void SimpleFontData::platformGlyphInit()
{
GlyphPage* glyphPageZero = GlyphPageTreeNode::getRootChild(this, 0)->page();
if (!glyphPageZero) {
WTF_LOG_ERROR("Failed to get glyph page zero.");
m_spaceGlyph = 0;
m_spaceWidth = 0;
m_zeroGlyph = 0;
m_adjustedSpaceWidth = 0;
determinePitch();
m_zeroWidthSpaceGlyph = 0;
m_missingGlyphData.fontData = this;
m_missingGlyphData.glyph = 0;
return;
}
m_zeroWidthSpaceGlyph = glyphPageZero->glyphForCharacter(0);
// 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 = glyphPageZero->glyphForCharacter(' ');
float width = widthForGlyph(m_spaceGlyph);
m_spaceWidth = width;
m_zeroGlyph = glyphPageZero->glyphForCharacter('0');
m_fontMetrics.setZeroWidth(widthForGlyph(m_zeroGlyph));
determinePitch();
m_adjustedSpaceWidth = m_treatAsFixedPitch ? ceilf(width) : roundf(width);
// Force the glyph for ZERO WIDTH SPACE to have zero width, unless it is shared with SPACE.
// Helvetica is an example of a non-zero width ZERO WIDTH SPACE glyph.
// See <http://bugs.webkit.org/show_bug.cgi?id=13178>
// Ask for the glyph for 0 to avoid paging in ZERO WIDTH SPACE. Control characters, including 0,
// are mapped to the ZERO WIDTH SPACE glyph.
if (m_zeroWidthSpaceGlyph == m_spaceGlyph) {
m_zeroWidthSpaceGlyph = 0;
WTF_LOG_ERROR("Font maps SPACE and ZERO WIDTH SPACE to the same glyph. Glyph width will not be overridden.");
}
m_missingGlyphData.fontData = this;
m_missingGlyphData.glyph = 0;
}
// Estimates of avgCharWidth and maxCharWidth for platforms that don't support accessing these values from the font.
void SimpleFontData::initCharWidths()
{
GlyphPage* glyphPageZero = GlyphPageTreeNode::getRootChild(this, 0)->page();
// Treat the width of a '0' as the avgCharWidth.
if (m_avgCharWidth <= 0.f && glyphPageZero) {
static const UChar32 digitZeroChar = '0';
Glyph digitZeroGlyph = glyphPageZero->glyphForCharacter(digitZeroChar);
if (digitZeroGlyph)
m_avgCharWidth = widthForGlyph(digitZeroGlyph);
}
// If we can't retrieve the width of a '0', fall back to the x height.
if (m_avgCharWidth <= 0.f)
m_avgCharWidth = m_fontMetrics.xHeight();
if (m_maxCharWidth <= 0.f)
m_maxCharWidth = max(m_avgCharWidth, m_fontMetrics.floatAscent());
}
void SimpleFontData::platformInit() {
if (!m_platformData.size()) {
m_fontMetrics.reset();
m_avgCharWidth = 0;
m_maxCharWidth = 0;
return;
}
SkPaint paint;
SkPaint::FontMetrics metrics;
m_platformData.setupPaint(&paint);
paint.getFontMetrics(&metrics);
SkTypeface* face = 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 GDI, the metrics will already have taken this into
// account (as needed). 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 (!paint.isAutohinted() &&
(paint.getHinting() == SkPaint::kFull_Hinting ||
paint.getHinting() == SkPaint::kNormal_Hinting)) {
size_t vdmxSize = face->getTableSize(vdmxTag);
if (vdmxSize && vdmxSize < maxVDMXTableSize) {
uint8_t* vdmxTable = (uint8_t*)fastMalloc(vdmxSize);
if (vdmxTable &&
face->getTableData(vdmxTag, 0, vdmxSize, vdmxTable) == vdmxSize &&
parseVDMX(&vdmxAscent, &vdmxDescent, vdmxTable, vdmxSize, pixelSize))
isVDMXValid = true;
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).
if (isVDMXValid) {
ascent = vdmxAscent;
descent = -vdmxDescent;
} else {
ascent = SkScalarRoundToInt(-metrics.fAscent);
descent = SkScalarRoundToInt(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().fontRenderStyle().useSubpixelPositioning &&
descent < SkScalarToFloat(metrics.fDescent) && ascent >= 1) {
++descent;
--ascent;
}
#endif
}
m_fontMetrics.setAscent(ascent);
m_fontMetrics.setDescent(descent);
float xHeight;
if (metrics.fXHeight) {
xHeight = metrics.fXHeight;
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));
SkScalar underlineThickness, underlinePosition;
if (metrics.hasUnderlineThickness(&underlineThickness) &&
metrics.hasUnderlinePosition(&underlinePosition)) {
m_fontMetrics.setUnderlineThickness(SkScalarToFloat(underlineThickness));
m_fontMetrics.setUnderlinePosition(SkScalarToFloat(-underlinePosition));
}
if (platformData().orientation() == Vertical &&
!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.
