nsMathMLFrame.cpp

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is Mozilla MathML Project.
 *
 * The Initial Developer of the Original Code is
 * The University Of Queensland.
 * Portions created by the Initial Developer are Copyright (C) 1999
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *   Roger B. Sidje <rbs@maths.uq.edu.au>
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either of the GNU General Public License Version 2 or later (the "GPL"),
 * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the MPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the MPL, the GPL or the LGPL.
 *
 * ***** END LICENSE BLOCK ***** */

#include "nsINameSpaceManager.h"
#include "nsMathMLFrame.h"
#include "nsMathMLChar.h"
#include "nsCSSPseudoElements.h"

// used to map attributes into CSS rules
#include "nsStyleSet.h"
#include "nsAutoPtr.h"
#include "nsDisplayList.h"
#include "nsRenderingContext.h"

eMathMLFrameType
nsMathMLFrame::GetMathMLFrameType()
{
  // see if it is an embellished operator (mapped to 'Op' in TeX)
  if (mEmbellishData.coreFrame)
    return GetMathMLFrameTypeFor(mEmbellishData.coreFrame);

  // if it has a prescribed base, fetch the type from there
  if (mPresentationData.baseFrame)
    return GetMathMLFrameTypeFor(mPresentationData.baseFrame);

  // everything else is treated as ordinary (mapped to 'Ord' in TeX)
  return eMathMLFrameType_Ordinary;  
}

// snippet of code used by <mstyle>, <mtable> and <math> which are the only
// three tags where the displaystyle attribute is allowed by the spec.
/* static */ void
nsMathMLFrame::FindAttrDisplaystyle(nsIContent*         aContent,
                                    nsPresentationData& aPresentationData)
{
  NS_ASSERTION(aContent->Tag() == nsGkAtoms::mstyle_ ||
               aContent->Tag() == nsGkAtoms::mtable_ ||
               aContent->Tag() == nsGkAtoms::math, "bad caller");
  static nsIContent::AttrValuesArray strings[] =
    {&nsGkAtoms::_false, &nsGkAtoms::_true, nsnull};
  // see if the explicit displaystyle attribute is there
  switch (aContent->FindAttrValueIn(kNameSpaceID_None,
    nsGkAtoms::displaystyle_, strings, eCaseMatters)) {
  case 0:
    aPresentationData.flags &= ~NS_MATHML_DISPLAYSTYLE;
    aPresentationData.flags |= NS_MATHML_EXPLICIT_DISPLAYSTYLE;
    break;
  case 1:
    aPresentationData.flags |= NS_MATHML_DISPLAYSTYLE;
    aPresentationData.flags |= NS_MATHML_EXPLICIT_DISPLAYSTYLE;
    break;
  }
  // no reset if the attr isn't found. so be sure to call it on inherited flags
}

NS_IMETHODIMP
nsMathMLFrame::InheritAutomaticData(nsIFrame* aParent) 
{
  mEmbellishData.flags = 0;
  mEmbellishData.coreFrame = nsnull;
  mEmbellishData.direction = NS_STRETCH_DIRECTION_UNSUPPORTED;
  mEmbellishData.leftSpace = 0;
  mEmbellishData.rightSpace = 0;

  mPresentationData.flags = 0;
  mPresentationData.baseFrame = nsnull;
  mPresentationData.mstyle = nsnull;

  // by default, just inherit the display of our parent
  nsPresentationData parentData;
  GetPresentationDataFrom(aParent, parentData);
  mPresentationData.mstyle = parentData.mstyle;
  if (NS_MATHML_IS_DISPLAYSTYLE(parentData.flags)) {
    mPresentationData.flags |= NS_MATHML_DISPLAYSTYLE;
  }

