void SimpleFontData::platformGlyphInit() {
SkTypeface* typeface = platformData().typeface();
if (!typeface->countGlyphs()) {
m_spaceGlyph = 0;
m_spaceWidth = 0;
m_zeroGlyph = 0;
m_missingGlyphData.fontData = this;
m_missingGlyphData.glyph = 0;
return;
}
// Nasty hack to determine if we should round or ceil space widths.
// If the font is monospace or fake monospace we ceil to ensure that
// every character and the space are the same width. Otherwise we round.
m_spaceGlyph = glyphForCharacter(' ');
float width = widthForGlyph(m_spaceGlyph);
m_spaceWidth = width;
m_zeroGlyph = glyphForCharacter('0');
m_fontMetrics.setZeroWidth(widthForGlyph(m_zeroGlyph));
m_missingGlyphData.fontData = this;
m_missingGlyphData.glyph = 0;
}
void SimpleFontData::platformInit(bool subpixelAscentDescent) {
if (!m_platformData.size()) {
m_fontMetrics.reset();
m_avgCharWidth = 0;
m_maxCharWidth = 0;
return;
}
SkPaint::FontMetrics metrics;
m_platformData.setupPaint(&m_paint);
m_paint.setTextEncoding(SkPaint::kGlyphID_TextEncoding);
m_paint.getFontMetrics(&metrics);
SkTypeface* face = m_paint.getTypeface();
ASSERT(face);
int vdmxAscent = 0, vdmxDescent = 0;
bool isVDMXValid = false;
#if OS(LINUX) || OS(ANDROID)
// Manually digging up VDMX metrics is only applicable when bytecode hinting
// using FreeType. With DirectWrite or CoreText, no bytecode hinting is ever
// done. This code should be pushed into FreeType (hinted font metrics).
static const uint32_t vdmxTag = SkSetFourByteTag('V', 'D', 'M', 'X');
int pixelSize = m_platformData.size() + 0.5;
if (!m_paint.isAutohinted() &&
(m_paint.getHinting() == SkPaint::kFull_Hinting ||
m_paint.getHinting() == SkPaint::kNormal_Hinting)) {
size_t vdmxSize = face->getTableSize(vdmxTag);
if (vdmxSize && vdmxSize < maxVDMXTableSize) {
uint8_t* vdmxTable = (uint8_t*)WTF::Partitions::fastMalloc(
vdmxSize, WTF_HEAP_PROFILER_TYPE_NAME(SimpleFontData));
if (vdmxTable &&
face->getTableData(vdmxTag, 0, vdmxSize, vdmxTable) == vdmxSize &&
parseVDMX(&vdmxAscent, &vdmxDescent, vdmxTable, vdmxSize, pixelSize))
isVDMXValid = true;
WTF::Partitions::fastFree(vdmxTable);
}
}
#endif
float ascent;
float descent;
// Beware those who step here: This code is designed to match Win32 font
// metrics *exactly* except:
// - the adjustment of ascent/descent on Linux/Android
// - metrics.fAscent and .fDesscent are not rounded to int for tiny fonts
if (isVDMXValid) {
ascent = vdmxAscent;
descent = -vdmxDescent;
} else {
// For tiny fonts, the rounding of fAscent and fDescent results in equal
// baseline for different types of text baselines (crbug.com/338908).
// Please see CanvasRenderingContext2D::getFontBaseline for the heuristic.
if (subpixelAscentDescent &&
(-metrics.fAscent < 3 || -metrics.fAscent + metrics.fDescent < 2)) {
ascent = -metrics.fAscent;
descent = metrics.fDescent;
} else {
ascent = SkScalarRoundToScalar(-metrics.fAscent);
descent = SkScalarRoundToScalar(metrics.fDescent);
}
#if OS(LINUX) || OS(ANDROID)
// When subpixel positioning is enabled, if the descent is rounded down, the
// descent part of the glyph may be truncated when displayed in a 'overflow:
// hidden' container. To avoid that, borrow 1 unit from the ascent when
// possible.
// FIXME: This can be removed if sub-pixel ascent/descent is supported.
if (platformData().getFontRenderStyle().useSubpixelPositioning &&
descent < SkScalarToFloat(metrics.fDescent) && ascent >= 1) {
++descent;
--ascent;
}
#endif
}
#if OS(MACOSX)
// We are preserving this ascent hack to match Safari's ascent adjustment
// in their SimpleFontDataMac.mm, for details see crbug.com/445830.
