# Source code for PIL.IcnsImagePlugin

    #
    # The Python Imaging Library.
    # $Id$
    #
    # macOS icns file decoder, based on icns.py by Bob Ippolito.
    #
    # history:
    # 2004-10-09 fl   Turned into a PIL plugin; removed 2.3 dependencies.
    # 2020-04-04      Allow saving on all operating systems.
    #
    # Copyright (c) 2004 by Bob Ippolito.
    # Copyright (c) 2004 by Secret Labs.
    # Copyright (c) 2004 by Fredrik Lundh.
    # Copyright (c) 2014 by Alastair Houghton.
    # Copyright (c) 2020 by Pan Jing.
    #
    # See the README file for information on usage and redistribution.
    #

    import io
    import os
    import struct
    import sys

    from PIL import Image, ImageFile, PngImagePlugin, features

    enable_jpeg2k = features.check_codec("jpg_2000")
    if enable_jpeg2k:
        from PIL import Jpeg2KImagePlugin

    MAGIC = b"icns"
    HEADERSIZE = 8

    def nextheader(fobj):
        return struct.unpack(">4sI", fobj.read(HEADERSIZE))

    def read_32t(fobj, start_length, size):
        # The 128x128 icon seems to have an extra header for some reason.
        (start, length) = start_length
        fobj.seek(start)
        sig = fobj.read(4)
        if sig != b"\x00\x00\x00\x00":
            raise SyntaxError("Unknown signature, expecting 0x00000000")
        return read_32(fobj, (start + 4, length - 4), size)

    def read_32(fobj, start_length, size):
        """
        Read a 32bit RGB icon resource.  Seems to be either uncompressed or
        an RLE packbits-like scheme.
        """
        (start, length) = start_length
        fobj.seek(start)
        pixel_size = (size[0] * size[2], size[1] * size[2])
        sizesq = pixel_size[0] * pixel_size[1]
        if length == sizesq * 3:
            # uncompressed ("RGBRGBGB")
            indata = fobj.read(length)
            im = Image.frombuffer("RGB", pixel_size, indata, "raw", "RGB", 0, 1)
        else:
            # decode image
            im = Image.new("RGB", pixel_size, None)
            for band_ix in range(3):
                data = []
                bytesleft = sizesq
                while bytesleft > 0:
                    byte = fobj.read(1)
                    if not byte:
                        break
                    byte = byte[0]
                    if byte & 0x80:
                        blocksize = byte - 125
                        byte = fobj.read(1)
                        for i in range(blocksize):
                            data.append(byte)
                    else:
                        blocksize = byte + 1
                        data.append(fobj.read(blocksize))
                    bytesleft -= blocksize
                    if bytesleft <= 0:
                        break
                if bytesleft != 0:
                    raise SyntaxError(f"Error reading channel [{repr(bytesleft)} left]")
                band = Image.frombuffer("L", pixel_size, b"".join(data), "raw", "L", 0, 1)
                im.im.putband(band.im, band_ix)
        return {"RGB": im}

    def read_mk(fobj, start_length, size):
        # Alpha masks seem to be uncompressed
        start = start_length[0]
        fobj.seek(start)
        pixel_size = (size[0] * size[2], size[1] * size[2])
        sizesq = pixel_size[0] * pixel_size[1]
        band = Image.frombuffer("L", pixel_size, fobj.read(sizesq), "raw", "L", 0, 1)
        return {"A": band}

    def read_png_or_jpeg2000(fobj, start_length, size):
        (start, length) = start_length
        fobj.seek(start)
        sig = fobj.read(12)
        if sig[:8] == b"\x89PNG\x0d\x0a\x1a\x0a":
            fobj.seek(start)
            im = PngImagePlugin.PngImageFile(fobj)
            Image._decompression_bomb_check(im.size)
            return {"RGBA": im}
        elif (
            sig[:4] == b"\xff\x4f\xff\x51"
            or sig[:4] == b"\x0d\x0a\x87\x0a"
            or sig == b"\x00\x00\x00\x0cjP  \x0d\x0a\x87\x0a"
        ):
            if not enable_jpeg2k:
                raise ValueError(
                    "Unsupported icon subimage format (rebuild PIL "
                    "with JPEG 2000 support to fix this)"
                )
            # j2k, jpc or j2c
            fobj.seek(start)
            jp2kstream = fobj.read(length)
            f = io.BytesIO(jp2kstream)
            im = Jpeg2KImagePlugin.Jpeg2KImageFile(f)
            Image._decompression_bomb_check(im.size)
            if im.mode != "RGBA":
                im = im.convert("RGBA")
            return {"RGBA": im}
        else:
            raise ValueError("Unsupported icon subimage format")

    class IcnsFile:

        SIZES = {
            (512, 512, 2): [(b"ic10", read_png_or_jpeg2000)],
            (512, 512, 1): [(b"ic09", read_png_or_jpeg2000)],
            (256, 256, 2): [(b"ic14", read_png_or_jpeg2000)],
            (256, 256, 1): [(b"ic08", read_png_or_jpeg2000)],
            (128, 128, 2): [(b"ic13", read_png_or_jpeg2000)],
            (128, 128, 1): [
                (b"ic07", read_png_or_jpeg2000),
                (b"it32", read_32t),
                (b"t8mk", read_mk),
            ],
            (64, 64, 1): [(b"icp6", read_png_or_jpeg2000)],
            (32, 32, 2): [(b"ic12", read_png_or_jpeg2000)],
            (48, 48, 1): [(b"ih32", read_32), (b"h8mk", read_mk)],
            (32, 32, 1): [
                (b"icp5", read_png_or_jpeg2000),
                (b"il32", read_32),
                (b"l8mk", read_mk),
            ],
            (16, 16, 2): [(b"ic11", read_png_or_jpeg2000)],
            (16, 16, 1): [
                (b"icp4", read_png_or_jpeg2000),
                (b"is32", read_32),
                (b"s8mk", read_mk),
            ],
        }

        def __init__(self, fobj):
            """
            fobj is a file-like object as an icns resource
            """
            # signature : (start, length)
            self.dct = dct = {}
            self.fobj = fobj
            sig, filesize = nextheader(fobj)
            if sig != MAGIC:
                raise SyntaxError("not an icns file")
            i = HEADERSIZE
            while i < filesize:
                sig, blocksize = nextheader(fobj)
                if blocksize <= 0:
                    raise SyntaxError("invalid block header")
                i += HEADERSIZE
                blocksize -= HEADERSIZE
                dct[sig] = (i, blocksize)
                fobj.seek(blocksize, io.SEEK_CUR)
                i += blocksize

        def itersizes(self):
            sizes = []
            for size, fmts in self.SIZES.items():
                for (fmt, reader) in fmts:
                    if fmt in self.dct:
                        sizes.append(size)
                        break
            return sizes

        def bestsize(self):
            sizes = self.itersizes()
            if not sizes:
                raise SyntaxError("No 32bit icon resources found")
            return max(sizes)

        def dataforsize(self, size):
            """
            Get an icon resource as {channel: array}.  Note that
            the arrays are bottom-up like windows bitmaps and will likely
            need to be flipped or transposed in some way.
            """
            dct = {}
            for code, reader in self.SIZES[size]:
                desc = self.dct.get(code)
                if desc is not None:
                    dct.update(reader(self.fobj, desc, size))
            return dct

        def getimage(self, size=None):
            if size is None:
                size = self.bestsize()
            if len(size) == 2:
                size = (size[0], size[1], 1)
            channels = self.dataforsize(size)

            im = channels.get("RGBA", None)
            if im:
                return im

            im = channels.get("RGB").copy()
            try:
                im.putalpha(channels["A"])
            except KeyError:
                pass
            return im

    ##
    # Image plugin for Mac OS icons.

    class IcnsImageFile(ImageFile.ImageFile):
        """
        PIL image support for Mac OS .icns files.
        Chooses the best resolution, but will possibly load
        a different size image if you mutate the size attribute
        before calling 'load'.

