The Tor Browser: layout/mathml/nsMathMLmrootFrame.cpp@8bccb770b82d

     1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */

     2 /* This Source Code Form is subject to the terms of the Mozilla Public

     3  * License, v. 2.0. If a copy of the MPL was not distributed with this

     4  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

     6 #include "nsMathMLmrootFrame.h"

     7 #include "nsPresContext.h"

     8 #include "nsRenderingContext.h"

     9 #include <algorithm>

    11 //

    12 // <msqrt> and <mroot> -- form a radical - implementation

    13 //

    15 //NOTE:

    16 //  The code assumes that TeX fonts are picked.

    17 //  There is no fall-back to draw the branches of the sqrt explicitly

    18 //  in the case where TeX fonts are not there. In general, there are no

    19 //  fall-back(s) in MathML when some (freely-downloadable) fonts are missing.

    20 //  Otherwise, this will add much work and unnecessary complexity to the core

    21 //  MathML  engine. Assuming that authors have the free fonts is part of the

    22 //  deal. We are not responsible for cases of misconfigurations out there.

    24 // additional style context to be used by our MathMLChar.

    25 #define NS_SQR_CHAR_STYLE_CONTEXT_INDEX   0

    27 static const char16_t kSqrChar = char16_t(0x221A);

    29 nsIFrame*

    30 NS_NewMathMLmrootFrame(nsIPresShell* aPresShell, nsStyleContext* aContext)

    31 {

    32   return new (aPresShell) nsMathMLmrootFrame(aContext);

    33 }

    35 NS_IMPL_FRAMEARENA_HELPERS(nsMathMLmrootFrame)

    37 nsMathMLmrootFrame::nsMathMLmrootFrame(nsStyleContext* aContext) :

    38   nsMathMLContainerFrame(aContext),

    39   mSqrChar(),

    40   mBarRect()

    41 {

    42 }

    44 nsMathMLmrootFrame::~nsMathMLmrootFrame()

    45 {

    46 }

    48 void

    49 nsMathMLmrootFrame::Init(nsIContent*      aContent,

    50                          nsIFrame*        aParent,

    51                          nsIFrame*        aPrevInFlow)

    52 {

    53   nsMathMLContainerFrame::Init(aContent, aParent, aPrevInFlow);

    55   nsPresContext *presContext = PresContext();

    57   // No need to track the style context given to our MathML char.

    58   // The Style System will use Get/SetAdditionalStyleContext() to keep it

    59   // up-to-date if dynamic changes arise.

    60   nsAutoString sqrChar; sqrChar.Assign(kSqrChar);

    61   mSqrChar.SetData(presContext, sqrChar);

    62   ResolveMathMLCharStyle(presContext, mContent, mStyleContext, &mSqrChar);

    63 }

    65 NS_IMETHODIMP

    66 nsMathMLmrootFrame::TransmitAutomaticData()

    67 {

    68   // 1. The REC says:

    69   //    The <mroot> element increments scriptlevel by 2, and sets displaystyle to

    70   //    "false", within index, but leaves both attributes unchanged within base.

    71   // 2. The TeXbook (Ch 17. p.141) says \sqrt is compressed

    72   UpdatePresentationDataFromChildAt(1, 1,

    73                                     NS_MATHML_COMPRESSED,

    74                                     NS_MATHML_COMPRESSED);

    75   UpdatePresentationDataFromChildAt(0, 0,

    76      NS_MATHML_COMPRESSED, NS_MATHML_COMPRESSED);

    78   PropagateFrameFlagFor(mFrames.LastChild(),

    79                         NS_FRAME_MATHML_SCRIPT_DESCENDANT);

    81   return NS_OK;

    82 }

    84 void

    85 nsMathMLmrootFrame::BuildDisplayList(nsDisplayListBuilder*   aBuilder,

    86                                      const nsRect&           aDirtyRect,

    87                                      const nsDisplayListSet& aLists)

    88 {

    89   /////////////

    90   // paint the content we are square-rooting

    91   nsMathMLContainerFrame::BuildDisplayList(aBuilder, aDirtyRect, aLists);

