| /* |
| * Copyright (C) 2003 - 2021 Apple Inc. All rights reserved. |
| * Copyright (C) 2008 Holger Hans Peter Freyther |
| * |
| * 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 "WidthIterator.h" |
| |
| #include "CharacterProperties.h" |
| #include "ComposedCharacterClusterTextIterator.h" |
| #include "Font.h" |
| #include "FontCascade.h" |
| #include "GlyphBuffer.h" |
| #include "Latin1TextIterator.h" |
| #include "SurrogatePairAwareTextIterator.h" |
| #include <algorithm> |
| #include <wtf/MathExtras.h> |
| |
| namespace WebCore { |
| |
| using namespace WTF::Unicode; |
| |
| WidthIterator::WidthIterator(const FontCascade& font, const TextRun& run, HashSet<const Font*>* fallbackFonts, bool accountForGlyphBounds, bool forTextEmphasis) |
| : m_font(font) |
| , m_run(run) |
| , m_fallbackFonts(fallbackFonts) |
| , m_expansion(run.expansion()) |
| , m_isAfterExpansion(run.expansionBehavior().left == ExpansionBehavior::Behavior::Forbid) |
| , m_accountForGlyphBounds(accountForGlyphBounds) |
| , m_enableKerning(font.enableKerning()) |
| , m_requiresShaping(font.requiresShaping()) |
| , m_forTextEmphasis(forTextEmphasis) |
| { |
| // FIXME: Should we clamp m_expansion so it can never be negative? |
| |
| if (!m_expansion) |
| m_expansionPerOpportunity = 0; |
| else { |
| unsigned expansionOpportunityCount = FontCascade::expansionOpportunityCount(m_run.text(), m_run.ltr() ? TextDirection::LTR : TextDirection::RTL, run.expansionBehavior()).first; |
| |
| if (!expansionOpportunityCount) |
| m_expansionPerOpportunity = 0; |
| else |
| m_expansionPerOpportunity = m_expansion / expansionOpportunityCount; |
| } |
| } |
| |
| struct OriginalAdvancesForCharacterTreatedAsSpace { |
| explicit OriginalAdvancesForCharacterTreatedAsSpace(GlyphBufferStringOffset stringOffset, bool isSpace, float advanceBefore, float advanceAt) |
| : stringOffset(stringOffset) |
| , characterIsSpace(isSpace) |
| , advanceBeforeCharacter(advanceBefore) |
| , advanceAtCharacter(advanceAt) |
| { |
| } |
| |
| GlyphBufferStringOffset stringOffset; |
| bool characterIsSpace; |
| float advanceBeforeCharacter; |
| float advanceAtCharacter; |
| }; |
| |
| inline auto WidthIterator::applyFontTransforms(GlyphBuffer& glyphBuffer, unsigned lastGlyphCount, const Font& font, CharactersTreatedAsSpace& charactersTreatedAsSpace) -> ApplyFontTransformsResult |
| { |
| auto glyphBufferSize = glyphBuffer.size(); |
| ASSERT(lastGlyphCount <= glyphBufferSize); |
| if (lastGlyphCount >= glyphBufferSize) |
| return { 0, makeGlyphBufferAdvance() }; |
| |
| GlyphBufferAdvance* advances = glyphBuffer.advances(0); |
| float beforeWidth = 0; |
| for (unsigned i = lastGlyphCount; i < glyphBufferSize; ++i) |
| beforeWidth += width(advances[i]); |
| |
| auto initialAdvance = font.applyTransforms(glyphBuffer, lastGlyphCount, m_currentCharacterIndex, m_enableKerning, m_requiresShaping, m_font.fontDescription().computedLocale(), m_run.text(), m_run.direction()); |
| |
| #if USE(CTFONTSHAPEGLYPHS_WORKAROUND) |
| // <rdar://problem/80798113>: If a character is not in BMP, and we don't have a glyph for it, |
| // we'll end up with two 0 glyphs in a row for the two surrogates of the character. |
| // We need to make sure that, after shaping, these double-0-glyphs aren't preserved. |
| if (&font == &m_font.primaryFont() && !m_run.text().is8Bit()) { |
| for (unsigned i = 0; i < glyphBuffer.size() - 1; ++i) { |
| if (!glyphBuffer.glyphAt(i) && !glyphBuffer.glyphAt(i + 1)) { |
| if (const auto& firstStringOffset = glyphBuffer.checkedStringOffsetAt(i, m_run.length())) { |
| if (const auto& secondStringOffset = glyphBuffer.checkedStringOffsetAt(i + 1, m_run.length())) { |
| if (secondStringOffset.value() == firstStringOffset.value() + 1 |
| && U_IS_LEAD(m_run.text()[firstStringOffset.value()]) && U_IS_TRAIL(m_run.text()[secondStringOffset.value()])) { |
