/* -*- 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/. */

#include "nsMathMLsemanticsFrame.h"

#include "nsMimeTypes.h"

#include "mozilla/gfx/2D.h"

//

// <semantics> -- associate annotations with a MathML expression

//

nsIFrame*

NS_NewMathMLsemanticsFrame(nsIPresShell* aPresShell, ComputedStyle* aStyle)

{

  return new (aPresShell) nsMathMLsemanticsFrame(aStyle);

}

NS_IMPL_FRAMEARENA_HELPERS(nsMathMLsemanticsFrame)

nsMathMLsemanticsFrame::~nsMathMLsemanticsFrame()

{

}

nsIFrame*

nsMathMLsemanticsFrame::GetSelectedFrame()

{

  // By default, we will display the first child of the <semantics> element.

  nsIFrame* childFrame = mFrames.FirstChild();

  mSelectedFrame = childFrame;

  // An empty <semantics> is invalid

  if (!childFrame) {

    mInvalidMarkup = true;

    return mSelectedFrame;

  }

  mInvalidMarkup = false;

  // Using <annotation> or <annotation-xml> as a first child is invalid.

  // However some people use this syntax so we take care of this case too.

  bool firstChildIsAnnotation = false;

  nsIContent* childContent = childFrame->GetContent();

  if (childContent->IsAnyOfMathMLElements(nsGkAtoms::annotation_,

                                          nsGkAtoms::annotation_xml_)) {

    firstChildIsAnnotation = true;

  }

  // If the first child is a presentation MathML element other than

  // <annotation> or <annotation-xml>, we are done.

  if (!firstChildIsAnnotation &&

      childFrame->IsFrameOfType(nsIFrame::eMathML)) {

    nsIMathMLFrame* mathMLFrame = do_QueryFrame(childFrame);

    if (mathMLFrame) {

      TransmitAutomaticData();

      return mSelectedFrame;

    }

    // The first child is not an annotation, so skip it.

    childFrame = childFrame->GetNextSibling();

  }

  // Otherwise, we read the list of annotations and select the first one that

  // could be displayed in place of the first child of <semantics>. If none is

  // found, we fallback to this first child.

  for ( ; childFrame; childFrame = childFrame->GetNextSibling()) {

    nsIContent* childContent = childFrame->GetContent();

    if (childContent->IsMathMLElement(nsGkAtoms::annotation_)) {

      // If the <annotation> element has an src attribute we ignore it.

      // XXXfredw Should annotation images be supported? See the related

      // bug 297465 for mglyph.

      if (childContent->AsElement()->HasAttr(kNameSpaceID_None, nsGkAtoms::src))

        continue;

      // Otherwise, we assume it is a text annotation that can always be

      // displayed and stop here.

      mSelectedFrame = childFrame;

      break;

    }

    if (childContent->IsMathMLElement(nsGkAtoms::annotation_xml_)) {

      // If the <annotation-xml> element has an src attribute we ignore it.

      if (childContent->AsElement()->HasAttr(kNameSpaceID_None, nsGkAtoms::src))

        continue;

      // If the <annotation-xml> element has an encoding attribute

      // describing presentation MathML, SVG or HTML we assume the content

      // can be displayed and stop here.

      //

      // We recognize the following encoding values:

      //

      // - "MathML-Presentation", which is mentioned in the MathML3 REC

      // - "SVG1.1" which is mentioned in the W3C note

      //                   http://www.w3.org/Math/Documents/Notes/graphics.xml

      // - Other mime Content-Types for SVG and HTML

      //

      // We exclude APPLICATION_MATHML_XML = "application/mathml+xml" which

      // is ambiguous about whether it is Presentation or Content MathML.

      // Authors must use a more explicit encoding value.

      nsAutoString value;

      childContent->AsElement()->GetAttr(kNameSpaceID_None,

                                         nsGkAtoms::encoding,

                                         value);

      if (value.EqualsLiteral("application/mathml-presentation+xml") ||

          value.EqualsLiteral("MathML-Presentation") ||

          value.EqualsLiteral(IMAGE_SVG_XML) ||

          value.EqualsLiteral("SVG1.1") ||

          value.EqualsLiteral(APPLICATION_XHTML_XML) ||

          value.EqualsLiteral(TEXT_HTML)) {

        mSelectedFrame = childFrame;

        break;

      }

    }

  }

  TransmitAutomaticData();

  return mSelectedFrame;

}