Files
Crosspoint/lib/Epub/Epub/ParsedText.cpp
T
2026-05-29 03:25:17 -04:00

970 lines
41 KiB
C++

#include "ParsedText.h"
#include <BidiUtils.h>
#include <GfxRenderer.h>
#include <Utf8.h>
#include <algorithm>
#include <cmath>
#include <functional>
#include <limits>
#include <vector>
#include "hyphenation/Hyphenator.h"
constexpr int MAX_COST = std::numeric_limits<int>::max();
namespace {
// Soft hyphen byte pattern used throughout EPUBs (UTF-8 for U+00AD).
constexpr char SOFT_HYPHEN_UTF8[] = "\xC2\xAD";
constexpr size_t SOFT_HYPHEN_BYTES = 2;
// Paragraph-level direction: scan the first N words to find base direction.
constexpr size_t RTL_PARAGRAPH_PROBE_WORDS = 3;
// Per-word: scan enough chars to see through leading neutrals (quotes, numbers)
// before giving up. 64 is a hedge for pathological cases like long numeric tokens.
constexpr int RTL_PER_WORD_PROBE_DEPTH = 64;
// Byte-level pre-check: Hebrew UTF-8 lead bytes 0xD6-0xD7, Arabic/Syriac 0xD8-0xDB.
bool mayContainRtlBytes(const char* str) {
for (const auto* p = reinterpret_cast<const unsigned char*>(str); *p; ++p) {
if (*p >= 0xD6 && *p <= 0xDB) return true;
}
return false;
}
// Returns the first rendered codepoint of a word (skipping leading soft hyphens).
uint32_t firstCodepoint(const std::string& word) {
const auto* ptr = reinterpret_cast<const unsigned char*>(word.c_str());
while (true) {
const uint32_t cp = utf8NextCodepoint(&ptr);
if (cp == 0) return 0;
if (cp != 0x00AD) return cp; // skip soft hyphens
}
}
// Returns the last codepoint of a word by scanning backward for the start of the last UTF-8 sequence.
uint32_t lastCodepoint(const std::string& word) {
if (word.empty()) return 0;
// UTF-8 continuation bytes start with 10xxxxxx; scan backward to find the leading byte.
size_t i = word.size() - 1;
while (i > 0 && (static_cast<uint8_t>(word[i]) & 0xC0) == 0x80) {
--i;
}
const auto* ptr = reinterpret_cast<const unsigned char*>(word.c_str() + i);
return utf8NextCodepoint(&ptr);
}
bool containsSoftHyphen(const std::string& word) { return word.find(SOFT_HYPHEN_UTF8) != std::string::npos; }
// Removes every soft hyphen in-place so rendered glyphs match measured widths.
void stripSoftHyphensInPlace(std::string& word) {
size_t pos = 0;
while ((pos = word.find(SOFT_HYPHEN_UTF8, pos)) != std::string::npos) {
word.erase(pos, SOFT_HYPHEN_BYTES);
}
}
// Returns the advance width for a word while ignoring soft hyphen glyphs and optionally appending a visible hyphen.
// Uses advance width (sum of glyph advances + kerning) rather than bounding box width so that italic glyph overhangs
// don't inflate inter-word spacing.
uint16_t measureWordWidth(const GfxRenderer& renderer, const int fontId, const std::string& word,
const EpdFontFamily::Style style, const bool appendHyphen = false) {
if (word.size() == 1 && word[0] == ' ' && !appendHyphen) {
return renderer.getSpaceWidth(fontId, style);
}
const bool hasSoftHyphen = containsSoftHyphen(word);
if (!hasSoftHyphen && !appendHyphen) {
return renderer.getTextAdvanceX(fontId, word.c_str(), style);
}
std::string sanitized = word;
if (hasSoftHyphen) {
stripSoftHyphensInPlace(sanitized);
}
if (appendHyphen) {
sanitized.push_back('-');
}
return renderer.getTextAdvanceX(fontId, sanitized.c_str(), style);
}
// Checks if a UTF-8 codepoint should be counted as part of a word for Focus Reading
bool isWordCharacter(uint32_t cp) {
// ASCII range (Catches 95%+ of characters immediately)
if (cp < 128) {
// Bitwise trick: (cp | 0x20) converts uppercase ASCII to lowercase.
// This checks for A-Z and a-z mathematically, avoiding memory lookups and <cctype>
return ((cp | 0x20) >= 'a' && (cp | 0x20) <= 'z') || cp == '\'';
}
// General Punctuation Block, Currency, Math, Arrows, & Symbols (0x2000 - 0x2BFF)
if (cp >= 0x2000 && cp <= 0x2BFF) {
// Explicitly allow smart quotes, reject all other general punctuation (em-dashes, etc.)
return cp == 0x2018 || cp == 0x2019;
}
// Latin-1 Punctuation Block (0x00A1 - 0x00BF)
if (cp >= 0x00A1 && cp <= 0x00BF) {
// Allow ordinal indicators and micro sign, reject the rest (¡, ¿, «, », etc.)
return cp == 0x00AA || cp == 0x00B5 || cp == 0x00BA;
}
// Rejects Two-em dash, Three-em dash, Double oblique hyphen, etc.
