64 lines
2.1 KiB
C
64 lines
2.1 KiB
C
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#pragma once
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#include <cstdint>
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#include <vector>
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#include "ThaiCharacter.h"
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#include "ThaiCluster.h"
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namespace ThaiShaper {
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/**
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* Thai Cluster Builder
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*
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* Takes a UTF-8 string containing Thai text and builds a sequence of
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* grapheme clusters with proper glyph positioning for rendering.
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*
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* Thai text shaping involves:
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* 1. Reordering: Leading vowels (เ แ โ ไ ใ) appear AFTER the consonant in
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* Unicode but must be rendered BEFORE the consonant visually.
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*
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* 2. Stacking: Above vowels, tone marks, and other marks must be stacked
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* vertically above the base consonant.
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*
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* 3. Below placement: Below vowels must be positioned under the consonant.
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*
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* Example: "เกี่ยว" (about/related) is stored as:
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* เ (U+0E40) + ก (U+0E01) + ี (U+0E35) + ่ (U+0E48) + ย (U+0E22) + ว (U+0E27)
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*
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* But renders as:
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* [เ][ก with ี and ่ stacked above][ย][ว]
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*
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* Note: Consonant "ascenders" - Some Thai consonants have tall ascenders
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* (ป ฝ ฟ etc.) that may cause above marks to shift position. This
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* implementation uses a simplified approach suitable for e-ink rendering.
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*/
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class ThaiClusterBuilder {
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public:
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/**
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* Build clusters from a UTF-8 Thai text string.
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*
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* @param text UTF-8 encoded string (may contain mixed Thai and non-Thai)
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* @return Vector of clusters, each representing one grapheme unit
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*/
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static std::vector<ThaiCluster> buildClusters(const char* text);
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/**
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* Build a single cluster from codepoints starting at the current position.
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* Advances the text pointer past the consumed codepoints.
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*
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* @param text Pointer to pointer of UTF-8 text (advanced on return)
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* @return Single cluster containing positioned glyphs
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*/
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static ThaiCluster buildNextCluster(const uint8_t** text);
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private:
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// Check if a consonant is a "tall" consonant that affects mark positioning
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static bool isAscenderConsonant(uint32_t cp);
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// Check if a consonant is a "descender" consonant that affects below-mark positioning
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static bool isDescenderConsonant(uint32_t cp);
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};
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} // namespace ThaiShaper
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