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# Copyright (C) 2010, Aleksey Lim
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
import logging
import os
import math
import gtk
import gio
import gobject
from sugar import dispatch
from sugar.util import LRU
from sugar.graphics import style
from jarabe.journal import model
fetched = dispatch.Signal()
THUMB_WIDTH = style.zoom(240)
THUMB_HEIGHT = style.zoom(180)
_CHUNK_SIZE = 1024 * 10 # 10K
_MAX_FILESIZE = 1024 * 1024 * 10 # 10M
_fetch_queue = []
def fetch(offset, metadata):
entry = _CacheEntry(offset, metadata)
if entry not in _fetch_queue:
_fetch_queue.append(entry)
if len(_fetch_queue) == 1:
gobject.idle_add(_process_queue)
def discard_queue(visible_range):
new_queue = []
for i in _fetch_queue:
if i.offset in visible_range:
new_queue.append(i)
global _fetch_queue
_fetch_queue = new_queue
def _process_queue():
while len(_fetch_queue):
entry = _fetch_queue[0]
logging.debug('Loading preview for %s', entry.uid)
if entry.uid.startswith('/'):
if not os.path.isfile(entry.uid):
logging.warning('Preview %s is not a file', entry.uid)
_commit(entry, None)
elif os.path.getsize(entry.uid) > _MAX_FILESIZE:
logging.debug('Preview %s is too big to load', entry.uid)
_commit(entry, None)
else:
_AsyncLoader(entry)
else:
_load_props(entry)
break
return False
def _commit(entry, pixbuf):
if not _fetch_queue or _fetch_queue[0] != entry:
logging.debug('Discard %r preview', entry.uid)
else:
del _fetch_queue[0]
if pixbuf is None:
logging.debug('Empty preview for %s', entry.uid)
else:
logging.debug('Ready preview for %s', entry.uid)
fetched.send(None, offset=entry.offset, pixbuf=pixbuf)
if len(_fetch_queue):
gobject.idle_add(_process_queue)
def _load_preview(entry, preview):
if not preview:
logging.debug('Empty preview for %s', entry.uid)
_commit(entry, None)
return
if preview[1:4] != 'PNG':
# TODO: We are close to be able to drop this.
import base64
preview = base64.b64decode(preview)
loader = gtk.gdk.PixbufLoader()
loader.connect('size-prepared', _size_prepared_cb)
try:
loader.write(preview)
except Exception:
logging.exception('Can not load preview from metadata for %s',
entry.uid)
finally:
loader.close()
pixbuf = loader.get_pixbuf()
if pixbuf is None:
_commit(entry, None)
else:
_commit(entry, pixbuf)
def _load_props(entry):
def reply_cb(props):
if props is None:
_commit(entry, None)
else:
_load_preview(entry, props.get('preview'))
model.get(entry.uid, reply_cb)
def _size_prepared_cb(loader, width, height):
dest_width = THUMB_WIDTH
dest_height = THUMB_HEIGHT
if width == dest_width and height == dest_height:
return
ratio_width = float(dest_width) / width
ratio_height = float(dest_height) / height
ratio = min(ratio_width, ratio_height)
# preserve original ration
if ratio_width != ratio:
dest_width = int(math.ceil(width * ratio))
elif ratio_height != ratio:
dest_height = int(math.ceil(height * ratio))
loader.set_size(dest_width, dest_height)
class _AsyncLoader(object):
def __init__(self, entry):
self._entry = entry
self._loader = gtk.gdk.PixbufLoader()
self._loader.connect('size-prepared', _size_prepared_cb)
self._stream = None
self._file = gio.File(entry.uid)
self._file.read_async(self.__file_read_async_cb)
def __file_read_async_cb(self, input_file, result):
try:
self._stream = self._file.read_finish(result)
except Exception:
logging.exception('Can not read preview for %s', self._entry.uid)
_commit(self._entry, None)
return
self._stream.read_async(_CHUNK_SIZE, self.__stream_read_async_cb,
gobject.PRIORITY_LOW)
def __stream_read_async_cb(self, input_stream, result):
data = self._stream.read_finish(result)
if data and self._process_loader(self._loader.write, data):
self._stream.read_async(_CHUNK_SIZE, self.__stream_read_async_cb,
gobject.PRIORITY_LOW)
return
if data is None:
logging.warning('Bad preview data from %s', self._entry.uid)
self._stream.close()
if self._process_loader(self._loader.close):
_commit(self._entry, self._loader.get_pixbuf())
else:
_commit(self._entry, None)
def _process_loader(self, method, *args):
try:
method(*args)
except Exception, e:
logging.debug('Can not process preview for %s: %r',
self._entry.uid, e)
return False
else:
return True
class _CacheEntry(object):
uid = None
offset = None
def __init__(self, offset, metadata):
self.uid = metadata['uid']
self.offset = offset
def __cmp__(self, other):
return cmp((self.uid, self.offset), (other.uid, other.offset))
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