if (cp >= 0x2E00 && cp <= 0x2E7F) return false;
// Rejects Modifier Minus (0x02D7), Small Hyphen (0xFE63), and Fullwidth Hyphen (0xFF0D)
if (cp == 0x02D7 || cp == 0xFE63 || cp == 0xFF0D) return false;
// Assume all other Unicode ranges (accented letters, Cyrillic, Greek, etc.) are valid
return true;
}
} // namespace
void ParsedText::addWord(std::string word, const EpdFontFamily::Style fontStyle, const bool underline,
const bool attachToPrevious) {
if (word.empty()) return;
EpdFontFamily::Style baseStyle = fontStyle;
if (underline) {
baseStyle = static_cast<EpdFontFamily::Style>(baseStyle | EpdFontFamily::UNDERLINE);
}
const bool wordStartsRtl = !hasRtlWord && mayContainRtlBytes(word.c_str()) &&
BidiUtils::startsWithRtl(word.c_str(), RTL_PER_WORD_PROBE_DEPTH);
// Already-bold text should stay fully bold; focus splitting would make its suffix regular later.
if (!this->focusReadingEnabled || (baseStyle & EpdFontFamily::BOLD) != 0) {
words.push_back(std::move(word));
wordStyles.push_back(baseStyle);
wordContinues.push_back(attachToPrevious);
wordIsFocusSuffix.push_back(false);
if (wordStartsRtl) {
hasRtlWord = true;
}
return;
}
// --- FOCUS READING LOGIC BELOW ---
// Pre-reserve capacity to prevent mid-word heap reallocations.
size_t maxPossibleNewTokens = word.length();
size_t requiredSize = words.size() + maxPossibleNewTokens;
if (words.capacity() < requiredSize) {
// Emulate standard geometric growth (doubling) to ensure we don't reallocate on every word.
size_t newCapacity = words.capacity() * 2;
// Ensure the doubled capacity is actually enough for this specific word
if (newCapacity < requiredSize) {
newCapacity = requiredSize;
}
// Set a sensible minimum starting size so the first few words don't trigger tiny reallocations
if (newCapacity < 16) {
newCapacity = 16;
}
words.reserve(newCapacity);
wordStyles.reserve(newCapacity);
wordContinues.reserve(newCapacity);
wordIsFocusSuffix.reserve(newCapacity);
}
// Lambda helper to process and push individual sub-segments of the string
// Use std::string_view to avoid heap allocations when slicing
auto processSegment = [&](std::string_view segment, bool isWord, bool attach) {
if (!isWord) {
// Punctuation and Numbers stay regular
words.emplace_back(segment);
wordStyles.push_back(baseStyle);
wordContinues.push_back(attach);
wordIsFocusSuffix.push_back(false);
} else {
size_t charCount = 0;
const unsigned char* countPtr = reinterpret_cast<const unsigned char*>(segment.data());
const unsigned char* countEnd = countPtr + segment.length();
while (countPtr < countEnd) {
utf8NextCodepoint(&countPtr);
charCount++;
}
// Target 45% for 1-bold at 4 chars and 3-bold at 7 chars with floor truncation
constexpr size_t FOCUS_READING_PERCENT = 45;
size_t targetBoldChars = (charCount * FOCUS_READING_PERCENT) / 100;
targetBoldChars = std::clamp<size_t>(targetBoldChars, 1, 9);
if (targetBoldChars >= charCount) {
// Whole segment is bold - no suffix split needed
words.emplace_back(segment);
wordStyles.push_back(static_cast<EpdFontFamily::Style>(baseStyle | EpdFontFamily::BOLD));
wordContinues.push_back(attach);
wordIsFocusSuffix.push_back(false);
} else {
countPtr = reinterpret_cast<const unsigned char*>(segment.data());
for (size_t i = 0; i < targetBoldChars; ++i) {
utf8NextCodepoint(&countPtr);
}
size_t splitByteOffset = countPtr - reinterpret_cast<const unsigned char*>(segment.data());
// Bold prefix
words.emplace_back(segment.substr(0, splitByteOffset));
wordStyles.push_back(static_cast<EpdFontFamily::Style>(baseStyle | EpdFontFamily::BOLD));
wordContinues.push_back(attach);
wordIsFocusSuffix.push_back(false);
// Regular suffix - marked so extractLine can merge it back into single TextBlock entry
words.emplace_back(segment.substr(splitByteOffset));
wordStyles.push_back(baseStyle);
wordContinues.push_back(true);
wordIsFocusSuffix.push_back(true);
}
}
};
// Tokenize the string by alternating states (Word vs. Non-Word)
const unsigned char* ptr = reinterpret_cast<const unsigned char*>(word.c_str());
const unsigned char* end = ptr + word.length();
const unsigned char* segmentStart = ptr;
uint32_t firstCp = utf8NextCodepoint(&ptr); // Consume the first char to determine initial state
bool inWordSegment = isWordCharacter(firstCp);
bool isFirstSegment = true;
while (ptr < end) {
const unsigned char* currentCpStart = ptr;
uint32_t cp = utf8NextCodepoint(&ptr);
bool isWordChar = isWordCharacter(cp);
// Whenever the character type flips, slice off the segment we just completed and process it
if (isWordChar != inWordSegment) {
size_t segmentLen = currentCpStart - segmentStart;
std::string_view segment(reinterpret_cast<const char*>(segmentStart), segmentLen);
// Only the very first segment inherits the original attachToPrevious flag.
