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#
# The Python Imaging Library.
#
# MSP file handling
#
# This is the format used by the Paint program in Windows 1 and 2.
#
# History:
# 95-09-05 fl Created
# 97-01-03 fl Read/write MSP images
# 17-02-21 es Fixed RLE interpretation
#
# Copyright (c) Secret Labs AB 1997.
# Copyright (c) Fredrik Lundh 1995-97.
# Copyright (c) Eric Soroos 2017.
#
# See the README file for information on usage and redistribution.
#
# More info on this format: https://archive.org/details/gg243631
# Page 313:
# Figure 205. Windows Paint Version 1: "DanM" Format
# Figure 206. Windows Paint Version 2: "LinS" Format. Used in Windows V2.03
#
# See also: https://www.fileformat.info/format/mspaint/egff.htm
import io
import struct
from . import Image, ImageFile
from ._binary import i16le as i16
from ._binary import o16le as o16
#
# read MSP files
def _accept(prefix):
return prefix[:4] in [b"DanM", b"LinS"]
##
# Image plugin for Windows MSP images. This plugin supports both
# uncompressed (Windows 1.0).
class MspImageFile(ImageFile.ImageFile):
format = "MSP"
format_description = "Windows Paint"
def _open(self):
# Header
s = self.fp.read(32)
if not _accept(s):
msg = "not an MSP file"
raise SyntaxError(msg)
# Header checksum
checksum = 0
for i in range(0, 32, 2):
checksum = checksum ^ i16(s, i)
if checksum != 0:
msg = "bad MSP checksum"
raise SyntaxError(msg)
self.mode = "1"
self._size = i16(s, 4), i16(s, 6)
if s[:4] == b"DanM":
self.tile = [("raw", (0, 0) + self.size, 32, ("1", 0, 1))]
else:
self.tile = [("MSP", (0, 0) + self.size, 32, None)]
class MspDecoder(ImageFile.PyDecoder):
# The algo for the MSP decoder is from
# https://www.fileformat.info/format/mspaint/egff.htm
# cc-by-attribution -- That page references is taken from the
# Encyclopedia of Graphics File Formats and is licensed by
# O'Reilly under the Creative Common/Attribution license
#
# For RLE encoded files, the 32byte header is followed by a scan
# line map, encoded as one 16bit word of encoded byte length per
# line.
#
# NOTE: the encoded length of the line can be 0. This was not
# handled in the previous version of this encoder, and there's no
# mention of how to handle it in the documentation. From the few
# examples I've seen, I've assumed that it is a fill of the
# background color, in this case, white.
#
#
# Pseudocode of the decoder:
# Read a BYTE value as the RunType
# If the RunType value is zero
# Read next byte as the RunCount
# Read the next byte as the RunValue
# Write the RunValue byte RunCount times
# If the RunType value is non-zero
# Use this value as the RunCount
# Read and write the next RunCount bytes literally
#
# e.g.:
# 0x00 03 ff 05 00 01 02 03 04
# would yield the bytes:
# 0xff ff ff 00 01 02 03 04
#
# which are then interpreted as a bit packed mode '1' image
_pulls_fd = True
def decode(self, buffer):
img = io.BytesIO()
blank_line = bytearray((0xFF,) * ((self.state.xsize + 7) // 8))
try:
self.fd.seek(32)
rowmap = struct.unpack_from(
f"<{self.state.ysize}H", self.fd.read(self.state.ysize * 2)
)
except struct.error as e:
msg = "Truncated MSP file in row map"
raise OSError(msg) from e
for x, rowlen in enumerate(rowmap):
try:
if rowlen == 0:
img.write(blank_line)
continue
row = self.fd.read(rowlen)
if len(row) != rowlen:
msg = f"Truncated MSP file, expected {rowlen} bytes on row {x}"
raise OSError(msg)
idx = 0
while idx < rowlen:
runtype = row[idx]
idx += 1
if runtype == 0:
(runcount, runval) = struct.unpack_from("Bc", row, idx)
img.write(runval * runcount)
idx += 2
else:
runcount = runtype
img.write(row[idx : idx + runcount])
idx += runcount
except struct.error as e:
msg = f"Corrupted MSP file in row {x}"
raise OSError(msg) from e
self.set_as_raw(img.getvalue(), ("1", 0, 1))
return -1, 0
Image.register_decoder("MSP", MspDecoder)
#
# write MSP files (uncompressed only)
def _save(im, fp, filename):
if im.mode != "1":
msg = f"cannot write mode {im.mode} as MSP"
raise OSError(msg)
# create MSP header
header = [0] * 16
header[0], header[1] = i16(b"Da"), i16(b"nM") # version 1
header[2], header[3] = im.size
header[4], header[5] = 1, 1
header[6], header[7] = 1, 1
header[8], header[9] = im.size
checksum = 0
for h in header:
checksum = checksum ^ h
header[12] = checksum # FIXME: is this the right field?
# header
for h in header:
fp.write(o16(h))
# image body
ImageFile._save(im, fp, [("raw", (0, 0) + im.size, 32, ("1", 0, 1))])
#
# registry
Image.register_open(MspImageFile.format, MspImageFile, _accept)
Image.register_save(MspImageFile.format, _save)
Image.register_extension(MspImageFile.format, ".msp")
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