#if defined(NS_DEBUG) && defined(SHOW_BOUNDING_BOX)
  mPresentationData.flags |= NS_MATHML_SHOW_BOUNDING_METRICS;
#endif

  return NS_OK;
}

NS_IMETHODIMP
nsMathMLFrame::UpdatePresentationData(PRUint32        aFlagsValues,
                                      PRUint32        aWhichFlags)
{
  // update flags that are relevant to this call
  if (NS_MATHML_IS_DISPLAYSTYLE(aWhichFlags)) {
    // updating the displaystyle flag is allowed
    if (NS_MATHML_IS_DISPLAYSTYLE(aFlagsValues)) {
      mPresentationData.flags |= NS_MATHML_DISPLAYSTYLE;
    }
    else {
      mPresentationData.flags &= ~NS_MATHML_DISPLAYSTYLE;
    }
  }
  if (NS_MATHML_IS_COMPRESSED(aWhichFlags)) {
    // updating the compression flag is allowed
    if (NS_MATHML_IS_COMPRESSED(aFlagsValues)) {
      // 'compressed' means 'prime' style in App. G, TeXbook
      mPresentationData.flags |= NS_MATHML_COMPRESSED;
    }
    // no else. the flag is sticky. it retains its value once it is set
  }
  return NS_OK;
}

// Helper to give a style context suitable for doing the stretching of
// a MathMLChar. Frame classes that use this should ensure that the 
// extra leaf style contexts given to the MathMLChars are accessible to
// the Style System via the Get/Set AdditionalStyleContext() APIs.
/* static */ void
nsMathMLFrame::ResolveMathMLCharStyle(nsPresContext*  aPresContext,
                                      nsIContent*      aContent,
                                      nsStyleContext*  aParentStyleContext,
                                      nsMathMLChar*    aMathMLChar,
                                      PRBool           aIsMutableChar)
{
  nsCSSPseudoElements::Type pseudoType = (aIsMutableChar) ?
    nsCSSPseudoElements::ePseudo_mozMathStretchy :
    nsCSSPseudoElements::ePseudo_mozMathAnonymous; // savings
  nsRefPtr<nsStyleContext> newStyleContext;
  newStyleContext = aPresContext->StyleSet()->
    ResolvePseudoElementStyle(aContent->AsElement(), pseudoType,
                              aParentStyleContext);

  if (newStyleContext)
    aMathMLChar->SetStyleContext(newStyleContext);
}

/* static */ void
nsMathMLFrame::GetEmbellishDataFrom(nsIFrame*        aFrame,
                                    nsEmbellishData& aEmbellishData)
{
  // initialize OUT params
  aEmbellishData.flags = 0;
  aEmbellishData.coreFrame = nsnull;
  aEmbellishData.direction = NS_STRETCH_DIRECTION_UNSUPPORTED;
  aEmbellishData.leftSpace = 0;
  aEmbellishData.rightSpace = 0;

  if (aFrame && aFrame->IsFrameOfType(nsIFrame::eMathML)) {
    nsIMathMLFrame* mathMLFrame = do_QueryFrame(aFrame);
    if (mathMLFrame) {
      mathMLFrame->GetEmbellishData(aEmbellishData);
    }
  }
}

// helper to get the presentation data of a frame, by possibly walking up
// the frame hierarchy if we happen to be surrounded by non-MathML frames.
/* static */ void
nsMathMLFrame::GetPresentationDataFrom(nsIFrame*           aFrame,
                                       nsPresentationData& aPresentationData,
                                       PRBool              aClimbTree)
{
  // initialize OUT params
  aPresentationData.flags = 0;
  aPresentationData.baseFrame = nsnull;
  aPresentationData.mstyle = nsnull;

  nsIFrame* frame = aFrame;
  while (frame) {
    if (frame->IsFrameOfType(nsIFrame::eMathML)) {
      nsIMathMLFrame* mathMLFrame = do_QueryFrame(frame);
      if (mathMLFrame) {
        mathMLFrame->GetPresentationData(aPresentationData);
        break;
      }
    }
    // stop if the caller doesn't want to lookup beyond the frame
    if (!aClimbTree) {
      break;
    }
    // stop if we reach the root <math> tag
    nsIContent* content = frame->GetContent();
    NS_ASSERTION(content || !frame->GetParent(), // no assert for the root
                 "dangling frame without a content node"); 
    if (!content)
      break;

    if (content->Tag() == nsGkAtoms::math) {
      const nsStyleDisplay* display = frame->GetStyleDisplay();
      if (display->mDisplay == NS_STYLE_DISPLAY_BLOCK) {
        aPresentationData.flags |= NS_MATHML_DISPLAYSTYLE;
      }
      FindAttrDisplaystyle(content, aPresentationData);
      aPresentationData.mstyle = frame->GetFirstContinuation();
      break;
    }
    frame = frame->GetParent();
  }
  NS_WARN_IF_FALSE(frame && frame->GetContent(),
                   "bad MathML markup - could not find the top <math> element");
}

