bool SVGTextLayoutEngine::currentVisualCharacterMetrics(SVGInlineTextBox* textBox, RenderSVGInlineText* text, SVGTextMetrics& metrics)
{
SVGTextLayoutAttributes& attributes = text->layoutAttributes();
Vector<SVGTextMetrics>& textMetricsValues = attributes.textMetricsValues();
ASSERT(!textMetricsValues.isEmpty());
unsigned textMetricsSize = textMetricsValues.size();
unsigned boxStart = textBox->start();
unsigned boxLength = textBox->len();
if (m_visualMetricsListOffset == textMetricsSize)
return false;
while (m_visualMetricsListOffset < textMetricsSize) {
SVGTextMetrics& visualMetrics = textMetricsValues.at(m_visualMetricsListOffset);
// Advance to text box start location.
if (m_visualCharacterOffset < boxStart) {
advanceToNextVisualCharacter(visualMetrics);
continue;
}
// Stop if we've finished processing this text box.
if (m_visualCharacterOffset >= boxStart + boxLength)
return false;
metrics = visualMetrics;
return true;
}
return false;
}
bool SVGTextLayoutEngine::currentVisualCharacterMetrics(SVGInlineTextBox* textBox, Vector<SVGTextMetrics>& visualMetricsValues, SVGTextMetrics& visualMetrics)
{
ASSERT(!visualMetricsValues.isEmpty());
unsigned textMetricsSize = visualMetricsValues.size();
unsigned boxStart = textBox->start();
unsigned boxLength = textBox->len();
if (m_visualMetricsListOffset == textMetricsSize)
return false;
while (m_visualMetricsListOffset < textMetricsSize) {
// Advance to text box start location.
if (m_visualCharacterOffset < boxStart) {
advanceToNextVisualCharacter(visualMetricsValues[m_visualMetricsListOffset]);
continue;
}
// Stop if we've finished processing this text box.
if (m_visualCharacterOffset >= boxStart + boxLength)
return false;
visualMetrics = visualMetricsValues[m_visualMetricsListOffset];
return true;
}
return false;
}
void SVGTextLayoutEngine::layoutTextOnLineOrPath(SVGInlineTextBox* textBox, RenderSVGInlineText* text, const RenderStyle* style)
{
SVGElement* lengthContext = static_cast<SVGElement*>(text->parent()->node());
RenderObject* textParent = text->parent();
bool definesTextLength = textParent ? parentDefinesTextLength(textParent) : false;
const SVGRenderStyle* svgStyle = style->svgStyle();
ASSERT(svgStyle);
m_visualMetricsListOffset = 0;
m_visualCharacterOffset = 0;
Vector<SVGTextMetrics>& textMetricsValues = text->layoutAttributes().textMetricsValues();
const UChar* characters = text->characters();
const Font& font = style->font();
SVGTextLayoutEngineSpacing spacingLayout(font);
SVGTextLayoutEngineBaseline baselineLayout(font);
bool didStartTextFragment = false;
bool applySpacingToNextCharacter = false;
float lastAngle = 0;
float baselineShift = baselineLayout.calculateBaselineShift(svgStyle, lengthContext);
baselineShift -= baselineLayout.calculateAlignmentBaselineShift(m_isVerticalText, text);
// Main layout algorithm.
while (true) {
// Find the start of the current text box in this list, respecting ligatures.
SVGTextMetrics visualMetrics = SVGTextMetrics::emptyMetrics();
if (!currentVisualCharacterMetrics(textBox, text, visualMetrics))
break;
if (visualMetrics == SVGTextMetrics::emptyMetrics()) {
advanceToNextVisualCharacter(visualMetrics);
continue;
}
SVGTextLayoutAttributes logicalAttributes;
if (!currentLogicalCharacterAttributes(logicalAttributes))
break;
SVGTextMetrics logicalMetrics = SVGTextMetrics::emptyMetrics();
if (!currentLogicalCharacterMetrics(logicalAttributes, logicalMetrics))
break;
Vector<float>& xValues = logicalAttributes.xValues();
Vector<float>& yValues = logicalAttributes.yValues();
Vector<float>& dxValues = logicalAttributes.dxValues();
Vector<float>& dyValues = logicalAttributes.dyValues();
Vector<float>& rotateValues = logicalAttributes.rotateValues();
float x = xValues.at(m_logicalCharacterOffset);
float y = yValues.at(m_logicalCharacterOffset);
// When we've advanced to the box start offset, determine using the original x/y values,
// whether this character starts a new text chunk, before doing any further processing.
if (m_visualCharacterOffset == textBox->start())
textBox->setStartsNewTextChunk(logicalAttributes.context()->characterStartsNewTextChunk(m_logicalCharacterOffset));
float angle = 0;
if (!rotateValues.isEmpty()) {
float newAngle = rotateValues.at(m_logicalCharacterOffset);
if (newAngle != SVGTextLayoutAttributes::emptyValue())
angle = newAngle;
}
// Calculate glyph orientation angle.
const UChar* currentCharacter = characters + m_visualCharacterOffset;
float orientationAngle = baselineLayout.calculateGlyphOrientationAngle(m_isVerticalText, svgStyle, *currentCharacter);
// Calculate glyph advance & x/y orientation shifts.
float xOrientationShift = 0;
float yOrientationShift = 0;
float glyphAdvance = baselineLayout.calculateGlyphAdvanceAndOrientation(m_isVerticalText, visualMetrics, orientationAngle, xOrientationShift, yOrientationShift);
// Assign current text position to x/y values, if needed.
updateCharacerPositionIfNeeded(x, y);
// Apply dx/dy value adjustments to current text position, if needed.
