text: #
  # The Python Imaging Library.
  # $Id$
  #
  # Windows Icon support for PIL
  #
  # History:
  #       96-05-27 fl     Created
  #
  # Copyright (c) Secret Labs AB 1997.
  # Copyright (c) Fredrik Lundh 1996.
  #
  # See the README file for information on usage and redistribution.
  #
  
  # This plugin is a refactored version of Win32IconImagePlugin by Bryan Davis
  # <casadebender@gmail.com>.
  # https://code.google.com/archive/p/casadebender/wikis/Win32IconImagePlugin.wiki
  #
  # Icon format references:
  #   * https://en.wikipedia.org/wiki/ICO_(file_format)
  #   * https://msdn.microsoft.com/en-us/library/ms997538.aspx
  
  
  import struct
  import warnings
  from io import BytesIO
  from math import ceil, log
  
  from . import BmpImagePlugin, Image, ImageFile, PngImagePlugin
  from ._binary import i16le as i16
  from ._binary import i32le as i32
  
  #
  # --------------------------------------------------------------------
  
  _MAGIC = b"\0\0\1\0"
  
  
  def _save(im, fp, filename):
      fp.write(_MAGIC)  # (2+2)
      sizes = im.encoderinfo.get(
          "sizes",
          [(16, 16), (24, 24), (32, 32), (48, 48), (64, 64), (128, 128), (256, 256)],
      )
      width, height = im.size
      sizes = filter(
          lambda x: False
          if (x[0] > width or x[1] > height or x[0] > 256 or x[1] > 256)
          else True,
          sizes,
      )
      sizes = list(sizes)
      fp.write(struct.pack("<H", len(sizes)))  # idCount(2)
      offset = fp.tell() + len(sizes) * 16
      provided_images = {im.size: im for im in im.encoderinfo.get("append_images", [])}
      for size in sizes:
          width, height = size
          # 0 means 256
          fp.write(struct.pack("B", width if width < 256 else 0))  # bWidth(1)
          fp.write(struct.pack("B", height if height < 256 else 0))  # bHeight(1)
          fp.write(b"\0")  # bColorCount(1)
          fp.write(b"\0")  # bReserved(1)
          fp.write(b"\0\0")  # wPlanes(2)
          fp.write(struct.pack("<H", 32))  # wBitCount(2)
  
          image_io = BytesIO()
          tmp = provided_images.get(size)
          if not tmp:
              # TODO: invent a more convenient method for proportional scalings
              tmp = im.copy()
              tmp.thumbnail(size, Image.LANCZOS, reducing_gap=None)
          tmp.save(image_io, "png")
          image_io.seek(0)
          image_bytes = image_io.read()
          bytes_len = len(image_bytes)
          fp.write(struct.pack("<I", bytes_len))  # dwBytesInRes(4)
          fp.write(struct.pack("<I", offset))  # dwImageOffset(4)
          current = fp.tell()
          fp.seek(offset)
          fp.write(image_bytes)
          offset = offset + bytes_len
          fp.seek(current)
  
  
  def _accept(prefix):
      return prefix[:4] == _MAGIC
  
  
  class IcoFile:
      def __init__(self, buf):
          """
          Parse image from file-like object containing ico file data
          """
  
          # check magic
          s = buf.read(6)
          if not _accept(s):
              raise SyntaxError("not an ICO file")
  
          self.buf = buf
          self.entry = []
  
          # Number of items in file
          self.nb_items = i16(s, 4)
  
          # Get headers for each item
          for i in range(self.nb_items):
              s = buf.read(16)
  
              icon_header = {
                  "width": s[0],
                  "height": s[1],
                  "nb_color": s[2],  # No. of colors in image (0 if >=8bpp)
                  "reserved": s[3],
                  "planes": i16(s, 4),
                  "bpp": i16(s, 6),
                  "size": i32(s, 8),
                  "offset": i32(s, 12),
              }
  
              # See Wikipedia
              for j in ("width", "height"):
                  if not icon_header[j]:
                      icon_header[j] = 256
  
              # See Wikipedia notes about color depth.
              # We need this just to differ images with equal sizes
              icon_header["color_depth"] = (
                  icon_header["bpp"]
                  or (
                      icon_header["nb_color"] != 0
                      and ceil(log(icon_header["nb_color"], 2))
                  )
                  or 256
              )
  
              icon_header["dim"] = (icon_header["width"], icon_header["height"])
              icon_header["square"] = icon_header["width"] * icon_header["height"]
  
              self.entry.append(icon_header)
  
          self.entry = sorted(self.entry, key=lambda x: x["color_depth"])
          # ICO images are usually squares
          # self.entry = sorted(self.entry, key=lambda x: x['width'])
          self.entry = sorted(self.entry, key=lambda x: x["square"])
          self.entry.reverse()
  
      def sizes(self):
          """
          Get a list of all available icon sizes and color depths.
          """
          return {(h["width"], h["height"]) for h in self.entry}
  
      def getentryindex(self, size, bpp=False):
          for (i, h) in enumerate(self.entry):
              if size == h["dim"] and (bpp is False or bpp == h["color_depth"]):
                  return i
          return 0
  
      def getimage(self, size, bpp=False):
          """
          Get an image from the icon
          """
          return self.frame(self.getentryindex(size, bpp))
  
      def frame(self, idx):
          """
          Get an image from frame idx
          """
  
          header = self.entry[idx]
  
          self.buf.seek(header["offset"])
          data = self.buf.read(8)
          self.buf.seek(header["offset"])
  
          if data[:8] == PngImagePlugin._MAGIC:
              # png frame
              im = PngImagePlugin.PngImageFile(self.buf)
              Image._decompression_bomb_check(im.size)
          else:
              # XOR + AND mask bmp frame
              im = BmpImagePlugin.DibImageFile(self.buf)
              Image._decompression_bomb_check(im.size)
  
