1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/layout/mathml/nsMathMLmrootFrame.cpp Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,413 @@
1.4 +/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
1.5 +/* This Source Code Form is subject to the terms of the Mozilla Public
1.6 + * License, v. 2.0. If a copy of the MPL was not distributed with this
1.7 + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
1.8 +
1.9 +#include "nsMathMLmrootFrame.h"
1.10 +#include "nsPresContext.h"
1.11 +#include "nsRenderingContext.h"
1.12 +#include <algorithm>
1.13 +
1.14 +//
1.15 +// <msqrt> and <mroot> -- form a radical - implementation
1.16 +//
1.17 +
1.18 +//NOTE:
1.19 +// The code assumes that TeX fonts are picked.
1.20 +// There is no fall-back to draw the branches of the sqrt explicitly
1.21 +// in the case where TeX fonts are not there. In general, there are no
1.22 +// fall-back(s) in MathML when some (freely-downloadable) fonts are missing.
1.23 +// Otherwise, this will add much work and unnecessary complexity to the core
1.24 +// MathML engine. Assuming that authors have the free fonts is part of the
1.25 +// deal. We are not responsible for cases of misconfigurations out there.
1.26 +
1.27 +// additional style context to be used by our MathMLChar.
1.28 +#define NS_SQR_CHAR_STYLE_CONTEXT_INDEX 0
1.29 +
1.30 +static const char16_t kSqrChar = char16_t(0x221A);
1.31 +
1.32 +nsIFrame*
1.33 +NS_NewMathMLmrootFrame(nsIPresShell* aPresShell, nsStyleContext* aContext)
1.34 +{
1.35 + return new (aPresShell) nsMathMLmrootFrame(aContext);
1.36 +}
1.37 +
1.38 +NS_IMPL_FRAMEARENA_HELPERS(nsMathMLmrootFrame)
1.39 +
1.40 +nsMathMLmrootFrame::nsMathMLmrootFrame(nsStyleContext* aContext) :
1.41 + nsMathMLContainerFrame(aContext),
1.42 + mSqrChar(),
1.43 + mBarRect()
1.44 +{
1.45 +}
1.46 +
1.47 +nsMathMLmrootFrame::~nsMathMLmrootFrame()
1.48 +{
1.49 +}
1.50 +
1.51 +void
1.52 +nsMathMLmrootFrame::Init(nsIContent* aContent,
1.53 + nsIFrame* aParent,
1.54 + nsIFrame* aPrevInFlow)
1.55 +{
1.56 + nsMathMLContainerFrame::Init(aContent, aParent, aPrevInFlow);
1.57 +
1.58 + nsPresContext *presContext = PresContext();
1.59 +
1.60 + // No need to track the style context given to our MathML char.
1.61 + // The Style System will use Get/SetAdditionalStyleContext() to keep it
1.62 + // up-to-date if dynamic changes arise.
1.63 + nsAutoString sqrChar; sqrChar.Assign(kSqrChar);
1.64 + mSqrChar.SetData(presContext, sqrChar);
1.65 + ResolveMathMLCharStyle(presContext, mContent, mStyleContext, &mSqrChar);
1.66 +}
1.67 +
1.68 +NS_IMETHODIMP
1.69 +nsMathMLmrootFrame::TransmitAutomaticData()
1.70 +{
1.71 + // 1. The REC says:
1.72 + // The <mroot> element increments scriptlevel by 2, and sets displaystyle to
1.73 + // "false", within index, but leaves both attributes unchanged within base.