    93   /////////////

    94   // paint the sqrt symbol

    95   if (!NS_MATHML_HAS_ERROR(mPresentationData.flags)) {

    96     mSqrChar.Display(aBuilder, this, aLists, 0);

    98     DisplayBar(aBuilder, this, mBarRect, aLists);

   100 #if defined(DEBUG) && defined(SHOW_BOUNDING_BOX)

   101     // for visual debug

   102     nsRect rect;

   103     mSqrChar.GetRect(rect);

   104     nsBoundingMetrics bm;

   105     mSqrChar.GetBoundingMetrics(bm);

   106     DisplayBoundingMetrics(aBuilder, this, rect.TopLeft(), bm, aLists);

   107 #endif

   108   }

   109 }

   111 static void

   112 GetRadicalXOffsets(nscoord aIndexWidth, nscoord aSqrWidth,

   113                    nsFontMetrics* aFontMetrics,

   114                    nscoord* aIndexOffset, nscoord* aSqrOffset)

   115 {

   116   // The index is tucked in closer to the radical while making sure

   117   // that the kern does not make the index and radical collide

   118   nscoord dxIndex, dxSqr;

   119   nscoord xHeight = aFontMetrics->XHeight();

   120   nscoord indexRadicalKern = NSToCoordRound(1.35f * xHeight);

   121   if (indexRadicalKern > aIndexWidth) {

   122     dxIndex = indexRadicalKern - aIndexWidth;

   123     dxSqr = 0;

   124   }

   125   else {

   126     dxIndex = 0;

   127     dxSqr = aIndexWidth - indexRadicalKern;

   128   }

   129   // avoid collision by leaving a minimum space between index and radical

   130   nscoord minimumClearance = aSqrWidth/2;

   131   if (dxIndex + aIndexWidth + minimumClearance > dxSqr + aSqrWidth) {

   132     if (aIndexWidth + minimumClearance < aSqrWidth) {

   133       dxIndex = aSqrWidth - (aIndexWidth + minimumClearance);

   134       dxSqr = 0;

   135     }

   136     else {

   137       dxIndex = 0;

   138       dxSqr = (aIndexWidth + minimumClearance) - aSqrWidth;

   139     }

   140   }

   142   if (aIndexOffset)

   143     *aIndexOffset = dxIndex;

   144   if (aSqrOffset)

   145     *aSqrOffset = dxSqr;

   146 }

   148 nsresult

   149 nsMathMLmrootFrame::Reflow(nsPresContext*          aPresContext,

   150                            nsHTMLReflowMetrics&     aDesiredSize,

   151                            const nsHTMLReflowState& aReflowState,

   152                            nsReflowStatus&          aStatus)

   153 {

   154   nsresult rv = NS_OK;

   155   nsSize availSize(aReflowState.ComputedWidth(), NS_UNCONSTRAINEDSIZE);

   156   nsReflowStatus childStatus;

   158   aDesiredSize.Width() = aDesiredSize.Height() = 0;

   159   aDesiredSize.SetTopAscent(0);

   161   nsBoundingMetrics bmSqr, bmBase, bmIndex;

   162   nsRenderingContext& renderingContext = *aReflowState.rendContext;

   164   //////////////////

   165   // Reflow Children

   167   int32_t count = 0;

   168   nsIFrame* baseFrame = nullptr;

   169   nsIFrame* indexFrame = nullptr;

   170   nsHTMLReflowMetrics baseSize(aReflowState);

   171   nsHTMLReflowMetrics indexSize(aReflowState);

   172   nsIFrame* childFrame = mFrames.FirstChild();

   173   while (childFrame) {

   174     // ask our children to compute their bounding metrics

   175     nsHTMLReflowMetrics childDesiredSize(aReflowState,

   176                                          aDesiredSize.mFlags

   177                                          | NS_REFLOW_CALC_BOUNDING_METRICS);

   178     nsHTMLReflowState childReflowState(aPresContext, aReflowState,

   179                                        childFrame, availSize);

   180     rv = ReflowChild(childFrame, aPresContext,

   181                      childDesiredSize, childReflowState, childStatus);

   182     //NS_ASSERTION(NS_FRAME_IS_COMPLETE(childStatus), "bad status");

   183     if (NS_FAILED(rv)) {

   184       // Call DidReflow() for the child frames we successfully did reflow.