// helper to get an attribute from the content or the surrounding <mstyle> hierarchy
/* static */ PRBool
nsMathMLFrame::GetAttribute(nsIContent* aContent,
                            nsIFrame*   aMathMLmstyleFrame,
                            nsIAtom*    aAttributeAtom,
                            nsString&   aValue)
{
  // see if we can get the attribute from the content
  if (aContent && aContent->GetAttr(kNameSpaceID_None, aAttributeAtom,
                                    aValue)) {
    return PR_TRUE;
  }

  // see if we can get the attribute from the mstyle frame
  if (!aMathMLmstyleFrame) {
    return PR_FALSE;
  }

  nsIFrame* mstyleParent = aMathMLmstyleFrame->GetParent();

  nsPresentationData mstyleParentData;
  mstyleParentData.mstyle = nsnull;

  if (mstyleParent) {
    nsIMathMLFrame* mathMLFrame = do_QueryFrame(mstyleParent);
    if (mathMLFrame) {
      mathMLFrame->GetPresentationData(mstyleParentData);
    }
  }

  // recurse all the way up into the <mstyle> hierarchy
  return GetAttribute(aMathMLmstyleFrame->GetContent(),
                      mstyleParentData.mstyle, aAttributeAtom, aValue);
}

/* static */ void
nsMathMLFrame::GetRuleThickness(nsRenderingContext& aRenderingContext,
                                nsFontMetrics*      aFontMetrics,
                                nscoord&             aRuleThickness)
{
  // get the bounding metrics of the overbar char, the rendering context
  // is assumed to have been set with the font of the current style context
  NS_ASSERTION(aRenderingContext.FontMetrics()->Font().
               Equals(aFontMetrics->Font()),
               "unexpected state");

  nscoord xHeight = aFontMetrics->XHeight();
  PRUnichar overBar = 0x00AF;
  nsBoundingMetrics bm = aRenderingContext.GetBoundingMetrics(&overBar, 1);
  aRuleThickness = bm.ascent + bm.descent;
  if (aRuleThickness <= 0 || aRuleThickness >= xHeight) {
    // fall-back to the other version
    GetRuleThickness(aFontMetrics, aRuleThickness);
  }
}

/* static */ void
nsMathMLFrame::GetAxisHeight(nsRenderingContext& aRenderingContext,
                             nsFontMetrics*      aFontMetrics,
                             nscoord&             aAxisHeight)
{
  // get the bounding metrics of the minus sign, the rendering context
  // is assumed to have been set with the font of the current style context
  NS_ASSERTION(aRenderingContext.FontMetrics()->Font().
               Equals(aFontMetrics->Font()),
               "unexpected state");

  nscoord xHeight = aFontMetrics->XHeight();
  PRUnichar minus = 0x2212; // not '-', but official Unicode minus sign
  nsBoundingMetrics bm = aRenderingContext.GetBoundingMetrics(&minus, 1);
  aAxisHeight = bm.ascent - (bm.ascent + bm.descent)/2;
  if (aAxisHeight <= 0 || aAxisHeight >= xHeight) {
    // fall-back to the other version
    GetAxisHeight(aFontMetrics, aAxisHeight);
  }
}

/* static */ nscoord
nsMathMLFrame::CalcLength(nsPresContext*   aPresContext,
                          nsStyleContext*   aStyleContext,
                          const nsCSSValue& aCSSValue)
{
  NS_ASSERTION(aCSSValue.IsLengthUnit(), "not a length unit");

  if (aCSSValue.IsFixedLengthUnit()) {
    return aCSSValue.GetFixedLength(aPresContext);
  }
  if (aCSSValue.IsPixelLengthUnit()) {
    return aCSSValue.GetPixelLength();
  }

  nsCSSUnit unit = aCSSValue.GetUnit();

  if (eCSSUnit_EM == unit) {
    const nsStyleFont* font = aStyleContext->GetStyleFont();
    return NSToCoordRound(aCSSValue.GetFloatValue() * (float)font->mFont.size);
  }
  else if (eCSSUnit_XHeight == unit) {
    nsRefPtr<nsFontMetrics> fm;
    nsLayoutUtils::GetFontMetricsForStyleContext(aStyleContext,
                                                 getter_AddRefs(fm));
    nscoord xHeight = fm->XHeight();
    return NSToCoordRound(aCSSValue.GetFloatValue() * (float)xHeight);
  }

