codekingpro/portable-devtools

1#
2# The Python Imaging Library.
3#
4# MSP file handling
5#
6# This is the format used by the Paint program in Windows 1 and 2.
7#
8# History:
9#       95-09-05 fl     Created
10#       97-01-03 fl     Read/write MSP images
11#       17-02-21 es     Fixed RLE interpretation
12#
13# Copyright (c) Secret Labs AB 1997.
14# Copyright (c) Fredrik Lundh 1995-97.
15# Copyright (c) Eric Soroos 2017.
16#
17# See the README file for information on usage and redistribution.
18#
19# More info on this format: https://archive.org/details/gg243631
20# Page 313:
21# Figure 205. Windows Paint Version 1: "DanM" Format
22# Figure 206. Windows Paint Version 2: "LinS" Format. Used in Windows V2.03
23#
24# See also: https://www.fileformat.info/format/mspaint/egff.htm
25from __future__ import annotations
26
27import io
28import struct
29from typing import IO
30
31from . import Image, ImageFile
32from ._binary import i16le as i16
33from ._binary import o16le as o16
34
35#
36# read MSP files
37
38
39def _accept(prefix: bytes) -> bool:
40    return prefix.startswith((b"DanM", b"LinS"))
41
42
43##
44# Image plugin for Windows MSP images.  This plugin supports both
45# uncompressed (Windows 1.0).
46
47
48class MspImageFile(ImageFile.ImageFile):
49    format = "MSP"
50    format_description = "Windows Paint"
51
52    def _open(self) -> None:
53        # Header
54        assert self.fp is not None
55
56        s = self.fp.read(32)
57        if not _accept(s):
58            msg = "not an MSP file"
59            raise SyntaxError(msg)
60
61        # Header checksum
62        checksum = 0
63        for i in range(0, 32, 2):
64            checksum = checksum ^ i16(s, i)
65        if checksum != 0:
66            msg = "bad MSP checksum"
67            raise SyntaxError(msg)
68
69        self._mode = "1"
70        self._size = i16(s, 4), i16(s, 6)
71
72        if s.startswith(b"DanM"):
73            self.tile = [ImageFile._Tile("raw", (0, 0) + self.size, 32, "1")]
74        else:
75            self.tile = [ImageFile._Tile("MSP", (0, 0) + self.size, 32)]
76
77
78class MspDecoder(ImageFile.PyDecoder):
79    # The algo for the MSP decoder is from
80    # https://www.fileformat.info/format/mspaint/egff.htm
81    # cc-by-attribution -- That page references is taken from the
82    # Encyclopedia of Graphics File Formats and is licensed by
83    # O'Reilly under the Creative Common/Attribution license
84    #
85    # For RLE encoded files, the 32byte header is followed by a scan
86    # line map, encoded as one 16bit word of encoded byte length per
87    # line.
88    #
89    # NOTE: the encoded length of the line can be 0. This was not
90    # handled in the previous version of this encoder, and there's no
91    # mention of how to handle it in the documentation. From the few
92    # examples I've seen, I've assumed that it is a fill of the
93    # background color, in this case, white.
94    #
95    #
96    # Pseudocode of the decoder:
97    # Read a BYTE value as the RunType
98    #  If the RunType value is zero
99    #   Read next byte as the RunCount
100    #   Read the next byte as the RunValue
101    #   Write the RunValue byte RunCount times
102    #  If the RunType value is non-zero
103    #   Use this value as the RunCount
104    #   Read and write the next RunCount bytes literally
105    #
106    #  e.g.:
107    #  0x00 03 ff 05 00 01 02 03 04
108    #  would yield the bytes:
109    #  0xff ff ff 00 01 02 03 04
110    #
111    # which are then interpreted as a bit packed mode '1' image
112
113    _pulls_fd = True
114
115    def decode(self, buffer: bytes | Image.SupportsArrayInterface) -> tuple[int, int]:
116        assert self.fd is not None
117
118        img = io.BytesIO()
119        blank_line = bytearray((0xFF,) * ((self.state.xsize + 7) // 8))
120        try:
121            self.fd.seek(32)
122            rowmap = struct.unpack_from(
123                f"<{self.state.ysize}H", self.fd.read(self.state.ysize * 2)
124            )
125        except struct.error as e:
126            msg = "Truncated MSP file in row map"
127            raise OSError(msg) from e
128
129        for x, rowlen in enumerate(rowmap):
130            try:
131                if rowlen == 0:
132                    img.write(blank_line)
133                    continue
134                row = self.fd.read(rowlen)
135                if len(row) != rowlen:
136                    msg = f"Truncated MSP file, expected {rowlen} bytes on row {x}"
137                    raise OSError(msg)
138                idx = 0
139                while idx < rowlen:
140                    runtype = row[idx]
141                    idx += 1
142                    if runtype == 0:
143                        runcount, runval = struct.unpack_from("Bc", row, idx)
144                        img.write(runval * runcount)
145                        idx += 2
146                    else:
147                        runcount = runtype
148                        img.write(row[idx : idx + runcount])
149                        idx += runcount
150
151            except struct.error as e:
152                msg = f"Corrupted MSP file in row {x}"
153                raise OSError(msg) from e
154
155        self.set_as_raw(img.getvalue(), "1")
156
157        return -1, 0
158
159
160Image.register_decoder("MSP", MspDecoder)
161
162
163#
164# write MSP files (uncompressed only)
165
166
167def _save(im: Image.Image, fp: IO[bytes], filename: str | bytes) -> None:
168    if im.mode != "1":
169        msg = f"cannot write mode {im.mode} as MSP"
170        raise OSError(msg)
171
172    # create MSP header
173    header = [0] * 16
174
175    header[0], header[1] = i16(b"Da"), i16(b"nM")  # version 1
176    header[2], header[3] = im.size
177    header[4], header[5] = 1, 1
178    header[6], header[7] = 1, 1
179    header[8], header[9] = im.size
180
181    checksum = 0
182    for h in header:
183        checksum = checksum ^ h
184    header[12] = checksum  # FIXME: is this the right field?
185
186    # header
187    for h in header:
188        fp.write(o16(h))
189
190    # image body
191    ImageFile._save(im, fp, [ImageFile._Tile("raw", (0, 0) + im.size, 32, "1")])
192
193
194#
195# registry
196
197Image.register_open(MspImageFile.format, MspImageFile, _accept)
198Image.register_save(MspImageFile.format, _save)
199
200Image.register_extension(MspImageFile.format, ".msp")
201