fix: Prepare SD card font caches from txt reader (#1973)
## Summary SD card font fixes: - `TxtReaderActivity` needs to call `renderer.ensureSdCardFontReady` to build the advance lookup table to support rendering with SD card fonts. This revealed that `TxtReaderActivity` was inconsistently performing layout with `getTextWidth`, when the renderer actually uses `getTextAdvanceX`, which can lead to minor inconsistencies in alignment. - Avoid allocating one big `allText` string in `ParsedText::layoutAndExtractLines`. Instead, pass the vector of word strings directly to `SdCardFont::buildAdvanceTable`, where the algorithm just needs to iterate codepoints anyway. --- ### AI Usage While CrossPoint doesn't have restrictions on AI tools in contributing, please be transparent about their usage as it helps set the right context for reviewers. Did you use AI tools to help write this code? _**PARTIALLY**_ --------- Co-authored-by: Justin Mitchell <justin@jmitch.com> # Conflicts: # lib/EpdFont/SdCardFont.cpp
This commit is contained in:
Zach Nelson
+88
-67
@@ -14,11 +14,13 @@ static_assert(sizeof(EpdUnicodeInterval) == 12, "EpdUnicodeInterval must be 12 b
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static_assert(sizeof(EpdKernClassEntry) == 3, "EpdKernClassEntry must be 3 bytes to match .cpfont file layout");
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static_assert(sizeof(EpdLigaturePair) == 8, "EpdLigaturePair must be 8 bytes to match .cpfont file layout");
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// FNV-1a hash for content-based font ID generation
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static constexpr uint32_t FNV_OFFSET = 2166136261u;
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static constexpr uint32_t FNV_PRIME = 16777619u;
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namespace {
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static uint32_t fnv1a(const uint8_t* data, size_t len, uint32_t hash = FNV_OFFSET) {
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// FNV-1a hash for content-based font ID generation
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constexpr uint32_t FNV_OFFSET = 2166136261u;
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constexpr uint32_t FNV_PRIME = 16777619u;
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uint32_t fnv1a(const uint8_t* data, size_t len, uint32_t hash = FNV_OFFSET) {
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for (size_t i = 0; i < len; i++) {
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hash ^= data[i];
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hash *= FNV_PRIME;
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@@ -27,16 +29,44 @@ static uint32_t fnv1a(const uint8_t* data, size_t len, uint32_t hash = FNV_OFFSE
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}
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// .cpfont magic bytes
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static constexpr char CPFONT_MAGIC[8] = {'C', 'P', 'F', 'O', 'N', 'T', '\0', '\0'};
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constexpr char CPFONT_MAGIC[8] = {'C', 'P', 'F', 'O', 'N', 'T', '\0', '\0'};
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// CPFONT_VERSION is defined as a #define in SdCardFont.h so it can be
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// stringified into FONT_MANIFEST_URL.
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static constexpr uint32_t HEADER_SIZE = 32;
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static constexpr uint32_t STYLE_TOC_ENTRY_SIZE = 32;
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constexpr uint32_t HEADER_SIZE = 32;
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constexpr uint32_t STYLE_TOC_ENTRY_SIZE = 32;
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// Helper to read little-endian values from byte buffer
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static inline uint16_t readU16(const uint8_t* p) { return p[0] | (p[1] << 8); }
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static inline int16_t readI16(const uint8_t* p) { return static_cast<int16_t>(p[0] | (p[1] << 8)); }
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static inline uint32_t readU32(const uint8_t* p) { return p[0] | (p[1] << 8) | (p[2] << 16) | (p[3] << 24); }
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inline uint16_t readU16(const uint8_t* p) { return p[0] | (p[1] << 8); }
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inline int16_t readI16(const uint8_t* p) { return static_cast<int16_t>(p[0] | (p[1] << 8)); }
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inline uint32_t readU32(const uint8_t* p) { return p[0] | (p[1] << 8) | (p[2] << 16) | (p[3] << 24); }
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// Walks a null-terminated UTF-8 string and appends each unique codepoint to
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// codepoints[0..cpCount-1] via O(n²) dedup. Returns true if the buffer
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// reached maxCount (cap hit), false if all codepoints fit.
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bool collectUniqueCodepoints(const char* text, uint32_t* codepoints, uint32_t& cpCount, uint32_t maxCount) {
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const unsigned char* p = reinterpret_cast<const unsigned char*>(text);
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while (*p) {
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uint32_t cp = utf8NextCodepoint(&p);
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if (cp == 0) break;
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bool found = false;
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for (uint32_t i = 0; i < cpCount; i++) {
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if (codepoints[i] == cp) {
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found = true;
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break;
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}
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}
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if (!found) {
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if (cpCount >= maxCount) return true;
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codepoints[cpCount++] = cp;
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}
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}
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return false;
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}
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const char* asCStr(const std::string& s) { return s.c_str(); }
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const char* asCStr(const char* s) { return s; }
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} // namespace
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SdCardFont::~SdCardFont() { freeAll(); }
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@@ -1015,62 +1045,10 @@ uint16_t SdCardFont::getAdvance(uint32_t codepoint, uint8_t style) const {
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return 0;
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}
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int SdCardFont::buildAdvanceTable(const char* utf8Text, uint8_t styleMask) {
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if (!loaded_) return -1;
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// Note: advance table is preserved across calls. We only fetch codepoints
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// not already present, then merge them in. Use clearPersistentCache() to
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// wipe the table when the font/size/family changes.