// We need to adjust Times, Helvetica, and Courier to closely match the
// vertical metrics of their Microsoft counterparts that are the de facto
// web standard. The AppKit adjustment of 20% is too big and is
// incorrectly added to line spacing, so we use a 15% adjustment instead
// and add it to the ascent.
DEFINE_STATIC_LOCAL(AtomicString, timesName, ("Times"));
DEFINE_STATIC_LOCAL(AtomicString, helveticaName, ("Helvetica"));
DEFINE_STATIC_LOCAL(AtomicString, courierName, ("Courier"));
String familyName = m_platformData.fontFamilyName();
if (familyName == timesName || familyName == helveticaName ||
familyName == courierName)
ascent += floorf(((ascent + descent) * 0.15f) + 0.5f);
#endif
m_fontMetrics.setAscent(ascent);
m_fontMetrics.setDescent(descent);
float xHeight;
if (metrics.fXHeight) {
xHeight = metrics.fXHeight;
#if OS(MACOSX)
// Mac OS CTFontGetXHeight reports the bounding box height of x,
// including parts extending below the baseline and apparently no x-height
// value from the OS/2 table. However, the CSS ex unit
// expects only parts above the baseline, hence measuring the glyph:
// http://www.w3.org/TR/css3-values/#ex-unit
const Glyph xGlyph = glyphForCharacter('x');
if (xGlyph) {
FloatRect glyphBounds(boundsForGlyph(xGlyph));
// SkGlyph bounds, y down, based on rendering at (0,0).
xHeight = -glyphBounds.y();
}
#endif
m_fontMetrics.setXHeight(xHeight);
} else {
xHeight = ascent * 0.56; // Best guess from Windows font metrics.
m_fontMetrics.setXHeight(xHeight);
m_fontMetrics.setHasXHeight(false);
}
float lineGap = SkScalarToFloat(metrics.fLeading);
m_fontMetrics.setLineGap(lineGap);
m_fontMetrics.setLineSpacing(lroundf(ascent) + lroundf(descent) +
lroundf(lineGap));
if (platformData().isVerticalAnyUpright() && !isTextOrientationFallback()) {
static const uint32_t vheaTag = SkSetFourByteTag('v', 'h', 'e', 'a');
static const uint32_t vorgTag = SkSetFourByteTag('V', 'O', 'R', 'G');
size_t vheaSize = face->getTableSize(vheaTag);
size_t vorgSize = face->getTableSize(vorgTag);
if ((vheaSize > 0) || (vorgSize > 0))
m_hasVerticalGlyphs = true;
}
// In WebKit/WebCore/platform/graphics/SimpleFontData.cpp, m_spaceWidth is
// calculated for us, but we need to calculate m_maxCharWidth and
// m_avgCharWidth in order for text entry widgets to be sized correctly.
#if OS(WIN)
m_maxCharWidth = SkScalarRoundToInt(metrics.fMaxCharWidth);
// Older version of the DirectWrite API doesn't implement support for max
// char width. Fall back on a multiple of the ascent. This is entirely
// arbitrary but comes pretty close to the expected value in most cases.
if (m_maxCharWidth < 1)
m_maxCharWidth = ascent * 2;
#elif OS(MACOSX)
// FIXME: The current avg/max character width calculation is not ideal,
// it should check either the OS2 table or, better yet, query FontMetrics.
// Sadly FontMetrics provides incorrect data on Mac at the moment.
// https://crbug.com/420901
m_maxCharWidth = std::max(m_avgCharWidth, m_fontMetrics.floatAscent());
#else
// Better would be to rely on either fMaxCharWidth or fAveCharWidth.
// skbug.com/3087
m_maxCharWidth = SkScalarRoundToInt(metrics.fXMax - metrics.fXMin);
#endif
#if !OS(MACOSX)
if (metrics.fAvgCharWidth) {
m_avgCharWidth = SkScalarRoundToInt(metrics.fAvgCharWidth);
} else {
#endif
m_avgCharWidth = xHeight;
const Glyph xGlyph = glyphForCharacter('x');
if (xGlyph) {
m_avgCharWidth = widthForGlyph(xGlyph);
}
#if !OS(MACOSX)
}
#endif
if (int unitsPerEm = face->getUnitsPerEm())
m_fontMetrics.setUnitsPerEm(unitsPerEm);
}
bool canUseFor(const RenderBlockFlow& flow)
{
#if !PLATFORM(MAC)
// FIXME: Non-mac platforms are hitting ASSERT(run.charactersLength() >= run.length())
// https://bugs.webkit.org/show_bug.cgi?id=123338
return false;
#endif
if (!flow.firstChild())
return false;
// This currently covers <blockflow>#text</blockflow> case.