| glyphBuffer.remove(i + 1, 1); |
| } |
| } |
| } |
| } |
| } |
| } |
| #endif |
| |
| glyphBufferSize = glyphBuffer.size(); |
| advances = glyphBuffer.advances(0); |
| |
| GlyphBufferOrigin* origins = glyphBuffer.origins(0); |
| for (unsigned i = lastGlyphCount; i < glyphBufferSize; ++i) { |
| setHeight(advances[i], -height(advances[i])); |
| setY(origins[i], -y(origins[i])); |
| } |
| |
| for (unsigned i = lastGlyphCount; i < glyphBufferSize; ++i) { |
| auto characterIndex = glyphBuffer.uncheckedStringOffsetAt(i); |
| auto iterator = std::lower_bound(charactersTreatedAsSpace.begin(), charactersTreatedAsSpace.end(), characterIndex, [](const OriginalAdvancesForCharacterTreatedAsSpace& l, GlyphBufferStringOffset r) -> bool { |
| return l.stringOffset < r; |
| }); |
| if (iterator == charactersTreatedAsSpace.end() || iterator->stringOffset != characterIndex) |
| continue; |
| const auto& originalAdvances = *iterator; |
| if (i && !originalAdvances.characterIsSpace) |
| setWidth(*glyphBuffer.advances(i - 1), originalAdvances.advanceBeforeCharacter); |
| setWidth(*glyphBuffer.advances(i), originalAdvances.advanceAtCharacter); |
| } |
| charactersTreatedAsSpace.clear(); |
| |
| float afterWidth = 0; |
| for (unsigned i = lastGlyphCount; i < glyphBufferSize; ++i) |
| afterWidth += width(advances[i]); |
| |
| return { afterWidth - beforeWidth, initialAdvance }; |
| } |
| |
| static inline std::pair<bool, bool> expansionLocation(bool ideograph, bool treatAsSpace, bool ltr, bool isAfterExpansion, bool forbidLeftExpansion, bool forbidRightExpansion, bool forceLeftExpansion, bool forceRightExpansion) |
| { |
| bool expandLeft = ideograph; |
| bool expandRight = ideograph; |
| if (treatAsSpace) { |
| if (ltr) |
| expandRight = true; |
| else |
| expandLeft = true; |
| } |
| if (isAfterExpansion) { |
| if (ltr) |
| expandLeft = false; |
| else |
| expandRight = false; |
| } |
| ASSERT(!forbidLeftExpansion || !forceLeftExpansion); |
| ASSERT(!forbidRightExpansion || !forceRightExpansion); |
| if (forbidLeftExpansion) |
| expandLeft = false; |
| if (forbidRightExpansion) |
| expandRight = false; |
| if (forceLeftExpansion) |
| expandLeft = true; |
| if (forceRightExpansion) |
| expandRight = true; |
| return std::make_pair(expandLeft, expandRight); |
| } |
| |
| static void expandWithInitialAdvance(GlyphBufferAdvance& advanceToExpand, const GlyphBufferAdvance& initialAdvance) |
| { |
| setWidth(advanceToExpand, width(advanceToExpand) + width(initialAdvance)); |
| setHeight(advanceToExpand, height(advanceToExpand) + height(initialAdvance)); |
| } |
| |
| void WidthIterator::applyInitialAdvance(GlyphBuffer& glyphBuffer, GlyphBufferAdvance initialAdvance, unsigned lastGlyphCount) |
| { |
| ASSERT(glyphBuffer.size() >= lastGlyphCount); |
| |
| if (glyphBuffer.size() <= lastGlyphCount) |
| return; |
| |
| ASSERT(lastGlyphCount || (!width(m_leftoverInitialAdvance) && !height(m_leftoverInitialAdvance))); |
| |
| if (m_run.direction() == TextDirection::RTL && lastGlyphCount) { |
| auto& visuallyLastAdvance = *glyphBuffer.advances(lastGlyphCount); |
| expandWithInitialAdvance(visuallyLastAdvance, m_leftoverInitialAdvance); |
| m_runWidthSoFar += width(m_leftoverInitialAdvance); |
| m_leftoverInitialAdvance = makeGlyphBufferAdvance(); |
| } |
| |
| if (m_run.direction() == TextDirection::RTL) |
| m_leftoverInitialAdvance = initialAdvance; |
| else { |
| if (lastGlyphCount) { |
| auto& visuallyPreviousAdvance = *glyphBuffer.advances(lastGlyphCount - 1); |
| expandWithInitialAdvance(visuallyPreviousAdvance, initialAdvance); |
| m_runWidthSoFar += width(initialAdvance); |
| } else |
| glyphBuffer.expandInitialAdvance(initialAdvance); |
| } |
| } |
| |
| void WidthIterator::commitCurrentFontRange(GlyphBuffer& glyphBuffer, unsigned& lastGlyphCount, unsigned currentCharacterIndex, const Font*& font, const Font& newFont, const Font& primaryFont, UChar32 character, float& widthOfCurrentFontRange, float nextCharacterWidth, CharactersTreatedAsSpace& charactersTreatedAsSpace) |