1.74 + // 2. The TeXbook (Ch 17. p.141) says \sqrt is compressed
1.75 + UpdatePresentationDataFromChildAt(1, 1,
1.76 + NS_MATHML_COMPRESSED,
1.77 + NS_MATHML_COMPRESSED);
1.78 + UpdatePresentationDataFromChildAt(0, 0,
1.79 + NS_MATHML_COMPRESSED, NS_MATHML_COMPRESSED);
1.80 +
1.81 + PropagateFrameFlagFor(mFrames.LastChild(),
1.82 + NS_FRAME_MATHML_SCRIPT_DESCENDANT);
1.83 +
1.84 + return NS_OK;
1.85 +}
1.86 +
1.87 +void
1.88 +nsMathMLmrootFrame::BuildDisplayList(nsDisplayListBuilder* aBuilder,
1.89 + const nsRect& aDirtyRect,
1.90 + const nsDisplayListSet& aLists)
1.91 +{
1.92 + /////////////
1.93 + // paint the content we are square-rooting
1.94 + nsMathMLContainerFrame::BuildDisplayList(aBuilder, aDirtyRect, aLists);
1.95 +
1.96 + /////////////
1.97 + // paint the sqrt symbol
1.98 + if (!NS_MATHML_HAS_ERROR(mPresentationData.flags)) {
1.99 + mSqrChar.Display(aBuilder, this, aLists, 0);
1.100 +
1.101 + DisplayBar(aBuilder, this, mBarRect, aLists);
1.102 +
1.103 +#if defined(DEBUG) && defined(SHOW_BOUNDING_BOX)
1.104 + // for visual debug
1.105 + nsRect rect;
1.106 + mSqrChar.GetRect(rect);
1.107 + nsBoundingMetrics bm;
1.108 + mSqrChar.GetBoundingMetrics(bm);
1.109 + DisplayBoundingMetrics(aBuilder, this, rect.TopLeft(), bm, aLists);
1.110 +#endif
1.111 + }
1.112 +}
1.113 +
1.114 +static void
1.115 +GetRadicalXOffsets(nscoord aIndexWidth, nscoord aSqrWidth,
1.116 + nsFontMetrics* aFontMetrics,
1.117 + nscoord* aIndexOffset, nscoord* aSqrOffset)
1.118 +{
1.119 + // The index is tucked in closer to the radical while making sure
1.120 + // that the kern does not make the index and radical collide
1.121 + nscoord dxIndex, dxSqr;
1.122 + nscoord xHeight = aFontMetrics->XHeight();
1.123 + nscoord indexRadicalKern = NSToCoordRound(1.35f * xHeight);
1.124 + if (indexRadicalKern > aIndexWidth) {
1.125 + dxIndex = indexRadicalKern - aIndexWidth;
1.126 + dxSqr = 0;
1.127 + }
1.128 + else {
1.129 + dxIndex = 0;
1.130 + dxSqr = aIndexWidth - indexRadicalKern;
1.131 + }
1.132 + // avoid collision by leaving a minimum space between index and radical
1.133 + nscoord minimumClearance = aSqrWidth/2;
1.134 + if (dxIndex + aIndexWidth + minimumClearance > dxSqr + aSqrWidth) {
1.135 + if (aIndexWidth + minimumClearance < aSqrWidth) {
1.136 + dxIndex = aSqrWidth - (aIndexWidth + minimumClearance);
1.137 + dxSqr = 0;
1.138 + }
1.139 + else {
1.140 + dxIndex = 0;
1.141 + dxSqr = (aIndexWidth + minimumClearance) - aSqrWidth;
1.142 + }
1.143 + }
1.144 +
1.145 + if (aIndexOffset)
1.146 + *aIndexOffset = dxIndex;
1.147 + if (aSqrOffset)
1.148 + *aSqrOffset = dxSqr;
1.149 +}
1.150 +
1.151 +nsresult
1.152 +nsMathMLmrootFrame::Reflow(nsPresContext* aPresContext,
1.153 + nsHTMLReflowMetrics& aDesiredSize,
1.154 + const nsHTMLReflowState& aReflowState,
1.155 + nsReflowStatus& aStatus)
1.156 +{
1.157 + nsresult rv = NS_OK;
1.158 + nsSize availSize(aReflowState.ComputedWidth(), NS_UNCONSTRAINEDSIZE);
1.159 + nsReflowStatus childStatus;
1.160 +
1.161 + aDesiredSize.Width() = aDesiredSize.Height() = 0;
1.162 + aDesiredSize.SetTopAscent(0);
1.163 +
1.164 + nsBoundingMetrics bmSqr, bmBase, bmIndex;
1.165 + nsRenderingContext& renderingContext = *aReflowState.rendContext;
1.166 +
1.167 + //////////////////
1.168 + // Reflow Children
1.169 +
1.170 + int32_t count = 0;
1.171 + nsIFrame* baseFrame = nullptr;
1.172 + nsIFrame* indexFrame = nullptr;
1.173 + nsHTMLReflowMetrics baseSize(aReflowState);
1.174 + nsHTMLReflowMetrics indexSize(aReflowState);
1.175 + nsIFrame* childFrame = mFrames.FirstChild();
1.176 + while (childFrame) {
1.177 + // ask our children to compute their bounding metrics
1.178 + nsHTMLReflowMetrics childDesiredSize(aReflowState,
1.179 + aDesiredSize.mFlags
1.180 + | NS_REFLOW_CALC_BOUNDING_METRICS);
1.181 + nsHTMLReflowState childReflowState(aPresContext, aReflowState,
1.182 + childFrame, availSize);
1.183 + rv = ReflowChild(childFrame, aPresContext,
1.184 + childDesiredSize, childReflowState, childStatus);
1.185 + //NS_ASSERTION(NS_FRAME_IS_COMPLETE(childStatus), "bad status");
1.186 + if (NS_FAILED(rv)) {
1.187 + // Call DidReflow() for the child frames we successfully did reflow.