// Every subsequent segment MUST attach=true so it glues seamlessly to the prefix.
processSegment(segment, inWordSegment, isFirstSegment ? attachToPrevious : true);
// Setup for the next segment
segmentStart = currentCpStart;
inWordSegment = isWordChar;
isFirstSegment = false;
}
}
// Process the final remaining segment
size_t segmentLen = end - segmentStart;
std::string_view segment(reinterpret_cast<const char*>(segmentStart), segmentLen);
processSegment(segment, inWordSegment, isFirstSegment ? attachToPrevious : true);
if (wordStartsRtl) {
hasRtlWord = true;
}
}
int ParsedText::resolveFirstLineIndent(const bool isFirstLine) const {
if (isFirstLine && blockStyle.textIndentDefined && (blockStyle.textIndent < 0 || !extraParagraphSpacing) &&
isNaturalAlign) {
return blockStyle.textIndent;
}
return 0;
}
// Consumes data to minimize memory usage
void ParsedText::layoutAndExtractLines(const GfxRenderer& renderer, const int fontId, const uint16_t viewportWidth,
const std::function<void(std::shared_ptr<TextBlock>)>& processLine,
const bool includeLastLine) {
if (words.empty()) {
return;
}
// Per-paragraph RTL auto-detection: only when CSS/HTML didn't explicitly set direction.
// Explicit dir="ltr" must be respected and not overridden by content heuristic.
if (!blockStyle.directionDefined && hasRtlWord) {
// Check the first few words for RTL letter codepoints (no heap allocation).
const size_t wordsToScan = std::min(words.size(), RTL_PARAGRAPH_PROBE_WORDS);
for (size_t i = 0; i < wordsToScan; ++i) {
if (BidiUtils::startsWithRtl(words[i].c_str(), BidiUtils::RTL_PARAGRAPH_PROBE_DEPTH)) {
blockStyle.isRtl = true;
break;
}
}
}
isNaturalAlign =
blockStyle.alignment == CssTextAlign::Justify ||
(blockStyle.isRtl ? blockStyle.alignment == CssTextAlign::Right : blockStyle.alignment == CssTextAlign::Left);
// Apply fixed transforms before any per-line layout work.
applyParagraphIndent();
// Ensure SD card font glyph metrics are loaded before measuring word widths.
// For flash-based fonts isSdCardFont() returns false and this block is skipped
// entirely — no heap allocation. For SD card fonts this reads glyph metadata
// (advanceX only, no bitmaps) for all unique codepoints in this paragraph so
// that calculateWordWidths() can measure text without on-demand SD I/O.
if (renderer.isSdCardFont(fontId)) {
// Style mask: only ask the SD font to load advances for styles actually
// used in this paragraph. Style index is the low two bits (regular/bold/
// italic/bold-italic); the underline bit is irrelevant to advance metrics.
uint8_t styleMask = 0;
for (auto s : wordStyles) {
styleMask |= static_cast<uint8_t>(1u << (static_cast<uint8_t>(s) & 0x03));
}
if (styleMask == 0) styleMask = 0x01; // defensive: regular only
renderer.ensureSdCardFontReady(fontId, words, hyphenationEnabled, styleMask);
}
const int pageWidth = viewportWidth;
auto wordWidths = calculateWordWidths(renderer, fontId);
std::vector<size_t> lineBreakIndices;
if (hyphenationEnabled) {
// Use greedy layout that can split words mid-loop when a hyphenated prefix fits.
lineBreakIndices = computeHyphenatedLineBreaks(renderer, fontId, pageWidth, wordWidths, wordContinues);
} else {
lineBreakIndices = computeLineBreaks(renderer, fontId, pageWidth, wordWidths, wordContinues);
}
const size_t lineCount = includeLastLine ? lineBreakIndices.size() : lineBreakIndices.size() - 1;
for (size_t i = 0; i < lineCount; ++i) {
extractLine(i, pageWidth, wordWidths, wordContinues, lineBreakIndices, processLine, renderer, fontId);
}
// Remove consumed words so size() reflects only remaining words
if (lineCount > 0) {
const size_t consumed = lineBreakIndices[lineCount - 1];
words.erase(words.begin(), words.begin() + consumed);
wordStyles.erase(wordStyles.begin(), wordStyles.begin() + consumed);
wordContinues.erase(wordContinues.begin(), wordContinues.begin() + consumed);
wordIsFocusSuffix.erase(wordIsFocusSuffix.begin(), wordIsFocusSuffix.begin() + consumed);
}
}
std::vector<uint16_t> ParsedText::calculateWordWidths(const GfxRenderer& renderer, const int fontId) {
std::vector<uint16_t> wordWidths;
wordWidths.reserve(words.size());
for (size_t i = 0; i < words.size(); ++i) {
wordWidths.push_back(measureWordWidth(renderer, fontId, words[i], wordStyles[i]));
}
return wordWidths;
}
std::vector<size_t> ParsedText::computeLineBreaks(const GfxRenderer& renderer, const int fontId, const int pageWidth,
std::vector<uint16_t>& wordWidths, std::vector<bool>& continuesVec) {
if (words.empty()) {
return {};
}
const int firstLineIndent = resolveFirstLineIndent(true);
// Ensure any word that would overflow even as the first entry on a line is split using fallback hyphenation.
