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/*
* Copyright (C) Research In Motion Limited 2010-2012. All rights reserved.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public License
* along with this library; see the file COPYING.LIB. If not, write to
* the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
* Boston, MA 02110-1301, USA.
*/
#include "config.h"
#include "SVGTextLayoutEngine.h"
#include "PathTraversalState.h"
#include "RenderSVGTextPath.h"
#include "SVGElement.h"
#include "SVGGeometryElement.h"
#include "SVGInlineTextBox.h"
#include "SVGLengthContext.h"
#include "SVGTextContentElement.h"
#include "SVGTextLayoutEngineBaseline.h"
#include "SVGTextLayoutEngineSpacing.h"
// Set to a value > 0 to dump the text fragments
#define DUMP_TEXT_FRAGMENTS 0
namespace WebCore {
SVGTextLayoutEngine::SVGTextLayoutEngine(Vector<SVGTextLayoutAttributes*>& layoutAttributes)
: m_layoutAttributes(layoutAttributes)
, m_layoutAttributesPosition(0)
, m_logicalCharacterOffset(0)
, m_logicalMetricsListOffset(0)
, m_visualCharacterOffset(0)
, m_visualMetricsListOffset(0)
, m_x(0)
, m_y(0)
, m_dx(0)
, m_dy(0)
, m_isVerticalText(false)
, m_inPathLayout(false)
, m_textPathLength(0)
, m_textPathCurrentOffset(0)
, m_textPathSpacing(0)
, m_textPathScaling(1)
{
ASSERT(!m_layoutAttributes.isEmpty());
}
void SVGTextLayoutEngine::updateCharacerPositionIfNeeded(float& x, float& y)
{
if (m_inPathLayout)
return;
// Replace characters x/y position, with the current text position plus any
// relative adjustments, if it doesn't specify an absolute position itself.
if (x == SVGTextLayoutAttributes::emptyValue())
x = m_x + m_dx;
if (y == SVGTextLayoutAttributes::emptyValue())
y = m_y + m_dy;
m_dx = 0;
m_dy = 0;
}
void SVGTextLayoutEngine::updateCurrentTextPosition(float x, float y, float glyphAdvance)
{
// Update current text position after processing the character.
if (m_isVerticalText) {
m_x = x;
m_y = y + glyphAdvance;
} else {
m_x = x + glyphAdvance;
m_y = y;
}
}
void SVGTextLayoutEngine::updateRelativePositionAdjustmentsIfNeeded(float dx, float dy)
{
// Update relative positioning information.
if (dx == SVGTextLayoutAttributes::emptyValue() && dy == SVGTextLayoutAttributes::emptyValue())
return;
if (dx == SVGTextLayoutAttributes::emptyValue())
dx = 0;
if (dy == SVGTextLayoutAttributes::emptyValue())
dy = 0;
if (m_inPathLayout) {
if (m_isVerticalText) {
m_dx += dx;
m_dy = dy;
} else {
m_dx = dx;
m_dy += dy;
}
return;
}
m_dx = dx;
m_dy = dy;
}
void SVGTextLayoutEngine::recordTextFragment(SVGInlineTextBox& textBox, Vector<SVGTextMetrics>& textMetricsValues)
{
ASSERT(!m_currentTextFragment.length);
ASSERT(m_visualMetricsListOffset > 0);
// Figure out length of fragment.
m_currentTextFragment.length = m_visualCharacterOffset - m_currentTextFragment.characterOffset;
// Figure out fragment metrics.
SVGTextMetrics& lastCharacterMetrics = textMetricsValues.at(m_visualMetricsListOffset - 1);
m_currentTextFragment.width = lastCharacterMetrics.width();
m_currentTextFragment.height = lastCharacterMetrics.height();
if (m_currentTextFragment.length > 1) {
// SVGTextLayoutAttributesBuilder assures that the length of the range is equal to the sum of the individual lengths of the glyphs.
