Files
Crosspoint/lib/EpdFont/FontDecompressor.h
T

93 lines
3.9 KiB
C++

#pragma once
#include <InflateReader.h>
#include "EpdFontData.h"
class FontDecompressor {
public:
static constexpr uint16_t MAX_PAGE_GLYPHS = 512;
static constexpr uint8_t MAX_PAGE_SLOTS = 4; // One per font style (R/B/I/BI)
FontDecompressor() = default;
~FontDecompressor();
bool init();
void deinit();
// Returns pointer to decompressed bitmap data for the given glyph.
// Checks the page buffer (from prewarm) first, then falls back to the hot group slot.
const uint8_t* getBitmap(const EpdFontData* fontData, const EpdGlyph* glyph, uint32_t glyphIndex);
// Free all cached data (page buffer + hot group).
void clearCache();
// Pre-scan UTF-8 text and extract needed glyph bitmaps into a flat page buffer.
// Each group is decompressed once into a temp buffer; only needed glyphs are kept.
// Returns the number of glyphs that couldn't be loaded (0 on full success).
int prewarmCache(const EpdFontData* fontData, const char* utf8Text);
struct Stats {
uint32_t cacheHits = 0;
uint32_t cacheMisses = 0;
uint32_t decompressTimeMs = 0;
uint16_t uniqueGroupsAccessed = 0;
uint32_t pageBufferBytes = 0; // pageBuffer allocation
uint32_t pageGlyphsBytes = 0; // pageGlyphs lookup table allocation
uint32_t hotGroupBytes = 0; // current hot group allocation
uint32_t peakTempBytes = 0; // largest temp buffer in prewarm
uint32_t getBitmapTimeUs = 0; // cumulative getBitmap time (micros)
uint32_t getBitmapCalls = 0; // number of getBitmap calls
};
void logStats(const char* label = "FDC");
void resetStats();
const Stats& getStats() const { return stats; }
private:
Stats stats;
InflateReader inflateReader;
// Page buffer slots: each style gets its own flat glyph buffer with sorted lookup.
// Up to MAX_PAGE_SLOTS (4) styles can be prewarmed simultaneously.
struct PageGlyphEntry {
uint32_t glyphIndex;
uint32_t bufferOffset;
uint32_t alignedOffset; // byte-aligned offset within its decompressed group (set during prewarm pre-scan)
};
struct PageSlot {
uint8_t* buffer = nullptr;
const EpdFontData* fontData = nullptr;
PageGlyphEntry* glyphs = nullptr;
uint16_t glyphCount = 0;
};
PageSlot pageSlots[MAX_PAGE_SLOTS] = {};
uint8_t pageSlotCount = 0;
// Hot group: last decompressed group (byte-aligned) for non-prewarmed fallback path.
// Kept in byte-aligned format; individual glyphs are compacted on demand into hotGlyphBuf.
// Nothrow high-water malloc buffers, NOT std::vector: getBitmap() runs on the render path,
// and under -fno-exceptions a vector resize that hits OOM abort()s the firmware instead of
// failing (field crash: hotGroup.resize() -> std::bad_alloc -> abort with ~11 KB free).
// ensureCapacity() returns false on OOM so the caller can skip the glyph gracefully.
const EpdFontData* hotGroupFont = nullptr;
uint16_t hotGroupIndex = UINT16_MAX;
uint8_t* hotGroup = nullptr; // owned; freed in freeHotGroup()/dtor
uint32_t hotGroupCapacity = 0;
// Scratch buffer for compacting a single glyph from the hot group.
// Valid until the next getBitmap() call. Same ownership/OOM contract as hotGroup.
uint8_t* hotGlyphBuf = nullptr;
uint32_t hotGlyphBufCapacity = 0;
// Grow (never shrink) an owned buffer to at least `needed` bytes; false on OOM, buffer freed.
static bool ensureCapacity(uint8_t*& buf, uint32_t& capacity, uint32_t needed);
void freePageBuffer();
void freeHotGroup();
uint16_t getGroupIndex(const EpdFontData* fontData, uint32_t glyphIndex);
uint32_t getAlignedOffset(const EpdFontData* fontData, uint16_t groupIndex, uint32_t glyphIndex);
bool decompressGroup(const EpdFontData* fontData, uint16_t groupIndex, uint8_t* outBuf, uint32_t outSize);
static void compactSingleGlyph(const uint8_t* alignedSrc, uint8_t* packedDst, uint8_t width, uint8_t height);
static int32_t findGlyphIndex(const EpdFontData* fontData, uint32_t codepoint);
};