Source code for PIL.MspImagePlugin

#
# 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).


[docs]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)]
[docs]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
[docs] 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")