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convertions-env/lib/python3.11/site-packages/PIL/PpmImagePlugin.py

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+#
+# The Python Imaging Library.
+# $Id$
+#
+# PPM support for PIL
+#
+# History:
+#       96-03-24 fl     Created
+#       98-03-06 fl     Write RGBA images (as RGB, that is)
+#
+# Copyright (c) Secret Labs AB 1997-98.
+# Copyright (c) Fredrik Lundh 1996.
+#
+# See the README file for information on usage and redistribution.
+#
+from __future__ import annotations
+
+import math
+from typing import IO
+
+from . import Image, ImageFile
+from ._binary import i16be as i16
+from ._binary import o8
+from ._binary import o32le as o32
+
+#
+# --------------------------------------------------------------------
+
+b_whitespace = b"\x20\x09\x0a\x0b\x0c\x0d"
+
+MODES = {
+    # standard
+    b"P1": "1",
+    b"P2": "L",
+    b"P3": "RGB",
+    b"P4": "1",
+    b"P5": "L",
+    b"P6": "RGB",
+    # extensions
+    b"P0CMYK": "CMYK",
+    b"Pf": "F",
+    # PIL extensions (for test purposes only)
+    b"PyP": "P",
+    b"PyRGBA": "RGBA",
+    b"PyCMYK": "CMYK",
+}
+
+
+def _accept(prefix: bytes) -> bool:
+    return prefix[0:1] == b"P" and prefix[1] in b"0123456fy"
+
+
+##
+# Image plugin for PBM, PGM, and PPM images.
+
+
+class PpmImageFile(ImageFile.ImageFile):
+    format = "PPM"
+    format_description = "Pbmplus image"
+
+    def _read_magic(self) -> bytes:
+        assert self.fp is not None
+
+        magic = b""
+        # read until whitespace or longest available magic number
+        for _ in range(6):
+            c = self.fp.read(1)
+            if not c or c in b_whitespace:
+                break
+            magic += c
+        return magic
+
+    def _read_token(self) -> bytes:
+        assert self.fp is not None
+
+        token = b""
+        while len(token) <= 10:  # read until next whitespace or limit of 10 characters
+            c = self.fp.read(1)
+            if not c:
+                break
+            elif c in b_whitespace:  # token ended
+                if not token:
+                    # skip whitespace at start
+                    continue
+                break
+            elif c == b"#":
+                # ignores rest of the line; stops at CR, LF or EOF
+                while self.fp.read(1) not in b"\r\n":
+                    pass
+                continue
+            token += c
+        if not token:
+            # Token was not even 1 byte
+            msg = "Reached EOF while reading header"
+            raise ValueError(msg)
+        elif len(token) > 10:
+            msg = f"Token too long in file header: {token.decode()}"
+            raise ValueError(msg)
+        return token
+
+    def _open(self) -> None:
+        assert self.fp is not None
+
+        magic_number = self._read_magic()
+        try:
+            mode = MODES[magic_number]
+        except KeyError:
+            msg = "not a PPM file"
+            raise SyntaxError(msg)
+        self._mode = mode
+
+        if magic_number in (b"P1", b"P4"):
+            self.custom_mimetype = "image/x-portable-bitmap"
+        elif magic_number in (b"P2", b"P5"):
+            self.custom_mimetype = "image/x-portable-graymap"
+        elif magic_number in (b"P3", b"P6"):
+            self.custom_mimetype = "image/x-portable-pixmap"
+
+        self._size = int(self._read_token()), int(self._read_token())
+
+        decoder_name = "raw"
+        if magic_number in (b"P1", b"P2", b"P3"):
+            decoder_name = "ppm_plain"
+
+        args: str | tuple[str | int, ...]