| { |
| #if ASSERT_ENABLED |
| ASSERT(font); |
| for (unsigned i = lastGlyphCount; i < glyphBuffer.size(); ++i) |
| ASSERT(&glyphBuffer.fontAt(i) == font); |
| #endif |
| |
| auto applyFontTransformsResult = applyFontTransforms(glyphBuffer, lastGlyphCount, *font, charactersTreatedAsSpace); |
| m_runWidthSoFar += applyFontTransformsResult.additionalAdvance; |
| applyInitialAdvance(glyphBuffer, applyFontTransformsResult.initialAdvance, lastGlyphCount); |
| m_currentCharacterIndex = currentCharacterIndex; |
| |
| if (widthOfCurrentFontRange && m_fallbackFonts && font != &primaryFont) { |
| // FIXME: This does a little extra work that could be avoided if |
| // glyphDataForCharacter() returned whether it chose to use a small caps font. |
| if (!m_font.isSmallCaps() || character == u_toupper(character)) |
| m_fallbackFonts->add(font); |
| else { |
| auto glyphFont = m_font.glyphDataForCharacter(u_toupper(character), m_run.rtl()).font; |
| if (glyphFont != &primaryFont) |
| m_fallbackFonts->add(glyphFont); |
| } |
| } |
| |
| lastGlyphCount = glyphBuffer.size(); |
| font = &newFont; |
| widthOfCurrentFontRange = nextCharacterWidth; |
| } |
| |
| bool WidthIterator::hasExtraSpacing() const |
| { |
| return (m_font.letterSpacing() || m_font.wordSpacing() || m_expansion) && !m_run.spacingDisabled(); |
| } |
| |
| static void addToGlyphBuffer(GlyphBuffer& glyphBuffer, Glyph glyph, const Font& font, float width, GlyphBufferStringOffset currentCharacterIndex, UChar32 character) |
| { |
| glyphBuffer.add(glyph, font, width, currentCharacterIndex); |
| #if USE(CTFONTSHAPEGLYPHS) |
| // These 0 glyphs are needed by shapers if the source text has surrogate pairs. |
| // However, CTFontTransformGlyphs() can't delete these 0 glyphs from the shaped text, |
| // so we shouldn't add them in the first place if we're using that shaping routine. |
| // Any other shaping routine should delete these glyphs from the shaped text. |
| if (!U_IS_BMP(character)) |
| glyphBuffer.add(0, font, 0, currentCharacterIndex + 1); |
| #else |
| UNUSED_PARAM(character); |
| #endif |
| } |
| |
| template <typename TextIterator> |
| inline void WidthIterator::advanceInternal(TextIterator& textIterator, GlyphBuffer& glyphBuffer) |
| { |
| // The core logic here needs to match FontCascade::widthForSimpleText() |
| bool rtl = m_run.rtl(); |
| |
| FloatRect bounds; |
| |
| const Font& primaryFont = m_font.primaryFont(); |
| const Font* lastFontData = &primaryFont; |
| unsigned lastGlyphCount = glyphBuffer.size(); |
| |
| auto currentCharacterIndex = textIterator.currentIndex(); |
| UChar32 character = 0; |
| float width = 0; |
| float previousWidth = 0; |
| unsigned clusterLength = 0; |
| CharactersTreatedAsSpace charactersTreatedAsSpace; |
| float widthOfCurrentFontRange = 0; |
| // We are iterating in string order, not glyph order. Compare this to ComplexTextController::adjustGlyphsAndAdvances() |
| while (textIterator.consume(character, clusterLength)) { |
| // FIXME: Should we replace unpaired surrogates with the object replacement character? |
| // Should we do this before or after shaping? What does a shaper do with an unpaired surrogate? |
| m_containsTabs |= character == tabCharacter; |
| currentCharacterIndex = textIterator.currentIndex(); |
| unsigned advanceLength = clusterLength; |
| if (currentCharacterIndex + advanceLength == m_run.length()) |
| m_lastCharacterIndex = currentCharacterIndex; |
| bool characterMustDrawSomething = !isDefaultIgnorableCodePoint(character); |
| #if USE(FREETYPE) |
| // Freetype based ports only override the characters with Default_Ignorable unicode property when the font |
| // doesn't support the code point. We should ignore them at this point to ensure they are not displayed. |
