237 lines
7.4 KiB
Python
237 lines
7.4 KiB
Python
"""二维码往返自检（开发工具，不参与运行时）。
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作用：解码我们自己生成的 QR SVG，验证 **能被读回原文本**——避免"看起来像二维码
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但扫不出来"的假成功。这不是完整 QR 解码器，只覆盖生成器用到的子集
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（Model 2 / 字节模式 / 纠错 L / 掩码 0），用于回归验证。
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用法：
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python -m apps.printing.qr_selftest
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"""
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from __future__ import annotations
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import base64
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import re
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import sys
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from .qr import VERSIONS_L, ALIGN_POS, _size_of, _pick_version
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def _svg_to_matrix(svg: str) -> list:
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"""从生成的 SVG 还原模块矩阵（正方形 rect 拼回去，无需图像库）。"""
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m = re.search(r'viewBox="0 0 (\d+) (\d+)"', svg)
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if not m:
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raise ValueError("no viewBox")
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total = int(m.group(1))
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# 模块边长 = 总边长 / (size + 2*border)，从第一个 rect 的 width 推断
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rects = re.findall(r'<rect x="(\d+)" y="(\d+)" width="(\d+)" height="(\d+)"/>', svg)
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if not rects:
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raise ValueError("no rects")
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scale = int(rects[0][3]) # height = scale
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size = total // scale
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grid = [[1] * size for _ in range(size)] # 背景白=0，先全填 0 再置黑
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grid = [[0] * size for _ in range(size)]
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for x, y, w, h in rects:
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x, y, w, h = int(x), int(y), int(w), int(h)
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r0, c0 = y // scale, x // scale
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for dc in range(w // scale):
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if 0 <= r0 < size and c0 + dc < size:
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grid[r0][c0 + dc] = 1
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return grid
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def _strip_border(grid: list) -> list:
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"""去掉静默区，回到纯模块矩阵。"""
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size = len(grid)
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# 找第一行/列全 0 的边界（静默区）
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def all_zero(values):
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return all(v == 0 for v in values)
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top = 0
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while top < size and all_zero(grid[top]):
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top += 1
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left = 0
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while left < size and all_zero([grid[r][left] for r in range(size)]):
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left += 1
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bottom = size - 1
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while bottom >= 0 and all_zero(grid[bottom]):
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bottom -= 1
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right = size - 1
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while right >= 0 and all_zero([grid[r][right] for r in range(size)]):
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right -= 1
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return [row[left:right + 1] for row in grid[top:bottom + 1]]
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def _read_format(mat: list) -> tuple:
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"""读左上格式信息 → (纠错级别, 掩码)。"""
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size = len(mat)
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seq = [(8, 0), (8, 1), (8, 2), (8, 3), (8, 4), (8, 5), (8, 7), (8, 8),
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(7, 8), (5, 8), (4, 8), (3, 8), (2, 8), (1, 8), (0, 8)]
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bits = 0
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for i, (r, c) in enumerate(seq):
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bits |= (mat[r][c] & 1) << i
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bits ^= 0b101010000010010
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ec = (bits >> 13) & 0b11
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mask = (bits >> 10) & 0b111
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return ec, mask
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def _unmask(mat: list, mask: int) -> list:
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"""按掩码规则还原数据区。"""
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from .qr import _is_function
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size = len(mat)
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version = (size - 17) // 4
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out = [row[:] for row in mat]
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for r in range(size):
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for c in range(size):
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if _is_function(r, c, version):
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continue
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invert = False
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if mask == 0:
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invert = (r + c) % 2 == 0
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elif mask == 1:
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invert = r % 2 == 0
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elif mask == 2:
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invert = c % 3 == 0
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elif mask == 3:
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invert = (r + c) % 3 == 0
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if invert:
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out[r][c] ^= 1
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return out
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def _extract_bits(mat: list, version: int | None = None) -> list:
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"""按之字形路径读出数据位（跳过功能模块）。"""
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from .qr import _is_function
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size = len(mat)
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version = version if version is not None else (size - 17) // 4
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bits = []
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col = size - 1
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upward = True
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while col > 0:
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if col == 6:
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col -= 1
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rows = range(size - 1, -1, -1) if upward else range(size)
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for row in rows:
