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;
}
static inline void calculateGlyphBoundaries(SVGTextQuery::Data* queryData, const SVGTextFragment& fragment, int startPosition, FloatRect& extent)
{
float scalingFactor = queryData->textRenderer->scalingFactor();
ASSERT(scalingFactor);
extent.setLocation(FloatPoint(fragment.x, fragment.y - queryData->textRenderer->scaledFont().fontMetrics().floatAscent() / scalingFactor));
if (startPosition) {
SVGTextMetrics metrics = SVGTextMetrics::measureCharacterRange(queryData->textRenderer, fragment.characterOffset, startPosition);
if (queryData->isVerticalText)
extent.move(0, metrics.height());
else
extent.move(metrics.width(), 0);
}
SVGTextMetrics metrics = SVGTextMetrics::measureCharacterRange(queryData->textRenderer, fragment.characterOffset + startPosition, 1);
extent.setSize(FloatSize(metrics.width(), metrics.height()));
AffineTransform fragmentTransform;
fragment.buildFragmentTransform(fragmentTransform, SVGTextFragment::TransformIgnoringTextLength);
if (fragmentTransform.isIdentity())
return;
extent = fragmentTransform.mapRect(extent);
}
bool SVGTextLayoutEngine::currentLogicalCharacterMetrics(SVGTextLayoutAttributes*& logicalAttributes, SVGTextMetrics& logicalMetrics)
{
const Vector<SVGTextMetrics>* textMetricsValues = &logicalAttributes->textMetricsValues();
unsigned textMetricsSize = textMetricsValues->size();
while (true) {
if (m_logicalMetricsListOffset == textMetricsSize) {
if (!currentLogicalCharacterAttributes(logicalAttributes))
return false;
textMetricsValues = &logicalAttributes->textMetricsValues();
textMetricsSize = textMetricsValues->size();
continue;
}
ASSERT(textMetricsSize);
ASSERT(m_logicalMetricsListOffset < textMetricsSize);
logicalMetrics = textMetricsValues->at(m_logicalMetricsListOffset);
if (logicalMetrics.isEmpty() || (!logicalMetrics.width() && !logicalMetrics.height())) {
advanceToNextLogicalCharacter(logicalMetrics);
continue;
}
// Stop if we found the next valid logical text metrics object.
return true;
}
ASSERT_NOT_REACHED();
return true;
}
bool SVGTextQuery::endPositionOfCharacterCallback(Data* queryData, const SVGTextFragment& fragment) const
{
EndPositionOfCharacterData* data = static_cast<EndPositionOfCharacterData*>(queryData);
int startPosition = data->position;
int endPosition = startPosition + 1;
if (!mapStartEndPositionsIntoFragmentCoordinates(queryData, fragment, startPosition, endPosition))
return false;
data->endPosition = FloatPoint(fragment.x, fragment.y);
SVGTextMetrics metrics = SVGTextMetrics::measureCharacterRange(queryData->textRenderer, fragment.characterOffset, startPosition + 1);
if (queryData->isVerticalText)
data->endPosition.move(0, metrics.height());
else
data->endPosition.move(metrics.width(), 0);
AffineTransform fragmentTransform;
fragment.buildFragmentTransform(fragmentTransform, SVGTextFragment::TransformIgnoringTextLength);
if (fragmentTransform.isIdentity())
return true;
data->endPosition = fragmentTransform.mapPoint(data->endPosition);
return true;
}
float SVGTextLayoutEngineBaseline::calculateGlyphAdvanceAndOrientation(bool isVerticalText, const SVGTextMetrics& metrics, float angle, float& xOrientationShift, float& yOrientationShift) const
{
bool orientationIsMultiplyOf180Degrees = glyphOrientationIsMultiplyOf180Degrees(angle);
// The function is based on spec requirements:
//
// Spec: If the 'glyph-orientation-horizontal' results in an orientation angle that is not a multiple of
// of 180 degrees, then the current text position is incremented according to the vertical metrics of the glyph.
//
// Spec: If if the 'glyph-orientation-vertical' results in an orientation angle that is not a multiple of
// 180 degrees, then the current text position is incremented according to the horizontal metrics of the glyph.
const FontMetrics& fontMetrics = m_font.fontMetrics();
float ascent = fontMetrics.floatAscent() / m_effectiveZoom;
float descent = fontMetrics.floatDescent() / m_effectiveZoom;
// Vertical orientation handling.
if (isVerticalText) {
float ascentMinusDescent = ascent - descent;
if (!angle) {
xOrientationShift = (ascentMinusDescent - metrics.width()) / 2;
yOrientationShift = ascent;
} else if (angle == 180) {
xOrientationShift = (ascentMinusDescent + metrics.width()) / 2;
} else if (angle == 270) {
yOrientationShift = metrics.width();
xOrientationShift = ascentMinusDescent;
}
// Vertical advance calculation.
if (angle && !orientationIsMultiplyOf180Degrees)
return metrics.width();
return metrics.height();
}
// Horizontal orientation handling.
if (angle == 90) {
yOrientationShift = -metrics.width();
} else if (angle == 180) {
xOrientationShift = metrics.width();
yOrientationShift = -ascent;
} else if (angle == 270) {
xOrientationShift = metrics.width();
}
// Horizontal advance calculation.
if (angle && !orientationIsMultiplyOf180Degrees)
return metrics.height();
return metrics.width();
}
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;
}
bool SVGTextQuery::subStringLengthCallback(Data* queryData, const SVGTextFragment& fragment) const
{
SubStringLengthData* data = static_cast<SubStringLengthData*>(queryData);
int startPosition = data->startPosition;
int endPosition = startPosition + data->length;
if (!mapStartEndPositionsIntoFragmentCoordinates(queryData, fragment, startPosition, endPosition))
return false;
SVGTextMetrics metrics = SVGTextMetrics::measureCharacterRange(queryData->textRenderer, fragment.characterOffset + startPosition, endPosition - startPosition);
data->subStringLength += queryData->isVerticalText ? metrics.height() : metrics.width();
return false;
}
static FloatPoint calculateGlyphPositionWithoutTransform(const QueryData* queryData, const SVGTextFragment& fragment, int offsetInFragment)
{
float glyphOffsetInDirection = 0;
if (offsetInFragment) {
SVGTextMetrics metrics = SVGTextMetrics::measureCharacterRange(queryData->textLayoutObject, fragment.characterOffset, offsetInFragment, queryData->textBox->direction());
if (queryData->isVerticalText)
glyphOffsetInDirection = metrics.height();
else
glyphOffsetInDirection = metrics.width();
}
if (!queryData->textBox->isLeftToRightDirection()) {
float fragmentExtent = queryData->isVerticalText ? fragment.height : fragment.width;
glyphOffsetInDirection = fragmentExtent - glyphOffsetInDirection;
}
FloatPoint glyphPosition(fragment.x, fragment.y);
if (queryData->isVerticalText)
glyphPosition.move(0, glyphOffsetInDirection);
else
glyphPosition.move(glyphOffsetInDirection, 0);
return glyphPosition;
}
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);
}
}
