void SVGTextLayoutEngine::layoutInlineTextBox(SVGInlineTextBox* textBox)
{
ASSERT(textBox);
RenderSVGInlineText* text = toRenderSVGInlineText(textBox->textRenderer());
ASSERT(text);
ASSERT(text->parent());
ASSERT(text->parent()->node());
ASSERT(text->parent()->node()->isSVGElement());
const RenderStyle* style = text->style();
ASSERT(style);
textBox->clearTextFragments();
m_isVerticalText = style->svgStyle()->isVerticalWritingMode();
layoutTextOnLineOrPath(textBox, text, style);
if (m_inPathLayout) {
m_pathLayoutBoxes.append(textBox);
return;
}
m_lineLayoutBoxes.append(textBox);
}
void SVGTextChunkBuilder::addTextChunk(Vector<SVGInlineTextBox*>& lineLayoutBoxes, unsigned boxStart, unsigned boxCount)
{
SVGInlineTextBox* textBox = lineLayoutBoxes[boxStart];
ASSERT(textBox);
RenderSVGInlineText* textRenderer = toRenderSVGInlineText(textBox->textRenderer());
ASSERT(textRenderer);
const RenderStyle* style = textRenderer->style();
ASSERT(style);
const SVGRenderStyle* svgStyle = style->svgStyle();
ASSERT(svgStyle);
// Build chunk style flags.
unsigned chunkStyle = SVGTextChunk::DefaultStyle;
// Handle 'direction' property.
if (!style->isLeftToRightDirection())
chunkStyle |= SVGTextChunk::RightToLeftText;
// Handle 'writing-mode' property.
if (svgStyle->isVerticalWritingMode())
chunkStyle |= SVGTextChunk::VerticalText;
// Handle 'text-anchor' property.
switch (svgStyle->textAnchor()) {
case TA_START:
break;
case TA_MIDDLE:
chunkStyle |= SVGTextChunk::MiddleAnchor;
break;
case TA_END:
chunkStyle |= SVGTextChunk::EndAnchor;
break;
};
// Handle 'lengthAdjust' property.
float desiredTextLength = 0;
if (SVGTextContentElement* textContentElement = SVGTextContentElement::elementFromRenderer(textRenderer->parent())) {
desiredTextLength = textContentElement->specifiedTextLength().value(textContentElement);
switch (textContentElement->lengthAdjust()) {
case SVGTextContentElement::LENGTHADJUST_UNKNOWN:
break;
case SVGTextContentElement::LENGTHADJUST_SPACING:
chunkStyle |= SVGTextChunk::LengthAdjustSpacing;
break;
case SVGTextContentElement::LENGTHADJUST_SPACINGANDGLYPHS:
chunkStyle |= SVGTextChunk::LengthAdjustSpacingAndGlyphs;
break;
};
}
SVGTextChunk chunk(chunkStyle, desiredTextLength);
Vector<SVGInlineTextBox*>& boxes = chunk.boxes();
for (unsigned i = boxStart; i < boxStart + boxCount; ++i)
boxes.append(lineLayoutBoxes[i]);
m_textChunks.append(chunk);
}
void SVGTextLayoutEngine::layoutTextOnLineOrPath(SVGInlineTextBox* textBox, const RenderSVGInlineText& text, const RenderStyle& style)
{
if (m_inPathLayout && !m_textPathCalculator)
return;
SVGElement* lengthContext = toSVGElement(text.parent()->node());
RenderObject* textParent = text.parent();
bool definesTextLength = textParent ? parentDefinesTextLength(textParent) : false;
const SVGRenderStyle& svgStyle = style.svgStyle();
m_visualMetricsListOffset = 0;
m_visualCharacterOffset = 0;
const Vector<SVGTextMetrics>& visualMetricsValues = text.layoutAttributes()->textMetricsValues();
ASSERT(!visualMetricsValues.isEmpty());
const Font& font = style.font();
SVGTextLayoutEngineSpacing spacingLayout(font, style.effectiveZoom());
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::SkippedSpaceMetrics);
if (!currentVisualCharacterMetrics(textBox, visualMetricsValues, visualMetrics))
break;
if (visualMetrics.isEmpty()) {
advanceToNextVisualCharacter(visualMetrics);
continue;
}
SVGTextLayoutAttributes* logicalAttributes = 0;
if (!currentLogicalCharacterAttributes(logicalAttributes))
break;
ASSERT(logicalAttributes);
SVGTextMetrics logicalMetrics(SVGTextMetrics::SkippedSpaceMetrics);
if (!currentLogicalCharacterMetrics(logicalAttributes, logicalMetrics))
break;
SVGCharacterDataMap& characterDataMap = logicalAttributes->characterDataMap();
SVGCharacterData data;
SVGCharacterDataMap::iterator it = characterDataMap.find(m_logicalCharacterOffset + 1);
if (it != characterDataMap.end())
data = it->value;
float x = data.x;
float y = data.y;
// 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 = data.rotate == SVGTextLayoutAttributes::emptyValue() ? 0 : data.rotate;
// Calculate glyph orientation angle.
UChar currentCharacter = text.characterAt(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.
updateCharacterPositionIfNeeded(x, y);
// Apply dx/dy value adjustments to current text position, if needed.
updateRelativePositionAdjustmentsIfNeeded(data.dx, data.dy);
// Calculate CSS 'letter-spacing' and 'word-spacing' for next character, if needed.
float spacing = spacingLayout.calculateCSSSpacing(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;
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;
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;
FloatPoint point;
bool ok = m_textPathCalculator->pointAndNormalAtLength(textPathOffset, point, angle);
ASSERT_UNUSED(ok, ok);
x = point.x();
y = point.y();
// 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;
else
y -= baselineShift;
x += m_dx;
y += m_dy;
}
// Determine whether we have to start a new fragment.
bool shouldStartNewFragment = m_dx || m_dy || m_isVerticalText || m_inPathLayout || angle || angle != lastAngle
|| orientationAngle || applySpacingToNextCharacter || definesTextLength;
// If we already started a fragment, close it now.
if (didStartTextFragment && shouldStartNewFragment) {
applySpacingToNextCharacter = false;
recordTextFragment(textBox, visualMetricsValues);
}
// 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, visualMetricsValues);
}