float length = 0;
if (m_isVerticalText) {
for (unsigned i = m_currentTextFragment.metricsListOffset; i < m_visualMetricsListOffset; ++i)
length += textMetricsValues.at(i).height();
m_currentTextFragment.height = length;
} else {
for (unsigned i = m_currentTextFragment.metricsListOffset; i < m_visualMetricsListOffset; ++i)
length += textMetricsValues.at(i).width();
m_currentTextFragment.width = length;
}
}
textBox.textFragments().append(m_currentTextFragment);
m_currentTextFragment = SVGTextFragment();
}
bool SVGTextLayoutEngine::parentDefinesTextLength(RenderObject* parent) const
{
RenderObject* currentParent = parent;
while (currentParent) {
if (SVGTextContentElement* textContentElement = SVGTextContentElement::elementFromRenderer(currentParent)) {
SVGLengthContext lengthContext(textContentElement);
if (textContentElement->lengthAdjust() == SVGLengthAdjustSpacing && textContentElement->specifiedTextLength().value(lengthContext) > 0)
return true;
}
if (currentParent->isSVGText())
return false;
currentParent = currentParent->parent();
}
ASSERT_NOT_REACHED();
return false;
}
void SVGTextLayoutEngine::beginTextPathLayout(RenderSVGTextPath& textPath, SVGTextLayoutEngine& lineLayout)
{
m_inPathLayout = true;
m_textPath = textPath.layoutPath();
if (m_textPath.isEmpty())
return;
const auto& startOffset = textPath.startOffset();
m_textPathLength = m_textPath.length();
if (textPath.startOffset().lengthType() == SVGLengthType::Percentage)
m_textPathStartOffset = startOffset.valueAsPercentage() * m_textPathLength;
else {
m_textPathStartOffset = startOffset.valueInSpecifiedUnits();
if (auto* tragetElement = textPath.targetElement()) {
// FIXME: A value of zero is valid. Need to differentiate this case from being unspecified.
if (float pathLength = tragetElement->pathLength())
m_textPathStartOffset *= m_textPathLength / pathLength;
}
}
lineLayout.m_chunkLayoutBuilder.buildTextChunks(lineLayout.m_lineLayoutBoxes);
// Handle text-anchor as additional start offset for text paths.
m_textPathStartOffset += lineLayout.m_chunkLayoutBuilder.totalAnchorShift();
m_textPathCurrentOffset = m_textPathStartOffset;
// Eventually handle textLength adjustments.
auto* textContentElement = SVGTextContentElement::elementFromRenderer(&textPath);
if (!textContentElement)
return;
SVGLengthContext lengthContext(textContentElement);
float desiredTextLength = textContentElement->specifiedTextLength().value(lengthContext);
if (!desiredTextLength)
return;
float totalLength = lineLayout.m_chunkLayoutBuilder.totalLength();
unsigned totalCharacters = lineLayout.m_chunkLayoutBuilder.totalCharacters();
if (textContentElement->lengthAdjust() == SVGLengthAdjustSpacing)
m_textPathSpacing = (desiredTextLength - totalLength) / totalCharacters;
else
m_textPathScaling = desiredTextLength / totalLength;
}
void SVGTextLayoutEngine::endTextPathLayout()
{
m_inPathLayout = false;
m_textPath = Path();
m_textPathLength = 0;
m_textPathStartOffset = 0;
m_textPathCurrentOffset = 0;
m_textPathSpacing = 0;
m_textPathScaling = 1;
}
void SVGTextLayoutEngine::layoutInlineTextBox(SVGInlineTextBox& textBox)
{
RenderSVGInlineText& text = textBox.renderer();
ASSERT(text.parent());
ASSERT(text.parent()->element());
ASSERT(text.parent()->element()->isSVGElement());
const RenderStyle& style = text.style();
textBox.clearTextFragments();
m_isVerticalText = style.isVerticalWritingMode();
layoutTextOnLineOrPath(textBox, text, style);
if (m_inPathLayout) {
m_pathLayoutBoxes.append(&textBox);
return;
}
m_lineLayoutBoxes.append(&textBox);
}
#if DUMP_TEXT_FRAGMENTS > 0
static inline void dumpTextBoxes(Vector<SVGInlineTextBox*>& boxes)
{
unsigned boxCount = boxes.size();
fprintf(stderr, "Dumping all text fragments in text sub tree, %i boxes\n", boxCount);
for (unsigned boxPosition = 0; boxPosition < boxCount; ++boxPosition) {
SVGInlineTextBox* textBox = boxes.at(boxPosition);
Vector<SVGTextFragment>& fragments = textBox->textFragments();
fprintf(stderr, "-> Box %i: Dumping text fragments for SVGInlineTextBox, textBox=%p, textRenderer=%p\n", boxPosition, textBox, textBox->renderer());
fprintf(stderr, " textBox properties, start=%i, len=%i, box direction=%i\n", textBox->start(), textBox->len(), textBox->direction());
fprintf(stderr, " textRenderer properties, textLength=%i\n", textBox->renderer()->textLength());
const UChar* characters = textBox->renderer()->characters();
unsigned fragmentCount = fragments.size();
for (unsigned i = 0; i < fragmentCount; ++i) {
SVGTextFragment& fragment = fragments.at(i);
String fragmentString(characters + fragment.characterOffset, fragment.length);
fprintf(stderr, " -> Fragment %i, x=%lf, y=%lf, width=%lf, height=%lf, characterOffset=%i, length=%i, characters='%s'\n"
, i, fragment.x, fragment.y, fragment.width, fragment.height, fragment.characterOffset, fragment.length, fragmentString.utf8().data());
}
}
}
#endif
void SVGTextLayoutEngine::finalizeTransformMatrices(Vector<SVGInlineTextBox*>& boxes)
{
unsigned boxCount = boxes.size();
if (!boxCount)
return;
AffineTransform textBoxTransformation;
for (unsigned boxPosition = 0; boxPosition < boxCount; ++boxPosition) {
SVGInlineTextBox* textBox = boxes.at(boxPosition);
Vector<SVGTextFragment>& fragments = textBox->textFragments();
unsigned fragmentCount = fragments.size();
for (unsigned i = 0; i < fragmentCount; ++i) {
textBoxTransformation = m_chunkLayoutBuilder.transformationForTextBox(textBox);
if (textBoxTransformation.isIdentity())
continue;
ASSERT(fragments[i].lengthAdjustTransform.isIdentity());
fragments[i].lengthAdjustTransform = textBoxTransformation;
}
}
boxes.clear();
}
void SVGTextLayoutEngine::finishLayout()
{
// After all text fragments are stored in their correpsonding SVGInlineTextBoxes, we can layout individual text chunks.