   185       DidReflowChildren(mFrames.FirstChild(), childFrame);

   186       return rv;

   187     }

   188     if (0 == count) {

   189       // base

   190       baseFrame = childFrame;

   191       baseSize = childDesiredSize;

   192       bmBase = childDesiredSize.mBoundingMetrics;

   193     }

   194     else if (1 == count) {

   195       // index

   196       indexFrame = childFrame;

   197       indexSize = childDesiredSize;

   198       bmIndex = childDesiredSize.mBoundingMetrics;

   199     }

   200     count++;

   201     childFrame = childFrame->GetNextSibling();

   202   }

   203   if (2 != count) {

   204     // report an error, encourage people to get their markups in order

   205     ReportChildCountError();

   206     rv = ReflowError(renderingContext, aDesiredSize);

   207     aStatus = NS_FRAME_COMPLETE;

   208     NS_FRAME_SET_TRUNCATION(aStatus, aReflowState, aDesiredSize);

   209     // Call DidReflow() for the child frames we successfully did reflow.

   210     DidReflowChildren(mFrames.FirstChild(), childFrame);

   211     return rv;

   212   }

   214   ////////////

   215   // Prepare the radical symbol and the overline bar

   217   nsRefPtr<nsFontMetrics> fm;

   218   nsLayoutUtils::GetFontMetricsForFrame(this, getter_AddRefs(fm));

   219   renderingContext.SetFont(fm);

   221   // For radical glyphs from TeX fonts and some of the radical glyphs from

   222   // Mathematica fonts, the thickness of the overline can be obtained from the

   223   // ascent of the glyph.  Most fonts however have radical glyphs above the

   224   // baseline so no assumption can be made about the meaning of the ascent.

   225   nscoord ruleThickness, leading, em;

   226   GetRuleThickness(renderingContext, fm, ruleThickness);

   228   char16_t one = '1';

   229   nsBoundingMetrics bmOne = renderingContext.GetBoundingMetrics(&one, 1);

   231   // get the leading to be left at the top of the resulting frame

   232   // this seems more reliable than using fm->GetLeading() on suspicious fonts

   233   GetEmHeight(fm, em);

   234   leading = nscoord(0.2f * em);

   236   // Rule 11, App. G, TeXbook

   237   // psi = clearance between rule and content

   238   nscoord phi = 0, psi = 0;

   239   if (StyleFont()->mMathDisplay == NS_MATHML_DISPLAYSTYLE_BLOCK)

   240     phi = fm->XHeight();

   241   else

   242     phi = ruleThickness;

   243   psi = ruleThickness + phi/4;

   245   // built-in: adjust clearance psi to emulate \mathstrut using '1' (TexBook, p.131)

   246   if (bmOne.ascent > bmBase.ascent)

   247     psi += bmOne.ascent - bmBase.ascent;

   249   // make sure that the rule appears on on screen

   250   nscoord onePixel = nsPresContext::CSSPixelsToAppUnits(1);

   251   if (ruleThickness < onePixel) {

   252     ruleThickness = onePixel;

   253   }

   255   // adjust clearance psi to get an exact number of pixels -- this

   256   // gives a nicer & uniform look on stacked radicals (bug 130282)

   257   nscoord delta = psi % onePixel;

   258   if (delta)

   259     psi += onePixel - delta; // round up

   261   // Stretch the radical symbol to the appropriate height if it is not big enough.

