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# The Python Imaging Library
# $Id$
#
# GRIB stub adapter
#
# Copyright (c) 1996-2003 by Fredrik Lundh
#
# See the README file for information on usage and redistribution.
#
from __future__ import annotations
import os
from typing import IO
from . import Image, ImageFile
_handler = None
def register_handler(handler: ImageFile.StubHandler | None) -> None:
"""
Install application-specific GRIB image handler.
:param handler: Handler object.
"""
global _handler
_handler = handler
# --------------------------------------------------------------------
# Image adapter
def _accept(prefix: bytes) -> bool:
return prefix.startswith(b"GRIB") and prefix[7] == 1
class GribStubImageFile(ImageFile.StubImageFile):
format = "GRIB"
format_description = "GRIB"
def _open(self) -> None:
if not _accept(self.fp.read(8)):
msg = "Not a GRIB file"
raise SyntaxError(msg)
self.fp.seek(-8, os.SEEK_CUR)
# make something up
self._mode = "F"
self._size = 1, 1
loader = self._load()
if loader:
loader.open(self)
def _load(self) -> ImageFile.StubHandler | None:
return _handler
def _save(im: Image.Image, fp: IO[bytes], filename: str | bytes) -> None:
if _handler is None or not hasattr(_handler, "save"):
msg = "GRIB save handler not installed"
raise OSError(msg)
_handler.save(im, fp, filename)
# --------------------------------------------------------------------
# Registry
Image.register_open(GribStubImageFile.format, GribStubImageFile, _accept)
Image.register_save(GribStubImageFile.format, _save)
Image.register_extension(GribStubImageFile.format, ".grib")
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