for (size_t i = 0; i < wordWidths.size(); ++i) {
// First word needs to fit in reduced width if there's an indent
const int effectiveWidth = i == 0 ? pageWidth - firstLineIndent : pageWidth;
while (wordWidths[i] > effectiveWidth) {
if (!hyphenateWordAtIndex(i, effectiveWidth, renderer, fontId, wordWidths, /*allowFallbackBreaks=*/true)) {
break;
}
}
}
const size_t totalWordCount = words.size();
// DP table to store the minimum badness (cost) of lines starting at index i
std::vector<int> dp(totalWordCount);
// 'ans[i]' stores the index 'j' of the *last word* in the optimal line starting at 'i'
std::vector<size_t> ans(totalWordCount);
// Base Case
dp[totalWordCount - 1] = 0;
ans[totalWordCount - 1] = totalWordCount - 1;
for (int i = totalWordCount - 2; i >= 0; --i) {
int currlen = 0;
dp[i] = MAX_COST;
// First line has reduced width due to text-indent
const int effectivePageWidth = i == 0 ? pageWidth - firstLineIndent : pageWidth;
for (size_t j = i; j < totalWordCount; ++j) {
// Add space before word j, unless it's the first word on the line or a continuation
int gap = 0;
if (j > static_cast<size_t>(i) && !continuesVec[j]) {
gap =
renderer.getSpaceAdvance(fontId, lastCodepoint(words[j - 1]), firstCodepoint(words[j]), wordStyles[j - 1]);
} else if (j > static_cast<size_t>(i) && continuesVec[j]) {
// Cross-boundary kerning for continuation words (e.g. nonbreaking spaces, attached punctuation)
gap = renderer.getKerning(fontId, lastCodepoint(words[j - 1]), firstCodepoint(words[j]), wordStyles[j - 1]);
}
currlen += wordWidths[j] + gap;
if (currlen > effectivePageWidth) {
break;
}
// Cannot break after word j if the next word attaches to it (continuation group)
if (j + 1 < totalWordCount && continuesVec[j + 1]) {
continue;
}
int cost;
if (j == totalWordCount - 1) {
cost = 0; // Last line
} else {
const int remainingSpace = effectivePageWidth - currlen;
// Use long long for the square to prevent overflow
const long long cost_ll = static_cast<long long>(remainingSpace) * remainingSpace + dp[j + 1];
if (cost_ll > MAX_COST) {
cost = MAX_COST;
} else {
cost = static_cast<int>(cost_ll);
}
}
if (cost < dp[i]) {
dp[i] = cost;
ans[i] = j; // j is the index of the last word in this optimal line
}
}
// Handle oversized word: if no valid configuration found, force single-word line
// This prevents cascade failure where one oversized word breaks all preceding words
if (dp[i] == MAX_COST) {
ans[i] = i; // Just this word on its own line
// Inherit cost from next word to allow subsequent words to find valid configurations
if (i + 1 < static_cast<int>(totalWordCount)) {
dp[i] = dp[i + 1];
} else {
dp[i] = 0;
}
}
}
// Stores the index of the word that starts the next line (last_word_index + 1)
std::vector<size_t> lineBreakIndices;
size_t currentWordIndex = 0;
while (currentWordIndex < totalWordCount) {
size_t nextBreakIndex = ans[currentWordIndex] + 1;
// Safety check: prevent infinite loop if nextBreakIndex doesn't advance
if (nextBreakIndex <= currentWordIndex) {
// Force advance by at least one word to avoid infinite loop
nextBreakIndex = currentWordIndex + 1;
}
lineBreakIndices.push_back(nextBreakIndex);
currentWordIndex = nextBreakIndex;
}
return lineBreakIndices;
}
void ParsedText::applyParagraphIndent() {
if (extraParagraphSpacing || words.empty()) {
return;
}
if (blockStyle.textIndentDefined) {
// CSS text-indent is explicitly set (even if 0) - don't use fallback EmSpace
// The actual indent positioning is handled in extractLine()
} else if (isNaturalAlign) {
// No CSS text-indent defined - use EmSpace fallback for visual indent
words.front().insert(0, "\xe2\x80\x83");
}
}
// Builds break indices while opportunistically splitting the word that would overflow the current line.
std::vector<size_t> ParsedText::computeHyphenatedLineBreaks(const GfxRenderer& renderer, const int fontId,
const int pageWidth, std::vector<uint16_t>& wordWidths,
std::vector<bool>& continuesVec) {
const int firstLineIndent = resolveFirstLineIndent(true);
std::vector<size_t> lineBreakIndices;
size_t currentIndex = 0;
bool isFirstLine = true;
while (currentIndex < wordWidths.size()) {
const size_t lineStart = currentIndex;
int lineWidth = 0;
// First line has reduced width due to text-indent
const int effectivePageWidth = isFirstLine ? pageWidth - firstLineIndent : pageWidth;
// Consume as many words as possible for current line, splitting when prefixes fit
while (currentIndex < wordWidths.size()) {
const bool isFirstWord = currentIndex == lineStart;
int spacing = 0;
if (!isFirstWord && !continuesVec[currentIndex]) {
spacing = renderer.getSpaceAdvance(fontId, lastCodepoint(words[currentIndex - 1]),
firstCodepoint(words[currentIndex]), wordStyles[currentIndex - 1]);
} else if (!isFirstWord && continuesVec[currentIndex]) {
// Cross-boundary kerning for continuation words (e.g. nonbreaking spaces, attached punctuation)
spacing = renderer.getKerning(fontId, lastCodepoint(words[currentIndex - 1]),
firstCodepoint(words[currentIndex]), wordStyles[currentIndex - 1]);
}
const int candidateWidth = spacing + wordWidths[currentIndex];
// Word fits on current line
if (lineWidth + candidateWidth <= effectivePageWidth) {
lineWidth += candidateWidth;
++currentIndex;
continue;
}
// Word would overflow — try to split based on hyphenation points
const int availableWidth = effectivePageWidth - lineWidth - spacing;
const bool allowFallbackBreaks = isFirstWord; // Only for first word on line
if (availableWidth > 0 &&
hyphenateWordAtIndex(currentIndex, availableWidth, renderer, fontId, wordWidths, allowFallbackBreaks)) {
// Prefix now fits; append it to this line and move to next line
lineWidth += spacing + wordWidths[currentIndex];
++currentIndex;
break;
}
// Could not split: force at least one word per line to avoid infinite loop
if (currentIndex == lineStart) {
lineWidth += candidateWidth;
++currentIndex;
}
break;
}
// Don't break before a continuation word (e.g., orphaned "?" after "question").
