Files
Crosspoint/lib/Epub/Epub/blocks/TextBlock.cpp
T

243 lines
10 KiB
C++

#include "TextBlock.h"
#include <BidiUtils.h>
#include <GfxRenderer.h>
#include <Logging.h>
#include <Serialization.h>
#include <cstring>
void TextBlock::render(const GfxRenderer& renderer, const int fontId, const int x, const int y) const {
// Focus annotations are optional: empty vectors mean no word in this block has a split.
// When present, they must be sized in lockstep with words[].
const bool hasFocus = !wordFocusBoundary.empty();
if (words.size() != wordXpos.size() || words.size() != wordStyles.size() ||
(hasFocus && (words.size() != wordFocusBoundary.size() || words.size() != wordFocusSuffixX.size()))) {
LOG_ERR("TXB", "Render skipped: size mismatch (words=%u, xpos=%u, styles=%u, boundary=%u, suffixX=%u)\n",
(uint32_t)words.size(), (uint32_t)wordXpos.size(), (uint32_t)wordStyles.size(),
(uint32_t)wordFocusBoundary.size(), (uint32_t)wordFocusSuffixX.size());
return;
}
const bool scanning = renderer.isFontCacheScanning();
const int ascender = renderer.getFontAscenderSize(fontId);
struct DecorationLineTracker {
EpdFontFamily::Style style;
int yOffset;
int startX = -1;
int endX = -1;
int yPos = 0;
bool active() const { return startX != -1; }
void reset() {
startX = -1;
endX = -1;
yPos = 0;
}
};
DecorationLineTracker decorationLines[] = {
{EpdFontFamily::UNDERLINE, ascender + 2},
{EpdFontFamily::STRIKETHROUGH, ascender * 4 / 5},
};
const auto flushDecoration = [&](DecorationLineTracker& line) {
if (line.active()) {
renderer.drawLine(line.startX, line.yPos, line.endX, line.yPos, 2, true);
line.reset();
}
};
const auto flushDecorations = [&]() {
for (auto& line : decorationLines) {
flushDecoration(line);
}
};
for (size_t i = 0; i < words.size(); i++) {
const int wordX = wordXpos[i] + x;
const EpdFontFamily::Style currentStyle = wordStyles[i];
const auto baseDir = static_cast<BidiUtils::BidiBaseDir>(
BidiUtils::detectParagraphLevel(words[i].c_str(), blockStyle.isRtl ? 1 : 0));
const uint8_t boundary = hasFocus ? wordFocusBoundary[i] : 0;
// SUP/SUB shift the baseline passed to drawText; the glyph is also scaled 50% inside
// drawText, so these offsets are chosen relative to the full-size ascender:
// SUP: raise by 40% of ascender — sits clearly above the cap-height
// SUB: lower by 25% of ascender — descends below baseline without clashing with ascenders below
int wordY = y;
if ((currentStyle & EpdFontFamily::SUP) != 0) {
wordY -= ascender * 2 / 5;
} else if ((currentStyle & EpdFontFamily::SUB) != 0) {
wordY += ascender / 4;
}
if (boundary > 0) {
// Focus split: draw bold prefix, then the regular suffix at a pre-computed x offset.
// The bold prefix is bounded to 9 codepoints by the clamp on targetBoldChars in
// ParsedText::addWord; 9 UTF-8 codepoints occupy at most 9 * 4 = 36 bytes, +1 for null = 37.
// suffixX is computed at cache-creation time to avoid font metric lookups at render time.
static constexpr size_t MAX_FOCUS_PREFIX_BYTES = 9 * 4 + 1;
char boldBuf[40];
static_assert(sizeof(boldBuf) >= MAX_FOCUS_PREFIX_BYTES,
"boldBuf too small for max focus prefix (9 codepoints * 4 UTF-8 bytes + null)");
const auto boldStyle = static_cast<EpdFontFamily::Style>(currentStyle | EpdFontFamily::BOLD);
const size_t boldLen = std::min<size_t>({static_cast<size_t>(boundary), words[i].size(), sizeof(boldBuf) - 1});
memcpy(boldBuf, words[i].c_str(), boldLen);
boldBuf[boldLen] = '\0';
renderer.drawText(fontId, wordX, wordY, boldBuf, true, boldStyle, baseDir);
const int suffixX = wordX + wordFocusSuffixX[i];
renderer.drawText(fontId, suffixX, wordY, words[i].c_str() + boldLen, true, currentStyle, baseDir);
} else {
renderer.drawText(fontId, wordX, wordY, words[i].c_str(), true, currentStyle, baseDir);
}
if (scanning) {
continue;
}
if (EpdFontFamily::hasTextDecoration(currentStyle)) {
const std::string& w = words[i];
int lineStartX = wordX;
int lineWidth = renderer.getTextWidth(fontId, w.c_str(), currentStyle, baseDir);
if ((currentStyle & (EpdFontFamily::SUP | EpdFontFamily::SUB)) != 0) {
lineWidth = (lineWidth + 1) / 2;
}
// Do not decorate the synthetic em-space used for paragraph indentation.
