Serendipity
ce9c8b1b6e
1. detect.rs: remove()索引bug — 元素前移后索引未更新，改用每次remove(0) 2. detect.rs: 版本估算公式修正 — (dist-14)/4 → (dist-10)/4，符合ZXing公式 3. extract.rs: 移除显式col 6跳过 — read_module已自动跳过保留区，显式skip导致列配对错位/行序反转 新增 test_roundtrip_png: 矩阵往返 + PNG往返双验证
91 lines
3.0 KiB
Rust
91 lines
3.0 KiB
Rust
//! 从 QR 矩阵数据区域蛇形读取码字比特
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//!
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//! 读取顺序严格对应 `placement.rs::place_data` 的写入顺序：
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//! 从右下角开始，两列一组上下交替扫描，跳过保留模块。
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use crate::matrix::grid::Matrix;
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/// 从矩阵非保留区域蛇形读取码字比特
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fn extract_bits(matrix: &Matrix, total_codewords: usize) -> Vec<bool> {
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let size = matrix.size as usize;
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let target_bits = total_codewords * 8;
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let mut bits: Vec<bool> = Vec::with_capacity(target_bits);
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let mut col = (size - 1) as i16;
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let mut going_up = true;
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while col >= 0 && bits.len() < target_bits {
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let actual_col = col as usize;
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if going_up {
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for row in (0..size).rev() {
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read_module(matrix, &mut bits, actual_col, row);
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if actual_col > 0 {
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read_module(matrix, &mut bits, actual_col - 1, row);
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}
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}
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} else {
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for row in 0..size {
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read_module(matrix, &mut bits, actual_col, row);
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if actual_col > 0 {
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read_module(matrix, &mut bits, actual_col - 1, row);
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}
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}
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}
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col -= 2;
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going_up = !going_up;
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// 垂直时序图案列（col 6）由 read_module 自动跳过保留区，
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// 无需显式 skip，否则会导致列配对错位、行序反转
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}
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bits.truncate(target_bits);
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bits
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}
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/// 读取单个非保留模块，追加 bool 到 bits
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fn read_module(matrix: &Matrix, bits: &mut Vec<bool>, x: usize, y: usize) {
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let xu = x as u8;
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let yu = y as u8;
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if xu < matrix.size && yu < matrix.size && !matrix.is_reserved(xu, yu) {
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bits.push(matrix.get(xu, yu));
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}
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}
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/// 将布尔比特打包为 u8 码字（MSB 优先）
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fn bits_to_bytes(bits: &[bool]) -> Vec<u8> {
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bits.chunks(8)
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.map(|chunk| {
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let mut byte = 0u8;
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for &b in chunk {
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byte = (byte << 1) | (b as u8);
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}
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// 不足 8 位的 chunk 左对齐
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byte <<= 8 - chunk.len();
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byte
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})
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.collect()
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}
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/// 从矩阵提取数据码字
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///
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/// *`total_codewords` 为数据码字总数（来自 EcInfo.total_codewords）*
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pub(crate) fn extract_codewords(matrix: &Matrix, total_codewords: usize) -> Vec<u8> {
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let bits = extract_bits(matrix, total_codewords);
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bits_to_bytes(&bits)
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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use crate::qr::{QrCode, QrConfig};
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use crate::version::get_data_capacity;
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#[test]
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fn test_extract_roundtrip_simple() {
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let qr = QrCode::encode("HELLO WORLD", QrConfig::default()).unwrap();
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let cap = get_data_capacity(qr.version, qr.level) as usize;
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let codewords = extract_codewords(qr.matrix(), cap);
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assert!(!codewords.is_empty());
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// 前 11 字节编码 "HELLO WORLD"（byte 模式 4b+8b+88b=100bits≈13字节）
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assert!(codewords.len() >= 5); // 至少有数据
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}
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}
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