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from __future__ import annotations
from collections.abc import Callable, Collection
from gaphas.item import Item
class Selection:
def __init__(self):
super().__init__()
self._selected_items: set[Item] = set()
self._focused_item: Item | None = None
self._hovered_item: Item | None = None
self._handlers: set[Callable[[Item | None], None]] = set()
def add_handler(self, handler: Callable[[Item | None], None]) -> None:
"""Add a callback handler, triggered when a constraint is resolved."""
self._handlers.add(handler)
def remove_handler(self, handler: Callable[[Item | None], None]) -> None:
"""Remove a previously assigned handler."""
self._handlers.discard(handler)
def notify(self, item: Item | None) -> None:
for handler in self._handlers:
handler(item)
def clear(self):
self._selected_items.clear()
self._focused_item = None
self._hovered_item = None
self.notify(None)
@property
def selected_items(self) -> Collection[Item]:
return self._selected_items
def select_items(self, *items: Item) -> None:
for item in items:
if item not in self._selected_items:
self._selected_items.add(item)
self.notify(item)
def unselect_item(self, item: Item) -> None:
"""Unselect an item.
If it's focused, it will be unfocused as well.
"""
if item is self._focused_item:
self._focused_item = None
if item in self._selected_items:
self._selected_items.discard(item)
self.notify(item)
def unselect_all(self) -> None:
"""Clearing the selected_item also clears the focused_item."""
for item in list(self._selected_items):
self.unselect_item(item)
self.focused_item = None
@property
def focused_item(self) -> Item | None:
return self._focused_item
@focused_item.setter
def focused_item(self, item: Item | None) -> None:
if item:
self.select_items(item)
if item is not self._focused_item:
self._focused_item = item
self.notify(item)
@property
def hovered_item(self) -> Item | None:
return self._hovered_item
@hovered_item.setter
def hovered_item(self, item: Item | None) -> None:
if item is not self._hovered_item:
self._hovered_item = item
self.notify(item)
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