1.188 + DidReflowChildren(mFrames.FirstChild(), childFrame);
1.189 + return rv;
1.190 + }
1.191 + if (0 == count) {
1.192 + // base
1.193 + baseFrame = childFrame;
1.194 + baseSize = childDesiredSize;
1.195 + bmBase = childDesiredSize.mBoundingMetrics;
1.196 + }
1.197 + else if (1 == count) {
1.198 + // index
1.199 + indexFrame = childFrame;
1.200 + indexSize = childDesiredSize;
1.201 + bmIndex = childDesiredSize.mBoundingMetrics;
1.202 + }
1.203 + count++;
1.204 + childFrame = childFrame->GetNextSibling();
1.205 + }
1.206 + if (2 != count) {
1.207 + // report an error, encourage people to get their markups in order
1.208 + ReportChildCountError();
1.209 + rv = ReflowError(renderingContext, aDesiredSize);
1.210 + aStatus = NS_FRAME_COMPLETE;
1.211 + NS_FRAME_SET_TRUNCATION(aStatus, aReflowState, aDesiredSize);
1.212 + // Call DidReflow() for the child frames we successfully did reflow.
1.213 + DidReflowChildren(mFrames.FirstChild(), childFrame);
1.214 + return rv;
1.215 + }
1.216 +
1.217 + ////////////
1.218 + // Prepare the radical symbol and the overline bar
1.219 +
1.220 + nsRefPtr<nsFontMetrics> fm;
1.221 + nsLayoutUtils::GetFontMetricsForFrame(this, getter_AddRefs(fm));
1.222 + renderingContext.SetFont(fm);
1.223 +
1.224 + // For radical glyphs from TeX fonts and some of the radical glyphs from
1.225 + // Mathematica fonts, the thickness of the overline can be obtained from the
1.226 + // ascent of the glyph. Most fonts however have radical glyphs above the
1.227 + // baseline so no assumption can be made about the meaning of the ascent.
1.228 + nscoord ruleThickness, leading, em;
1.229 + GetRuleThickness(renderingContext, fm, ruleThickness);
1.230 +
1.231 + char16_t one = '1';
1.232 + nsBoundingMetrics bmOne = renderingContext.GetBoundingMetrics(&one, 1);
1.233 +
1.234 + // get the leading to be left at the top of the resulting frame
1.235 + // this seems more reliable than using fm->GetLeading() on suspicious fonts
1.236 + GetEmHeight(fm, em);
1.237 + leading = nscoord(0.2f * em);
1.238 +
1.239 + // Rule 11, App. G, TeXbook
1.240 + // psi = clearance between rule and content
1.241 + nscoord phi = 0, psi = 0;
1.242 + if (StyleFont()->mMathDisplay == NS_MATHML_DISPLAYSTYLE_BLOCK)
1.243 + phi = fm->XHeight();
1.244 + else
1.245 + phi = ruleThickness;
1.246 + psi = ruleThickness + phi/4;
1.247 +
1.248 + // built-in: adjust clearance psi to emulate \mathstrut using '1' (TexBook, p.131)
1.249 + if (bmOne.ascent > bmBase.ascent)
1.250 + psi += bmOne.ascent - bmBase.ascent;
1.251 +
1.252 + // make sure that the rule appears on on screen
1.253 + nscoord onePixel = nsPresContext::CSSPixelsToAppUnits(1);
1.254 + if (ruleThickness < onePixel) {
1.255 + ruleThickness = onePixel;
1.256 + }
1.257 +
1.258 + // adjust clearance psi to get an exact number of pixels -- this
1.259 + // gives a nicer & uniform look on stacked radicals (bug 130282)
1.260 + nscoord delta = psi % onePixel;
1.261 + if (delta)
1.262 + psi += onePixel - delta; // round up
1.263 +
1.264 + // Stretch the radical symbol to the appropriate height if it is not big enough.