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for c in (col, col - 1):
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if not _is_function(row, c, version):
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bits.append(mat[row][c] & 1)
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upward = not upward
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col -= 2
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return bits
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def _bits_to_bytes(bits: list) -> bytes:
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out = bytearray()
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for i in range(0, len(bits) - 7, 8):
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b = 0
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for j in range(8):
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b = (b << 1) | bits[i + j]
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out.append(b)
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return bytes(out)
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def decode(svg: str) -> str | None:
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"""解码本模块生成的 QR SVG，返回原文；失败返回 None。
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流程：SVG → 模块矩阵 → 去静默区 → 读格式信息(纠错/掩码) → 去掩码
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→ 之字形读位 → 字节模式解析。
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"""
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from .qr import _is_function
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grid = _svg_to_matrix(svg)
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mat = _strip_border(grid)
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size = len(mat)
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version = (size - 17) // 4
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if version not in VERSIONS_L:
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return None
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ec, mask = _read_format(mat)
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if ec != 0b01: # 只支持纠错 L
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return None
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# 去掩码
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base = [row[:] for row in mat]
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for r in range(size):
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for c in range(size):
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if _is_function(r, c, version):
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continue
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if mask == 0 and (r + c) % 2 == 0:
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base[r][c] ^= 1
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elif mask == 1 and r % 2 == 0:
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base[r][c] ^= 1
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elif mask == 2 and c % 3 == 0:
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base[r][c] ^= 1
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elif mask == 3 and (r + c) % 3 == 0:
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base[r][c] ^= 1
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# 之字形读位
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bits = []
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col = size - 1
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upward = True
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while col > 0:
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if col == 6:
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col -= 1
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rows = range(size - 1, -1, -1) if upward else range(size)
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for row in rows:
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for c in (col, col - 1):
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if not _is_function(row, c, version):
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bits.append(base[row][c] & 1)
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upward = not upward
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col -= 2
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# 位流解析（注意：不能按字节边界切——模式 4 位 + 长度 8 位 = 12 位，
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# 数据从第 12 位开始，跨字节。早期版本按字节取导致整体错位。）
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if len(bits) < 12:
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return None
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if bits[0:4] != [0, 1, 0, 0]: # 字节模式
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return None
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length = 0
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for b in bits[4:12]: # 版本 1-9：长度 8 位
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length = (length << 1) | b
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need = 12 + length * 8
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if length <= 0 or len(bits) < need:
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return None
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payload = bytearray()
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for i in range(length):
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byte = 0
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for j in range(8):
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byte = (byte << 1) | bits[12 + i * 8 + j]
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payload.append(byte)
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try:
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return payload.decode("utf-8")
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except UnicodeDecodeError:
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return None
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def selftest() -> int:
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"""往返测试若干载荷，返回失败数。"""
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from .qr import qr_svg_data_uri
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samples = [
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"/api/v1/open/statements/9eb70e10-82e1-47d1-bc5b-fb3e0716ba19/",
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"https://dealerhub.example.com/api/v1/open/statements/c71ac955-27d6-4942-968c-720a6afe5394/",
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"HELLO-DEALERHUB-2026",
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"1",
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"a" * 60,
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"对账单-中文测试",
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]
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failed = 0
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for text in samples:
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uri = qr_svg_data_uri(text, scale=4)
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svg = base64.b64decode(uri.split(",", 1)[1]).decode("utf-8")
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got = decode(svg)
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ok = got == text
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failed += 0 if ok else 1
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mark = "✓" if ok else "✗"
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print(f" {mark} len={len(text):3d} expect={text[:45]!r}"
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+ ("" if ok else f" got={got!r}"))
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print(f"\n往返测试：{len(samples) - failed}/{len(samples)} 通过")
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return failed
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if __name__ == "__main__":
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sys.exit(1 if selftest() else 0)
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