This commit is contained in:
Tim Bentley 2011-06-28 17:13:30 +01:00
commit 37c77623b4

View File

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