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 /* -*- 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 "nsMathMLsemanticsFrame.h"

 #include "nsMimeTypes.h"

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

 //

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

 //

 nsIFrame*

 NS_NewMathMLsemanticsFrame(nsIPresShell* aPresShell, nsStyleContext* aContext)

 {

   return new (aPresShell) nsMathMLsemanticsFrame(aContext);

 }

 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->GetNameSpaceID() == kNameSpaceID_MathML &&

       (childContent->Tag() == nsGkAtoms::annotation_ ||

        childContent->Tag() == 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->GetNameSpaceID() != kNameSpaceID_MathML) continue;

     if (childContent->Tag() == 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->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->Tag() == nsGkAtoms::annotation_xml_) {

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

       if (childContent->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->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;

 }