layout/mathml/nsMathMLsemanticsFrame.cpp

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #include "nsMathMLsemanticsFrame.h"
   8
   9 #include "nsMimeTypes.h"
  10 #include "mozilla/PresShell.h"
  11 #include "mozilla/dom/Element.h"
  12 #include "mozilla/gfx/2D.h"
  13
  14 using namespace mozilla;
  15
  16 //
  17 // <semantics> -- associate annotations with a MathML expression
  18 //
  19
  20 nsIFrame* NS_NewMathMLsemanticsFrame(PresShell* aPresShell,
  21                                      ComputedStyle* aStyle) {
  22   return new (aPresShell)
  23       nsMathMLsemanticsFrame(aStyle, aPresShell->GetPresContext());
  24 }
  25
  26 NS_IMPL_FRAMEARENA_HELPERS(nsMathMLsemanticsFrame)
  27
  28 nsMathMLsemanticsFrame::~nsMathMLsemanticsFrame() = default;
  29
  30 nsIFrame* nsMathMLsemanticsFrame::GetSelectedFrame() {
  31   // By default, we will display the first child of the <semantics> element.
  32   nsIFrame* childFrame = mFrames.FirstChild();
  33   mSelectedFrame = childFrame;
  34
  35   // An empty <semantics> is invalid
  36   if (!childFrame) {
  37     mInvalidMarkup = true;
  38     return mSelectedFrame;
  39   }
  40   mInvalidMarkup = false;
  41
  42   // Using <annotation> or <annotation-xml> as a first child is invalid.
  43   // However some people use this syntax so we take care of this case too.
  44   bool firstChildIsAnnotation = false;
  45   nsIContent* childContent = childFrame->GetContent();
  46   if (childContent->IsAnyOfMathMLElements(nsGkAtoms::annotation_,
  47                                           nsGkAtoms::annotation_xml_)) {
  48     firstChildIsAnnotation = true;
  49   }
  50
  51   // If the first child is a presentation MathML element other than
  52   // <annotation> or <annotation-xml>, we are done.
  53   if (!firstChildIsAnnotation && childFrame->IsFrameOfType(nsIFrame::eMathML)) {
  54     nsIMathMLFrame* mathMLFrame = do_QueryFrame(childFrame);
  55     if (mathMLFrame) {
  56       TransmitAutomaticData();
  57       return mSelectedFrame;
  58     }
  59     // The first child is not an annotation, so skip it.
  60     childFrame = childFrame->GetNextSibling();
  61   }
  62
  63   // Otherwise, we read the list of annotations and select the first one that
  64   // could be displayed in place of the first child of <semantics>. If none is
  65   // found, we fallback to this first child.
  66   for (; childFrame; childFrame = childFrame->GetNextSibling()) {
  67     nsIContent* childContent = childFrame->GetContent();
  68
  69     if (childContent->IsMathMLElement(nsGkAtoms::annotation_)) {
  70       // If the <annotation> element has an src attribute we ignore it.
  71       // XXXfredw Should annotation images be supported? See the related
  72       // bug 297465 for mglyph.
  73       if (childContent->AsElement()->HasAttr(kNameSpaceID_None, nsGkAtoms::src))
  74         continue;
  75
  76       // Otherwise, we assume it is a text annotation that can always be
  77       // displayed and stop here.
  78       mSelectedFrame = childFrame;
  79       break;
  80     }
  81
  82     if (childContent->IsMathMLElement(nsGkAtoms::annotation_xml_)) {
  83       // If the <annotation-xml> element has an src attribute we ignore it.
  84       if (childContent->AsElement()->HasAttr(kNameSpaceID_None, nsGkAtoms::src))
  85         continue;
  86
  87       // If the <annotation-xml> element has an encoding attribute
  88       // describing presentation MathML, SVG or HTML we assume the content
  89       // can be displayed and stop here.
  90       //
  91       // We recognize the following encoding values:
  92       //
  93       // - "MathML-Presentation", which is mentioned in the MathML3 REC
  94       // - "SVG1.1" which is mentioned in the W3C note
  95       //                   http://www.w3.org/Math/Documents/Notes/graphics.xml
  96       // - Other mime Content-Types for SVG and HTML
  97       //
  98       // We exclude APPLICATION_MATHML_XML = "application/mathml+xml" which
  99       // is ambiguous about whether it is Presentation or Content MathML.
 100       // Authors must use a more explicit encoding value.
 101       nsAutoString value;
 102       childContent->AsElement()->GetAttr(kNameSpaceID_None, nsGkAtoms::encoding,
 103                                          value);
 104       if (value.EqualsLiteral("application/mathml-presentation+xml") ||
 105           value.EqualsLiteral("MathML-Presentation") ||
 106           value.EqualsLiteral(IMAGE_SVG_XML) || value.EqualsLiteral("SVG1.1") ||
 107           value.EqualsLiteral(APPLICATION_XHTML_XML) ||
 108           value.EqualsLiteral(TEXT_HTML)) {
 109         mSelectedFrame = childFrame;
 110         break;
 111       }
 112     }
 113   }
 114
 115   TransmitAutomaticData();
 116   return mSelectedFrame;
 117 }