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added secondary criterion for the image queue to privilege images which were added earlier over images which were added later, when both have the same priority

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This commit is contained in:
Andreas Preikschat 2012-05-05 14:23:42 +02:00
parent 792ac861ee
commit 785787d7f3
1 changed files with 19 additions and 5 deletions
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24
openlp/core/lib/imagemanager.py
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@ -100,6 +100,7 @@ class Image(object):
variables ``image`` and ``image_bytes`` to ``None`` and add the image object
to the queue of images to process.
"""
NUMBER = 0
def __init__(self, name, path, source, background):
self.name = name
self.path = path
@ -108,11 +109,24 @@ class Image(object):
self.priority = Priority.Normal
self.source = source
self.background = background
self._number = Image.NUMBER
Image.NUMBER += 1
class PriorityQueue(Queue.PriorityQueue):
"""
Customised ``Queue.PriorityQueue``.
Each item in the queue must be tuple with three values. The fist value
is the priority, the second value the image's ``_number`` attribute. The
last value the :class:`image` instance itself::
(Priority.Normal, image._number, image)
Doing this, the :class:`Queue.PriorityQueue` will sort the images according
to their priorities, but also according to there number. However, the number
only has an impact on the result if there are more images with the same
priority. In such case the image which has been added earlier is privileged.
"""
def modify_priority(self, image, new_priority):
"""
@ -126,7 +140,7 @@ class PriorityQueue(Queue.PriorityQueue):
"""
self.remove(image)
image.priority = new_priority
self.put((image.priority, image))
self.put((image.priority, image._number, image))
def remove(self, image):
"""
@ -135,8 +149,8 @@ class PriorityQueue(Queue.PriorityQueue):
``image``
The image to remove. This should be an ``Image`` instance.
"""
if (image.priority, image) in self.queue:
self.queue.remove((image.priority, image))
if (image.priority, image._number, image) in self.queue:
self.queue.remove((image.priority, image._number, image))
class ImageManager(QtCore.QObject):
@ -261,7 +275,7 @@ class ImageManager(QtCore.QObject):
if not name in self._cache:
image = Image(name, path, source, background)
self._cache[name] = image
self._conversion_queue.put((image.priority, image))
self._conversion_queue.put((image.priority, image._number, image))
else:
log.debug(u'Image in cache %s:%s' % (name, path))
# We want only one thread.
@ -282,7 +296,7 @@ class ImageManager(QtCore.QObject):
Actually does the work.
"""
log.debug(u'_process_cache')
image = self._conversion_queue.get()[1]
image = self._conversion_queue.get()[2]
# Generate the QImage for the image.
if image.image is None:
image.image = resize_image(image.path, self.width, self.height,