1.265 + nsBoundingMetrics contSize = bmBase;
1.266 + contSize.descent = bmBase.ascent + bmBase.descent + psi;
1.267 + contSize.ascent = ruleThickness;
1.268 +
1.269 + // height(radical) should be >= height(base) + psi + ruleThickness
1.270 + nsBoundingMetrics radicalSize;
1.271 + mSqrChar.Stretch(aPresContext, renderingContext,
1.272 + NS_STRETCH_DIRECTION_VERTICAL,
1.273 + contSize, radicalSize,
1.274 + NS_STRETCH_LARGER,
1.275 + StyleVisibility()->mDirection);
1.276 + // radicalSize have changed at this point, and should match with
1.277 + // the bounding metrics of the char
1.278 + mSqrChar.GetBoundingMetrics(bmSqr);
1.279 +
1.280 + // Update the desired size for the container (like msqrt, index is not yet included)
1.281 + // the baseline will be that of the base.
1.282 + mBoundingMetrics.ascent = bmBase.ascent + psi + ruleThickness;
1.283 + mBoundingMetrics.descent =
1.284 + std::max(bmBase.descent,
1.285 + (bmSqr.ascent + bmSqr.descent - mBoundingMetrics.ascent));
1.286 + mBoundingMetrics.width = bmSqr.width + bmBase.width;
1.287 + mBoundingMetrics.leftBearing = bmSqr.leftBearing;
1.288 + mBoundingMetrics.rightBearing = bmSqr.width +
1.289 + std::max(bmBase.width, bmBase.rightBearing); // take also care of the rule
1.290 +
1.291 + aDesiredSize.SetTopAscent(mBoundingMetrics.ascent + leading);
1.292 + aDesiredSize.Height() = aDesiredSize.TopAscent() +
1.293 + std::max(baseSize.Height() - baseSize.TopAscent(),
1.294 + mBoundingMetrics.descent + ruleThickness);
1.295 + aDesiredSize.Width() = mBoundingMetrics.width;
1.296 +
1.297 + /////////////
1.298 + // Re-adjust the desired size to include the index.
1.299 +
1.300 + // the index is raised by some fraction of the height
1.301 + // of the radical, see \mroot macro in App. B, TexBook
1.302 + nscoord raiseIndexDelta = NSToCoordRound(0.6f * (bmSqr.ascent + bmSqr.descent));
1.303 + nscoord indexRaisedAscent = mBoundingMetrics.ascent // top of radical
1.304 + - (bmSqr.ascent + bmSqr.descent) // to bottom of radical
1.305 + + raiseIndexDelta + bmIndex.ascent + bmIndex.descent; // to top of raised index
1.306 +
1.307 + nscoord indexClearance = 0;
1.308 + if (mBoundingMetrics.ascent < indexRaisedAscent) {
1.309 + indexClearance =
1.310 + indexRaisedAscent - mBoundingMetrics.ascent; // excess gap introduced by a tall index
1.311 + mBoundingMetrics.ascent = indexRaisedAscent;
1.312 + nscoord descent = aDesiredSize.Height() - aDesiredSize.TopAscent();
1.313 + aDesiredSize.SetTopAscent(mBoundingMetrics.ascent + leading);
1.314 + aDesiredSize.Height() = aDesiredSize.TopAscent() + descent;
1.315 + }
1.316 +
1.317 + nscoord dxIndex, dxSqr;
1.318 + GetRadicalXOffsets(bmIndex.width, bmSqr.width, fm, &dxIndex, &dxSqr);
1.319 +
1.320 + mBoundingMetrics.width = dxSqr + bmSqr.width + bmBase.width;
1.321 + mBoundingMetrics.leftBearing =
1.322 + std::min(dxIndex + bmIndex.leftBearing, dxSqr + bmSqr.leftBearing);
1.323 + mBoundingMetrics.rightBearing = dxSqr + bmSqr.width +
1.324 + std::max(bmBase.width, bmBase.rightBearing);
1.325 +
1.326 + aDesiredSize.Width() = mBoundingMetrics.width;
1.327 + aDesiredSize.mBoundingMetrics = mBoundingMetrics;
1.328 + GatherAndStoreOverflow(&aDesiredSize);
1.329 +
1.330 + // place the index
1.331 + nscoord dx = dxIndex;
