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Pillow/src/PIL/IcoImagePlugin.py
Andrew Murray 1e365d8c72 Return PixelAccess on first load
2025-04-23 21:10:54 +10:00

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#
# 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
from __future__ import annotations
import warnings
from io import BytesIO
from math import ceil, log
from typing import IO, NamedTuple
from . import BmpImagePlugin, Image, ImageFile, PngImagePlugin
from ._binary import i16le as i16
from ._binary import i32le as i32
from ._binary import o8
from ._binary import o16le as o16
from ._binary import o32le as o32
#
# --------------------------------------------------------------------
_MAGIC = b"\0\0\1\0"
def _save(im: Image.Image, fp: IO[bytes], filename: str | bytes) -> None:
fp.write(_MAGIC) # (2+2)
bmp = im.encoderinfo.get("bitmap_format") == "bmp"
sizes = im.encoderinfo.get(
"sizes",
[(16, 16), (24, 24), (32, 32), (48, 48), (64, 64), (128, 128), (256, 256)],
)
frames = []
provided_ims = [im] + im.encoderinfo.get("append_images", [])
width, height = im.size
for size in sorted(set(sizes)):
if size[0] > width or size[1] > height or size[0] > 256 or size[1] > 256:
continue
for provided_im in provided_ims:
if provided_im.size != size:
continue
frames.append(provided_im)
if bmp:
bits = BmpImagePlugin.SAVE[provided_im.mode][1]
bits_used = [bits]
for other_im in provided_ims:
if other_im.size != size:
continue
bits = BmpImagePlugin.SAVE[other_im.mode][1]
if bits not in bits_used:
# Another image has been supplied for this size
# with a different bit depth
frames.append(other_im)
bits_used.append(bits)
break
else:
# TODO: invent a more convenient method for proportional scalings
frame = provided_im.copy()
frame.thumbnail(size, Image.Resampling.LANCZOS, reducing_gap=None)
frames.append(frame)
fp.write(o16(len(frames))) # idCount(2)
offset = fp.tell() + len(frames) * 16
for frame in frames:
width, height = frame.size
# 0 means 256
fp.write(o8(width if width < 256 else 0)) # bWidth(1)
fp.write(o8(height if height < 256 else 0)) # bHeight(1)
bits, colors = BmpImagePlugin.SAVE[frame.mode][1:] if bmp else (32, 0)
fp.write(o8(colors)) # bColorCount(1)
fp.write(b"\0") # bReserved(1)
fp.write(b"\0\0") # wPlanes(2)
fp.write(o16(bits)) # wBitCount(2)
image_io = BytesIO()
if bmp:
frame.save(image_io, "dib")
if bits != 32:
and_mask = Image.new("1", size)
ImageFile._save(
and_mask,
image_io,
[ImageFile._Tile("raw", (0, 0) + size, 0, ("1", 0, -1))],
)
else:
frame.save(image_io, "png")
image_io.seek(0)
image_bytes = image_io.read()
if bmp:
image_bytes = image_bytes[:8] + o32(height * 2) + image_bytes[12:]
bytes_len = len(image_bytes)
fp.write(o32(bytes_len)) # dwBytesInRes(4)
fp.write(o32(offset)) # dwImageOffset(4)
current = fp.tell()
fp.seek(offset)
fp.write(image_bytes)
offset = offset + bytes_len
fp.seek(current)
def _accept(prefix: bytes) -> bool:
return prefix.startswith(_MAGIC)
class IconHeader(NamedTuple):
width: int
height: int
nb_color: int
reserved: int
planes: int
bpp: int
size: int
offset: int
dim: tuple[int, int]
square: int
color_depth: int
class IcoFile:
def __init__(self, buf: IO[bytes]) -> None:
"""
Parse image from file-like object containing ico file data
"""
# check magic
s = buf.read(6)
if not _accept(s):
msg = "not an ICO file"
raise SyntaxError(msg)
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)
# See Wikipedia
width = s[0] or 256
height = s[1] or 256
# No. of colors in image (0 if >=8bpp)
nb_color = s[2]
bpp = i16(s, 6)
icon_header = IconHeader(
width=width,
height=height,
nb_color=nb_color,
reserved=s[3],
planes=i16(s, 4),
bpp=i16(s, 6),
size=i32(s, 8),
offset=i32(s, 12),
dim=(width, height),
square=width * height,
# See Wikipedia notes about color depth.
# We need this just to differ images with equal sizes
color_depth=bpp or (nb_color != 0 and ceil(log(nb_color, 2))) or 256,
)
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.square, reverse=True)
def sizes(self) -> set[tuple[int, int]]:
"""
Get a set of all available icon sizes and color depths.
"""
return {(h.width, h.height) for h in self.entry}
def getentryindex(self, size: tuple[int, int], bpp: int | bool = False) -> int:
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: tuple[int, int], bpp: int | bool = False) -> Image.Image:
"""
Get an image from the icon
"""
return self.frame(self.getentryindex(size, bpp))
def frame(self, idx: int) -> Image.Image:
"""
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)
im: Image.Image
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] = ImageFile._Tile(d, (0, 0) + im.size, o, a)
# figure out where AND mask image starts
if header.bpp == 32:
# 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
try:
mask = Image.frombuffer(
"L", # 8bpp
im.size, # (w, h)
alpha_bytes, # source chars
"raw", # raw decoder
("L", 0, -1), # 8bpp inverted, unpadded, reversed
)
except ValueError:
if ImageFile.LOAD_TRUNCATED_IMAGES:
mask = None
else:
raise
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
total_bytes = int((w * im.size[1]) / 8)
and_mask_offset = header.offset + header.size - total_bytes
self.buf.seek(and_mask_offset)
mask_data = self.buf.read(total_bytes)
# convert raw data to image
try:
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
)
except ValueError:
if ImageFile.LOAD_TRUNCATED_IMAGES:
mask = None
else:
raise
# now we have two images, im is XOR image and mask is AND image
# apply mask image as alpha channel
if mask:
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. If you are unable to view the icon in Windows, convert the
image to "RGBA" mode before saving.
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) -> None:
self.ico = IcoFile(self.fp)
self.info["sizes"] = self.ico.sizes()
self.size = self.ico.entry[0].dim
self.load()
@property
def size(self) -> tuple[int, int]:
return self._size
@size.setter
def size(self, value: tuple[int, int]) -> None:
if value not in self.info["sizes"]:
msg = "This is not one of the allowed sizes of this image"
raise ValueError(msg)
self._size = value
def load(self) -> Image.core.PixelAccess | None:
if self._im is not None and self.im.size == self.size:
# Already loaded
return Image.Image.load(self)
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.palette:
self.palette = im.palette
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
return Image.Image.load(self)
def load_seek(self, pos: int) -> None:
# 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")
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