| if (!characterMustDrawSomething) { |
| textIterator.advance(advanceLength); |
| currentCharacterIndex = textIterator.currentIndex(); |
| continue; |
| } |
| #endif |
| const GlyphData& glyphData = m_font.glyphDataForCharacter(character, rtl); |
| Glyph glyph = glyphData.glyph; |
| if (!glyph && !characterMustDrawSomething) { |
| commitCurrentFontRange(glyphBuffer, lastGlyphCount, currentCharacterIndex, lastFontData, primaryFont, primaryFont, character, widthOfCurrentFontRange, width, charactersTreatedAsSpace); |
| |
| Glyph deletedGlyph = 0xFFFF; |
| addToGlyphBuffer(glyphBuffer, deletedGlyph, primaryFont, 0, currentCharacterIndex, character); |
| |
| textIterator.advance(advanceLength); |
| currentCharacterIndex = textIterator.currentIndex(); |
| continue; |
| } |
| const Font& font = glyphData.font ? *glyphData.font : primaryFont; |
| |
| previousWidth = width; |
| width = font.widthForGlyph(glyph, Font::SyntheticBoldInclusion::Exclude); // We apply synthetic bold after shaping, in applyCSSVisibilityRules(). |
| |
| if (&font != lastFontData) |
| commitCurrentFontRange(glyphBuffer, lastGlyphCount, currentCharacterIndex, lastFontData, font, primaryFont, character, widthOfCurrentFontRange, width, charactersTreatedAsSpace); |
| else |
| widthOfCurrentFontRange += width; |
| |
| if (FontCascade::treatAsSpace(character)) |
| charactersTreatedAsSpace.constructAndAppend(currentCharacterIndex, character == space, previousWidth, character == tabCharacter ? width : font.spaceWidth(Font::SyntheticBoldInclusion::Exclude)); |
| |
| if (m_accountForGlyphBounds) { |
| bounds = font.boundsForGlyph(glyph); |
| if (!currentCharacterIndex) |
| m_firstGlyphOverflow = std::max<float>(0, -bounds.x()); |
| } |
| |
| if (m_forTextEmphasis && !FontCascade::canReceiveTextEmphasis(character)) |
| glyph = 0; |
| |
| addToGlyphBuffer(glyphBuffer, glyph, font, width, currentCharacterIndex, character); |
| |
| // Advance past the character we just dealt with. |
| textIterator.advance(advanceLength); |
| currentCharacterIndex = textIterator.currentIndex(); |
| |
| m_runWidthSoFar += width; |
| |
| if (m_accountForGlyphBounds) { |
| m_maxGlyphBoundingBoxY = std::max(m_maxGlyphBoundingBoxY, bounds.maxY()); |
| m_minGlyphBoundingBoxY = std::min(m_minGlyphBoundingBoxY, bounds.y()); |
| m_lastGlyphOverflow = std::max<float>(0, bounds.maxX() - width); |
| } |
| } |
| |
| commitCurrentFontRange(glyphBuffer, lastGlyphCount, currentCharacterIndex, lastFontData, primaryFont, primaryFont, character, widthOfCurrentFontRange, width, charactersTreatedAsSpace); |
| } |
| |
| auto WidthIterator::calculateAdditionalWidth(GlyphBuffer& glyphBuffer, GlyphBufferStringOffset currentCharacterIndex, unsigned leadingGlyphIndex, unsigned trailingGlyphIndex, float position) const -> AdditionalWidth |
| { |
| float leftAdditionalWidth = 0; |
| float rightAdditionalWidth = 0; |
| float leftExpansionAdditionalWidth = 0; |
| float rightExpansionAdditionalWidth = 0; |
| |
| auto character = m_run[currentCharacterIndex]; |
| |
| if (character == tabCharacter && m_run.allowTabs()) { |
| auto& font = glyphBuffer.fontAt(trailingGlyphIndex); |
| // Synthetic bold will be handled in applyCSSVisibilityRules() later. |
| auto newWidth = m_font.tabWidth(font, m_run.tabSize(), position, Font::SyntheticBoldInclusion::Exclude); |
| auto currentWidth = width(glyphBuffer.advanceAt(trailingGlyphIndex)); |
| rightAdditionalWidth += newWidth - currentWidth; |
| } |
| |
| if (hasExtraSpacing()) { |
| bool treatAsSpace = FontCascade::treatAsSpace(character); |
| |
| // This is a heuristic to determine if the character is non-visible. Non-visible characters don't get letter-spacing. |
| float baseWidth = 0; |
| for (unsigned i = leadingGlyphIndex; i <= trailingGlyphIndex; ++i) |
| baseWidth += width(glyphBuffer.advanceAt(i)); |
