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# SPDX-FileCopyrightText: 2015-2023 Blender Authors
#
# SPDX-License-Identifier: GPL-2.0-or-later
"""
This module contains utility functions to handle custom previews.
It behaves as a high-level 'cached' previews manager.
This allows scripts to generate their own previews, and use them as icons in UI widgets
('icon_value' for UILayout functions).
Custom Icon Example
-------------------
.. literalinclude:: __/__/__/scripts/templates_py/ui_previews_custom_icon.py
"""
__all__ = (
"new",
"remove",
"ImagePreviewCollection",
)
from _bpy import _utils_previews
_uuid_open = set()
# High-level previews manager.
# not accessed directly
class ImagePreviewCollection(dict):
"""
Dictionary-like class of previews.
This is a subclass of Python's built-in dict type,
used to store multiple image previews.
.. note::
- instance with :mod:`bpy.utils.previews.new`
- keys must be ``str`` type.
- values will be :class:`bpy.types.ImagePreview`
"""
# Internal notes:
# - Blender's internal 'PreviewImage' struct uses 'self._uuid' prefix.
# - Blender's preview.new/load return the data if it exists,
# don't do this for the Python API as it allows accidental re-use of names,
# anyone who wants to reuse names can use dict.get() to check if it exists.
# We could use this for the C API too (would need some investigation).
def __init__(self):
super().__init__()
self._uuid = hex(id(self))
_uuid_open.add(self._uuid)
def __del__(self):
if self._uuid not in _uuid_open:
return
raise ResourceWarning(
"{!r}: left open, remove with 'bpy.utils.previews.remove()'".format(self)
)
self.close()
def _gen_key(self, name):
return ":".join((self._uuid, name))
def new(self, name):
if name in self:
raise KeyError("key {!r} already exists".format(name))
p = self[name] = _utils_previews.new(
self._gen_key(name))
return p
new.__doc__ = _utils_previews.new.__doc__
def load(self, name, path, path_type, force_reload=False):
if name in self:
raise KeyError("key {!r} already exists".format(name))
p = self[name] = _utils_previews.load(
self._gen_key(name), path, path_type, force_reload)
return p
load.__doc__ = _utils_previews.load.__doc__
def clear(self):
"""Clear all previews."""
for name in self.keys():
_utils_previews.release(self._gen_key(name))
super().clear()
def close(self):
"""Close the collection and clear all previews."""
self.clear()
_uuid_open.remove(self._uuid)
def __delitem__(self, key):
_utils_previews.release(self._gen_key(key))
super().__delitem__(key)
def __repr__(self):
return "<{:s} id={:s}[{:d}], {!r}>".format(
self.__class__.__name__, self._uuid, len(self), super()
)
def new():
"""
:return: a new preview collection.
:rtype: :class:`ImagePreviewCollection`
"""
return ImagePreviewCollection()
def remove(pcoll):
"""
Remove the specified previews collection.
:arg pcoll: Preview collection to close.
:type pcoll: :class:`ImagePreviewCollection`
"""
pcoll.close()
# don't complain about resources on exit (only unregister)
import atexit
def exit_clear_warning():
del ImagePreviewCollection.__del__
atexit.register(exit_clear_warning)
del atexit, exit_clear_warning
|