        The info dictionary has a key 'sizes' that is a list
        of sizes that the icns file has.
        """

        format = "ICNS"
        format_description = "Mac OS icns resource"

        def _open(self):
            self.icns = IcnsFile(self.fp)
            self.mode = "RGBA"
            self.info["sizes"] = self.icns.itersizes()
            self.best_size = self.icns.bestsize()
            self.size = (
                self.best_size[0] * self.best_size[2],
                self.best_size[1] * self.best_size[2],
            )

        @property
        def size(self):
            return self._size

        @size.setter
        def size(self, value):
            info_size = value
            if info_size not in self.info["sizes"] and len(info_size) == 2:
                info_size = (info_size[0], info_size[1], 1)
            if (
                info_size not in self.info["sizes"]
                and len(info_size) == 3
                and info_size[2] == 1
            ):
                simple_sizes = [
                    (size[0] * size[2], size[1] * size[2]) for size in self.info["sizes"]
                ]
                if value in simple_sizes:
                    info_size = self.info["sizes"][simple_sizes.index(value)]
            if info_size not in self.info["sizes"]:
                raise ValueError("This is not one of the allowed sizes of this image")
            self._size = value

        def load(self):
            if len(self.size) == 3:
                self.best_size = self.size
                self.size = (
                    self.best_size[0] * self.best_size[2],
                    self.best_size[1] * self.best_size[2],
                )

            Image.Image.load(self)
            if self.im and self.im.size == self.size:
                # Already loaded
                return
            self.load_prepare()
            # This is likely NOT the best way to do it, but whatever.
            im = self.icns.getimage(self.best_size)

            # If this is a PNG or JPEG 2000, it won't be loaded yet
            im.load()

            self.im = im.im
            self.mode = im.mode
            self.size = im.size
            self.load_end()

    def _save(im, fp, filename):
        """
        Saves the image as a series of PNG files,
        that are then combined into a .icns file.
        """
        if hasattr(fp, "flush"):
            fp.flush()

        sizes = {
            b"ic07": 128,
            b"ic08": 256,
            b"ic09": 512,
            b"ic10": 1024,
            b"ic11": 32,
            b"ic12": 64,
            b"ic13": 256,
            b"ic14": 512,
        }
        provided_images = {im.width: im for im in im.encoderinfo.get("append_images", [])}
        size_streams = {}
        for size in set(sizes.values()):
            image = (
                provided_images[size]
                if size in provided_images
                else im.resize((size, size))
            )

            temp = io.BytesIO()
            image.save(temp, "png")
            size_streams[size] = temp.getvalue()

        entries = []
        for type, size in sizes.items():
            stream = size_streams[size]
            entries.append(
                {"type": type, "size": HEADERSIZE + len(stream), "stream": stream}
            )

        # Header
        fp.write(MAGIC)
        file_length = HEADERSIZE  # Header
        file_length += HEADERSIZE + 8 * len(entries)  # TOC
        file_length += sum(entry["size"] for entry in entries)
        fp.write(struct.pack(">i", file_length))

        # TOC
        fp.write(b"TOC ")
        fp.write(struct.pack(">i", HEADERSIZE + len(entries) * HEADERSIZE))
        for entry in entries:
            fp.write(entry["type"])
            fp.write(struct.pack(">i", entry["size"]))

        # Data
        for entry in entries:
            fp.write(entry["type"])
            fp.write(struct.pack(">i", entry["size"]))
            fp.write(entry["stream"])

        if hasattr(fp, "flush"):
            fp.flush()

    def _accept(prefix):
        return prefix[:4] == MAGIC

    Image.register_open(IcnsImageFile.format, IcnsImageFile, _accept)
    Image.register_extension(IcnsImageFile.format, ".icns")

    Image.register_save(IcnsImageFile.format, _save)
    Image.register_mime(IcnsImageFile.format, "image/icns")

    if __name__ == "__main__":
        if len(sys.argv) < 2:
            print("Syntax: python3 IcnsImagePlugin.py [file]")
            sys.exit()

        with open(sys.argv[1], "rb") as fp:
            imf = IcnsImageFile(fp)
            for size in imf.info["sizes"]:
                imf.size = size
                imf.save("out-%s-%s-%s.png" % size)
            with Image.open(sys.argv[1]) as im:
                im.save("out.png")
            if sys.platform == "windows":
                os.startfile("out.png")