| if (baseWidth) |
| rightAdditionalWidth += m_font.letterSpacing(); |
| |
| if (treatAsSpace && (character != tabCharacter || !m_run.allowTabs()) && (currentCharacterIndex || character == noBreakSpace) && m_font.wordSpacing()) |
| rightAdditionalWidth += m_font.wordSpacing(); |
| |
| if (m_expansion > 0) { |
| bool currentIsLastCharacter = m_lastCharacterIndex && currentCharacterIndex == static_cast<GlyphBufferStringOffset>(*m_lastCharacterIndex); |
| |
| bool isLeftmostCharacter = !currentCharacterIndex; |
| bool isRightmostCharacter = currentIsLastCharacter; |
| if (!m_run.ltr()) |
| std::swap(isLeftmostCharacter, isRightmostCharacter); |
| |
| bool forceLeftExpansion = isLeftmostCharacter && m_run.expansionBehavior().left == ExpansionBehavior::Behavior::Force; |
| bool forceRightExpansion = isRightmostCharacter && m_run.expansionBehavior().right == ExpansionBehavior::Behavior::Force; |
| bool forbidLeftExpansion = isLeftmostCharacter && m_run.expansionBehavior().left == ExpansionBehavior::Behavior::Forbid; |
| bool forbidRightExpansion = isRightmostCharacter && m_run.expansionBehavior().right == ExpansionBehavior::Behavior::Forbid; |
| |
| bool isIdeograph = FontCascade::canExpandAroundIdeographsInComplexText() && FontCascade::isCJKIdeographOrSymbol(character); |
| |
| if (treatAsSpace || isIdeograph || forceLeftExpansion || forceRightExpansion) { |
| auto [expandLeft, expandRight] = expansionLocation(isIdeograph, treatAsSpace, m_run.ltr(), m_isAfterExpansion, forbidLeftExpansion, forbidRightExpansion, forceLeftExpansion, forceRightExpansion); |
| |
| if (expandLeft) |
| leftExpansionAdditionalWidth += m_expansionPerOpportunity; |
| if (expandRight) |
| rightExpansionAdditionalWidth += m_expansionPerOpportunity; |
| } |
| } |
| } |
| |
| return { leftAdditionalWidth, rightAdditionalWidth, leftExpansionAdditionalWidth, rightExpansionAdditionalWidth }; |
| } |
| |
| struct GlyphIndexRange { |
| // This means the character got expanded to glyphs inside the GlyphBuffer at indices [leadingGlyphIndex, trailingGlyphIndex]. |
| unsigned leadingGlyphIndex; |
| unsigned trailingGlyphIndex; |
| }; |
| |
| void WidthIterator::applyAdditionalWidth(GlyphBuffer& glyphBuffer, GlyphIndexRange glyphIndexRange, float leftAdditionalWidth, float rightAdditionalWidth, float leftExpansionAdditionalWidth, float rightExpansionAdditionalWidth) |
| { |
| m_expansion -= leftExpansionAdditionalWidth + rightExpansionAdditionalWidth; |
| |
| leftAdditionalWidth += leftExpansionAdditionalWidth; |
| rightAdditionalWidth += rightExpansionAdditionalWidth; |
| |
| m_runWidthSoFar += leftAdditionalWidth; |
| m_runWidthSoFar += rightAdditionalWidth; |
| |
| if (leftAdditionalWidth) { |
| if (m_run.ltr()) { |
| // Left additional width in LTR means the previous (leading) glyph's right side gets expanded. |
| auto leadingGlyphIndex = glyphIndexRange.leadingGlyphIndex; |
| if (leadingGlyphIndex) |
| glyphBuffer.expandAdvance(leadingGlyphIndex - 1, leftAdditionalWidth); |
| else |
| glyphBuffer.expandInitialAdvance(leftAdditionalWidth); |
| } else { |
| // Left additional width in RTL means the next (trailing) glyph's right side gets expanded. |
| auto trailingGlyphIndex = glyphIndexRange.trailingGlyphIndex; |
| if (trailingGlyphIndex + 1 < glyphBuffer.size()) |
| glyphBuffer.expandAdvance(trailingGlyphIndex + 1, leftAdditionalWidth); |
| else { |
| m_leftoverJustificationWidth = leftAdditionalWidth; |
| // We can't actually add in this width just yet. |
| // Add it in when the client calls advance() again or finalize(). |
| m_runWidthSoFar -= m_leftoverJustificationWidth; |
| } |
| } |
| } |
| |
| if (rightAdditionalWidth) { |
| // Right additional width means the current glyph's right side gets expanded. This is true for both LTR and RTL. |
| glyphBuffer.expandAdvance(glyphIndexRange.trailingGlyphIndex, rightAdditionalWidth); |
