gecko-dev/layout/mathml/nsMathMLmrootFrame.cpp

414 lines
15 KiB
C++

/* -*- 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 "nsMathMLmrootFrame.h"
#include "nsPresContext.h"
#include "nsRenderingContext.h"
#include <algorithm>
//
// <msqrt> and <mroot> -- form a radical - implementation
//
//NOTE:
// The code assumes that TeX fonts are picked.
// There is no fall-back to draw the branches of the sqrt explicitly
// in the case where TeX fonts are not there. In general, there are no
// fall-back(s) in MathML when some (freely-downloadable) fonts are missing.
// Otherwise, this will add much work and unnecessary complexity to the core
// MathML engine. Assuming that authors have the free fonts is part of the
// deal. We are not responsible for cases of misconfigurations out there.
// additional style context to be used by our MathMLChar.
#define NS_SQR_CHAR_STYLE_CONTEXT_INDEX 0
static const char16_t kSqrChar = char16_t(0x221A);
nsIFrame*
NS_NewMathMLmrootFrame(nsIPresShell* aPresShell, nsStyleContext* aContext)
{
return new (aPresShell) nsMathMLmrootFrame(aContext);
}
NS_IMPL_FRAMEARENA_HELPERS(nsMathMLmrootFrame)
nsMathMLmrootFrame::nsMathMLmrootFrame(nsStyleContext* aContext) :
nsMathMLContainerFrame(aContext),
mSqrChar(),
mBarRect()
{
}
nsMathMLmrootFrame::~nsMathMLmrootFrame()
{
}
void
nsMathMLmrootFrame::Init(nsIContent* aContent,
nsIFrame* aParent,
nsIFrame* aPrevInFlow)
{
nsMathMLContainerFrame::Init(aContent, aParent, aPrevInFlow);
nsPresContext *presContext = PresContext();
// No need to track the style context given to our MathML char.
// The Style System will use Get/SetAdditionalStyleContext() to keep it
// up-to-date if dynamic changes arise.
nsAutoString sqrChar; sqrChar.Assign(kSqrChar);
mSqrChar.SetData(presContext, sqrChar);
ResolveMathMLCharStyle(presContext, mContent, mStyleContext, &mSqrChar, true);
}
NS_IMETHODIMP
nsMathMLmrootFrame::TransmitAutomaticData()
{
// 1. The REC says:
// The <mroot> element increments scriptlevel by 2, and sets displaystyle to
// "false", within index, but leaves both attributes unchanged within base.
// 2. The TeXbook (Ch 17. p.141) says \sqrt is compressed
UpdatePresentationDataFromChildAt(1, 1,
NS_MATHML_COMPRESSED,
NS_MATHML_COMPRESSED);
UpdatePresentationDataFromChildAt(0, 0,
NS_MATHML_COMPRESSED, NS_MATHML_COMPRESSED);
PropagateFrameFlagFor(mFrames.LastChild(),
NS_FRAME_MATHML_SCRIPT_DESCENDANT);
return NS_OK;
}
void
nsMathMLmrootFrame::BuildDisplayList(nsDisplayListBuilder* aBuilder,
const nsRect& aDirtyRect,
const nsDisplayListSet& aLists)
{
/////////////
// paint the content we are square-rooting
nsMathMLContainerFrame::BuildDisplayList(aBuilder, aDirtyRect, aLists);
/////////////
// paint the sqrt symbol
if (!NS_MATHML_HAS_ERROR(mPresentationData.flags)) {
mSqrChar.Display(aBuilder, this, aLists, 0);
DisplayBar(aBuilder, this, mBarRect, aLists);
#if defined(DEBUG) && defined(SHOW_BOUNDING_BOX)
// for visual debug
nsRect rect;
mSqrChar.GetRect(rect);
nsBoundingMetrics bm;
mSqrChar.GetBoundingMetrics(bm);