// Backtrack to the start of the continuation group so the whole group moves to the next line.
while (currentIndex > lineStart + 1 && currentIndex < wordWidths.size() && continuesVec[currentIndex]) {
--currentIndex;
}
lineBreakIndices.push_back(currentIndex);
isFirstLine = false;
}
return lineBreakIndices;
}
// Splits words[wordIndex] into prefix (adding a hyphen only when needed) and remainder when a legal breakpoint fits the
// available width.
bool ParsedText::hyphenateWordAtIndex(const size_t wordIndex, const int availableWidth, const GfxRenderer& renderer,
const int fontId, std::vector<uint16_t>& wordWidths,
const bool allowFallbackBreaks) {
// Guard against invalid indices or zero available width before attempting to split.
if (availableWidth <= 0 || wordIndex >= words.size()) {
return false;
}
const std::string& word = words[wordIndex];
const auto style = wordStyles[wordIndex];
// Collect candidate breakpoints (byte offsets and hyphen requirements).
auto breakInfos = Hyphenator::breakOffsets(word, allowFallbackBreaks);
if (breakInfos.empty()) {
return false;
}
size_t chosenOffset = 0;
int chosenWidth = -1;
bool chosenNeedsHyphen = true;
// Iterate over each legal breakpoint and retain the widest prefix that still fits.
for (const auto& info : breakInfos) {
const size_t offset = info.byteOffset;
if (offset == 0 || offset >= word.size()) {
continue;
}
const bool needsHyphen = info.requiresInsertedHyphen;
const int prefixWidth = measureWordWidth(renderer, fontId, word.substr(0, offset), style, needsHyphen);
if (prefixWidth > availableWidth || prefixWidth <= chosenWidth) {
continue; // Skip if too wide or not an improvement
}
chosenWidth = prefixWidth;
chosenOffset = offset;
chosenNeedsHyphen = needsHyphen;
}
if (chosenWidth < 0) {
// No hyphenation point produced a prefix that fits in the remaining space.
return false;
}
// Split the word at the selected breakpoint and append a hyphen if required.
std::string remainder = word.substr(chosenOffset);
words[wordIndex].resize(chosenOffset);
if (chosenNeedsHyphen) {
words[wordIndex].push_back('-');
}
// Insert the remainder word (with matching style and continuation flag) directly after the prefix.
words.insert(words.begin() + wordIndex + 1, remainder);
wordStyles.insert(wordStyles.begin() + wordIndex + 1, style);
// The hyphen remainder is not a focus suffix - it starts fresh on the next line.
wordIsFocusSuffix.insert(wordIsFocusSuffix.begin() + wordIndex + 1, false);
// Continuation flag handling after splitting a word into prefix + remainder.
//
// The prefix keeps the original word's continuation flag so that no-break-space groups
// stay linked. The remainder always gets continues=false because it starts on the next
// line and is not attached to the prefix.
//
// Example: "200&#xA0;Quadratkilometer" produces tokens:
// [0] "200" continues=false
// [1] " " continues=true
// [2] "Quadratkilometer" continues=true <-- the word being split
//
// After splitting "Quadratkilometer" at "Quadrat-" / "kilometer":
// [0] "200" continues=false
// [1] " " continues=true
// [2] "Quadrat-" continues=true (KEPT — still attached to the no-break group)
// [3] "kilometer" continues=false (NEW — starts fresh on the next line)
//
// This lets the backtracking loop keep the entire prefix group ("200 Quadrat-") on one
// line, while "kilometer" moves to the next line.
// wordContinues[wordIndex] is intentionally left unchanged — the prefix keeps its original attachment.
wordContinues.insert(wordContinues.begin() + wordIndex + 1, false);
// Update cached widths to reflect the new prefix/remainder pairing.
