File size: 2,463 Bytes
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图像编码：把本地图片读成 OpenAI / Anthropic 等通用网关接受的 data URI。
"""
from __future__ import annotations
import base64
import os
from io import BytesIO
from PIL import Image
MAX_IMAGE_SIZE = 8 * 1024 * 1024 # 8MB，超过则压缩
try:
import imghdr
def _detect_format(image_bytes: bytes) -> str | None:
return imghdr.what(None, image_bytes)
except ImportError:
def _detect_format(image_bytes: bytes) -> str | None:
try:
with Image.open(BytesIO(image_bytes)) as img:
return (img.format or "").lower() or None
except Exception:
return None
def _compress(image_bytes: bytes, max_size: int = MAX_IMAGE_SIZE) -> tuple[bytes, str]:
with Image.open(BytesIO(image_bytes)) as img:
if img.mode in ("RGBA", "P"):
img = img.convert("RGB")
for quality in (95, 90, 85, 80, 75, 70, 60):
buf = BytesIO()
img.save(buf, format="JPEG", quality=quality)
if buf.tell() <= max_size:
return buf.getvalue(), "jpeg"
# 仍超限：缩小分辨率
scale = 0.95
while scale > 0.1:
new_size = (int(img.width * scale), int(img.height * scale))
resized = img.resize(new_size, Image.LANCZOS)
buf = BytesIO()
resized.save(buf, format="JPEG", quality=50)
if buf.tell() <= max_size:
return buf.getvalue(), "jpeg"
scale -= 0.05
return buf.getvalue(), "jpeg"
def encode_image(image_path: str) -> str:
"""把本地图片文件读成 ``data:image/<fmt>;base64,<b64>`` data URI。"""
if not isinstance(image_path, str) or not image_path:
raise ValueError(f"invalid image path: {image_path!r}")
if not os.path.isfile(image_path):
raise FileNotFoundError(image_path)
with open(image_path, "rb") as f:
image_bytes = f.read()
fmt = None
try:
with Image.open(BytesIO(image_bytes)) as img:
fmt = (img.format or "").lower() or None
except Exception:
fmt = _detect_format(image_bytes)
if not fmt:
raise ValueError(f"无法识别图像格式: {image_path}")
if len(image_bytes) > MAX_IMAGE_SIZE:
image_bytes, fmt = _compress(image_bytes)
if fmt == "jpeg":
fmt = "jpg"
b64 = base64.b64encode(image_bytes).decode("utf-8")
return f"data:image/{fmt};base64,{b64}"
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