| } |
| } |
| |
| void WidthIterator::applyExtraSpacingAfterShaping(GlyphBuffer& glyphBuffer, unsigned characterStartIndex, unsigned glyphBufferStartIndex, unsigned characterDestinationIndex, float startingRunWidth) |
| { |
| Vector<std::optional<GlyphIndexRange>> characterIndexToGlyphIndexRange(m_run.length(), std::nullopt); |
| Vector<float> advanceWidths(m_run.length(), 0); |
| for (unsigned i = glyphBufferStartIndex; i < glyphBuffer.size(); ++i) { |
| auto stringOffset = glyphBuffer.checkedStringOffsetAt(i, m_run.length()); |
| if (!stringOffset) |
| continue; |
| advanceWidths[stringOffset.value()] += width(glyphBuffer.advanceAt(i)); |
| auto& glyphIndexRange = characterIndexToGlyphIndexRange[stringOffset.value()]; |
| if (glyphIndexRange) |
| glyphIndexRange->trailingGlyphIndex = i; |
| else |
| glyphIndexRange = {{i, i}}; |
| } |
| |
| // SVG can stretch advances |
| if (m_run.horizontalGlyphStretch() != 1) { |
| for (unsigned i = glyphBufferStartIndex; i < glyphBuffer.size(); ++i) { |
| // All characters' advances get stretched, except apparently tab characters... |
| // This doesn't make much sense, because even tab characters get letter-spacing... |
| auto stringOffset = glyphBuffer.checkedStringOffsetAt(i, m_run.length()); |
| if (stringOffset && m_run[stringOffset.value()] == tabCharacter) |
| continue; |
| |
| auto currentAdvance = width(glyphBuffer.advanceAt(i)); |
| auto newAdvance = currentAdvance * m_run.horizontalGlyphStretch(); |
| glyphBuffer.expandAdvance(i, newAdvance - currentAdvance); |
| } |
| } |
| |
| float position = m_run.xPos() + startingRunWidth; |
| for (auto i = characterStartIndex; i < characterDestinationIndex; ++i) { |
| auto& glyphIndexRange = characterIndexToGlyphIndexRange[i]; |
| if (!glyphIndexRange) |
| continue; |
| |
| auto width = calculateAdditionalWidth(glyphBuffer, i, glyphIndexRange->leadingGlyphIndex, glyphIndexRange->trailingGlyphIndex, position); |
| applyAdditionalWidth(glyphBuffer, glyphIndexRange.value(), width.left, width.right, width.leftExpansion, width.rightExpansion); |
| |
| m_isAfterExpansion = (m_run.ltr() && width.rightExpansion) || (!m_run.ltr() && width.leftExpansion); |
| |
| // This isn't quite perfect, because we may come across a tab character in between two glyphs which both report to correspond to a previous character. |
| // But, the fundamental concept of tabs isn't really compatible with complex text shaping, so this is probably okay. |
| // We can probably just do the best we can here. |
| // The only alternative, to calculate this position in glyph-space rather than character-space, |
| // is O(n^2) because we're iterating across the string here, rather than glyphs, so we can't keep the calculation up-to-date, |
| // which means calculateAdditionalWidth() would have to calculate the result from scratch whenever it's needed. |
| // And we can't do some sort of prefix-sum thing because applyAdditionalWidth() would modify the values, |
| // so updating the data structure each turn of this loop would also end up being O(n^2). |
| // Unfortunately, strings with tabs are more likely to be long data-table kind of strings, which means O(n^2) is not acceptable. |
| // Also, even if we did the O(n^2) thing, there would still be cases that wouldn't be perfect |
| // (because the fundamental concept of tabs isn't really compatible with complex text shaping), |
| // so let's choose the fast-wrong approach here instead of the slow-wrong approach. |
| position += advanceWidths[i] |
| + width.left |
| + width.right |
| + width.leftExpansion |
| + width.rightExpansion; |
| } |
| } |
| |
| bool WidthIterator::characterCanUseSimplifiedTextMeasuring(UChar character, bool whitespaceIsCollapsed) |
| { |
| // This function needs to be kept in sync with applyCSSVisibilityRules(). |
| |
| switch (character) { |