wordWidths[wordIndex] = static_cast<uint16_t>(chosenWidth);
const uint16_t remainderWidth = measureWordWidth(renderer, fontId, remainder, style);
wordWidths.insert(wordWidths.begin() + wordIndex + 1, remainderWidth);
return true;
}
void ParsedText::extractLine(const size_t breakIndex, const int pageWidth, const std::vector<uint16_t>& wordWidths,
const std::vector<bool>& continuesVec, const std::vector<size_t>& lineBreakIndices,
const std::function<void(std::shared_ptr<TextBlock>)>& processLine,
const GfxRenderer& renderer, const int fontId) {
const size_t lineBreak = lineBreakIndices[breakIndex];
const size_t lastBreakAt = breakIndex > 0 ? lineBreakIndices[breakIndex - 1] : 0;
const size_t lineWordCount = lineBreak - lastBreakAt;
const int firstLineIndent = resolveFirstLineIndent(breakIndex == 0);
// Build line data by moving from the original vectors using index range
std::vector<std::string> lineWords;
lineWords.reserve(lineWordCount);
std::vector<EpdFontFamily::Style> lineWordStyles;
lineWordStyles.reserve(lineWordCount);
for (size_t i = 0; i < lineWordCount; ++i) {
std::string word = std::move(words[lastBreakAt + i]);
if (containsSoftHyphen(word)) {
stripSoftHyphensInPlace(word);
}
lineWords.push_back(std::move(word));
lineWordStyles.push_back(wordStyles[lastBreakAt + i]);
}
// Calculate total word width for this line, count actual word gaps,
// and accumulate total natural gap widths (including space kerning adjustments).
int lineWordWidthSum = 0;
size_t actualGapCount = 0;
int totalNaturalGaps = 0;
for (size_t wordIdx = 0; wordIdx < lineWordCount; wordIdx++) {
lineWordWidthSum += wordWidths[lastBreakAt + wordIdx];
// Count gaps: each word after the first creates a gap, unless it's a continuation
if (wordIdx > 0 && !continuesVec[lastBreakAt + wordIdx]) {
actualGapCount++;
totalNaturalGaps += renderer.getSpaceAdvance(fontId, lastCodepoint(lineWords[wordIdx - 1]),
firstCodepoint(lineWords[wordIdx]), lineWordStyles[wordIdx - 1]);
} else if (wordIdx > 0 && continuesVec[lastBreakAt + wordIdx]) {
// Non-breaking space tokens (" " with continues=true) are visible, stretchable spaces —
// count them as justifiable gaps so justifyExtra is distributed to them too.
if (lineWords[wordIdx] == " ") {
actualGapCount++;
}
// Cross-boundary kerning for continuation words (e.g. nonbreaking spaces, attached punctuation)
totalNaturalGaps += renderer.getKerning(fontId, lastCodepoint(lineWords[wordIdx - 1]),
firstCodepoint(lineWords[wordIdx]), lineWordStyles[wordIdx - 1]);
}
}
// Calculate spacing (account for indent reducing effective page width on first line)
const int effectivePageWidth = pageWidth - firstLineIndent;
const bool isLastLine = breakIndex == lineBreakIndices.size() - 1;
// For RTL, implicit/default Left alignment becomes Right alignment.
// Explicit text-align:left must remain left for CSS correctness.
const CssTextAlign effectiveAlignment =
(blockStyle.isRtl && !blockStyle.textAlignDefined && blockStyle.alignment == CssTextAlign::Left)
? CssTextAlign::Right
: blockStyle.alignment;
// For justified text, compute per-gap extra to distribute remaining space evenly
const int spareSpace = effectivePageWidth - lineWordWidthSum - totalNaturalGaps;
const int justifyExtra = (effectiveAlignment == CssTextAlign::Justify && !isLastLine && actualGapCount >= 1)
? spareSpace / static_cast<int>(actualGapCount)
: 0;
// BiDi processing: reorder words with UAX#9 in full-line context.
visualOrderScratch.clear();
visualOrderScratch.reserve(lineWordCount);
// Skip expensive visual-order resolution for pure LTR paragraphs that have no RTL words.
const bool shouldResolveVisualOrder = blockStyle.isRtl || hasRtlWord;
const bool willReorder =
shouldResolveVisualOrder && BidiUtils::computeVisualWordOrder(lineWords, blockStyle.isRtl, visualOrderScratch);
std::vector<int16_t> lineXPos;
lineXPos.reserve(lineWordCount);
if (willReorder) {
reorderedWordsScratch.clear();
reorderedStylesScratch.clear();
reorderedWidthsScratch.clear();
reorderedContinuesScratch.clear();
reorderedFocusSuffixScratch.clear();
reorderedWordsScratch.reserve(visualOrderScratch.size());
reorderedStylesScratch.reserve(visualOrderScratch.size());
reorderedWidthsScratch.reserve(visualOrderScratch.size());
reorderedContinuesScratch.reserve(visualOrderScratch.size());
reorderedFocusSuffixScratch.reserve(visualOrderScratch.size());
for (size_t i = 0; i < visualOrderScratch.size(); ++i) {
const uint16_t src = visualOrderScratch[i];
reorderedWordsScratch.push_back(std::move(lineWords[src]));
reorderedStylesScratch.push_back(lineWordStyles[src]);
reorderedWidthsScratch.push_back(wordWidths[lastBreakAt + src]);
reorderedFocusSuffixScratch.push_back(wordIsFocusSuffix[lastBreakAt + src]);
// Continuation means "no break/gap between two adjacent logical tokens".
