264 lines
7.7 KiB
Python
264 lines
7.7 KiB
Python
#
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# The Python Imaging Library.
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# $Id$
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#
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# image palette object
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#
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# History:
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# 1996-03-11 fl Rewritten.
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# 1997-01-03 fl Up and running.
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# 1997-08-23 fl Added load hack
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# 2001-04-16 fl Fixed randint shadow bug in random()
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#
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# Copyright (c) 1997-2001 by Secret Labs AB
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# Copyright (c) 1996-1997 by Fredrik Lundh
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#
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# See the README file for information on usage and redistribution.
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#
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from __future__ import annotations
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import array
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from typing import Sequence
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from . import GimpGradientFile, GimpPaletteFile, ImageColor, PaletteFile
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class ImagePalette:
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"""
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Color palette for palette mapped images
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:param mode: The mode to use for the palette. See:
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:ref:`concept-modes`. Defaults to "RGB"
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:param palette: An optional palette. If given, it must be a bytearray,
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an array or a list of ints between 0-255. The list must consist of
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all channels for one color followed by the next color (e.g. RGBRGBRGB).
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Defaults to an empty palette.
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"""
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def __init__(self, mode: str = "RGB", palette: Sequence[int] | None = None) -> None:
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self.mode = mode
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self.rawmode = None # if set, palette contains raw data
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self.palette = palette or bytearray()
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self.dirty: int | None = None
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@property
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def palette(self):
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return self._palette
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@palette.setter
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def palette(self, palette):
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self._colors = None
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self._palette = palette
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@property
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def colors(self):
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if self._colors is None:
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mode_len = len(self.mode)
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self._colors = {}
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for i in range(0, len(self.palette), mode_len):
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color = tuple(self.palette[i : i + mode_len])
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if color in self._colors:
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continue
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self._colors[color] = i // mode_len
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return self._colors
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@colors.setter
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def colors(self, colors):
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self._colors = colors
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def copy(self):
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new = ImagePalette()
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new.mode = self.mode
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new.rawmode = self.rawmode
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if self.palette is not None:
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new.palette = self.palette[:]
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new.dirty = self.dirty
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return new
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def getdata(self):
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"""
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Get palette contents in format suitable for the low-level
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``im.putpalette`` primitive.
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.. warning:: This method is experimental.
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"""
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if self.rawmode:
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return self.rawmode, self.palette
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return self.mode, self.tobytes()
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def tobytes(self):
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"""Convert palette to bytes.
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.. warning:: This method is experimental.
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"""
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if self.rawmode:
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msg = "palette contains raw palette data"
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raise ValueError(msg)
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if isinstance(self.palette, bytes):
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return self.palette
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arr = array.array("B", self.palette)
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return arr.tobytes()
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# Declare tostring as an alias for tobytes
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tostring = tobytes
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def _new_color_index(self, image=None, e=None):
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if not isinstance(self.palette, bytearray):
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self._palette = bytearray(self.palette)
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index = len(self.palette) // 3
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special_colors = ()
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if image:
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special_colors = (
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image.info.get("background"),
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image.info.get("transparency"),
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)
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while index in special_colors:
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index += 1
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if index >= 256:
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if image:
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# Search for an unused index
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for i, count in reversed(list(enumerate(image.histogram()))):
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if count == 0 and i not in special_colors:
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index = i
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break
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if index >= 256:
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msg = "cannot allocate more than 256 colors"
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raise ValueError(msg) from e
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return index
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def getcolor(self, color, image=None) -> int:
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"""Given an rgb tuple, allocate palette entry.
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.. warning:: This method is experimental.
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"""
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if self.rawmode:
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msg = "palette contains raw palette data"
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raise ValueError(msg)
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if isinstance(color, tuple):
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if self.mode == "RGB":
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if len(color) == 4:
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if color[3] != 255:
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msg = "cannot add non-opaque RGBA color to RGB palette"
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raise ValueError(msg)
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color = color[:3]
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elif self.mode == "RGBA":
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if len(color) == 3:
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color += (255,)
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try:
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return self.colors[color]
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except KeyError as e:
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# allocate new color slot
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index = self._new_color_index(image, e)
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self.colors[color] = index
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if index * 3 < len(self.palette):
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self._palette = (
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self.palette[: index * 3]
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+ bytes(color)
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+ self.palette[index * 3 + 3 :]
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)
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else:
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self._palette += bytes(color)
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self.dirty = 1
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return index
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else:
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msg = f"unknown color specifier: {repr(color)}"
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raise ValueError(msg)
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def save(self, fp):
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"""Save palette to text file.
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.. warning:: This method is experimental.
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"""
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if self.rawmode:
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msg = "palette contains raw palette data"
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raise ValueError(msg)
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if isinstance(fp, str):
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fp = open(fp, "w")
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fp.write("# Palette\n")
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fp.write(f"# Mode: {self.mode}\n")
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for i in range(256):
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fp.write(f"{i}")
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for j in range(i * len(self.mode), (i + 1) * len(self.mode)):
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try:
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fp.write(f" {self.palette[j]}")
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except IndexError:
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fp.write(" 0")
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fp.write("\n")
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fp.close()
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# --------------------------------------------------------------------
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# Internal
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def raw(rawmode, data) -> ImagePalette:
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palette = ImagePalette()
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palette.rawmode = rawmode
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palette.palette = data
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palette.dirty = 1
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return palette
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# --------------------------------------------------------------------
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# Factories
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def make_linear_lut(black, white):
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if black == 0:
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return [white * i // 255 for i in range(256)]
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msg = "unavailable when black is non-zero"
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raise NotImplementedError(msg) # FIXME
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def make_gamma_lut(exp):
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return [int(((i / 255.0) ** exp) * 255.0 + 0.5) for i in range(256)]
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def negative(mode="RGB"):
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palette = list(range(256 * len(mode)))
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palette.reverse()
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return ImagePalette(mode, [i // len(mode) for i in palette])
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def random(mode="RGB"):
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from random import randint
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palette = [randint(0, 255) for _ in range(256 * len(mode))]
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return ImagePalette(mode, palette)
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def sepia(white="#fff0c0"):
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bands = [make_linear_lut(0, band) for band in ImageColor.getrgb(white)]
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return ImagePalette("RGB", [bands[i % 3][i // 3] for i in range(256 * 3)])
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def wedge(mode="RGB"):
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palette = list(range(256 * len(mode)))
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return ImagePalette(mode, [i // len(mode) for i in palette])
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def load(filename):
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# FIXME: supports GIMP gradients only
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with open(filename, "rb") as fp:
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for paletteHandler in [
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GimpPaletteFile.GimpPaletteFile,
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GimpGradientFile.GimpGradientFile,
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PaletteFile.PaletteFile,
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]:
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try:
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fp.seek(0)
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lut = paletteHandler(fp).getpalette()
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if lut:
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break
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except (SyntaxError, ValueError):
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pass
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else:
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msg = "cannot load palette"
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raise OSError(msg)
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return lut # data, rawmode
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