  // MathML doesn't specify other CSS units such as rem or ch
  NS_ERROR("Unsupported unit");
  return 0;
}

/* static */ PRBool
nsMathMLFrame::ParseNamedSpaceValue(nsIFrame*   aMathMLmstyleFrame,
                                    nsString&   aString,
                                    nsCSSValue& aCSSValue)
{
  aCSSValue.Reset();
  aString.CompressWhitespace(); //  aString is not a const in this code...
  if (!aString.Length()) return PR_FALSE;

  // See if it is one of the 'namedspace' (ranging 1/18em...7/18em)
  PRInt32 i = 0;
  nsIAtom* namedspaceAtom = nsnull;
  if (aString.EqualsLiteral("veryverythinmathspace")) {
    i = 1;
    namedspaceAtom = nsGkAtoms::veryverythinmathspace_;
  }
  else if (aString.EqualsLiteral("verythinmathspace")) {
    i = 2;
    namedspaceAtom = nsGkAtoms::verythinmathspace_;
  }
  else if (aString.EqualsLiteral("thinmathspace")) {
    i = 3;
    namedspaceAtom = nsGkAtoms::thinmathspace_;
  }
  else if (aString.EqualsLiteral("mediummathspace")) {
    i = 4;
    namedspaceAtom = nsGkAtoms::mediummathspace_;
  }
  else if (aString.EqualsLiteral("thickmathspace")) {
    i = 5;
    namedspaceAtom = nsGkAtoms::thickmathspace_;
  }
  else if (aString.EqualsLiteral("verythickmathspace")) {
    i = 6;
    namedspaceAtom = nsGkAtoms::verythickmathspace_;
  }
  else if (aString.EqualsLiteral("veryverythickmathspace")) {
    i = 7;
    namedspaceAtom = nsGkAtoms::veryverythickmathspace_;
  }
  else if (aString.EqualsLiteral("negativeveryverythinmathspace")) {
    i = -1;
    namedspaceAtom = nsGkAtoms::negativeveryverythinmathspace_;
  }
  else if (aString.EqualsLiteral("negativeverythinmathspace")) {
    i = -2;
    namedspaceAtom = nsGkAtoms::negativeverythinmathspace_;
  }
  else if (aString.EqualsLiteral("negativethinmathspace")) {
    i = -3;
    namedspaceAtom = nsGkAtoms::negativethinmathspace_;
  }
  else if (aString.EqualsLiteral("negativemediummathspace")) {
    i = -4;
    namedspaceAtom = nsGkAtoms::negativemediummathspace_;
  }
  else if (aString.EqualsLiteral("negativethickmathspace")) {
    i = -5;
    namedspaceAtom = nsGkAtoms::negativethickmathspace_;
  }
  else if (aString.EqualsLiteral("negativeverythickmathspace")) {
    i = -6;
    namedspaceAtom = nsGkAtoms::negativeverythickmathspace_;
  }
  else if (aString.EqualsLiteral("negativeveryverythickmathspace")) {
    i = -7;
    namedspaceAtom = nsGkAtoms::negativeveryverythickmathspace_;
  }

  if (0 != i) {
    if (aMathMLmstyleFrame) {
      // see if there is a <mstyle> that has overriden the default value
      // GetAttribute() will recurse all the way up into the <mstyle> hierarchy
      nsAutoString value;
      GetAttribute(nsnull, aMathMLmstyleFrame, namedspaceAtom, value);
      if (!value.IsEmpty()) {
        if (ParseNumericValue(value, aCSSValue) &&
            aCSSValue.IsLengthUnit()) {
          return PR_TRUE;
        }
      }
    }

