    case 2:
    case 3:
      area = MakeUnique<CircleArea>(aArea);
      break;
    case 4:
      area = MakeUnique<DefaultArea>(aArea);
      break;
    case 5:
    case 6:
      area = MakeUnique<PolyArea>(aArea);
      break;
    default:
      area = nullptr;
      MOZ_ASSERT_UNREACHABLE("FindAttrValueIn returned an unexpected value.");
      break;
  }

  // Add focus listener to track area focus changes
  aArea->AddSystemEventListener(NS_LITERAL_STRING("focus"), this, false, false);
  aArea->AddSystemEventListener(NS_LITERAL_STRING("blur"), this, false, false);

  // This is a nasty hack.  It needs to go away: see bug 135040.  Once this is
  // removed, the code added to RestyleManager::RestyleElement,
  // nsCSSFrameConstructor::ContentRemoved (both hacks there), and
  // RestyleManager::ProcessRestyledFrames to work around this issue can
  // be removed.
  aArea->SetPrimaryFrame(mImageFrame);

  nsAutoString coords;
  aArea->GetAttr(kNameSpaceID_None, nsGkAtoms::coords, coords);
  area->ParseCoords(coords);
  mAreas.AppendElement(Move(area));
}

nsIContent* nsImageMap::GetArea(nscoord aX, nscoord aY) const {
  NS_ASSERTION(mMap, "Not initialized");
  for (const auto& area : mAreas) {
    if (area->IsInside(aX, aY)) {
      return area->mArea;
    }
  }

  return nullptr;
}

nsIContent* nsImageMap::GetAreaAt(uint32_t aIndex) const {
  return mAreas.ElementAt(aIndex)->mArea;
}

void nsImageMap::Draw(nsIFrame* aFrame, DrawTarget& aDrawTarget,
                      const ColorPattern& aColor,
                      const StrokeOptions& aStrokeOptions) {
  for (auto& area : mAreas) {
    area->Draw(aFrame, aDrawTarget, aColor, aStrokeOptions);
  }
}

void nsImageMap::MaybeUpdateAreas(nsIContent* aContent) {
  if (aContent == mMap || mConsiderWholeSubtree) {
    UpdateAreas();
  }
}

void nsImageMap::AttributeChanged(dom::Element* aElement, int32_t aNameSpaceID,
                                  nsAtom* aAttribute, int32_t aModType,
                                  const nsAttrValue* aOldValue) {
  // If the parent of the changing content node is our map then update
  // the map.  But only do this if the node is an HTML <area> or <a>
  // and the attribute that's changing is "shape" or "coords" -- those
  // are the only cases we care about.
  if ((aElement->NodeInfo()->Equals(nsGkAtoms::area) ||
       aElement->NodeInfo()->Equals(nsGkAtoms::a)) &&
      aElement->IsHTMLElement() && aNameSpaceID == kNameSpaceID_None &&
      (aAttribute == nsGkAtoms::shape || aAttribute == nsGkAtoms::coords)) {
    MaybeUpdateAreas(aElement->GetParent());
  } else if (aElement == mMap && aNameSpaceID == kNameSpaceID_None &&
             (aAttribute == nsGkAtoms::name || aAttribute == nsGkAtoms::id) &&
             mImageFrame) {
    // ID or name has changed. Let ImageFrame recreate ImageMap.
    mImageFrame->DisconnectMap();
  }
}

void nsImageMap::ContentAppended(nsIContent* aFirstNewContent) {
  MaybeUpdateAreas(aFirstNewContent->GetParent());
}

void nsImageMap::ContentInserted(nsIContent* aChild) {
  MaybeUpdateAreas(aChild->GetParent());
}

static UniquePtr<Area> TakeArea(nsImageMap::AreaList& aAreas,
                                HTMLAreaElement* aArea) {
  UniquePtr<Area> result;
  size_t index = 0;
  for (UniquePtr<Area>& area : aAreas) {
    if (area->mArea == aArea) {
      result = Move(area);
      break;
    }
    index++;
  }

  if (result) {
    aAreas.RemoveElementAt(index);
  }

  return result;
}

void nsImageMap::ContentRemoved(nsIContent* aChild,
                                nsIContent* aPreviousSibling) {
  if (aChild->GetParent() != mMap && !mConsiderWholeSubtree) {
    return;
  }

  auto* areaElement = HTMLAreaElement::FromContent(aChild);
  if (!areaElement) {
    return;
  }

  UniquePtr<Area> area = TakeArea(mAreas, areaElement);
  if (!area) {
    return;
  }

  AreaRemoved(area->mArea);

#ifdef ACCESSIBILITY
  if (nsAccessibilityService* accService = GetAccService()) {
    accService->UpdateImageMap(mImageFrame);
  }
#endif
}

void nsImageMap::ParentChainChanged(nsIContent* aContent) {
  NS_ASSERTION(aContent == mMap, "Unexpected ParentChainChanged notification!");
  if (mImageFrame) {
    mImageFrame->DisconnectMap();
  }
}

nsresult nsImageMap::HandleEvent(nsIDOMEvent* aEvent) {
  nsAutoString eventType;
  aEvent->GetType(eventType);
  bool focus = eventType.EqualsLiteral("focus");
  MOZ_ASSERT(focus == !eventType.EqualsLiteral("blur"),
             "Unexpected event type");

  // Set which one of our areas changed focus
  nsCOMPtr<nsIContent> targetContent =
      do_QueryInterface(aEvent->InternalDOMEvent()->GetTarget());
  if (!targetContent) {
    return NS_OK;
  }

  for (auto& area : mAreas) {
    if (area->mArea == targetContent) {
      // Set or Remove internal focus
      area->HasFocus(focus);
      // Now invalidate the rect
      if (mImageFrame) {
        mImageFrame->InvalidateFrame();
      }
      break;
    }
  }
  return NS_OK;
}

void nsImageMap::Destroy() {
  FreeAreas();
  mImageFrame = nullptr;
  mMap->RemoveMutationObserver(this);
}