// Chunk layouting is only performed for line layout boxes, not for path layout, where it has already been done.
m_chunkLayoutBuilder.layoutTextChunks(m_lineLayoutBoxes);
// Finalize transform matrices, after the chunk layout corrections have been applied, and all fragment x/y positions are finalized.
if (!m_lineLayoutBoxes.isEmpty()) {
#if DUMP_TEXT_FRAGMENTS > 0
fprintf(stderr, "Line layout: ");
dumpTextBoxes(m_lineLayoutBoxes);
#endif
finalizeTransformMatrices(m_lineLayoutBoxes);
}
if (!m_pathLayoutBoxes.isEmpty()) {
#if DUMP_TEXT_FRAGMENTS > 0
fprintf(stderr, "Path layout: ");
dumpTextBoxes(m_pathLayoutBoxes);
#endif
finalizeTransformMatrices(m_pathLayoutBoxes);
}
}
bool SVGTextLayoutEngine::currentLogicalCharacterAttributes(SVGTextLayoutAttributes*& logicalAttributes)
{
if (m_layoutAttributesPosition == m_layoutAttributes.size())
return false;
logicalAttributes = m_layoutAttributes[m_layoutAttributesPosition];
ASSERT(logicalAttributes);
if (m_logicalCharacterOffset != logicalAttributes->context().text().length())
return true;
++m_layoutAttributesPosition;
if (m_layoutAttributesPosition == m_layoutAttributes.size())
return false;
logicalAttributes = m_layoutAttributes[m_layoutAttributesPosition];
m_logicalMetricsListOffset = 0;
m_logicalCharacterOffset = 0;
return true;
}
bool SVGTextLayoutEngine::currentLogicalCharacterMetrics(SVGTextLayoutAttributes*& logicalAttributes, SVGTextMetrics& logicalMetrics)
{
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_WITH_SECURITY_IMPLICATION(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 SVGTextLayoutEngine::currentVisualCharacterMetrics(const 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::advanceToNextLogicalCharacter(const SVGTextMetrics& logicalMetrics)
{
++m_logicalMetricsListOffset;
m_logicalCharacterOffset += logicalMetrics.length();
}
void SVGTextLayoutEngine::advanceToNextVisualCharacter(const SVGTextMetrics& visualMetrics)
{
++m_visualMetricsListOffset;
m_visualCharacterOffset += visualMetrics.length();
}
void SVGTextLayoutEngine::layoutTextOnLineOrPath(SVGInlineTextBox& textBox, RenderSVGInlineText& text, const RenderStyle& style)
{
if (m_inPathLayout && m_textPath.isEmpty())
return;
RenderElement* textParent = text.parent();
ASSERT(textParent);
SVGElement* lengthContext = downcast<SVGElement>(textParent->element());
bool definesTextLength = parentDefinesTextLength(textParent);
const SVGRenderStyle& svgStyle = style.svgStyle();
m_visualMetricsListOffset = 0;
m_visualCharacterOffset = 0;
Vector<SVGTextMetrics>& visualMetricsValues = text.layoutAttributes()->textMetricsValues();
ASSERT(!visualMetricsValues.isEmpty());
auto upconvertedCharacters = StringView(text.text()).upconvertedCharacters();
const UChar* characters = upconvertedCharacters;
const FontCascade& font = style.fontCascade();
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::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.
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(data.dx, data.dy);
// 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;
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;
auto traversalState(m_textPath.traversalStateAtLength(textPathOffset));
ASSERT(traversalState.success());
FloatPoint point = traversalState.current();
x = point.x();
y = point.y();
angle = traversalState.normalAngle();
// 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);
}
}