gecko-dev/accessible/generic/ImageAccessible.cpp

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* 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 "ImageAccessible.h"

#include "nsAccUtils.h"
#include "Role.h"
#include "AccIterator.h"
#include "States.h"

#include "imgIContainer.h"
#include "imgIRequest.h"
#include "nsGenericHTMLElement.h"
#include "mozilla/dom/BrowsingContext.h"
#include "mozilla/dom/Document.h"
#include "nsIImageLoadingContent.h"
#include "nsIPersistentProperties2.h"
#include "nsPIDOMWindow.h"
#include "nsIURI.h"

using namespace mozilla::a11y;

////////////////////////////////////////////////////////////////////////////////
// ImageAccessible
////////////////////////////////////////////////////////////////////////////////

ImageAccessible::ImageAccessible(nsIContent* aContent, DocAccessible* aDoc)
    : LinkableAccessible(aContent, aDoc) {
  mType = eImageType;
}

ImageAccessible::~ImageAccessible() {}

////////////////////////////////////////////////////////////////////////////////
// Accessible public

uint64_t ImageAccessible::NativeState() const {
  // The state is a bitfield, get our inherited state, then logically OR it with
  // states::ANIMATED if this is an animated image.

  uint64_t state = LinkableAccessible::NativeState();

  nsCOMPtr<nsIImageLoadingContent> content(do_QueryInterface(mContent));
  nsCOMPtr<imgIRequest> imageRequest;

  if (content)
    content->GetRequest(nsIImageLoadingContent::CURRENT_REQUEST,
                        getter_AddRefs(imageRequest));

  if (imageRequest) {
    nsCOMPtr<imgIContainer> imgContainer;
    imageRequest->GetImage(getter_AddRefs(imgContainer));
    if (imgContainer) {
      bool animated = false;
      imgContainer->GetAnimated(&animated);
      if (animated) {
        state |= states::ANIMATED;
      }
    }

    nsIFrame* frame = GetFrame();
    MOZ_ASSERT(!frame || frame->AccessibleType() == eImageType ||
               frame->AccessibleType() == a11y::eHTMLImageMapType);
    if (frame && !(frame->GetStateBits() & IMAGE_SIZECONSTRAINED)) {
      uint32_t status = imgIRequest::STATUS_NONE;
      imageRequest->GetImageStatus(&status);
      if (!(status & imgIRequest::STATUS_SIZE_AVAILABLE)) {
        // The size of this image hasn't been constrained and we haven't loaded
        // enough of the image to know its size yet. This means it currently
        // has 0 width and height.
        state |= states::INVISIBLE;
      }
    }
  }

  return state;
}

ENameValueFlag ImageAccessible::NativeName(nsString& aName) const {
  bool hasAltAttrib =
      mContent->AsElement()->GetAttr(kNameSpaceID_None, nsGkAtoms::alt, aName);
  if (!aName.IsEmpty()) return eNameOK;

  ENameValueFlag nameFlag = Accessible::NativeName(aName);
  if (!aName.IsEmpty()) return nameFlag;

  // No accessible name but empty 'alt' attribute is present. If further name
  // computation algorithm doesn't provide non empty name then it means
  // an empty 'alt' attribute was used to indicate a decorative image (see
  // Accessible::Name() method for details).
  return hasAltAttrib ? eNoNameOnPurpose : eNameOK;
}

role ImageAccessible::NativeRole() const { return roles::GRAPHIC; }

////////////////////////////////////////////////////////////////////////////////
// Accessible

uint8_t ImageAccessible::ActionCount() const {
  uint8_t actionCount = LinkableAccessible::ActionCount();
  return HasLongDesc() ? actionCount + 1 : actionCount;
}

void ImageAccessible::ActionNameAt(uint8_t aIndex, nsAString& aName) {
  aName.Truncate();
  if (IsLongDescIndex(aIndex) && HasLongDesc())
    aName.AssignLiteral("showlongdesc");
  else
    LinkableAccessible::ActionNameAt(aIndex, aName);
}