// After visual reordering (common in RTL), an adjacent logical pair can appear
// as either (prev -> curr) or (curr -> prev) in visual order; preserve both.
bool continues = false;
if (i > 0) {
const size_t prevSrc = visualOrderScratch[i - 1];
const size_t currSrc = src;
const bool forwardAdjacent = currSrc == prevSrc + 1;
const bool reverseAdjacent = prevSrc == currSrc + 1;
if (forwardAdjacent && continuesVec[lastBreakAt + currSrc]) {
continues = true;
} else if (reverseAdjacent && continuesVec[lastBreakAt + prevSrc]) {
continues = true;
}
}
reorderedContinuesScratch.push_back(continues);
}
int reorderedWordWidthSum = 0;
size_t reorderedGapCount = 0;
int reorderedNaturalGaps = 0;
for (size_t wordIdx = 0; wordIdx < reorderedWidthsScratch.size(); wordIdx++) {
reorderedWordWidthSum += reorderedWidthsScratch[wordIdx];
if (wordIdx > 0 && !reorderedContinuesScratch[wordIdx]) {
reorderedGapCount++;
reorderedNaturalGaps += renderer.getSpaceAdvance(fontId, lastCodepoint(reorderedWordsScratch[wordIdx - 1]),
firstCodepoint(reorderedWordsScratch[wordIdx]),
reorderedStylesScratch[wordIdx - 1]);
} else if (wordIdx > 0 && reorderedContinuesScratch[wordIdx]) {
if (reorderedWordsScratch[wordIdx] == " ") {
reorderedGapCount++;
}
reorderedNaturalGaps +=
renderer.getKerning(fontId, lastCodepoint(reorderedWordsScratch[wordIdx - 1]),
firstCodepoint(reorderedWordsScratch[wordIdx]), reorderedStylesScratch[wordIdx - 1]);
}
}
const int reorderedSpare = effectivePageWidth - reorderedWordWidthSum - reorderedNaturalGaps;
const int reorderedJustifyExtra =
(effectiveAlignment == CssTextAlign::Justify && !isLastLine && reorderedGapCount >= 1)
? reorderedSpare / static_cast<int>(reorderedGapCount)
: 0;
const int justifyContribution = (effectiveAlignment == CssTextAlign::Justify && !isLastLine)
? reorderedJustifyExtra * static_cast<int>(reorderedGapCount)
: 0;
const int contentWidth = reorderedWordWidthSum + reorderedNaturalGaps + justifyContribution;
int xpos = 0;
if (blockStyle.isRtl) {
if (effectiveAlignment == CssTextAlign::Right || effectiveAlignment == CssTextAlign::Justify) {
xpos = effectivePageWidth - contentWidth;
} else if (effectiveAlignment == CssTextAlign::Center) {
xpos = (effectivePageWidth - contentWidth) / 2;
}
} else {
xpos = firstLineIndent;
if (effectiveAlignment == CssTextAlign::Right) {
xpos = effectivePageWidth - contentWidth;
} else if (effectiveAlignment == CssTextAlign::Center) {
xpos = (effectivePageWidth - contentWidth) / 2;
}
}
for (size_t wordIdx = 0; wordIdx < reorderedWidthsScratch.size(); wordIdx++) {
lineXPos.push_back(static_cast<int16_t>(xpos < 0 ? 0 : xpos));
xpos += reorderedWidthsScratch[wordIdx];
const bool nextIsContinuation =
wordIdx + 1 < reorderedWidthsScratch.size() && reorderedContinuesScratch[wordIdx + 1];
if (nextIsContinuation) {
int advance =
renderer.getKerning(fontId, lastCodepoint(reorderedWordsScratch[wordIdx]),
firstCodepoint(reorderedWordsScratch[wordIdx + 1]), reorderedStylesScratch[wordIdx]);
if (reorderedWordsScratch[wordIdx] == " " && reorderedContinuesScratch[wordIdx] &&
effectiveAlignment == CssTextAlign::Justify && !isLastLine) {
advance += reorderedJustifyExtra;
}
xpos += advance;
} else if (wordIdx + 1 < reorderedWidthsScratch.size()) {
int gap = renderer.getSpaceAdvance(fontId, lastCodepoint(reorderedWordsScratch[wordIdx]),
firstCodepoint(reorderedWordsScratch[wordIdx + 1]),
reorderedStylesScratch[wordIdx]);
if (effectiveAlignment == CssTextAlign::Justify && !isLastLine) {
gap += reorderedJustifyExtra;
}
xpos += gap;
}
}
lineWords.swap(reorderedWordsScratch);
lineWordStyles.swap(reorderedStylesScratch);
} else {
// Standard LTR/RTL positioning loop when no visual reordering is needed
if (blockStyle.isRtl) {
// RTL: position words from right to left
auto xpos = static_cast<int>(effectivePageWidth);
if (effectiveAlignment == CssTextAlign::Left) {
// Explicit left alignment in RTL context
xpos = lineWordWidthSum + totalNaturalGaps;
} else if (effectiveAlignment == CssTextAlign::Center) {
xpos = (effectivePageWidth + lineWordWidthSum + totalNaturalGaps) / 2;
}
// For Right and Justify, start from right edge (xpos = effectivePageWidth)
for (size_t wordIdx = 0; wordIdx < lineWordCount; wordIdx++) {
xpos -= wordWidths[lastBreakAt + wordIdx];
lineXPos.push_back(static_cast<int16_t>(xpos < 0 ? 0 : xpos));
const bool nextIsContinuation = wordIdx + 1 < lineWordCount && continuesVec[lastBreakAt + wordIdx + 1];
if (nextIsContinuation) {
// Cross-boundary kerning for continuation words
int advance = renderer.getKerning(fontId, lastCodepoint(lineWords[wordIdx]),
