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# Source code for PIL.GdImageFile

    #
    # The Python Imaging Library.
    # $Id$
    #
    # GD file handling
    #
    # History:
    # 1996-04-12 fl   Created
    #
    # Copyright (c) 1997 by Secret Labs AB.
    # Copyright (c) 1996 by Fredrik Lundh.
    #
    # See the README file for information on usage and redistribution.
    #

    """
    .. note::
        This format cannot be automatically recognized, so the
        class is not registered for use with :py:func:`PIL.Image.open()`.  To open a
        gd file, use the :py:func:`PIL.GdImageFile.open()` function instead.

    .. warning::
        THE GD FORMAT IS NOT DESIGNED FOR DATA INTERCHANGE.  This
        implementation is provided for convenience and demonstrational
        purposes only.
    """

    from __future__ import annotations

    from typing import IO

    from . import Image, ImageFile, ImagePalette, UnidentifiedImageError
    from ._binary import i16be as i16
    from ._binary import i32be as i32
    from ._typing import StrOrBytesPath

    class GdImageFile(ImageFile.ImageFile):
        """
        Image plugin for the GD uncompressed format.  Note that this format
        is not supported by the standard :py:func:`PIL.Image.open()` function.  To use
        this plugin, you have to import the :py:mod:`PIL.GdImageFile` module and
        use the :py:func:`PIL.GdImageFile.open()` function.
        """

        format = "GD"
        format_description = "GD uncompressed images"

        def _open(self) -> None:
            # Header
            assert self.fp is not None

            s = self.fp.read(1037)

            if i16(s) not in [65534, 65535]:
                msg = "Not a valid GD 2.x .gd file"
                raise SyntaxError(msg)

            self._mode = "P"
            self._size = i16(s, 2), i16(s, 4)
            Image._decompression_bomb_check(self.size)

            true_color = s[6]
            true_color_offset = 2 if true_color else 0

            # transparency index
            tindex = i32(s, 7 + true_color_offset)
            if tindex < 256:
                self.info["transparency"] = tindex

            self.palette = ImagePalette.raw(
                "RGBX", s[7 + true_color_offset + 6 : 7 + true_color_offset + 6 + 256 * 4]
            )

            self.tile = [
                ImageFile._Tile(
                    "raw",
                    (0, 0) + self.size,
                    7 + true_color_offset + 6 + 256 * 4,
                    "L",
                )
            ]

    def open(fp: StrOrBytesPath | IO[bytes], mode: str = "r") -> GdImageFile:
        """
        Load texture from a GD image file.

        :param fp: GD file name, or an opened file handle.
        :param mode: Optional mode.  In this version, if the mode argument
            is given, it must be "r".
        :returns: An image instance.
        :raises OSError: If the image could not be read.
        """
        if mode != "r":
            msg = "bad mode"
            raise ValueError(msg)

        try:
            return GdImageFile(fp)
        except SyntaxError as e:
            msg = "cannot identify this image file"
            raise UnidentifiedImageError(msg) from e