   262   nsBoundingMetrics contSize = bmBase;

   263   contSize.descent = bmBase.ascent + bmBase.descent + psi;

   264   contSize.ascent = ruleThickness;

   266   // height(radical) should be >= height(base) + psi + ruleThickness

   267   nsBoundingMetrics radicalSize;

   268   mSqrChar.Stretch(aPresContext, renderingContext,

   269                    NS_STRETCH_DIRECTION_VERTICAL,

   270                    contSize, radicalSize,

   271                    NS_STRETCH_LARGER,

   272                    StyleVisibility()->mDirection);

   273   // radicalSize have changed at this point, and should match with

   274   // the bounding metrics of the char

   275   mSqrChar.GetBoundingMetrics(bmSqr);

   277   // Update the desired size for the container (like msqrt, index is not yet included)

   278   // the baseline will be that of the base.

   279   mBoundingMetrics.ascent = bmBase.ascent + psi + ruleThickness;

   280   mBoundingMetrics.descent =

   281     std::max(bmBase.descent,

   282            (bmSqr.ascent + bmSqr.descent - mBoundingMetrics.ascent));

   283   mBoundingMetrics.width = bmSqr.width + bmBase.width;

   284   mBoundingMetrics.leftBearing = bmSqr.leftBearing;

   285   mBoundingMetrics.rightBearing = bmSqr.width +

   286     std::max(bmBase.width, bmBase.rightBearing); // take also care of the rule

   288   aDesiredSize.SetTopAscent(mBoundingMetrics.ascent + leading);

   289   aDesiredSize.Height() = aDesiredSize.TopAscent() +

   290     std::max(baseSize.Height() - baseSize.TopAscent(),

   291            mBoundingMetrics.descent + ruleThickness);

   292   aDesiredSize.Width() = mBoundingMetrics.width;

   294   /////////////

   295   // Re-adjust the desired size to include the index.

   297   // the index is raised by some fraction of the height

   298   // of the radical, see \mroot macro in App. B, TexBook

   299   nscoord raiseIndexDelta = NSToCoordRound(0.6f * (bmSqr.ascent + bmSqr.descent));

   300   nscoord indexRaisedAscent = mBoundingMetrics.ascent // top of radical

   301     - (bmSqr.ascent + bmSqr.descent) // to bottom of radical

   302     + raiseIndexDelta + bmIndex.ascent + bmIndex.descent; // to top of raised index

   304   nscoord indexClearance = 0;

   305   if (mBoundingMetrics.ascent < indexRaisedAscent) {

   306     indexClearance =

   307       indexRaisedAscent - mBoundingMetrics.ascent; // excess gap introduced by a tall index

   308     mBoundingMetrics.ascent = indexRaisedAscent;

   309     nscoord descent = aDesiredSize.Height() - aDesiredSize.TopAscent();

   310     aDesiredSize.SetTopAscent(mBoundingMetrics.ascent + leading);

   311     aDesiredSize.Height() = aDesiredSize.TopAscent() + descent;

   312   }

   314   nscoord dxIndex, dxSqr;

   315   GetRadicalXOffsets(bmIndex.width, bmSqr.width, fm, &dxIndex, &dxSqr);

   317   mBoundingMetrics.width = dxSqr + bmSqr.width + bmBase.width;

   318   mBoundingMetrics.leftBearing =

   319     std::min(dxIndex + bmIndex.leftBearing, dxSqr + bmSqr.leftBearing);

   320   mBoundingMetrics.rightBearing = dxSqr + bmSqr.width +

   321     std::max(bmBase.width, bmBase.rightBearing);

   323   aDesiredSize.Width() = mBoundingMetrics.width;

   324   aDesiredSize.mBoundingMetrics = mBoundingMetrics;

   325   GatherAndStoreOverflow(&aDesiredSize);

   327   // place the index

   328   nscoord dx = dxIndex;

   329   nscoord dy = aDesiredSize.TopAscent() - (indexRaisedAscent + indexSize.TopAscent() - bmIndex.ascent);

   330   FinishReflowChild(indexFrame, aPresContext, indexSize, nullptr,

   331                     MirrorIfRTL(aDesiredSize.Width(), indexSize.Width(), dx),

   332                     dy, 0);