DisplayBoundingMetrics(aBuilder, this, rect.TopLeft(), bm, aLists);
#endif
}
}
static void
GetRadicalXOffsets(nscoord aIndexWidth, nscoord aSqrWidth,
nsFontMetrics* aFontMetrics,
nscoord* aIndexOffset, nscoord* aSqrOffset)
{
// The index is tucked in closer to the radical while making sure
// that the kern does not make the index and radical collide
nscoord dxIndex, dxSqr;
nscoord xHeight = aFontMetrics->XHeight();
nscoord indexRadicalKern = NSToCoordRound(1.35f * xHeight);
if (indexRadicalKern > aIndexWidth) {
dxIndex = indexRadicalKern - aIndexWidth;
dxSqr = 0;
}
else {
dxIndex = 0;
dxSqr = aIndexWidth - indexRadicalKern;
}
// avoid collision by leaving a minimum space between index and radical
nscoord minimumClearance = aSqrWidth/2;
if (dxIndex + aIndexWidth + minimumClearance > dxSqr + aSqrWidth) {
if (aIndexWidth + minimumClearance < aSqrWidth) {
dxIndex = aSqrWidth - (aIndexWidth + minimumClearance);
dxSqr = 0;
}
else {
dxIndex = 0;
dxSqr = (aIndexWidth + minimumClearance) - aSqrWidth;
}
}
if (aIndexOffset)
*aIndexOffset = dxIndex;
if (aSqrOffset)
*aSqrOffset = dxSqr;
}
nsresult
nsMathMLmrootFrame::Reflow(nsPresContext* aPresContext,
nsHTMLReflowMetrics& aDesiredSize,
const nsHTMLReflowState& aReflowState,
nsReflowStatus& aStatus)
{
nsresult rv = NS_OK;
nsSize availSize(aReflowState.ComputedWidth(), NS_UNCONSTRAINEDSIZE);
nsReflowStatus childStatus;
aDesiredSize.Width() = aDesiredSize.Height() = 0;
aDesiredSize.SetTopAscent(0);
nsBoundingMetrics bmSqr, bmBase, bmIndex;
nsRenderingContext& renderingContext = *aReflowState.rendContext;
//////////////////
// Reflow Children
int32_t count = 0;
nsIFrame* baseFrame = nullptr;
nsIFrame* indexFrame = nullptr;
nsHTMLReflowMetrics baseSize(aReflowState.GetWritingMode());
nsHTMLReflowMetrics indexSize(aReflowState.GetWritingMode());
nsIFrame* childFrame = mFrames.FirstChild();
while (childFrame) {
// ask our children to compute their bounding metrics
nsHTMLReflowMetrics childDesiredSize(aReflowState.GetWritingMode(),
aDesiredSize.mFlags
| NS_REFLOW_CALC_BOUNDING_METRICS);
nsHTMLReflowState childReflowState(aPresContext, aReflowState,
childFrame, availSize);
rv = ReflowChild(childFrame, aPresContext,
childDesiredSize, childReflowState, childStatus);
//NS_ASSERTION(NS_FRAME_IS_COMPLETE(childStatus), "bad status");
if (NS_FAILED(rv)) {
// Call DidReflow() for the child frames we successfully did reflow.
DidReflowChildren(mFrames.FirstChild(), childFrame);
return rv;
}
if (0 == count) {
// base
baseFrame = childFrame;
baseSize = childDesiredSize;
bmBase = childDesiredSize.mBoundingMetrics;
}
else if (1 == count) {
// index
indexFrame = childFrame;
indexSize = childDesiredSize;
bmIndex = childDesiredSize.mBoundingMetrics;
}
count++;
childFrame = childFrame->GetNextSibling();
}
if (2 != count) {
// report an error, encourage people to get their markups in order
ReportChildCountError();
rv = ReflowError(renderingContext, aDesiredSize);
aStatus = NS_FRAME_COMPLETE;
NS_FRAME_SET_TRUNCATION(aStatus, aReflowState, aDesiredSize);
// Call DidReflow() for the child frames we successfully did reflow.