if (w.size() >= 3 && static_cast<uint8_t>(w[0]) == 0xE2 && static_cast<uint8_t>(w[1]) == 0x80 &&
static_cast<uint8_t>(w[2]) == 0x83) {
const char* visibleText = w.c_str() + 3;
lineStartX += renderer.getTextAdvanceX(fontId, "\xe2\x80\x83", currentStyle);
lineWidth = renderer.getTextWidth(fontId, visibleText, currentStyle, baseDir);
if ((currentStyle & (EpdFontFamily::SUP | EpdFontFamily::SUB)) != 0) {
lineWidth = (lineWidth + 1) / 2;
}
}
for (auto& line : decorationLines) {
if ((currentStyle & line.style) == 0) {
flushDecoration(line);
continue;
}
const int lineY = wordY + line.yOffset;
if (line.active() && line.yPos != lineY) {
flushDecoration(line);
}
if (!line.active()) {
line.startX = lineStartX;
line.yPos = lineY;
}
line.endX = lineStartX + lineWidth;
}
} else {
flushDecorations();
}
}
flushDecorations();
}
bool TextBlock::serialize(HalFile& file) const {
// Focus annotations are optional; vectors are either empty (no splits in this block)
// or sized in lockstep with words[].
const bool hasFocus = !wordFocusBoundary.empty();
if (words.size() != wordXpos.size() || words.size() != wordStyles.size() ||
(hasFocus && (words.size() != wordFocusBoundary.size() || words.size() != wordFocusSuffixX.size()))) {
LOG_ERR("TXB", "Serialization failed: size mismatch (words=%u, xpos=%u, styles=%u, boundary=%u, suffixX=%u)\n",
static_cast<uint32_t>(words.size()), static_cast<uint32_t>(wordXpos.size()),
static_cast<uint32_t>(wordStyles.size()), static_cast<uint32_t>(wordFocusBoundary.size()),
static_cast<uint32_t>(wordFocusSuffixX.size()));
return false;
}
// Word data
serialization::writePod(file, static_cast<uint16_t>(words.size()));
for (const auto& w : words) serialization::writeString(file, w);
for (auto x : wordXpos) serialization::writePod(file, x);
for (auto s : wordStyles) serialization::writePod(file, s);
// Focus block: 1-byte presence flag, followed by per-word vectors only when present.
// Saves 3 bytes/word when focus reading is disabled or no word on this line was split.
serialization::writePod(file, static_cast<uint8_t>(hasFocus ? 1 : 0));
if (hasFocus) {
for (auto b : wordFocusBoundary) serialization::writePod(file, b);
for (auto sx : wordFocusSuffixX) serialization::writePod(file, sx);
}
// Style (alignment + margins/padding/indent)
serialization::writePod(file, blockStyle.alignment);
serialization::writePod(file, blockStyle.textAlignDefined);
serialization::writePod(file, blockStyle.marginTop);
serialization::writePod(file, blockStyle.marginBottom);
serialization::writePod(file, blockStyle.marginLeft);
serialization::writePod(file, blockStyle.marginRight);
serialization::writePod(file, blockStyle.paddingTop);
serialization::writePod(file, blockStyle.paddingBottom);
serialization::writePod(file, blockStyle.paddingLeft);
serialization::writePod(file, blockStyle.paddingRight);
serialization::writePod(file, blockStyle.textIndent);
serialization::writePod(file, blockStyle.textIndentDefined);
serialization::writePod(file, blockStyle.isRtl);
serialization::writePod(file, blockStyle.directionDefined);
return true;
}
std::unique_ptr<TextBlock> TextBlock::deserialize(HalFile& file) {
uint16_t wc;
std::vector<std::string> words;
std::vector<int16_t> wordXpos;
std::vector<EpdFontFamily::Style> wordStyles;
std::vector<uint8_t> wordFocusBoundary;
std::vector<uint16_t> wordFocusSuffixX;
BlockStyle blockStyle;
// Word count
serialization::readPod(file, wc);
// Sanity check: prevent allocation of unreasonably large vectors (max 10000 words per block)
if (wc > 10000) {
LOG_ERR("TXB", "Deserialization failed: word count %u exceeds maximum", wc);
return nullptr;
}
// Word data
words.resize(wc);
wordXpos.resize(wc);
wordStyles.resize(wc);
for (auto& w : words) serialization::readString(file, w);
for (auto& x : wordXpos) serialization::readPod(file, x);
for (auto& s : wordStyles) serialization::readPod(file, s);
// Focus block: presence flag, then vectors only if present. Empty vectors when absent
// signal "no splits in this block" to render() (zero per-word RAM cost).
uint8_t hasFocus;
serialization::readPod(file, hasFocus);
if (hasFocus) {
wordFocusBoundary.resize(wc);
wordFocusSuffixX.resize(wc);
for (auto& b : wordFocusBoundary) serialization::readPod(file, b);
for (auto& sx : wordFocusSuffixX) serialization::readPod(file, sx);
}
// Style (alignment + margins/padding/indent)
serialization::readPod(file, blockStyle.alignment);
serialization::readPod(file, blockStyle.textAlignDefined);
serialization::readPod(file, blockStyle.marginTop);
serialization::readPod(file, blockStyle.marginBottom);
serialization::readPod(file, blockStyle.marginLeft);
serialization::readPod(file, blockStyle.marginRight);
serialization::readPod(file, blockStyle.paddingTop);
serialization::readPod(file, blockStyle.paddingBottom);
serialization::readPod(file, blockStyle.paddingLeft);
serialization::readPod(file, blockStyle.paddingRight);
serialization::readPod(file, blockStyle.textIndent);
serialization::readPod(file, blockStyle.textIndentDefined);
serialization::readPod(file, blockStyle.isRtl);
serialization::readPod(file, blockStyle.directionDefined);
return std::unique_ptr<TextBlock>(new TextBlock(std::move(words), std::move(wordXpos), std::move(wordStyles),
std::move(wordFocusBoundary), std::move(wordFocusSuffixX),
blockStyle));
}