Pillow/src/PIL/ImageMode.py

#
# The Python Imaging Library.
# $Id$
#
# standard mode descriptors
#
# History:
# 2006-03-20 fl   Added
#
# Copyright (c) 2006 by Secret Labs AB.
# Copyright (c) 2006 by Fredrik Lundh.
#
# See the README file for information on usage and redistribution.
#

# mode descriptor cache
_modes = None


class ModeDescriptor:
    """Wrapper for mode strings."""

    def __init__(self, mode, bands, basemode, basetype):
        self.mode = mode
        self.bands = bands
        self.basemode = basemode
        self.basetype = basetype

    def __str__(self):
        return self.mode


def getmode(mode):
    """Gets a mode descriptor for the given mode."""
    global _modes
    if not _modes:
        # initialize mode cache
        modes = {}
        for m, (basemode, basetype, bands) in {
            # core modes
            "1": ("L", "L", ("1",)),
            "L": ("L", "L", ("L",)),
            "I": ("L", "I", ("I",)),
            "F": ("L", "F", ("F",)),
            "P": ("P", "L", ("P",)),
            "RGB": ("RGB", "L", ("R", "G", "B")),
            "RGBX": ("RGB", "L", ("R", "G", "B", "X")),
            "RGBA": ("RGB", "L", ("R", "G", "B", "A")),
            "CMYK": ("RGB", "L", ("C", "M", "Y", "K")),
            "YCbCr": ("RGB", "L", ("Y", "Cb", "Cr")),
            "LAB": ("RGB", "L", ("L", "A", "B")),
            "HSV": ("RGB", "L", ("H", "S", "V")),
            # extra experimental modes
            "RGBa": ("RGB", "L", ("R", "G", "B", "a")),
            "LA": ("L", "L", ("L", "A")),
            "La": ("L", "L", ("L", "a")),
            "PA": ("RGB", "L", ("P", "A")),
        }.items():
            modes[m] = ModeDescriptor(m, bands, basemode, basetype)
        # mapping modes
        for i16mode in (
            "I;16",
            "I;16S",
            "I;16L",
            "I;16LS",
            "I;16B",
            "I;16BS",
            "I;16N",
            "I;16NS",
        ):
            modes[i16mode] = ModeDescriptor(i16mode, ("I",), "L", "L")
        # set global mode cache atomically
        _modes = modes
    return _modes[mode]