DidReflowChildren(mFrames.FirstChild(), childFrame);
return rv;
}
////////////
// Prepare the radical symbol and the overline bar
nsRefPtr<nsFontMetrics> fm;
nsLayoutUtils::GetFontMetricsForFrame(this, getter_AddRefs(fm));
renderingContext.SetFont(fm);
// For radical glyphs from TeX fonts and some of the radical glyphs from
// Mathematica fonts, the thickness of the overline can be obtained from the
// ascent of the glyph. Most fonts however have radical glyphs above the
// baseline so no assumption can be made about the meaning of the ascent.
nscoord ruleThickness, leading, em;
GetRuleThickness(renderingContext, fm, ruleThickness);
char16_t one = '1';
nsBoundingMetrics bmOne = renderingContext.GetBoundingMetrics(&one, 1);
// get the leading to be left at the top of the resulting frame
// this seems more reliable than using fm->GetLeading() on suspicious fonts
GetEmHeight(fm, em);
leading = nscoord(0.2f * em);
// Rule 11, App. G, TeXbook
// psi = clearance between rule and content
nscoord phi = 0, psi = 0;
if (StyleFont()->mMathDisplay == NS_MATHML_DISPLAYSTYLE_BLOCK)
phi = fm->XHeight();
else
phi = ruleThickness;
psi = ruleThickness + phi/4;
// built-in: adjust clearance psi to emulate \mathstrut using '1' (TexBook, p.131)
if (bmOne.ascent > bmBase.ascent)
psi += bmOne.ascent - bmBase.ascent;
// make sure that the rule appears on on screen
nscoord onePixel = nsPresContext::CSSPixelsToAppUnits(1);
if (ruleThickness < onePixel) {
ruleThickness = onePixel;
}
// adjust clearance psi to get an exact number of pixels -- this
// gives a nicer & uniform look on stacked radicals (bug 130282)
nscoord delta = psi % onePixel;
if (delta)
psi += onePixel - delta; // round up
// Stretch the radical symbol to the appropriate height if it is not big enough.
nsBoundingMetrics contSize = bmBase;
contSize.descent = bmBase.ascent + bmBase.descent + psi;
contSize.ascent = ruleThickness;
// height(radical) should be >= height(base) + psi + ruleThickness
nsBoundingMetrics radicalSize;
mSqrChar.Stretch(aPresContext, renderingContext,
NS_STRETCH_DIRECTION_VERTICAL,
contSize, radicalSize,
NS_STRETCH_LARGER,
StyleVisibility()->mDirection);
// radicalSize have changed at this point, and should match with
// the bounding metrics of the char
mSqrChar.GetBoundingMetrics(bmSqr);
// Update the desired size for the container (like msqrt, index is not yet included)
// the baseline will be that of the base.
mBoundingMetrics.ascent = bmBase.ascent + psi + ruleThickness;
mBoundingMetrics.descent =
std::max(bmBase.descent,
(bmSqr.ascent + bmSqr.descent - mBoundingMetrics.ascent));
mBoundingMetrics.width = bmSqr.width + bmBase.width;
mBoundingMetrics.leftBearing = bmSqr.leftBearing;
mBoundingMetrics.rightBearing = bmSqr.width +
std::max(bmBase.width, bmBase.rightBearing); // take also care of the rule
aDesiredSize.SetTopAscent(mBoundingMetrics.ascent + leading);
aDesiredSize.Height() = aDesiredSize.TopAscent() +
std::max(baseSize.Height() - baseSize.TopAscent(),
mBoundingMetrics.descent + ruleThickness);
aDesiredSize.Width() = mBoundingMetrics.width;
/////////////
// Re-adjust the desired size to include the index.
