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Pillow/PIL/BmpImagePlugin.py
Andrew Murray 37b293f593 Flake8 fixes
2017-04-20 21:14:23 +10:00

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#
# The Python Imaging Library.
# $Id$
#
# BMP file handler
#
# Windows (and OS/2) native bitmap storage format.
#
# history:
# 1995-09-01 fl Created
# 1996-04-30 fl Added save
# 1997-08-27 fl Fixed save of 1-bit images
# 1998-03-06 fl Load P images as L where possible
# 1998-07-03 fl Load P images as 1 where possible
# 1998-12-29 fl Handle small palettes
# 2002-12-30 fl Fixed load of 1-bit palette images
# 2003-04-21 fl Fixed load of 1-bit monochrome images
# 2003-04-23 fl Added limited support for BI_BITFIELDS compression
#
# Copyright (c) 1997-2003 by Secret Labs AB
# Copyright (c) 1995-2003 by Fredrik Lundh
#
# See the README file for information on usage and redistribution.
#
from . import Image, ImageFile, ImagePalette
from ._binary import i8, i16le as i16, i32le as i32, \
o8, o16le as o16, o32le as o32
import math
__version__ = "0.7"
#
# --------------------------------------------------------------------
# Read BMP file
BIT2MODE = {
# bits => mode, rawmode
1: ("P", "P;1"),
4: ("P", "P;4"),
8: ("P", "P"),
16: ("RGB", "BGR;15"),
24: ("RGB", "BGR"),
32: ("RGB", "BGRX"),
}
def _accept(prefix):
return prefix[:2] == b"BM"
# ==============================================================================
# Image plugin for the Windows BMP format.
# ==============================================================================
class BmpImageFile(ImageFile.ImageFile):
""" Image plugin for the Windows Bitmap format (BMP) """
# -------------------------------------------------------------- Description
format_description = "Windows Bitmap"
format = "BMP"
# --------------------------------------------------- BMP Compression values
COMPRESSIONS = {'RAW': 0, 'RLE8': 1, 'RLE4': 2, 'BITFIELDS': 3, 'JPEG': 4, 'PNG': 5}
RAW, RLE8, RLE4, BITFIELDS, JPEG, PNG = 0, 1, 2, 3, 4, 5
def _bitmap(self, header=0, offset=0):
""" Read relevant info about the BMP """
read, seek = self.fp.read, self.fp.seek
if header:
seek(header)
file_info = {}
file_info['header_size'] = i32(read(4)) # read bmp header size @offset 14 (this is part of the header size)
file_info['direction'] = -1
# --------------------- If requested, read header at a specific position
header_data = ImageFile._safe_read(self.fp, file_info['header_size'] - 4) # read the rest of the bmp header, without its size
# --------------------------------------------------- IBM OS/2 Bitmap v1
# ------ This format has different offsets because of width/height types
if file_info['header_size'] == 12:
file_info['width'] = i16(header_data[0:2])
file_info['height'] = i16(header_data[2:4])
file_info['planes'] = i16(header_data[4:6])
file_info['bits'] = i16(header_data[6:8])
file_info['compression'] = self.RAW
file_info['palette_padding'] = 3
# ---------------------------------------------- Windows Bitmap v2 to v5
elif file_info['header_size'] in (40, 64, 108, 124): # v3, OS/2 v2, v4, v5
if file_info['header_size'] >= 40: # v3 and OS/2
file_info['y_flip'] = i8(header_data[7]) == 0xff
file_info['direction'] = 1 if file_info['y_flip'] else -1
file_info['width'] = i32(header_data[0:4])
file_info['height'] = i32(header_data[4:8]) if not file_info['y_flip'] else 2**32 - i32(header_data[4:8])
file_info['planes'] = i16(header_data[8:10])
file_info['bits'] = i16(header_data[10:12])
file_info['compression'] = i32(header_data[12:16])
file_info['data_size'] = i32(header_data[16:20]) # byte size of pixel data
