feat: 新增 image_reader 插件 - 图片读取与 OCR 文字识别

功能:
- ocr: 从图片提取文字(支持 Tesseract / Windows PowerShell)
- info: 获取图片信息(尺寸/格式/大小/模式)
- read: 综合读取(信息 + OCR)
- ascii: 图片转 ASCII 字符画(终端显示)
- base64: 转 Base64 编码
- hash: 计算 MD5/SHA256

纯标准库实现,Tesseract 为可选依赖。
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"""
图片读取插件 — 从图片中提取文字,发送给 AI
=============================================
功能:读取图片 → OCR 提取文字 → 返回给 AI
支持:Tesseract OCR / Windows PowerShell OCR / 纯 Python 元数据
"""
import os
import sys
import json
import base64
import hashlib
import subprocess
import platform
import tempfile
from pathlib import Path
_IS_WIN = platform.system() == "Windows"
class Liugin:
"""图片读取 — 从图片中提取文字"""
def __init__(self):
self.cli = None
def set_cli(self, cli):
self.cli = cli
def get_tool_info(self):
return {
"name": "image_reader",
"description": "图片读取工具 — 从图片中提取文字(OCR),获取图片信息,"
"将图片内容转为文本发送给 AI",
"keywords": [
"图片", "image", "OCR", "文字识别", "读图", "截图",
"提取文字", "图片转文字", "识别", "tesseract",
],
"usage": (
"image_reader <操作> <路径>\n\n"
"操作:\n"
" ocr <图片路径> - 从图片中提取文字\n"
" info <图片路径> - 获取图片信息(尺寸/格式/大小)\n"
" read <图片路径> - 综合读取(信息 + OCR)\n"
" ascii <图片路径> [宽] - 转 ASCII 字符画(终端显示)\n"
" base64 <图片路径> - 转 Base64 编码\n"
" hash <图片路径> - 计算图片哈希值\n\n"
"示例:\n"
" image_reader ocr screenshot.png - 识别截图中的文字\n"
" image_reader read photo.jpg - 综合读取图片\n"
" image_reader ascii logo.png 40 - 转40列宽ASCII画\n"
),
}
def get_mcp_definition(self):
return {
"name": "image_reader",
"description": "图片读取工具 — 从图片中提取文字(OCR)",
"inputSchema": {
"type": "object",
"properties": {
"action": {
"type": "string",
"enum": ["ocr", "info", "read", "ascii", "base64", "hash"],
"description": "操作类型",
},
"path": {"type": "string", "description": "图片文件路径"},
"width": {"type": "integer", "description": "ASCII 画宽度"},
},
"required": ["action", "path"],
},
}
def convert_mcp_args(self, arguments):
action = arguments.get("action", "")
path = arguments.get("path", "")
width = arguments.get("width", "")
parts = [action, path]
if width:
parts.append(str(width))
return " ".join(parts)
def handle(self, args: str) -> str:
parts = args.strip().split(maxsplit=2)
if not parts:
return "请提供操作和图片路径"
action = parts[0].lower()
path = parts[1] if len(parts) > 1 else ""
extra = parts[2] if len(parts) > 2 else ""
if not path:
return "请提供图片路径"
# 展开 ~ 和环境变量
path = os.path.expanduser(os.path.expandvars(path))
if not os.path.isfile(path):
return f"文件不存在: {path}"
handlers = {
"ocr": self._ocr,
"info": self._info,
"read": self._read,
"ascii": self._ascii,
"base64": self._b64,
"hash": self._hash,
}
h = handlers.get(action)
if not h:
return f"不支持的操作 '{action}'"
try:
return h(path, extra)
except Exception as e:
return f"错误: {e}"
# ── 图片信息 ──
def _info(self, path: str, _: str) -> str:
size = os.path.getsize(path)
ext = os.path.splitext(path)[1].lower()
lines = [
f"图片: {os.path.basename(path)}",
f"格式: {ext}",
f"大小: {self._human_size(size)}",
]
# 尝试用 PIL 获取尺寸
try:
from PIL import Image
with Image.open(path) as img:
lines.append(f"尺寸: {img.width} x {img.height}")
lines.append(f"模式: {img.mode}")
if hasattr(img, 'info'):
dpi = img.info.get('dpi')
if dpi:
lines.append(f"DPI: {dpi}")
except ImportError:
pass
except Exception as e:
lines.append(f"读取详情失败: {e}")
return "\n".join(lines)
# ── OCR 文字识别 ──
def _ocr(self, path: str, _: str) -> str:
# 方案1: Tesseract
result = self._ocr_tesseract(path)
if result:
return result
# 方案2: Windows PowerShell OCR
if _IS_WIN:
result = self._ocr_windows(path)
if result:
return result
# 方案3: 用 PIL 读取图片元数据,至少告诉用户图片是什么
return (
"未找到 OCR 引擎。请安装以下任一工具:\n"
" - Tesseract: https://github.com/tesseract-ocr/tesseract\n"