   334   // place the radical symbol and the radical bar

   335   dx = dxSqr;

   336   dy = indexClearance + leading; // leave a leading at the top

   337   mSqrChar.SetRect(nsRect(MirrorIfRTL(aDesiredSize.Width(), bmSqr.width, dx),

   338                           dy, bmSqr.width, bmSqr.ascent + bmSqr.descent));

   339   dx += bmSqr.width;

   340   mBarRect.SetRect(MirrorIfRTL(aDesiredSize.Width(), bmBase.width, dx),

   341                    dy, bmBase.width, ruleThickness);

   343   // place the base

   344   dy = aDesiredSize.TopAscent() - baseSize.TopAscent();

   345   FinishReflowChild(baseFrame, aPresContext, baseSize, nullptr,

   346                     MirrorIfRTL(aDesiredSize.Width(), baseSize.Width(), dx),

   347                     dy, 0);

   349   mReference.x = 0;

   350   mReference.y = aDesiredSize.TopAscent();

   352   aStatus = NS_FRAME_COMPLETE;

   353   NS_FRAME_SET_TRUNCATION(aStatus, aReflowState, aDesiredSize);

   354   return NS_OK;

   355 }

   357 /* virtual */ void

   358 nsMathMLmrootFrame::GetIntrinsicWidthMetrics(nsRenderingContext* aRenderingContext, nsHTMLReflowMetrics& aDesiredSize)

   359 {

   360   nsIFrame* baseFrame = mFrames.FirstChild();

   361   nsIFrame* indexFrame = nullptr;

   362   if (baseFrame)

   363     indexFrame = baseFrame->GetNextSibling();

   364   if (!indexFrame || indexFrame->GetNextSibling()) {

   365     ReflowError(*aRenderingContext, aDesiredSize);

   366     return;

   367   }

   369   nscoord baseWidth =

   370     nsLayoutUtils::IntrinsicForContainer(aRenderingContext, baseFrame,

   371                                          nsLayoutUtils::PREF_WIDTH);

   372   nscoord indexWidth =

   373     nsLayoutUtils::IntrinsicForContainer(aRenderingContext, indexFrame,

   374                                          nsLayoutUtils::PREF_WIDTH);

   375   nscoord sqrWidth = mSqrChar.GetMaxWidth(PresContext(), *aRenderingContext);

   377   nscoord dxSqr;

   378   nsRefPtr<nsFontMetrics> fm;

   379   nsLayoutUtils::GetFontMetricsForFrame(this, getter_AddRefs(fm));

   380   GetRadicalXOffsets(indexWidth, sqrWidth, fm, nullptr, &dxSqr);

   382   nscoord width = dxSqr + sqrWidth + baseWidth;

   384   aDesiredSize.Width() = width;

   385   aDesiredSize.mBoundingMetrics.width = width;

   386   aDesiredSize.mBoundingMetrics.leftBearing = 0;

   387   aDesiredSize.mBoundingMetrics.rightBearing = width;

   388 }

   390 // ----------------------

   391 // the Style System will use these to pass the proper style context to our MathMLChar

   392 nsStyleContext*

   393 nsMathMLmrootFrame::GetAdditionalStyleContext(int32_t aIndex) const

   394 {

   395   switch (aIndex) {

   396   case NS_SQR_CHAR_STYLE_CONTEXT_INDEX:

   397     return mSqrChar.GetStyleContext();

   398     break;

   399   default:

   400     return nullptr;

   401   }

   402 }

   404 void

   405 nsMathMLmrootFrame::SetAdditionalStyleContext(int32_t          aIndex,

   406                                               nsStyleContext*  aStyleContext)

   407 {

   408   switch (aIndex) {

   409   case NS_SQR_CHAR_STYLE_CONTEXT_INDEX:

   410     mSqrChar.SetStyleContext(aStyleContext);

   411     break;

   412   }

   413 }

The Tor Browser / file revision

layout/mathml/nsMathMLmrootFrame.cpp@8bccb770b82d

layout/mathml/nsMathMLmrootFrame.cpp