file_info['pixels_per_meter'] = (i32(header_data[20:24]), i32(header_data[24:28]))
file_info['colors'] = i32(header_data[28:32])
file_info['palette_padding'] = 4
self.info["dpi"] = tuple(
map(lambda x: int(math.ceil(x / 39.3701)),
file_info['pixels_per_meter']))
if file_info['compression'] == self.BITFIELDS:
if len(header_data) >= 52:
for idx, mask in enumerate(['r_mask', 'g_mask', 'b_mask', 'a_mask']):
file_info[mask] = i32(header_data[36+idx*4:40+idx*4])
else:
# 40 byte headers only have the three components in the bitfields masks,
# ref: https://msdn.microsoft.com/en-us/library/windows/desktop/dd183376(v=vs.85).aspx
# See also https://github.com/python-pillow/Pillow/issues/1293
# There is a 4th component in the RGBQuad, in the alpha location, but it
# is listed as a reserved component, and it is not generally an alpha channel
file_info['a_mask'] = 0x0
for mask in ['r_mask', 'g_mask', 'b_mask']:
file_info[mask] = i32(read(4))
file_info['rgb_mask'] = (file_info['r_mask'], file_info['g_mask'], file_info['b_mask'])
file_info['rgba_mask'] = (file_info['r_mask'], file_info['g_mask'], file_info['b_mask'], file_info['a_mask'])
else:
raise IOError("Unsupported BMP header type (%d)" % file_info['header_size'])
# ------------------ Special case : header is reported 40, which
# ---------------------- is shorter than real size for bpp >= 16
self.size = file_info['width'], file_info['height']
# -------- If color count was not found in the header, compute from bits
file_info['colors'] = file_info['colors'] if file_info.get('colors', 0) else (1 << file_info['bits'])
# -------------------------------- Check abnormal values for DOS attacks
if file_info['width'] * file_info['height'] > 2**31:
raise IOError("Unsupported BMP Size: (%dx%d)" % self.size)
# ----------------------- Check bit depth for unusual unsupported values
self.mode, raw_mode = BIT2MODE.get(file_info['bits'], (None, None))
if self.mode is None:
raise IOError("Unsupported BMP pixel depth (%d)" % file_info['bits'])
# ----------------- Process BMP with Bitfields compression (not palette)
if file_info['compression'] == self.BITFIELDS:
SUPPORTED = {
32: [(0xff0000, 0xff00, 0xff, 0x0), (0xff0000, 0xff00, 0xff, 0xff000000), (0x0, 0x0, 0x0, 0x0), (0xff000000, 0xff0000, 0xff00, 0x0)],
24: [(0xff0000, 0xff00, 0xff)],
16: [(0xf800, 0x7e0, 0x1f), (0x7c00, 0x3e0, 0x1f)]
}
MASK_MODES = {
(32, (0xff0000, 0xff00, 0xff, 0x0)): "BGRX",
(32, (0xff000000, 0xff0000, 0xff00, 0x0)): "XBGR",
(32, (0xff0000, 0xff00, 0xff, 0xff000000)): "BGRA",
(32, (0x0, 0x0, 0x0, 0x0)): "BGRA",
(24, (0xff0000, 0xff00, 0xff)): "BGR",
(16, (0xf800, 0x7e0, 0x1f)): "BGR;16",
(16, (0x7c00, 0x3e0, 0x1f)): "BGR;15"
}
if file_info['bits'] in SUPPORTED:
if file_info['bits'] == 32 and file_info['rgba_mask'] in SUPPORTED[file_info['bits']]:
raw_mode = MASK_MODES[(file_info['bits'], file_info['rgba_mask'])]
self.mode = "RGBA" if raw_mode in ("BGRA",) else self.mode
elif file_info['bits'] in (24, 16) and file_info['rgb_mask'] in SUPPORTED[file_info['bits']]:
raw_mode = MASK_MODES[(file_info['bits'], file_info['rgb_mask'])]
else:
raise IOError("Unsupported BMP bitfields layout")
else:
raise IOError("Unsupported BMP bitfields layout")
elif file_info['compression'] == self.RAW:
if file_info['bits'] == 32 and header == 22: # 32-bit .cur offset
raw_mode, self.mode = "BGRA", "RGBA"
else:
raise IOError("Unsupported BMP compression (%d)" % file_info['compression'])
# ---------------- Once the header is processed, process the palette/LUT
if self.mode == "P": # Paletted for 1, 4 and 8 bit images
# ----------------------------------------------------- 1-bit images
if not (0 < file_info['colors'] <= 65536):
