SVGTextMetrics SVGTextMetricsCalculator::computeMetricsForCharacter(unsigned textPosition)
{
if (m_bidiRun) {
if (textPosition >= static_cast<unsigned>(m_bidiRun->stop())) {
m_bidiRun = m_bidiRun->next();
// New BiDi run means new reference position for measurements, so reset |m_totalWidth|.
m_totalWidth = 0;
}
ASSERT(m_bidiRun);
ASSERT(static_cast<int>(textPosition) < m_bidiRun->stop());
m_textDirection = m_bidiRun->direction();
}
unsigned metricsLength = characterStartsSurrogatePair(textPosition) ? 2 : 1;
SVGTextMetrics metrics = SVGTextMetrics::measureCharacterRange(m_text, textPosition, metricsLength, m_textDirection);
ASSERT(metrics.length() == metricsLength);
unsigned startPosition = m_bidiRun ? m_bidiRun->start() : 0;
ASSERT(startPosition <= textPosition);
SVGTextMetrics complexStartToCurrentMetrics = SVGTextMetrics::measureCharacterRange(m_text, startPosition, textPosition - startPosition + metricsLength, m_textDirection);
// Frequent case for Arabic text: when measuring a single character the arabic isolated form is taken
// when laying out the glyph "in context" (with it's surrounding characters) it changes due to shaping.
// So whenever currentWidth != currentMetrics.width(), we are processing a text run whose length is
// not equal to the sum of the individual lengths of the glyphs, when measuring them isolated.
float currentWidth = complexStartToCurrentMetrics.width() - m_totalWidth;
if (currentWidth != metrics.width())
metrics.setWidth(currentWidth);
m_totalWidth = complexStartToCurrentMetrics.width();
return metrics;
}
SVGTextMetrics SVGTextMetricsCalculator::computeMetricsForCharacterComplex(unsigned textPosition)
{
unsigned metricsLength = characterStartsSurrogatePair(textPosition) ? 2 : 1;
SVGTextMetrics metrics = SVGTextMetrics::measureCharacterRange(m_text, textPosition, metricsLength, m_textDirection);
ASSERT(metrics.length() == metricsLength);
unsigned startPosition = m_bidiRun ? m_bidiRun->start() : 0;
ASSERT(startPosition <= textPosition);
SVGTextMetrics complexStartToCurrentMetrics = SVGTextMetrics::measureCharacterRange(m_text, startPosition, textPosition - startPosition + metricsLength, m_textDirection);
// Frequent case for Arabic text: when measuring a single character the arabic isolated form is taken
// when rendering the glyph "in context" (with it's surrounding characters) it changes due to shaping.
// So whenever currentWidth != currentMetrics.width(), we are processing a text run whose length is
// not equal to the sum of the individual lengths of the glyphs, when measuring them isolated.
float currentWidth = complexStartToCurrentMetrics.width() - m_totalWidth;
if (currentWidth != metrics.width())
metrics.setWidth(currentWidth);
m_totalWidth = complexStartToCurrentMetrics.width();
return metrics;
}
void SVGTextLayoutAttributesBuilder::propagateLayoutAttributes(RenderObject* start, Vector<SVGTextLayoutAttributes>& allAttributes, unsigned& atCharacter, UChar& lastCharacter) const
{
for (RenderObject* child = start->firstChild(); child; child = child->nextSibling()) {
if (child->isSVGInlineText()) {
RenderSVGInlineText* text = toRenderSVGInlineText(child);
const UChar* characters = text->characters();
unsigned textLength = text->textLength();
bool preserveWhiteSpace = shouldPreserveAllWhiteSpace(text->style());
SVGTextLayoutAttributes attributes(text);
attributes.reserveCapacity(textLength);
unsigned valueListPosition = atCharacter;
unsigned metricsLength = 1;
SVGTextMetrics lastMetrics(SVGTextMetrics::SkippedSpaceMetrics);
for (unsigned textPosition = 0; textPosition < textLength; textPosition += metricsLength) {
const UChar& currentCharacter = characters[textPosition];
SVGTextMetrics startToCurrentMetrics;
SVGTextMetrics currentMetrics;
unsigned valueListAdvance = 0;
if (U16_IS_LEAD(currentCharacter) && (textPosition + 1) < textLength && U16_IS_TRAIL(characters[textPosition + 1])) {
// Handle surrogate pairs.
startToCurrentMetrics = SVGTextMetrics::measureCharacterRange(text, 0, textPosition + 2);
currentMetrics = SVGTextMetrics::measureCharacterRange(text, textPosition, 2);
metricsLength = currentMetrics.length();
valueListAdvance = 1;
} else {
// Handle BMP characters.
startToCurrentMetrics = SVGTextMetrics::measureCharacterRange(text, 0, textPosition + 1);
currentMetrics = SVGTextMetrics::measureCharacterRange(text, textPosition, 1);
metricsLength = currentMetrics.length();
valueListAdvance = metricsLength;
}
if (!metricsLength)
break;
// Frequent case for Arabic text: when measuring a single character the arabic isolated form is taken
// when rendering the glyph "in context" (with it's surrounding characters) it changes due to shaping.
// So whenever runWidthAdvance != currentMetrics.width(), we are processing a text run whose length is
// not equal to the sum of the individual lengths of the glyphs, when measuring them isolated.
float runWidthAdvance = startToCurrentMetrics.width() - lastMetrics.width();
if (runWidthAdvance != currentMetrics.width())
currentMetrics.setWidth(runWidthAdvance);
lastMetrics = startToCurrentMetrics;
if (!preserveWhiteSpace && characterIsSpace(currentCharacter) && characterIsSpaceOrNull(lastCharacter)) {
attributes.positioningLists().appendEmptyValues();
attributes.textMetricsValues().append(SVGTextMetrics(SVGTextMetrics::SkippedSpaceMetrics));
continue;
}
SVGTextLayoutAttributes::PositioningLists& positioningLists = attributes.positioningLists();
positioningLists.appendValuesFromPosition(m_positioningLists, valueListPosition);
attributes.textMetricsValues().append(currentMetrics);
// Pad x/y/dx/dy/rotate value lists with empty values, if the metrics span more than one character.
if (metricsLength > 1) {
for (unsigned i = 0; i < metricsLength - 1; ++i)
positioningLists.appendEmptyValues();
}
lastCharacter = currentCharacter;
valueListPosition += valueListAdvance;
}
#if DUMP_TEXT_LAYOUT_ATTRIBUTES > 0
fprintf(stderr, "\nDumping layout attributes for RenderSVGInlineText, renderer=%p, node=%p (atCharacter: %i)\n", text, text->node(), atCharacter);
fprintf(stderr, "BiDi properties: unicode-bidi=%i, block direction=%i\n", text->style()->unicodeBidi(), text->style()->direction());
attributes.dump();
#endif
text->storeLayoutAttributes(attributes);
allAttributes.append(attributes);
atCharacter = valueListPosition;
continue;
}
if (!child->isSVGInline())
continue;
propagateLayoutAttributes(child, allAttributes, atCharacter, lastCharacter);
}
}