| case newlineCharacter: |
| case carriageReturn: |
| case zeroWidthNoBreakSpace: |
| case zeroWidthNonJoiner: |
| case zeroWidthJoiner: |
| return true; |
| case tabCharacter: |
| if (!whitespaceIsCollapsed) |
| return false; |
| break; |
| case noBreakSpace: |
| case softHyphen: |
| case leftToRightMark: |
| case rightToLeftMark: |
| case leftToRightEmbed: |
| case rightToLeftEmbed: |
| case leftToRightOverride: |
| case rightToLeftOverride: |
| case leftToRightIsolate: |
| case rightToLeftIsolate: |
| case popDirectionalFormatting: |
| case popDirectionalIsolate: |
| case firstStrongIsolate: |
| case objectReplacementCharacter: |
| return false; |
| break; |
| } |
| |
| if (character >= HiraganaLetterSmallA |
| || u_charType(character) == U_CONTROL_CHAR |
| || (character >= nullCharacter && character < space) |
| || (character >= deleteCharacter && character < noBreakSpace)) |
| return false; |
| |
| return true; |
| } |
| |
| void WidthIterator::applyCSSVisibilityRules(GlyphBuffer& glyphBuffer, unsigned glyphBufferStartIndex) |
| { |
| // This function needs to be kept in sync with characterCanUseSimplifiedTextMeasuring(). |
| |
| Vector<unsigned> glyphsIndicesToBeDeleted; |
| |
| float yPosition = height(glyphBuffer.initialAdvance()); |
| |
| auto adjustForSyntheticBold = [&](auto index) { |
| auto glyph = glyphBuffer.glyphAt(index); |
| static constexpr const GlyphBufferGlyph deletedGlyph = 0xFFFF; |
| auto syntheticBoldOffset = glyph == deletedGlyph ? 0 : glyphBuffer.fontAt(index).syntheticBoldOffset(); |
| m_runWidthSoFar += syntheticBoldOffset; |
| auto& advance = glyphBuffer.advances(index)[0]; |
| setWidth(advance, width(advance) + syntheticBoldOffset); |
| }; |
| |
| auto clobberGlyph = [&](auto index, auto newGlyph) { |
| glyphBuffer.glyphs(index)[0] = newGlyph; |
| }; |
| |
| // FIXME: It's technically wrong to call clobberAdvance or deleteGlyph here, because this is after initialAdvances have been |
| // applied. If the last glyph in a run needs to have its advance clobbered, but the next run has an initial advance, we need |
| // to apply the initial advance on the new clobbered advance, rather than clobbering the initial advance entirely. |
| |
| auto clobberAdvance = [&](auto index, auto newAdvance) { |
| auto advanceBeforeClobbering = glyphBuffer.advanceAt(index); |
| glyphBuffer.advances(index)[0] = makeGlyphBufferAdvance(newAdvance, height(advanceBeforeClobbering)); |
| m_runWidthSoFar += width(glyphBuffer.advanceAt(index)) - width(advanceBeforeClobbering); |
| glyphBuffer.origins(index)[0] = makeGlyphBufferOrigin(0, -yPosition); |
| }; |
| |
| auto deleteGlyph = [&](auto index) { |
| m_runWidthSoFar -= width(glyphBuffer.advanceAt(index)); |
| glyphBuffer.deleteGlyphWithoutAffectingSize(index); |
| }; |
| |
| auto makeGlyphInvisible = [&](auto index) { |
| glyphBuffer.makeGlyphInvisible(index); |
| }; |
| |
| for (unsigned i = glyphBufferStartIndex; i < glyphBuffer.size(); yPosition += height(glyphBuffer.advanceAt(i)), ++i) { |
| auto stringOffset = glyphBuffer.checkedStringOffsetAt(i, m_run.length()); |
| if (!stringOffset) |
| continue; |
| auto characterResponsibleForThisGlyph = m_run[stringOffset.value()]; |
| |
| switch (characterResponsibleForThisGlyph) { |
| case newlineCharacter: |
| case carriageReturn: |
| ASSERT(glyphBuffer.fonts(i)[0]); |
| // FIXME: It isn't quite right to use the space glyph here, because the space character may be supposed to render with a totally unrelated font (because of fallback). |
| // Instead, we should probably somehow have the caller pass in a Font/glyph pair to use in this situation. |
| if (auto spaceGlyph = glyphBuffer.fontAt(i).spaceGlyph()) |
| clobberGlyph(i, spaceGlyph); |
| adjustForSyntheticBold(i); |
| continue; |
| case noBreakSpace: |
| adjustForSyntheticBold(i); |
| continue; |
| case tabCharacter: |
| makeGlyphInvisible(i); |