              # change tile dimension to only encompass XOR image
              im._size = (im.size[0], int(im.size[1] / 2))
              d, e, o, a = im.tile[0]
              im.tile[0] = d, (0, 0) + im.size, o, a
  
              # figure out where AND mask image starts
              mode = a[0]
              bpp = 8
              for k, v in BmpImagePlugin.BIT2MODE.items():
                  if mode == v[1]:
                      bpp = k
                      break
  
              if 32 == bpp:
                  # 32-bit color depth icon image allows semitransparent areas
                  # PIL's DIB format ignores transparency bits, recover them.
                  # The DIB is packed in BGRX byte order where X is the alpha
                  # channel.
  
                  # Back up to start of bmp data
                  self.buf.seek(o)
                  # extract every 4th byte (eg. 3,7,11,15,...)
                  alpha_bytes = self.buf.read(im.size[0] * im.size[1] * 4)[3::4]
  
                  # convert to an 8bpp grayscale image
                  mask = Image.frombuffer(
                      "L",  # 8bpp
                      im.size,  # (w, h)
                      alpha_bytes,  # source chars
                      "raw",  # raw decoder
                      ("L", 0, -1),  # 8bpp inverted, unpadded, reversed
                  )
              else:
                  # get AND image from end of bitmap
                  w = im.size[0]
                  if (w % 32) > 0:
                      # bitmap row data is aligned to word boundaries
                      w += 32 - (im.size[0] % 32)
  
                  # the total mask data is
                  # padded row size * height / bits per char
  
                  and_mask_offset = o + int(im.size[0] * im.size[1] * (bpp / 8.0))
                  total_bytes = int((w * im.size[1]) / 8)
  
                  self.buf.seek(and_mask_offset)
                  mask_data = self.buf.read(total_bytes)
  
                  # convert raw data to image
                  mask = Image.frombuffer(
                      "1",  # 1 bpp
                      im.size,  # (w, h)
                      mask_data,  # source chars
                      "raw",  # raw decoder
                      ("1;I", int(w / 8), -1),  # 1bpp inverted, padded, reversed
                  )
  
                  # now we have two images, im is XOR image and mask is AND image
  
              # apply mask image as alpha channel
              im = im.convert("RGBA")
              im.putalpha(mask)
  
          return im
  
  
  ##
  # Image plugin for Windows Icon files.
  
  
  class IcoImageFile(ImageFile.ImageFile):
      """
      PIL read-only image support for Microsoft Windows .ico files.
  
      By default the largest resolution image in the file will be loaded. This
      can be changed by altering the 'size' attribute before calling 'load'.
  
      The info dictionary has a key 'sizes' that is a list of the sizes available
      in the icon file.
  
      Handles classic, XP and Vista icon formats.
  
      When saving, PNG compression is used. Support for this was only added in
      Windows Vista.
  
      This plugin is a refactored version of Win32IconImagePlugin by Bryan Davis
      <casadebender@gmail.com>.
      https://code.google.com/archive/p/casadebender/wikis/Win32IconImagePlugin.wiki
      """
  
      format = "ICO"
      format_description = "Windows Icon"
  
      def _open(self):
          self.ico = IcoFile(self.fp)
          self.info["sizes"] = self.ico.sizes()
          self.size = self.ico.entry[0]["dim"]
          self.load()
  
      @property
      def size(self):
          return self._size
  
      @size.setter
      def size(self, value):
          if value 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 self.im and self.im.size == self.size:
              # Already loaded
              return
          im = self.ico.getimage(self.size)
          # if tile is PNG, it won't really be loaded yet
          im.load()
          self.im = im.im
          self.mode = im.mode
          if im.size != self.size:
              warnings.warn("Image was not the expected size")
  
              index = self.ico.getentryindex(self.size)
              sizes = list(self.info["sizes"])
              sizes[index] = im.size
              self.info["sizes"] = set(sizes)
  
              self.size = im.size
  
      def load_seek(self):
          # Flag the ImageFile.Parser so that it
          # just does all the decode at the end.
          pass
  
  
  #
  # --------------------------------------------------------------------
  
  
  Image.register_open(IcoImageFile.format, IcoImageFile, _accept)
  Image.register_save(IcoImageFile.format, _save)
  Image.register_extension(IcoImageFile.format, ".ico")
  
  Image.register_mime(IcoImageFile.format, "image/x-icon")
  