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