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This commit is contained in:
Tim Bentley
commit
37c77623b4
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@ -32,6 +32,7 @@ to wait for the conversion to happen.
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"""
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import logging
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import time
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import Queue
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from PyQt4 import QtCore
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@ -42,8 +43,8 @@ log = logging.getLogger(__name__)
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class ImageThread(QtCore.QThread):
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"""
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A special Qt thread class to speed up the display of text based frames.
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This is threaded so it loads the frames in background
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A special Qt thread class to speed up the display of images. This is
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threaded so it loads the frames and generates byte stream in background.
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"""
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def __init__(self, manager):
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QtCore.QThread.__init__(self, None)
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@ -53,15 +54,75 @@ class ImageThread(QtCore.QThread):
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"""
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Run the thread.
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"""
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self.imageManager.process()
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self.imageManager._process()
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class Priority(object):
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"""
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Enumeration class for different priorities.
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``Lowest``
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Only the image's byte stream has to be generated. But neither the
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``QImage`` nor the byte stream has been requested yet.
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``Low``
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Only the image's byte stream has to be generated. Because the image's
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``QImage`` has been requested previously it is reasonable to assume that
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the byte stream will be needed before the byte stream of other images
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whose ``QImage`` were not generated due to a request.
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``Normal``
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The image's byte stream as well as the image has to be generated.
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Neither the ``QImage`` nor the byte stream has been requested yet.
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``High``
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The image's byte stream as well as the image has to be generated. The
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``QImage`` for this image has been requested.
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**Note**, this priority is only set when the ``QImage`` has not been
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generated yet.
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``Urgent``
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The image's byte stream as well as the image has to be generated. The
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byte stream for this image has been requested.
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**Note**, this priority is only set when the byte stream has not been
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generated yet.
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"""
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Lowest = 4
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Low = 3
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Normal = 2
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High = 1
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Urgent = 0
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class Image(object):
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name = ''
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path = ''
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dirty = True
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image = None
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image_bytes = None
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"""
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This class represents an image. To mark an image as *dirty* set the instance
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variables ``image`` and ``image_bytes`` to ``None`` and add the image object
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to the queue of images to process.
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"""
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def __init__(self, name='', path=''):
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self.name = name
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self.path = path
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self.image = None
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self.image_bytes = None
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self.priority = Priority.Normal
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class PriorityQueue(Queue.PriorityQueue):
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"""
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Customised ``Queue.PriorityQueue``.
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"""
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def remove(self, item):
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"""
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Removes the given ``item`` from the queue.
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``item``
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The item to remove. This should be a tuple::
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``(Priority, Image)``
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"""
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if item in self.queue:
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self.queue.remove(item)
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class ImageManager(QtCore.QObject):
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@ -76,96 +137,120 @@ class ImageManager(QtCore.QObject):
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self.width = current_screen[u'size'].width()
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self.height = current_screen[u'size'].height()
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self._cache = {}
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self._thread_running = False
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self._cache_dirty = False
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self.image_thread = ImageThread(self)
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self._imageThread = ImageThread(self)
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self._conversion_queue = PriorityQueue()
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def update_display(self):
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"""
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Screen has changed size so rebuild the cache to new size
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Screen has changed size so rebuild the cache to new size.
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"""
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log.debug(u'update_display')
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current_screen = ScreenList.get_instance().current
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self.width = current_screen[u'size'].width()
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self.height = current_screen[u'size'].height()
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# mark the images as dirty for a rebuild
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for key in self._cache.keys():
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image = self._cache[key]
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image.dirty = True
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image.image = resize_image(image.path, self.width, self.height)
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self._cache_dirty = True
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# only one thread please
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if not self._thread_running:
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self.image_thread.start()
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# Mark the images as dirty for a rebuild by setting the image and byte
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# stream to None.
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self._conversion_queue = PriorityQueue()
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for key, image in self._cache.iteritems():
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image.priority = Priority.Normal
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image.image = None
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image.image_bytes = None
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self._conversion_queue.put((image.priority, image))
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# We want only one thread.