updateRelativePositionAdjustmentsIfNeeded(dxValues, dyValues);
// Calculate SVG Fonts kerning, if needed.
float kerning = spacingLayout.calculateSVGKerning(m_isVerticalText, visualMetrics.glyph());
// Calculate CSS 'kerning', 'letter-spacing' and 'word-spacing' for next character, if needed.
float spacing = spacingLayout.calculateCSSKerningAndSpacing(svgStyle, lengthContext, currentCharacter);
float textPathOffset = 0;
if (m_inPathLayout) {
float scaledGlyphAdvance = glyphAdvance * m_textPathScaling;
if (m_isVerticalText) {
// If there's an absolute y position available, it marks the beginning of a new position along the path.
if (y != SVGTextLayoutAttributes::emptyValue())
m_textPathCurrentOffset = y + m_textPathStartOffset;
m_textPathCurrentOffset += m_dy - kerning;
m_dy = 0;
// Apply dx/dy correction and setup translations that move to the glyph midpoint.
xOrientationShift += m_dx + baselineShift;
yOrientationShift -= scaledGlyphAdvance / 2;
} else {
// If there's an absolute x position available, it marks the beginning of a new position along the path.
if (x != SVGTextLayoutAttributes::emptyValue())
m_textPathCurrentOffset = x + m_textPathStartOffset;
m_textPathCurrentOffset += m_dx - kerning;
m_dx = 0;
// Apply dx/dy correction and setup translations that move to the glyph midpoint.
xOrientationShift -= scaledGlyphAdvance / 2;
yOrientationShift += m_dy - baselineShift;
}
// Calculate current offset along path.
textPathOffset = m_textPathCurrentOffset + scaledGlyphAdvance / 2;
// Move to next character.
m_textPathCurrentOffset += scaledGlyphAdvance + m_textPathSpacing + spacing * m_textPathScaling;
// Skip character, if we're before the path.
if (textPathOffset < 0) {
advanceToNextLogicalCharacter(logicalMetrics);
advanceToNextVisualCharacter(visualMetrics);
continue;
}
// Stop processing, if the next character lies behind the path.
if (textPathOffset > m_textPathLength)
break;
bool ok = false;
FloatPoint point = m_textPath.pointAtLength(textPathOffset, ok);
ASSERT(ok);
x = point.x();
y = point.y();
angle = m_textPath.normalAngleAtLength(textPathOffset, ok);
ASSERT(ok);
// For vertical text on path, the actual angle has to be rotated 90 degrees anti-clockwise, not the orientation angle!
if (m_isVerticalText)
angle -= 90;
} else {
// Apply all previously calculated shift values.
if (m_isVerticalText) {
x += baselineShift;
y -= kerning;
} else {
x -= kerning;
y -= baselineShift;
}
x += m_dx;
y += m_dy;
}
// Determine wheter we have to start a new fragment.
bool shouldStartNewFragment = false;
if (m_dx || m_dy)
shouldStartNewFragment = true;
if (!shouldStartNewFragment && (m_isVerticalText || m_inPathLayout))
shouldStartNewFragment = true;
if (!shouldStartNewFragment && (angle || angle != lastAngle || orientationAngle))
shouldStartNewFragment = true;
if (!shouldStartNewFragment && (kerning || applySpacingToNextCharacter || definesTextLength))
shouldStartNewFragment = true;
// If we already started a fragment, close it now.
if (didStartTextFragment && shouldStartNewFragment) {
applySpacingToNextCharacter = false;
recordTextFragment(textBox, textMetricsValues);
}
// Eventually start a new fragment, if not yet done.
if (!didStartTextFragment || shouldStartNewFragment) {
ASSERT(!m_currentTextFragment.characterOffset);
ASSERT(!m_currentTextFragment.length);
didStartTextFragment = true;
m_currentTextFragment.characterOffset = m_visualCharacterOffset;
m_currentTextFragment.metricsListOffset = m_visualMetricsListOffset;
m_currentTextFragment.x = x;
m_currentTextFragment.y = y;
// Build fragment transformation.
if (angle)
m_currentTextFragment.transform.rotate(angle);
if (xOrientationShift || yOrientationShift)
m_currentTextFragment.transform.translate(xOrientationShift, yOrientationShift);
if (orientationAngle)
m_currentTextFragment.transform.rotate(orientationAngle);
m_currentTextFragment.isTextOnPath = m_inPathLayout && m_textPathScaling != 1;
if (m_currentTextFragment.isTextOnPath) {
if (m_isVerticalText)
m_currentTextFragment.lengthAdjustTransform.scaleNonUniform(1, m_textPathScaling);
else
m_currentTextFragment.lengthAdjustTransform.scaleNonUniform(m_textPathScaling, 1);
}
}
// Update current text position, after processing of the current character finished.
if (m_inPathLayout)
updateCurrentTextPosition(x, y, glyphAdvance);
else {
// Apply CSS 'kerning', 'letter-spacing' and 'word-spacing' to next character, if needed.
if (spacing)
applySpacingToNextCharacter = true;
float xNew = x - m_dx;
float yNew = y - m_dy;
if (m_isVerticalText)
xNew -= baselineShift;
else
yNew += baselineShift;
updateCurrentTextPosition(xNew, yNew, glyphAdvance + spacing);
}
advanceToNextLogicalCharacter(logicalMetrics);
advanceToNextVisualCharacter(visualMetrics);
lastAngle = angle;
}
if (!didStartTextFragment)
return;
// Close last open fragment, if needed.
recordTextFragment(textBox, textMetricsValues);
}