bool ImageAccessible::DoAction(uint8_t aIndex) const {
  // Get the long description uri and open in a new window.
  if (!IsLongDescIndex(aIndex)) return LinkableAccessible::DoAction(aIndex);

  nsCOMPtr<nsIURI> uri = GetLongDescURI();
  if (!uri) return false;

  nsAutoCString utf8spec;
  uri->GetSpec(utf8spec);
  NS_ConvertUTF8toUTF16 spec(utf8spec);

  dom::Document* document = mContent->OwnerDoc();
  nsCOMPtr<nsPIDOMWindowOuter> piWindow = document->GetWindow();
  if (!piWindow) return false;

  RefPtr<mozilla::dom::BrowsingContext> tmp;
  return NS_SUCCEEDED(piWindow->Open(spec, EmptyString(), EmptyString(),
                                     /* aLoadInfo = */ nullptr,
                                     /* aForceNoOpener = */ false,
                                     getter_AddRefs(tmp)));
}

////////////////////////////////////////////////////////////////////////////////
// ImageAccessible

nsIntPoint ImageAccessible::Position(uint32_t aCoordType) {
  nsIntPoint point = Bounds().TopLeft();
  nsAccUtils::ConvertScreenCoordsTo(&point.x, &point.y, aCoordType, this);
  return point;
}

nsIntSize ImageAccessible::Size() { return Bounds().Size(); }

// Accessible
already_AddRefed<nsIPersistentProperties> ImageAccessible::NativeAttributes() {
  nsCOMPtr<nsIPersistentProperties> attributes =
      LinkableAccessible::NativeAttributes();

  nsAutoString src;
  mContent->AsElement()->GetAttr(kNameSpaceID_None, nsGkAtoms::src, src);
  if (!src.IsEmpty()) nsAccUtils::SetAccAttr(attributes, nsGkAtoms::src, src);

  return attributes.forget();
}

////////////////////////////////////////////////////////////////////////////////
// Private methods

already_AddRefed<nsIURI> ImageAccessible::GetLongDescURI() const {
  if (mContent->AsElement()->HasAttr(kNameSpaceID_None, nsGkAtoms::longdesc)) {
    // To check if longdesc contains an invalid url.
    nsAutoString longdesc;
    mContent->AsElement()->GetAttr(kNameSpaceID_None, nsGkAtoms::longdesc,
                                   longdesc);
    if (longdesc.FindChar(' ') != -1 || longdesc.FindChar('\t') != -1 ||
        longdesc.FindChar('\r') != -1 || longdesc.FindChar('\n') != -1) {
      return nullptr;
    }
    nsCOMPtr<nsIURI> uri;
    nsContentUtils::NewURIWithDocumentCharset(getter_AddRefs(uri), longdesc,
                                              mContent->OwnerDoc(),
                                              mContent->GetBaseURI());
    return uri.forget();
  }

  DocAccessible* document = Document();
  if (document) {
    IDRefsIterator iter(document, mContent, nsGkAtoms::aria_describedby);
    while (nsIContent* target = iter.NextElem()) {
      if ((target->IsHTMLElement(nsGkAtoms::a) ||
           target->IsHTMLElement(nsGkAtoms::area)) &&
          target->AsElement()->HasAttr(kNameSpaceID_None, nsGkAtoms::href)) {
        nsGenericHTMLElement* element = nsGenericHTMLElement::FromNode(target);

        nsCOMPtr<nsIURI> uri;
        element->GetURIAttr(nsGkAtoms::href, nullptr, getter_AddRefs(uri));
        return uri.forget();
      }
    }
  }

  return nullptr;
}

bool ImageAccessible::IsLongDescIndex(uint8_t aIndex) const {
  return aIndex == LinkableAccessible::ActionCount();
}