+        if mode == "1":
+            args = "1;I"
+        elif mode == "F":
+            scale = float(self._read_token())
+            if scale == 0.0 or not math.isfinite(scale):
+                msg = "scale must be finite and non-zero"
+                raise ValueError(msg)
+            self.info["scale"] = abs(scale)
+
+            rawmode = "F;32F" if scale < 0 else "F;32BF"
+            args = (rawmode, 0, -1)
+        else:
+            maxval = int(self._read_token())
+            if not 0 < maxval < 65536:
+                msg = "maxval must be greater than 0 and less than 65536"
+                raise ValueError(msg)
+            if maxval > 255 and mode == "L":
+                self._mode = "I"
+
+            rawmode = mode
+            if decoder_name != "ppm_plain":
+                # If maxval matches a bit depth, use the raw decoder directly
+                if maxval == 65535 and mode == "L":
+                    rawmode = "I;16B"
+                elif maxval != 255:
+                    decoder_name = "ppm"
+
+            args = rawmode if decoder_name == "raw" else (rawmode, maxval)
+        self.tile = [(decoder_name, (0, 0) + self.size, self.fp.tell(), args)]
+
+
+#
+# --------------------------------------------------------------------
+
+
+class PpmPlainDecoder(ImageFile.PyDecoder):
+    _pulls_fd = True
+    _comment_spans: bool
+
+    def _read_block(self) -> bytes:
+        assert self.fd is not None
+
+        return self.fd.read(ImageFile.SAFEBLOCK)
+
+    def _find_comment_end(self, block: bytes, start: int = 0) -> int:
+        a = block.find(b"\n", start)
+        b = block.find(b"\r", start)
+        return min(a, b) if a * b > 0 else max(a, b)  # lowest nonnegative index (or -1)
+
+    def _ignore_comments(self, block: bytes) -> bytes:
+        if self._comment_spans:
+            # Finish current comment
+            while block:
+                comment_end = self._find_comment_end(block)
+                if comment_end != -1:
+                    # Comment ends in this block
+                    # Delete tail of comment
+                    block = block[comment_end + 1 :]
+                    break
+                else:
+                    # Comment spans whole block
+                    # So read the next block, looking for the end
+                    block = self._read_block()
+
+        # Search for any further comments
+        self._comment_spans = False
+        while True:
+            comment_start = block.find(b"#")
+            if comment_start == -1:
+                # No comment found
+                break
+            comment_end = self._find_comment_end(block, comment_start)
+            if comment_end != -1:
+                # Comment ends in this block
+                # Delete comment
+                block = block[:comment_start] + block[comment_end + 1 :]
+            else:
+                # Comment continues to next block(s)
+                block = block[:comment_start]
+                self._comment_spans = True
+                break
+        return block
+
+    def _decode_bitonal(self) -> bytearray:
+        """
+        This is a separate method because in the plain PBM format, all data tokens are
+        exactly one byte, so the inter-token whitespace is optional.
+        """
+        data = bytearray()
+        total_bytes = self.state.xsize * self.state.ysize
+
+        while len(data) != total_bytes:
+            block = self._read_block()  # read next block
+            if not block:
+                # eof
+                break
+
+            block = self._ignore_comments(block)
+
+            tokens = b"".join(block.split())
+            for token in tokens:
+                if token not in (48, 49):
+                    msg = b"Invalid token for this mode: %s" % bytes([token])
+                    raise ValueError(msg)
+            data = (data + tokens)[:total_bytes]
+        invert = bytes.maketrans(b"01", b"\xFF\x00")
+        return data.translate(invert)
+
+    def _decode_blocks(self, maxval: int) -> bytearray:
+        data = bytearray()
+        max_len = 10
+        out_byte_count = 4 if self.mode == "I" else 1
+        out_max = 65535 if self.mode == "I" else 255
+        bands = Image.getmodebands(self.mode)
+        total_bytes = self.state.xsize * self.state.ysize * bands * out_byte_count
+
+        half_token = b""
+        while len(data) != total_bytes:
+            block = self._read_block()  # read next block
+            if not block:
+                if half_token:
+                    block = bytearray(b" ")  # flush half_token
+                else:
+                    # eof
+                    break
+
+            block = self._ignore_comments(block)
+
+            if half_token:
+                block = half_token + block  # stitch half_token to new block
+                half_token = b""
+
+            tokens = block.split()
+
+            if block and not block[-1:].isspace():  # block might split token
+                half_token = tokens.pop()  # save half token for later
+                if len(half_token) > max_len:  # prevent buildup of half_token
+                    msg = (
+                        b"Token too long found in data: %s" % half_token[: max_len + 1]
+                    )
+                    raise ValueError(msg)
+
+            for token in tokens:
+                if len(token) > max_len:
+                    msg = b"Token too long found in data: %s" % token[: max_len + 1]
+                    raise ValueError(msg)
+                value = int(token)
+                if value < 0:
+                    msg_str = f"Channel value is negative: {value}"
+                    raise ValueError(msg_str)
+                if value > maxval:
+                    msg_str = f"Channel value too large for this mode: {value}"
+                    raise ValueError(msg_str)
+                value = round(value / maxval * out_max)
+                data += o32(value) if self.mode == "I" else o8(value)
+                if len(data) == total_bytes:  # finished!