1.332 + nscoord dy = aDesiredSize.TopAscent() - (indexRaisedAscent + indexSize.TopAscent() - bmIndex.ascent);
1.333 + FinishReflowChild(indexFrame, aPresContext, indexSize, nullptr,
1.334 + MirrorIfRTL(aDesiredSize.Width(), indexSize.Width(), dx),
1.335 + dy, 0);
1.336 +
1.337 + // place the radical symbol and the radical bar
1.338 + dx = dxSqr;
1.339 + dy = indexClearance + leading; // leave a leading at the top
1.340 + mSqrChar.SetRect(nsRect(MirrorIfRTL(aDesiredSize.Width(), bmSqr.width, dx),
1.341 + dy, bmSqr.width, bmSqr.ascent + bmSqr.descent));
1.342 + dx += bmSqr.width;
1.343 + mBarRect.SetRect(MirrorIfRTL(aDesiredSize.Width(), bmBase.width, dx),
1.344 + dy, bmBase.width, ruleThickness);
1.345 +
1.346 + // place the base
1.347 + dy = aDesiredSize.TopAscent() - baseSize.TopAscent();
1.348 + FinishReflowChild(baseFrame, aPresContext, baseSize, nullptr,
1.349 + MirrorIfRTL(aDesiredSize.Width(), baseSize.Width(), dx),
1.350 + dy, 0);
1.351 +
1.352 + mReference.x = 0;
1.353 + mReference.y = aDesiredSize.TopAscent();
1.354 +
1.355 + aStatus = NS_FRAME_COMPLETE;
1.356 + NS_FRAME_SET_TRUNCATION(aStatus, aReflowState, aDesiredSize);
1.357 + return NS_OK;
1.358 +}
1.359 +
1.360 +/* virtual */ void
1.361 +nsMathMLmrootFrame::GetIntrinsicWidthMetrics(nsRenderingContext* aRenderingContext, nsHTMLReflowMetrics& aDesiredSize)
1.362 +{
1.363 + nsIFrame* baseFrame = mFrames.FirstChild();
1.364 + nsIFrame* indexFrame = nullptr;
1.365 + if (baseFrame)
1.366 + indexFrame = baseFrame->GetNextSibling();
1.367 + if (!indexFrame || indexFrame->GetNextSibling()) {
1.368 + ReflowError(*aRenderingContext, aDesiredSize);
1.369 + return;
1.370 + }
1.371 +
1.372 + nscoord baseWidth =
1.373 + nsLayoutUtils::IntrinsicForContainer(aRenderingContext, baseFrame,
1.374 + nsLayoutUtils::PREF_WIDTH);
1.375 + nscoord indexWidth =
1.376 + nsLayoutUtils::IntrinsicForContainer(aRenderingContext, indexFrame,
1.377 + nsLayoutUtils::PREF_WIDTH);
1.378 + nscoord sqrWidth = mSqrChar.GetMaxWidth(PresContext(), *aRenderingContext);
1.379 +
1.380 + nscoord dxSqr;
1.381 + nsRefPtr<nsFontMetrics> fm;
1.382 + nsLayoutUtils::GetFontMetricsForFrame(this, getter_AddRefs(fm));
1.383 + GetRadicalXOffsets(indexWidth, sqrWidth, fm, nullptr, &dxSqr);
1.384 +
1.385 + nscoord width = dxSqr + sqrWidth + baseWidth;
1.386 +
1.387 + aDesiredSize.Width() = width;
1.388 + aDesiredSize.mBoundingMetrics.width = width;
1.389 + aDesiredSize.mBoundingMetrics.leftBearing = 0;
1.390 + aDesiredSize.mBoundingMetrics.rightBearing = width;
1.391 +}
1.392 +
1.393 +// ----------------------
1.394 +// the Style System will use these to pass the proper style context to our MathMLChar
1.395 +nsStyleContext*
1.396 +nsMathMLmrootFrame::GetAdditionalStyleContext(int32_t aIndex) const
1.397 +{
1.398 + switch (aIndex) {
1.399 + case NS_SQR_CHAR_STYLE_CONTEXT_INDEX:
1.400 + return mSqrChar.GetStyleContext();
1.401 + break;
1.402 + default:
1.403 + return nullptr;
1.404 + }
1.405 +}
1.406 +
1.407 +void
1.408 +nsMathMLmrootFrame::SetAdditionalStyleContext(int32_t aIndex,
1.409 + nsStyleContext* aStyleContext)
1.410 +{
1.411 + switch (aIndex) {
1.412 + case NS_SQR_CHAR_STYLE_CONTEXT_INDEX:
1.413 + mSqrChar.SetStyleContext(aStyleContext);
1.414 + break;
1.415 + }
1.416 +}