raise IOError("Unsupported BMP Palette size (%d)" % file_info['colors'])
else:
padding = file_info['palette_padding']
palette = read(padding * file_info['colors'])
greyscale = True
indices = (0, 255) if file_info['colors'] == 2 else list(range(file_info['colors']))
# ------------------ Check if greyscale and ignore palette if so
for ind, val in enumerate(indices):
rgb = palette[ind*padding:ind*padding + 3]
if rgb != o8(val) * 3:
greyscale = False
# -------- If all colors are grey, white or black, ditch palette
if greyscale:
self.mode = "1" if file_info['colors'] == 2 else "L"
raw_mode = self.mode
else:
self.mode = "P"
self.palette = ImagePalette.raw("BGRX" if padding == 4 else "BGR", palette)
# ----------------------------- Finally set the tile data for the plugin
self.info['compression'] = file_info['compression']
self.tile = [('raw', (0, 0, file_info['width'], file_info['height']), offset or self.fp.tell(),
(raw_mode, ((file_info['width'] * file_info['bits'] + 31) >> 3) & (~3), file_info['direction'])
)]
def _open(self):
""" Open file, check magic number and read header """
# read 14 bytes: magic number, filesize, reserved, header final offset
head_data = self.fp.read(14)
# choke if the file does not have the required magic bytes
if head_data[0:2] != b"BM":
raise SyntaxError("Not a BMP file")
# read the start position of the BMP image data (u32)
offset = i32(head_data[10:14])
# load bitmap information (offset=raster info)
self._bitmap(offset=offset)
# ==============================================================================
# Image plugin for the DIB format (BMP alias)
# ==============================================================================
class DibImageFile(BmpImageFile):
format = "DIB"
format_description = "Windows Bitmap"
def _open(self):
self._bitmap()
#
# --------------------------------------------------------------------
# Write BMP file
SAVE = {
"1": ("1", 1, 2),
"L": ("L", 8, 256),
"P": ("P", 8, 256),
"RGB": ("BGR", 24, 0),
"RGBA": ("BGRA", 32, 0),
}
def _save(im, fp, filename, check=0):
try:
rawmode, bits, colors = SAVE[im.mode]
except KeyError:
raise IOError("cannot write mode %s as BMP" % im.mode)
if check:
return check
info = im.encoderinfo
dpi = info.get("dpi", (96, 96))
# 1 meter == 39.3701 inches
ppm = tuple(map(lambda x: int(x * 39.3701), dpi))
stride = ((im.size[0]*bits+7)//8+3) & (~3)
header = 40 # or 64 for OS/2 version 2
offset = 14 + header + colors * 4
image = stride * im.size[1]
# bitmap header
fp.write(b"BM" + # file type (magic)
o32(offset+image) + # file size
o32(0) + # reserved
o32(offset)) # image data offset
# bitmap info header
fp.write(o32(header) + # info header size
o32(im.size[0]) + # width
o32(im.size[1]) + # height
o16(1) + # planes
o16(bits) + # depth
o32(0) + # compression (0=uncompressed)
o32(image) + # size of bitmap
o32(ppm[0]) + o32(ppm[1]) + # resolution
o32(colors) + # colors used
o32(colors)) # colors important
fp.write(b"\0" * (header - 40)) # padding (for OS/2 format)
if im.mode == "1":
for i in (0, 255):
fp.write(o8(i) * 4)
elif im.mode == "L":
for i in range(256):
fp.write(o8(i) * 4)
elif im.mode == "P":
fp.write(im.im.getpalette("RGB", "BGRX"))
ImageFile._save(im, fp, [("raw", (0, 0)+im.size, 0,
(rawmode, stride, -1))])
#
# --------------------------------------------------------------------
# Registry
Image.register_open(BmpImageFile.format, BmpImageFile, _accept)
Image.register_save(BmpImageFile.format, _save)
Image.register_extension(BmpImageFile.format, ".bmp")
Image.register_mime(BmpImageFile.format, "image/bmp")
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