// the index is raised by some fraction of the height
// of the radical, see \mroot macro in App. B, TexBook
nscoord raiseIndexDelta = NSToCoordRound(0.6f * (bmSqr.ascent + bmSqr.descent));
nscoord indexRaisedAscent = mBoundingMetrics.ascent // top of radical
- (bmSqr.ascent + bmSqr.descent) // to bottom of radical
+ raiseIndexDelta + bmIndex.ascent + bmIndex.descent; // to top of raised index
nscoord indexClearance = 0;
if (mBoundingMetrics.ascent < indexRaisedAscent) {
indexClearance =
indexRaisedAscent - mBoundingMetrics.ascent; // excess gap introduced by a tall index
mBoundingMetrics.ascent = indexRaisedAscent;
nscoord descent = aDesiredSize.Height() - aDesiredSize.TopAscent();
aDesiredSize.SetTopAscent(mBoundingMetrics.ascent + leading);
aDesiredSize.Height() = aDesiredSize.TopAscent() + descent;
}
nscoord dxIndex, dxSqr;
GetRadicalXOffsets(bmIndex.width, bmSqr.width, fm, &dxIndex, &dxSqr);
mBoundingMetrics.width = dxSqr + bmSqr.width + bmBase.width;
mBoundingMetrics.leftBearing =
std::min(dxIndex + bmIndex.leftBearing, dxSqr + bmSqr.leftBearing);
mBoundingMetrics.rightBearing = dxSqr + bmSqr.width +
std::max(bmBase.width, bmBase.rightBearing);
aDesiredSize.Width() = mBoundingMetrics.width;
aDesiredSize.mBoundingMetrics = mBoundingMetrics;
GatherAndStoreOverflow(&aDesiredSize);
// place the index
nscoord dx = dxIndex;
nscoord dy = aDesiredSize.TopAscent() - (indexRaisedAscent + indexSize.TopAscent() - bmIndex.ascent);
FinishReflowChild(indexFrame, aPresContext, indexSize, nullptr,
MirrorIfRTL(aDesiredSize.Width(), indexSize.Width(), dx),
dy, 0);
// place the radical symbol and the radical bar
dx = dxSqr;
dy = indexClearance + leading; // leave a leading at the top
mSqrChar.SetRect(nsRect(MirrorIfRTL(aDesiredSize.Width(), bmSqr.width, dx),
dy, bmSqr.width, bmSqr.ascent + bmSqr.descent));
dx += bmSqr.width;
mBarRect.SetRect(MirrorIfRTL(aDesiredSize.Width(), bmBase.width, dx),
dy, bmBase.width, ruleThickness);
// place the base
dy = aDesiredSize.TopAscent() - baseSize.TopAscent();
FinishReflowChild(baseFrame, aPresContext, baseSize, nullptr,
MirrorIfRTL(aDesiredSize.Width(), baseSize.Width(), dx),
dy, 0);
mReference.x = 0;
mReference.y = aDesiredSize.TopAscent();
aStatus = NS_FRAME_COMPLETE;
NS_FRAME_SET_TRUNCATION(aStatus, aReflowState, aDesiredSize);
return NS_OK;
}
/* virtual */ void
nsMathMLmrootFrame::GetIntrinsicWidthMetrics(nsRenderingContext* aRenderingContext, nsHTMLReflowMetrics& aDesiredSize)
{
nsIFrame* baseFrame = mFrames.FirstChild();
nsIFrame* indexFrame = nullptr;
if (baseFrame)
indexFrame = baseFrame->GetNextSibling();
if (!indexFrame || indexFrame->GetNextSibling()) {
ReflowError(*aRenderingContext, aDesiredSize);
return;
}
nscoord baseWidth =
nsLayoutUtils::IntrinsicForContainer(aRenderingContext, baseFrame,
nsLayoutUtils::PREF_WIDTH);
nscoord indexWidth =
nsLayoutUtils::IntrinsicForContainer(aRenderingContext, indexFrame,
nsLayoutUtils::PREF_WIDTH);
nscoord sqrWidth = mSqrChar.GetMaxWidth(PresContext(), *aRenderingContext);
nscoord dxSqr;
nsRefPtr<nsFontMetrics> fm;
nsLayoutUtils::GetFontMetricsForFrame(this, getter_AddRefs(fm));
GetRadicalXOffsets(indexWidth, sqrWidth, fm, nullptr, &dxSqr);
nscoord width = dxSqr + sqrWidth + baseWidth;
aDesiredSize.Width() = width;
aDesiredSize.mBoundingMetrics.width = width;
aDesiredSize.mBoundingMetrics.leftBearing = 0;
aDesiredSize.mBoundingMetrics.rightBearing = width;
}
// ----------------------
// the Style System will use these to pass the proper style context to our MathMLChar
nsStyleContext*
nsMathMLmrootFrame::GetAdditionalStyleContext(int32_t aIndex) const
{
switch (aIndex) {
case NS_SQR_CHAR_STYLE_CONTEXT_INDEX:
return mSqrChar.GetStyleContext();
break;
default:
return nullptr;
}
}
void
nsMathMLmrootFrame::SetAdditionalStyleContext(int32_t aIndex,
nsStyleContext* aStyleContext)
{
switch (aIndex) {
case NS_SQR_CHAR_STYLE_CONTEXT_INDEX:
mSqrChar.SetStyleContext(aStyleContext);
break;
}
}