f1e9dc7f30
## Purpose This PR includes some preparatory changes that are needed for an upcoming performant CJK font feature. The changes have no impact on render time and heap allocation for latin text. **Despite this, I think these changes stand on their own as a better font compression/decompression implementation.** ## Summary - Font decompressor rewrite: Replaced the 4-slot LRU group cache with a two-tier system — a page buffer (glyphs prewarmed before rendering begins) and a hot-group fallback (last decompressed group retained for non-prewarmed glyphs). - Byte-aligned compressed bitmap format: Glyph bitmaps within compressed groups are now stored row-padded rather than tightly packed before DEFLATE compression, improving compression ratios by making identical pixel rows produce identical byte patterns. Glyphs are compacted back to packed format on demand at render time. Reduces flash size by 155 KB. - Page prewarm system: Added `Page::collectText` and `Page::getDominantStyle` to extract per-style glyph requirements before rendering, and `GfxRenderer::prewarmFontCache` to pre-decompress only the groups needed for the dominant style — eliminating mid-render decompression for the common case. - UTF-8 robustness fixes: `utf8NextCodepoint` now validates continuation bytes and returns a replacement glyph on malformed input; `ChapterHtmlSlimParser` correctly preserves incomplete multi-byte sequences across word-buffer flush boundaries rather than splitting them. --- ### 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? _**YES**_ Architecture and design was done by me, refined a bit by Claude. Code mostly by Claude, but not entirely.
25 lines
1.1 KiB
C++
25 lines
1.1 KiB
C++
#pragma once
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#include <cstdint>
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#include <string>
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#define REPLACEMENT_GLYPH 0xFFFD
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uint32_t utf8NextCodepoint(const unsigned char** string);
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// Remove the last UTF-8 codepoint from a std::string and return the new size.
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size_t utf8RemoveLastChar(std::string& str);
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// Truncate string by removing N UTF-8 codepoints from the end.
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void utf8TruncateChars(std::string& str, size_t numChars);
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// Truncate a raw char buffer to the last complete UTF-8 codepoint boundary.
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// Returns the new length (<= len). If the buffer ends mid-sequence, the
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// incomplete trailing bytes are excluded.
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int utf8SafeTruncateBuffer(const char* buf, int len);
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// Returns true for Unicode combining diacritical marks that should not advance the cursor.
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inline bool utf8IsCombiningMark(const uint32_t cp) {
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return (cp >= 0x0300 && cp <= 0x036F) // Combining Diacritical Marks
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|| (cp >= 0x1DC0 && cp <= 0x1DFF) // Combining Diacritical Marks Supplement
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|| (cp >= 0x20D0 && cp <= 0x20FF) // Combining Diacritical Marks for Symbols
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|| (cp >= 0xFE20 && cp <= 0xFE2F); // Combining Half Marks
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}
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