firstCodepoint(lineWords[wordIdx + 1]), lineWordStyles[wordIdx]);
if (lineWords[wordIdx] == " " && continuesVec[lastBreakAt + wordIdx] &&
effectiveAlignment == CssTextAlign::Justify && !isLastLine) {
advance += justifyExtra;
}
xpos -= advance;
} else {
int gap = 0;
if (wordIdx + 1 < lineWordCount) {
gap = renderer.getSpaceAdvance(fontId, lastCodepoint(lineWords[wordIdx]),
firstCodepoint(lineWords[wordIdx + 1]), lineWordStyles[wordIdx]);
}
if (effectiveAlignment == CssTextAlign::Justify && !isLastLine) {
gap += justifyExtra;
}
xpos -= gap;
}
}
} else {
// LTR: position words from left to right
auto xpos = static_cast<int16_t>(firstLineIndent);
if (effectiveAlignment == CssTextAlign::Right) {
xpos = effectivePageWidth - lineWordWidthSum - totalNaturalGaps;
} else if (effectiveAlignment == CssTextAlign::Center) {
xpos = (effectivePageWidth - lineWordWidthSum - totalNaturalGaps) / 2;
}
for (size_t wordIdx = 0; wordIdx < lineWordCount; wordIdx++) {
lineXPos.push_back(static_cast<int16_t>(xpos < 0 ? 0 : xpos));
const bool nextIsContinuation = wordIdx + 1 < lineWordCount && continuesVec[lastBreakAt + wordIdx + 1];
if (nextIsContinuation) {
int advance = wordWidths[lastBreakAt + wordIdx];
advance += renderer.getKerning(fontId, lastCodepoint(lineWords[wordIdx]),
firstCodepoint(lineWords[wordIdx + 1]), lineWordStyles[wordIdx]);
if (lineWords[wordIdx] == " " && continuesVec[lastBreakAt + wordIdx] &&
effectiveAlignment == CssTextAlign::Justify && !isLastLine) {
advance += justifyExtra;
}
xpos += advance;
} else {
int gap = 0;
if (wordIdx + 1 < lineWordCount) {
gap = renderer.getSpaceAdvance(fontId, lastCodepoint(lineWords[wordIdx]),
firstCodepoint(lineWords[wordIdx + 1]), lineWordStyles[wordIdx]);
}
if (effectiveAlignment == CssTextAlign::Justify && !isLastLine) {
gap += justifyExtra;
}
xpos += wordWidths[lastBreakAt + wordIdx] + gap;
}
}
}
}
const auto isFocusSuffixAt = [&](const size_t idx) {
return willReorder ? reorderedFocusSuffixScratch[idx] : wordIsFocusSuffix[lastBreakAt + idx];
};
// Fast path: when no word on this line was split for focus reading, skip the merge work
// entirely and pass empty boundary/suffixX vectors. TextBlock pays zero per-word RAM cost
// for these annotations when the vectors are empty.
bool lineHasFocusSplit = false;
for (size_t i = 0; i < lineWordCount; i++) {
if (isFocusSuffixAt(i)) {
lineHasFocusSplit = true;
break;
}
}
if (!lineHasFocusSplit) {
processLine(std::make_shared<TextBlock>(std::move(lineWords), std::move(lineXPos), std::move(lineWordStyles),
std::vector<uint8_t>{}, std::vector<uint16_t>{}, blockStyle));
return;
}
// Slow path: merge focus suffix tokens back into their preceding word entry so each
// original word occupies one TextBlock slot. Splits are recorded as per-word annotations
// applied at render time, cutting the token count significantly when the feature is active.
std::vector<std::string> outWords;
std::vector<int16_t> outXPos;
std::vector<EpdFontFamily::Style> outStyles;
std::vector<uint8_t> outBoundaries;
std::vector<uint16_t> outSuffixX;
outWords.reserve(lineWordCount);
outXPos.reserve(lineWordCount);
outStyles.reserve(lineWordCount);
outBoundaries.reserve(lineWordCount);
outSuffixX.reserve(lineWordCount);
for (size_t i = 0; i < lineWordCount; i++) {
if (isFocusSuffixAt(i) && !outWords.empty()) {
// Focus suffix: merge string into the preceding bold-prefix entry.
outWords.back() += lineWords[i];
} else {
// Normal word: check for a following focus suffix to record the byte boundary.
uint8_t boundary = 0;
uint16_t suffixX = 0;
if (i + 1 < lineWordCount && isFocusSuffixAt(i + 1)) {
boundary = static_cast<uint8_t>(std::min(lineWords[i].size(), size_t{255}));
// Suffix x offset = layout-time advance of the bold prefix, already known from xpos table.
const int suffixDelta = static_cast<int>(lineXPos[i + 1]) - static_cast<int>(lineXPos[i]);
suffixX = static_cast<uint16_t>(suffixDelta > 0 ? suffixDelta : 0);
}
outWords.push_back(std::move(lineWords[i]));
outXPos.push_back(lineXPos[i]);
// For focus entries with a suffix, strip BOLD from the stored style.
// Render re-applies it to the prefix portion only, via the boundary field.
const EpdFontFamily::Style storedStyle =
boundary > 0 ? static_cast<EpdFontFamily::Style>(lineWordStyles[i] & ~EpdFontFamily::BOLD)
: lineWordStyles[i];
outStyles.push_back(storedStyle);
outBoundaries.push_back(boundary);
outSuffixX.push_back(suffixX);
}
}
processLine(std::make_shared<TextBlock>(std::move(outWords), std::move(outXPos), std::move(outStyles),
std::move(outBoundaries), std::move(outSuffixX), blockStyle));
}