// FIXME: This seems incorrect and should probably use fMaxCharWidth as
// the code path above.
SkScalar xRange = metrics.fXMax - metrics.fXMin;
m_maxCharWidth =
SkScalarRoundToInt(xRange * SkScalarRoundToInt(m_platformData.size()));
if (metrics.fAvgCharWidth)
m_avgCharWidth = SkScalarRoundToInt(metrics.fAvgCharWidth);
else {
m_avgCharWidth = xHeight;
GlyphPage* glyphPageZero = GlyphPageTreeNode::getRootChild(this, 0)->page();
if (glyphPageZero) {
static const UChar32 xChar = 'x';
const Glyph xGlyph = glyphPageZero->glyphForCharacter(xChar);
if (xGlyph) {
// In widthForGlyph(), xGlyph will be compared with
// m_zeroWidthSpaceGlyph, which isn't initialized yet here.
// Initialize it with zero to make sure widthForGlyph() returns
// the right width.
m_zeroWidthSpaceGlyph = 0;
m_avgCharWidth = widthForGlyph(xGlyph);
}
}
}
if (int unitsPerEm = face->getUnitsPerEm())
m_fontMetrics.setUnitsPerEm(unitsPerEm);
}
void SVGFontData::initializeFontData(SimpleFontData* fontData, float fontSize)
{
ASSERT(fontData);
SVGFontFaceElement* svgFontFaceElement = this->svgFontFaceElement();
ASSERT(svgFontFaceElement);
SVGFontElement* svgFontElement = svgFontFaceElement->associatedFontElement();
ASSERT(svgFontElement);
GlyphData missingGlyphData;
missingGlyphData.fontData = fontData;
missingGlyphData.glyph = svgFontElement->missingGlyph();
fontData->setMissingGlyphData(missingGlyphData);
fontData->setZeroWidthSpaceGlyph(0);
fontData->determinePitch();
unsigned unitsPerEm = svgFontFaceElement->unitsPerEm();
float scale = scaleEmToUnits(fontSize, unitsPerEm);
float xHeight = svgFontFaceElement->xHeight() * scale;
float ascent = svgFontFaceElement->ascent() * scale;
float descent = svgFontFaceElement->descent() * scale;
float lineGap = 0.1f * fontSize;
GlyphPage* glyphPageZero = GlyphPageTreeNode::getRootChild(fontData, 0)->page();
if (!xHeight && glyphPageZero) {
// Fallback if x_heightAttr is not specified for the font element.
Glyph letterXGlyph = glyphPageZero->glyphForCharacter('x');
xHeight = letterXGlyph ? fontData->widthForGlyph(letterXGlyph) : 2 * ascent / 3;
}
FontMetrics& fontMetrics = fontData->fontMetrics();
fontMetrics.setUnitsPerEm(unitsPerEm);
fontMetrics.setAscent(ascent);
fontMetrics.setDescent(descent);
fontMetrics.setLineGap(lineGap);
fontMetrics.setLineSpacing(roundf(ascent) + roundf(descent) + roundf(lineGap));
fontMetrics.setXHeight(xHeight);
if (!glyphPageZero) {
fontData->setSpaceGlyph(0);
fontData->setSpaceWidth(0);
fontData->setAvgCharWidth(0);
fontData->setMaxCharWidth(ascent);
return;
}
// Calculate space width.
Glyph spaceGlyph = glyphPageZero->glyphForCharacter(' ');
fontData->setSpaceGlyph(spaceGlyph);
fontData->setSpaceWidth(fontData->widthForGlyph(spaceGlyph));
// Estimate average character width.
Glyph numeralZeroGlyph = glyphPageZero->glyphForCharacter('0');
fontData->setAvgCharWidth(numeralZeroGlyph ? fontData->widthForGlyph(numeralZeroGlyph) : fontData->spaceWidth());
// Estimate maximum character width.
Glyph letterWGlyph = glyphPageZero->glyphForCharacter('W');
fontData->setMaxCharWidth(letterWGlyph ? fontData->widthForGlyph(letterWGlyph) : ascent);
}