    // fall back to the default value
    aCSSValue.SetFloatValue(float(i)/float(18), eCSSUnit_EM);
    return PR_TRUE;
  }

  return PR_FALSE;
}

// ================
// Utils to map attributes into CSS rules (work-around to bug 69409 which
// is not scheduled to be fixed anytime soon)
//

static const PRInt32 kMathMLversion1 = 1;
static const PRInt32 kMathMLversion2 = 2;

struct
nsCSSMapping {
  PRInt32        compatibility;
  const nsIAtom* attrAtom;
  const char*    cssProperty;
};

#if defined(NS_DEBUG) && defined(SHOW_BOUNDING_BOX)
class nsDisplayMathMLBoundingMetrics : public nsDisplayItem {
public:
  nsDisplayMathMLBoundingMetrics(nsDisplayListBuilder* aBuilder,
                                 nsIFrame* aFrame, const nsRect& aRect)
    : nsDisplayItem(aBuilder, aFrame), mRect(aRect) {
    MOZ_COUNT_CTOR(nsDisplayMathMLBoundingMetrics);
  }
#ifdef NS_BUILD_REFCNT_LOGGING
  virtual ~nsDisplayMathMLBoundingMetrics() {
    MOZ_COUNT_DTOR(nsDisplayMathMLBoundingMetrics);
  }
#endif

  virtual void Paint(nsDisplayListBuilder* aBuilder,
                     nsRenderingContext* aCtx);
  NS_DISPLAY_DECL_NAME("MathMLBoundingMetrics", TYPE_MATHML_BOUNDING_METRICS)
private:
  nsRect    mRect;
};

void nsDisplayMathMLBoundingMetrics::Paint(nsDisplayListBuilder* aBuilder,
                                           nsRenderingContext* aCtx)
{
  aCtx->SetColor(NS_RGB(0,0,255));
  aCtx->DrawRect(mRect + ToReferenceFrame());
}

nsresult
nsMathMLFrame::DisplayBoundingMetrics(nsDisplayListBuilder* aBuilder,
                                      nsIFrame* aFrame, const nsPoint& aPt,
                                      const nsBoundingMetrics& aMetrics,
                                      const nsDisplayListSet& aLists) {
  if (!NS_MATHML_PAINT_BOUNDING_METRICS(mPresentationData.flags))
    return NS_OK;
    
  nscoord x = aPt.x + aMetrics.leftBearing;
  nscoord y = aPt.y - aMetrics.ascent;
  nscoord w = aMetrics.rightBearing - aMetrics.leftBearing;
  nscoord h = aMetrics.ascent + aMetrics.descent;

  return aLists.Content()->AppendNewToTop(new (aBuilder)
      nsDisplayMathMLBoundingMetrics(aBuilder, this, nsRect(x,y,w,h)));
}
#endif

class nsDisplayMathMLBar : public nsDisplayItem {
public:
  nsDisplayMathMLBar(nsDisplayListBuilder* aBuilder,
                     nsIFrame* aFrame, const nsRect& aRect)
    : nsDisplayItem(aBuilder, aFrame), mRect(aRect) {
    MOZ_COUNT_CTOR(nsDisplayMathMLBar);
  }
#ifdef NS_BUILD_REFCNT_LOGGING
  virtual ~nsDisplayMathMLBar() {
    MOZ_COUNT_DTOR(nsDisplayMathMLBar);
  }
#endif

  virtual void Paint(nsDisplayListBuilder* aBuilder,
                     nsRenderingContext* aCtx);
  NS_DISPLAY_DECL_NAME("MathMLBar", TYPE_MATHML_BAR)
private:
  nsRect    mRect;
};

void nsDisplayMathMLBar::Paint(nsDisplayListBuilder* aBuilder,
                               nsRenderingContext* aCtx)
{
  // paint the bar with the current text color
  aCtx->SetColor(mFrame->GetStyleColor()->mColor);
  aCtx->FillRect(mRect + ToReferenceFrame());
}

nsresult
nsMathMLFrame::DisplayBar(nsDisplayListBuilder* aBuilder,
                          nsIFrame* aFrame, const nsRect& aRect,
                          const nsDisplayListSet& aLists) {
  if (!aFrame->GetStyleVisibility()->IsVisible() || aRect.IsEmpty())
    return NS_OK;

  return aLists.Content()->AppendNewToTop(new (aBuilder)
      nsDisplayMathMLBar(aBuilder, aFrame, aRect));
}