+                    break
+        return data
+
+    def decode(self, buffer: bytes) -> tuple[int, int]:
+        self._comment_spans = False
+        if self.mode == "1":
+            data = self._decode_bitonal()
+            rawmode = "1;8"
+        else:
+            maxval = self.args[-1]
+            data = self._decode_blocks(maxval)
+            rawmode = "I;32" if self.mode == "I" else self.mode
+        self.set_as_raw(bytes(data), rawmode)
+        return -1, 0
+
+
+class PpmDecoder(ImageFile.PyDecoder):
+    _pulls_fd = True
+
+    def decode(self, buffer: bytes) -> tuple[int, int]:
+        assert self.fd is not None
+
+        data = bytearray()
+        maxval = self.args[-1]
+        in_byte_count = 1 if maxval < 256 else 2
+        out_byte_count = 4 if self.mode == "I" else 1
+        out_max = 65535 if self.mode == "I" else 255
+        bands = Image.getmodebands(self.mode)
+        dest_length = self.state.xsize * self.state.ysize * bands * out_byte_count
+        while len(data) < dest_length:
+            pixels = self.fd.read(in_byte_count * bands)
+            if len(pixels) < in_byte_count * bands:
+                # eof
+                break
+            for b in range(bands):
+                value = (
+                    pixels[b] if in_byte_count == 1 else i16(pixels, b * in_byte_count)
+                )
+                value = min(out_max, round(value / maxval * out_max))
+                data += o32(value) if self.mode == "I" else o8(value)
+        rawmode = "I;32" if self.mode == "I" else self.mode
+        self.set_as_raw(bytes(data), rawmode)
+        return -1, 0
+
+
+#
+# --------------------------------------------------------------------
+
+
+def _save(im: Image.Image, fp: IO[bytes], filename: str) -> None:
+    if im.mode == "1":
+        rawmode, head = "1;I", b"P4"
+    elif im.mode == "L":
+        rawmode, head = "L", b"P5"
+    elif im.mode == "I":
+        rawmode, head = "I;16B", b"P5"
+    elif im.mode in ("RGB", "RGBA"):
+        rawmode, head = "RGB", b"P6"
+    elif im.mode == "F":
+        rawmode, head = "F;32F", b"Pf"
+    else:
+        msg = f"cannot write mode {im.mode} as PPM"
+        raise OSError(msg)
+    fp.write(head + b"\n%d %d\n" % im.size)
+    if head == b"P6":
+        fp.write(b"255\n")
+    elif head == b"P5":
+        if rawmode == "L":
+            fp.write(b"255\n")
+        else:
+            fp.write(b"65535\n")
+    elif head == b"Pf":
+        fp.write(b"-1.0\n")
+    row_order = -1 if im.mode == "F" else 1
+    ImageFile._save(im, fp, [("raw", (0, 0) + im.size, 0, (rawmode, 0, row_order))])
+
+
+#
+# --------------------------------------------------------------------
+
+
+Image.register_open(PpmImageFile.format, PpmImageFile, _accept)
+Image.register_save(PpmImageFile.format, _save)
+
+Image.register_decoder("ppm", PpmDecoder)
+Image.register_decoder("ppm_plain", PpmPlainDecoder)
+
+Image.register_extensions(PpmImageFile.format, [".pbm", ".pgm", ".ppm", ".pnm", ".pfm"])
+
+Image.register_mime(PpmImageFile.format, "image/x-portable-anymap")