| adjustForSyntheticBold(i); |
| continue; |
| } |
| |
| // https://www.w3.org/TR/css-text-3/#white-space-processing |
| // "Control characters (Unicode category Cc)—other than tabs (U+0009), line feeds (U+000A), carriage returns (U+000D) and sequences that form a segment break—must be rendered as a visible glyph" |
| // Also, we're omitting NULL (U+0000) from this set because Chrome and Firefox do so and it's needed for compat. See https://github.com/w3c/csswg-drafts/pull/6983. |
| if (characterResponsibleForThisGlyph != nullCharacter |
| && u_charType(characterResponsibleForThisGlyph) == U_CONTROL_CHAR) { |
| // Let's assume that .notdef is visible. |
| GlyphBufferGlyph visibleGlyph = 0; |
| clobberGlyph(i, visibleGlyph); |
| clobberAdvance(i, glyphBuffer.fontAt(i).widthForGlyph(visibleGlyph)); |
| continue; |
| } |
| |
| adjustForSyntheticBold(i); |
| |
| // https://drafts.csswg.org/css-text-3/#white-space-processing |
| // "Unsupported Default_ignorable characters must be ignored for text rendering." |
| if (FontCascade::isCharacterWhoseGlyphsShouldBeDeletedForTextRendering(characterResponsibleForThisGlyph)) { |
| deleteGlyph(i); |
| continue; |
| } |
| } |
| } |
| |
| void WidthIterator::finalize(GlyphBuffer& buffer) |
| { |
| ASSERT(m_run.rtl() || !m_leftoverJustificationWidth); |
| // In LTR these do nothing. In RTL, these add left width by moving the whole run to the right. |
| buffer.expandInitialAdvance(m_leftoverInitialAdvance); |
| m_runWidthSoFar += width(m_leftoverInitialAdvance); |
| buffer.expandInitialAdvance(m_leftoverJustificationWidth); |
| m_runWidthSoFar += m_leftoverJustificationWidth; |
| m_leftoverJustificationWidth = 0; |
| } |
| |
| void WidthIterator::advance(unsigned offset, GlyphBuffer& glyphBuffer) |
| { |
| m_containsTabs = false; |
| unsigned length = m_run.length(); |
| |
| if (offset > length) |
| offset = length; |
| |
| if (m_currentCharacterIndex >= offset) |
| return; |
| |
| unsigned characterStartIndex = m_currentCharacterIndex; |
| unsigned glyphBufferStartIndex = glyphBuffer.size(); |
| float startingRunWidth = m_runWidthSoFar; |
| |
| if (m_run.is8Bit()) { |
| Latin1TextIterator textIterator(m_run.data8(m_currentCharacterIndex), m_currentCharacterIndex, offset, length); |
| advanceInternal(textIterator, glyphBuffer); |
| } else { |
| #if USE(CLUSTER_AWARE_WIDTH_ITERATOR) |
| ComposedCharacterClusterTextIterator textIterator(m_run.data16(m_currentCharacterIndex), m_currentCharacterIndex, offset, length); |
| #else |
| SurrogatePairAwareTextIterator textIterator(m_run.data16(m_currentCharacterIndex), m_currentCharacterIndex, offset, length); |
| #endif |
| advanceInternal(textIterator, glyphBuffer); |
| } |
| |
| // In general, we have to apply spacing after shaping, because shaping requires its input to be unperturbed (see https://bugs.webkit.org/show_bug.cgi?id=215052). |
| // So, if there's extra spacing to add, do it here after shaping occurs. |
| if (glyphBufferStartIndex < glyphBuffer.size()) { |
| glyphBuffer.expandAdvance(glyphBufferStartIndex, m_leftoverJustificationWidth); |
| m_runWidthSoFar += m_leftoverJustificationWidth; |
| m_leftoverJustificationWidth = 0; |
| } |
| |
| if (hasExtraSpacing() || m_containsTabs || m_run.horizontalGlyphStretch() != 1) |
| applyExtraSpacingAfterShaping(glyphBuffer, characterStartIndex, glyphBufferStartIndex, offset, startingRunWidth); |
| |
| applyCSSVisibilityRules(glyphBuffer, glyphBufferStartIndex); |
| } |
| |
| bool WidthIterator::advanceOneCharacter(float& width, GlyphBuffer& glyphBuffer) |
| { |
| unsigned oldSize = glyphBuffer.size(); |
| advance(m_currentCharacterIndex + 1, glyphBuffer); |
| float w = 0; |
| for (unsigned i = oldSize; i < glyphBuffer.size(); ++i) |
| w += WebCore::width(glyphBuffer.advanceAt(i)); |
| width = w; |
| return glyphBuffer.size() > oldSize; |
| } |
| |
| } |