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unsigned long startMs = millis();
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// Step 1: Extract unique codepoints, capped at MAX_UNIQUE_CODEPOINTS.
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// The dedup buffer is sized to the cap, not total chars — a large EPUB section
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// may contain 50K+ characters but real text has far fewer unique codepoints.
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// 4096 × 4 bytes = 16KB temporary; bounded regardless of input size.
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static constexpr uint32_t MAX_UNIQUE_CODEPOINTS = 4096;
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uint32_t* codepoints = new (std::nothrow) uint32_t[MAX_UNIQUE_CODEPOINTS];
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if (!codepoints) {
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LOG_ERR("SDCF", "buildAdvanceTable: failed to allocate codepoint buffer (%u bytes)", MAX_UNIQUE_CODEPOINTS * 4);
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return -1;
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}
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uint32_t cpCount = 0;
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bool hitCap = false;
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// Second pass: collect unique codepoints via O(n²) dedup.
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// Bounded by uniqueCount × totalChars comparisons. For 2000 unique from 2291 total,
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// worst case ~4.6M comparisons of uint32_t — ~30ms on 160MHz RISC-V, acceptable
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// for one-time section indexing.
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const unsigned char* p = reinterpret_cast<const unsigned char*>(utf8Text);
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while (*p) {
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uint32_t cp = utf8NextCodepoint(&p);
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if (cp == 0) break;
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bool found = false;
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for (uint32_t i = 0; i < cpCount; i++) {
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if (codepoints[i] == cp) {
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found = true;
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break;
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}
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}
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if (!found) {
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if (cpCount >= MAX_UNIQUE_CODEPOINTS) {
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hitCap = true;
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break;
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}
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codepoints[cpCount++] = cp;
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}
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}
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if (hitCap) {
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LOG_ERR("SDCF", "buildAdvanceTable: unique codepoint cap (%u) hit, layout may be approximate",
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MAX_UNIQUE_CODEPOINTS);
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}
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// Sort for ordered glyph index mapping and final table output
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std::sort(codepoints, codepoints + cpCount);
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// Step 2: For each requested style, fetch any codepoints not yet cached and
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// merge them into the persistent advance table.
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// Given a sorted array of unique codepoints, resolve glyph indices per style,
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// batch-read advanceX from SD, and merge into the persistent advance table.
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// Caller owns the codepoints buffer.
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int SdCardFont::fetchAdvancesForCodepoints(uint32_t* codepoints, uint32_t cpCount, uint8_t styleMask) {
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int totalMissed = 0;
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for (uint8_t si = 0; si < MAX_STYLES; si++) {
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if (!(styleMask & (1 << si)) || !styles_[si].present) continue;
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@@ -1165,12 +1143,55 @@ int SdCardFont::buildAdvanceTable(const char* utf8Text, uint8_t styleMask) {
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ADVANCE_CACHE_LIMIT);
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}
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delete[] codepoints;
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return totalMissed;
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}
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template <typename Iter>
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int SdCardFont::buildAdvanceTableRange(Iter begin, Iter end, bool includeSpace, bool includeHyphen, uint8_t styleMask) {
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if (!loaded_) return -1;
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styleMask = resolveStyleMask(styleMask);
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if (styleMask == 0) return 0;
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unsigned long startMs = millis();
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// +2 reserved slots for space and hyphen injected after the main scan.
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static constexpr uint32_t MAX_UNIQUE_CODEPOINTS = 4096;
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uint32_t* codepoints = new (std::nothrow) uint32_t[MAX_UNIQUE_CODEPOINTS + 2];
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if (!codepoints) {
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LOG_ERR("SDCF", "buildAdvanceTable: failed to allocate codepoint buffer (%u bytes)", MAX_UNIQUE_CODEPOINTS * 4);
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return -1;
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}
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uint32_t cpCount = 0;
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bool hitCap = false;
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for (auto it = begin; it != end && !hitCap; ++it) {
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hitCap = collectUniqueCodepoints(asCStr(*it), codepoints, cpCount, MAX_UNIQUE_CODEPOINTS);
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}
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if (includeSpace && std::none_of(codepoints, codepoints + cpCount, [](uint32_t c) { return c == ' '; }))
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codepoints[cpCount++] = ' ';
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if (includeHyphen && std::none_of(codepoints, codepoints + cpCount, [](uint32_t c) { return c == '-'; }))
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codepoints[cpCount++] = '-';
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if (hitCap) {
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LOG_ERR("SDCF", "buildAdvanceTable: unique codepoint cap (%u) hit, layout may be approximate",
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MAX_UNIQUE_CODEPOINTS);
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}
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std::sort(codepoints, codepoints + cpCount);
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int totalMissed = fetchAdvancesForCodepoints(codepoints, cpCount, styleMask);
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delete[] codepoints;
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stats_.prewarmTotalMs = millis() - startMs;
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return totalMissed;
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}
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int SdCardFont::buildAdvanceTable(const char* utf8Text, uint8_t styleMask) {
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return buildAdvanceTableRange(&utf8Text, &utf8Text + 1, false, false, styleMask);
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}
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int SdCardFont::buildAdvanceTable(const std::vector<std::string>& words, bool includeHyphen, uint8_t styleMask) {
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return buildAdvanceTableRange(words.begin(), words.end(), words.size() > 1, includeHyphen, styleMask);
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}
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// --- Stats ---
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void SdCardFont::logStats(const char* label) {
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