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Optimise ImageMode.getmode

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This commit is contained in:
Hugo van Kemenade 2023-12-22 16:30:45 +02:00
parent ef0b0d232a
commit 26f58e7afc
1 changed files with 55 additions and 56 deletions
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31
src/PIL/ImageMode.py
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@ -15,9 +15,7 @@
from __future__ import annotations from __future__ import annotations
import sys import sys
from functools import lru_cache
# mode descriptor cache
_modes = None
class ModeDescriptor: class ModeDescriptor:
@ -41,14 +39,14 @@ class ModeDescriptor:
return self.mode return self.mode
@lru_cache
def getmode(mode: str) -> ModeDescriptor: def getmode(mode: str) -> ModeDescriptor:
"""Gets a mode descriptor for the given mode.""" """Gets a mode descriptor for the given mode."""
global _modes # if not _modes:
if not _modes:
# initialize mode cache # initialize mode cache
modes = {}
endian = "<" if sys.byteorder == "little" else ">" endian = "<" if sys.byteorder == "little" else ">"
for m, (basemode, basetype, bands, typestr) in {
modes = {
# core modes # core modes
# Bits need to be extended to bytes # Bits need to be extended to bytes
"1": ("L", "L", ("1",), "|b1"), "1": ("L", "L", ("1",), "|b1"),
@ -72,10 +70,12 @@ def getmode(mode: str) -> ModeDescriptor:
"LA": ("L", "L", ("L", "A"), "|u1"), "LA": ("L", "L", ("L", "A"), "|u1"),
"La": ("L", "L", ("L", "a"), "|u1"), "La": ("L", "L", ("L", "a"), "|u1"),
"PA": ("RGB", "L", ("P", "A"), "|u1"), "PA": ("RGB", "L", ("P", "A"), "|u1"),
}.items(): }
modes[m] = ModeDescriptor(m, bands, basemode, basetype, typestr) if mode in modes:
# mapping modes base_mode, base_type, bands, type_str = modes[mode]
for i16mode, typestr in { return ModeDescriptor(mode, bands, base_mode, base_type, type_str)
mapping_modes = {
# I;16 == I;16L, and I;32 == I;32L # I;16 == I;16L, and I;32 == I;32L
"I;16": "<u2", "I;16": "<u2",
"I;16S": "<i2", "I;16S": "<i2",
@ -91,8 +91,7 @@ def getmode(mode: str) -> ModeDescriptor:
"I;32S": "<i4", "I;32S": "<i4",
"I;32BS": ">i4", "I;32BS": ">i4",
"I;32LS": "<i4", "I;32LS": "<i4",
}.items(): }
modes[i16mode] = ModeDescriptor(i16mode, ("I",), "L", "L", typestr)
# set global mode cache atomically type_str = mapping_modes[mode]
_modes = modes return ModeDescriptor(mode, ("I",), "L", "L", type_str)
return _modes[mode]