"""
Enums and related functions.
"""
__all__ = ['Dither', 'Range', 'EXPR_VARS']
# this file only depends on the stdlib and should stay that way
from enum import Enum
from typing import Any, Callable, Optional, Type, TypeVar, Union
E = TypeVar('E', bound=Enum)
class _NoSubmoduleRepr:
def __repr__(self):
"""Removes submodule name from standard repr, helpful since we re-export everything at the top-level."""
return '<%s.%s.%s: %r>' % (self.__module__.split('.')[0], self.__class__.__name__, self.name, self.value)
[docs]class Dither(_NoSubmoduleRepr, str, Enum):
"""
Enum for `zimg_dither_type_e`.
"""
NONE = 'none'
"""Round to nearest."""
ORDERED = 'ordered'
"""Bayer patterned dither."""
RANDOM = 'random'
"""Pseudo-random noise of magnitude 0.5."""
ERROR_DIFFUSION = 'error_diffusion'
"""Floyd-Steinberg error diffusion."""
[docs]class Range(_NoSubmoduleRepr, int, Enum):
"""
Enum for `zimg_pixel_range_e`.
"""
LIMITED = 0
"""Studio (TV) legal range, 16-235 in 8 bits."""
FULL = 1
"""Full (PC) dynamic range, 0-255 in 8 bits."""
EXPR_VARS: str = 'xyzabcdefghijklmnopqrstuvw'
"""
This constant contains a list of all variables that can appear inside an expr-string ordered
by assignment. So the first clip will have the name EXPR_VAR_NAMES[0], the second one will
have the name EXPR_VAR_NAMES[1], and so on.
This can be used to automatically generate Expr-strings.
"""
def _readable_enums(enum: Type[Enum]) -> str:
"""
Returns a list of all possible values in `enum`.
Since VapourSynth imported enums don't carry the correct module name, use a special case for them.
"""
if 'importlib' in enum.__module__:
return ', '.join([f'<vapoursynth.{i.name}: {i.value}>' for i in enum])
else:
return ', '.join([repr(i) for i in enum])
def _resolve_enum(enum: Type[E], value: Any, var_name: str, fn: Optional[Callable] = None) -> Union[E, None]:
"""
Attempts to evaluate `value` in `enum` if value is not None, otherwise returns None.
Basically checks if a supplied enum value is valid and returns a readable error message
explaining the possible enum values if it isn't.
"""
if value is None:
return None
try:
return enum(value)
except ValueError:
raise ValueError(f"{fn.__name__ + ': ' if fn else ''}{var_name} must be in {_readable_enums(enum)}.") from None