69 lines
2.2 KiB
Python
69 lines
2.2 KiB
Python
"""A PyQT4 class to load a page image from a ComicArchive in a background thread"""
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#
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# Copyright 2012-2014 Anthony Beville
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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from __future__ import annotations
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import logging
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from PyQt5 import QtCore
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from comicapi.comicarchive import ComicArchive
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logger = logging.getLogger(__name__)
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class PageLoader(QtCore.QThread):
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"""
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This class holds onto a reference of each instance in a list since
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problems occur if the ref count goes to zero and the GC tries to reap
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the object while the thread is going.
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If the client class wants to stop the thread, they should mark it as
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"abandoned", and no signals will be issued.
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"""
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loadComplete = QtCore.pyqtSignal(bytes)
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instanceList: list[QtCore.QThread] = []
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mutex = QtCore.QMutex()
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# Remove all finished threads from the list
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@staticmethod
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def reap_instances() -> None:
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for obj in reversed(PageLoader.instanceList):
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if obj.isFinished():
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PageLoader.instanceList.remove(obj)
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def __init__(self, ca: ComicArchive, page_num: int) -> None:
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QtCore.QThread.__init__(self)
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self.ca: ComicArchive = ca
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self.page_num: int = page_num
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self.abandoned = False
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# remove any old instances, and then add ourself
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PageLoader.mutex.lock()
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PageLoader.reap_instances()
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PageLoader.instanceList.append(self)
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PageLoader.mutex.unlock()
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def run(self) -> None:
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image_data = self.ca.get_page(self.page_num)
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if self.abandoned:
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return
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if image_data:
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if self.abandoned:
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return
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self.loadComplete.emit(image_data)
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