// The <blockflow><inline>#text</inline></blockflow> case is also popular and should be relatively easy to cover.
if (flow.firstChild() != flow.lastChild())
return false;
if (!flow.firstChild()->isText())
return false;
// Supporting floats would be very beneficial.
if (flow.containsFloats())
return false;
if (!flow.isHorizontalWritingMode())
return false;
if (flow.flowThreadState() != RenderObject::NotInsideFlowThread)
return false;
if (flow.hasOutline())
return false;
if (flow.isRubyText() || flow.isRubyBase())
return false;
// These tests only works during layout. Outside layout this function may give false positives.
if (flow.view().layoutState()) {
#if ENABLE(CSS_SHAPES)
if (flow.view().layoutState()->shapeInsideInfo())
return false;
#endif
if (flow.view().layoutState()->m_columnInfo)
return false;
}
const RenderStyle& style = *flow.style();
// It shoudn't be hard to support other alignments.
if (style.textAlign() != LEFT && style.textAlign() != WEBKIT_LEFT && style.textAlign() != TASTART)
return false;
// Non-visible overflow should be pretty easy to support.
if (style.overflowX() != OVISIBLE || style.overflowY() != OVISIBLE)
return false;
// Pre/no-wrap would be very helpful to support.
if (style.whiteSpace() != NORMAL)
return false;
if (!style.textIndent().isZero())
return false;
if (style.wordSpacing() || style.letterSpacing())
return false;
if (style.textTransform() != TTNONE)
return false;
if (!style.isLeftToRightDirection())
return false;
if (style.lineBoxContain() != RenderStyle::initialLineBoxContain())
return false;
if (style.writingMode() != TopToBottomWritingMode)
return false;
if (style.lineBreak() != LineBreakAuto)
return false;
if (style.wordBreak() != NormalWordBreak)
return false;
if (style.unicodeBidi() != UBNormal || style.rtlOrdering() != LogicalOrder)
return false;
if (style.lineAlign() != LineAlignNone || style.lineSnap() != LineSnapNone)
return false;
if (style.hyphens() == HyphensAuto)
return false;
if (style.textEmphasisFill() != TextEmphasisFillFilled || style.textEmphasisMark() != TextEmphasisMarkNone)
return false;
if (style.textShadow())
return false;
#if ENABLE(CSS_SHAPES)
if (style.resolvedShapeInside())
return true;
#endif
if (style.textOverflow() || (flow.isAnonymousBlock() && flow.parent()->style()->textOverflow()))
return false;
if (style.hasPseudoStyle(FIRST_LINE) || style.hasPseudoStyle(FIRST_LETTER))
return false;
if (style.hasTextCombine())
return false;
if (style.overflowWrap() != NormalOverflowWrap)
return false;
if (style.backgroundClip() == TextFillBox)
return false;
if (style.borderFit() == BorderFitLines)
return false;
const RenderText& textRenderer = toRenderText(*flow.firstChild());
if (textRenderer.isCombineText() || textRenderer.isCounter() || textRenderer.isQuote() || textRenderer.isTextFragment()
#if ENABLE(SVG)
|| textRenderer.isSVGInlineText()
#endif
)
return false;
if (style.font().codePath(TextRun(textRenderer.text())) != Font::Simple)
return false;
auto primaryFontData = style.font().primaryFont();
unsigned length = textRenderer.textLength();
unsigned consecutiveSpaceCount = 0;
for (unsigned i = 0; i < length; ++i) {
// This rejects anything with more than one consecutive whitespace, except at the beginning or end.
// This is because we don't currently do subruns within lines. Fixing this would improve coverage significantly.
UChar character = textRenderer.characterAt(i);
if (isWhitespace(character))
++consecutiveSpaceCount;
else {
if (consecutiveSpaceCount != i && consecutiveSpaceCount > 1)
return false;
consecutiveSpaceCount = 0;
}
// These would be easy to support.
if (character == noBreakSpace)
return false;
if (character == softHyphen)
return false;
static const UChar lowestRTLCharacter = 0x590;
if (character >= lowestRTLCharacter) {
UCharDirection direction = u_charDirection(character);
if (direction == U_RIGHT_TO_LEFT || direction == U_RIGHT_TO_LEFT_ARABIC
|| direction == U_RIGHT_TO_LEFT_EMBEDDING || direction == U_RIGHT_TO_LEFT_OVERRIDE
|| direction == U_LEFT_TO_RIGHT_EMBEDDING || direction == U_LEFT_TO_RIGHT_OVERRIDE)
return false;
}
if (!primaryFontData->glyphForCharacter(character))
return false;
}
return true;
}
