up follow livre

venv/lib/python3.13/site-packages/PIL/MspImagePlugin.py

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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
+from __future__ import annotations
+
+import io
+import struct
+from typing import IO
+
+from . import Image, ImageFile
+from ._binary import i16le as i16
+from ._binary import o16le as o16
+
+#
+# read MSP files
+
+
+def _accept(prefix: bytes) -> bool:
+    return prefix.startswith((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) -> None:
+        # Header
+        assert self.fp is not None
+
+        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.startswith(b"DanM"):
+            self.tile = [ImageFile._Tile("raw", (0, 0) + self.size, 32, "1")]
+        else:
+            self.tile = [ImageFile._Tile("MSP", (0, 0) + self.size, 32)]
+
+
+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: bytes | Image.SupportsArrayInterface) -> tuple[int, int]:
+        assert self.fd is not None
+
+        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")
+
+        return -1, 0
+
+
+Image.register_decoder("MSP", MspDecoder)
+
+
+#
+# write MSP files (uncompressed only)
+
+
+def _save(im: Image.Image, fp: IO[bytes], filename: str | bytes) -> None:
+    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, [ImageFile._Tile("raw", (0, 0) + im.size, 32, "1")])
+
+
+#
+# registry
+
+Image.register_open(MspImageFile.format, MspImageFile, _accept)
+Image.register_save(MspImageFile.format, _save)
+
+Image.register_extension(MspImageFile.format, ".msp")