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if not self._imageThread.isRunning():
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self._imageThread.start()
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def get_image(self, name):
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"""
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Return the Qimage from the cache
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Return the ``QImage`` from the cache. If not present wait for the
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background thread to process it.
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"""
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log.debug(u'get_image %s' % name)
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return self._cache[name].image
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image = self._cache[name]
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if image.image is None:
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self._conversion_queue.remove((image.priority, image))
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image.priority = Priority.High
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self._conversion_queue.put((image.priority, image))
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while image.image is None:
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log.debug(u'get_image - waiting')
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time.sleep(0.1)
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return image.image
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def get_image_bytes(self, name):
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"""
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Returns the byte string for an image
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If not present wait for the background thread to process it.
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Returns the byte string for an image. If not present wait for the
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background thread to process it.
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"""
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log.debug(u'get_image_bytes %s' % name)
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if not self._cache[name].image_bytes:
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while self._cache[name].dirty:
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image = self._cache[name]
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if image.image_bytes is None:
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self._conversion_queue.remove((image.priority, image))
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image.priority = Priority.Urgent
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self._conversion_queue.put((image.priority, image))
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while image.image_bytes is None:
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log.debug(u'get_image_bytes - waiting')
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time.sleep(0.1)
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return self._cache[name].image_bytes
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return image.image_bytes
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def del_image(self, name):
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"""
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Delete the Image from the Cache
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Delete the Image from the cache.
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"""
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log.debug(u'del_image %s' % name)
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if name in self._cache:
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self._conversion_queue.remove(
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(self._cache[name].priority, self._cache[name]))
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del self._cache[name]
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def add_image(self, name, path):
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"""
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Add image to cache if it is not already there
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Add image to cache if it is not already there.
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"""
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log.debug(u'add_image %s:%s' % (name, path))
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if not name in self._cache:
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image = Image()
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image.name = name
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image.path = path
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image.image = resize_image(path, self.width, self.height)
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image = Image(name, path)
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self._cache[name] = image
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self._conversion_queue.put((image.priority, image))
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else:
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log.debug(u'Image in cache %s:%s' % (name, path))
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self._cache_dirty = True
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# only one thread please
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if not self._thread_running:
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self.image_thread.start()
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# We want only one thread.
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if not self._imageThread.isRunning():
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self._imageThread.start()
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def process(self):
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def _process(self):
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"""
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Controls the processing called from a QThread
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Controls the processing called from a ``QtCore.QThread``.
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"""
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log.debug(u'process - started')
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self._thread_running = True
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self.clean_cache()
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# data loaded since we started ?
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while self._cache_dirty:
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log.debug(u'process - recycle')
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self.clean_cache()
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self._thread_running = False
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log.debug(u'process - ended')
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log.debug(u'_process - started')
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while not self._conversion_queue.empty():
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self._process_cache()
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log.debug(u'_process - ended')
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def clean_cache(self):
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def _process_cache(self):
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"""
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Actually does the work.
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"""
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log.debug(u'clean_cache')
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# we will clean the cache now
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self._cache_dirty = False
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for key in self._cache.keys():
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image = self._cache[key]
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if image.dirty:
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image.image_bytes = image_to_byte(image.image)
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image.dirty = False
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log.debug(u'_process_cache')
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image = self._conversion_queue.get()[1]
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# Generate the QImage for the image.
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if image.image is None:
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image.image = resize_image(image.path, self.width, self.height)
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# Set the priority to Lowest and stop here as we need to process
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# more important images first.
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if image.priority == Priority.Normal:
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self._conversion_queue.remove((image.priority, image))
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image.priority = Priority.Lowest
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self._conversion_queue.put((image.priority, image))
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return
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# For image with high priority we set the priority to Low, as the
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# byte stream might be needed earlier the byte stream of image with
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# Normal priority. We stop here as we need to process more important
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# images first.
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elif image.priority == Priority.High:
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self._conversion_queue.remove((image.priority, image))
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image.priority = Priority.Low
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self._conversion_queue.put((image.priority, image))
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return
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# Generate the byte stream for the image.
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if image.image_bytes is None:
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image.image_bytes = image_to_byte(image.image)
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