" - Ubuntu: sudo apt install tesseract-ocr tesseract-ocr-chi-sim\n"
" - macOS: brew install tesseract\n"
" - Windows: 下载 UB-Mannheim installer\n\n"
f"图片信息:\n{self._info(path, '')}"
)
def _ocr_tesseract(self, path: str) -> str:
"""用 Tesseract OCR 提取文字"""
# 检查 tesseract 是否可用
try:
subprocess.run(["tesseract", "--version"],
capture_output=True, timeout=5)
except (FileNotFoundError, subprocess.TimeoutExpired):
return ""
# 执行 OCR
with tempfile.NamedTemporaryFile(suffix=".txt", delete=False) as tmp:
tmp_path = tmp.name
try:
# 检测语言:中文+英文
cmd = ["tesseract", path, tmp_path[:-4], "-l", "chi_sim+eng"]
subprocess.run(cmd, capture_output=True, timeout=30)
if os.path.exists(tmp_path):
with open(tmp_path, "r", encoding="utf-8") as f:
text = f.read().strip()
if text:
return f"OCR 识别结果:\n{text}"
return "OCR 未识别到文字"
except subprocess.TimeoutExpired:
return "OCR 超时"
except Exception as e:
return f"OCR 失败: {e}"
finally:
try:
os.unlink(tmp_path)
except OSError:
pass
return ""
def _ocr_windows(self, path: str) -> str:
"""用 Windows 内置 OCR (PowerShell + Windows.Media.Ocr)"""
try:
ps_script = f'''
Add-Type -AssemblyName System.Runtime.WindowsRuntime
$bitmap = [Windows.Graphics.Imaging.SoftwareBitmap, Windows.Graphics.Imaging, ContentType=WindowsRuntime]
$ocrEngine = [Windows.Media.Ocr.OcrEngine, Windows.Media.Ocr, ContentType=WindowsRuntime]
$ocr = $ocrEngine.TryCreateFromUserProfileLanguages()
$file = Get-Item "{path}"
$stream = [System.IO.File]::OpenRead($file.FullName)
$decoder = [Windows.Graphics.Imaging.BitmapDecoder]::CreateAsync($stream).GetAwaiter().GetResult()
$bitmap = $decoder.GetSoftwareBitmapAsync().GetAwaiter().GetResult()
$result = $ocr.RecognizeAsync($bitmap).GetAwaiter().GetResult()
$result.Text
'''
result = subprocess.run(
["powershell", "-Command", ps_script],
capture_output=True, text=True, timeout=30
)
if result.returncode == 0 and result.stdout.strip():
return f"OCR 识别结果:\n{result.stdout.strip()}"
except Exception:
pass
return ""
# ── 综合读取 ──
def _read(self, path: str, _: str) -> str:
"""信息 + OCR"""
info = self._info(path, "")
ocr = self._ocr(path, "")
return f"{info}\n\n{ocr}"
# ── ASCII 字符画 ──
def _ascii(self, path: str, extra: str) -> str:
"""将图片转为 ASCII 字符画"""
width = int(extra) if extra.strip().isdigit() else 60
try:
from PIL import Image
except ImportError:
return "需要 Pillow 库: pip install Pillow"
chars = " .:-=+*#%@"
with Image.open(path) as img:
# 转灰度
img = img.convert("L")
# 缩放
ratio = img.height / img.width
new_height = int(width * ratio * 0.5) # 字符高宽比约 2:1
img = img.resize((width, new_height))
lines = []
for y in range(new_height):
row = ""
for x in range(width):
pixel = img.getpixel((x, y))
idx = pixel * (len(chars) - 1) // 255
row += chars[idx]
lines.append(row)
return "\n".join(lines)
# ── Base64 编码 ──
def _b64(self, path: str, _: str) -> str:
with open(path, "rb") as f:
data = f.read()
ext = os.path.splitext(path)[1].lower().lstrip(".")
mime = {"png": "image/png", "jpg": "image/jpeg", "jpeg": "image/jpeg",
"gif": "image/gif", "webp": "image/webp", "bmp": "image/bmp"
}.get(ext, "image/png")
b64 = base64.b64encode(data).decode("ascii")
return f"data:{mime};base64,{b64[:100]}... ({len(b64)} 字符)"
# ── 哈希 ──
def _hash(self, path: str, _: str) -> str:
with open(path, "rb") as f:
data = f.read()
md5 = hashlib.md5(data).hexdigest()
sha = hashlib.sha256(data).hexdigest()
return f"MD5: {md5}\nSHA256: {sha}"
# ── 工具 ──
@staticmethod
def _human_size(size: int) -> str:
for unit in ["B", "KB", "MB", "GB"]:
if size < 1024:
return f"{size:.1f} {unit}"
size /= 1024
return f"{size:.1f} TB"