Add ImageManager

openlp/core/lib/imagemanager.py

@@ -0,0 +1,145 @@
+# -*- coding: utf-8 -*-
+# vim: autoindent shiftwidth=4 expandtab textwidth=80 tabstop=4 softtabstop=4
+
+###############################################################################
+# OpenLP - Open Source Lyrics Projection                                      #
+# --------------------------------------------------------------------------- #
+# Copyright (c) 2008-2010 Raoul Snyman                                        #
+# Portions copyright (c) 2008-2010 Tim Bentley, Jonathan Corwin, Michael      #
+# Gorven, Scott Guerrieri, Meinert Jordan, Andreas Preikschat, Christian      #
+# Richter, Philip Ridout, Maikel Stuivenberg, Martin Thompson, Jon Tibble,    #
+# Carsten Tinggaard, Frode Woldsund                                           #
+# --------------------------------------------------------------------------- #
+# 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; version 2 of the License.                              #
+#                                                                             #
+# 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., 59  #
+# Temple Place, Suite 330, Boston, MA 02111-1307 USA                          #
+###############################################################################
+"""
+Provides the store and management for Images automatically caching them and
+resizing them when needed.  Only one copy of each image is needed in the system.
+A Thread is used to convert the image to a byte array so the user does not need
+to wait for the conversion to happen.
+"""
+import logging
+import os
+
+from PyQt4 import QtCore, QtGui
+
+from openlp.core.lib import resize_image, image_to_byte
+
+log = logging.getLogger(__name__)
+
+class ImageThread(QtCore.QThread):
+    """
+    A special Qt thread class to speed up the display of text based frames.
+    This is threaded so it loads the frames in background
+    """
+    def __init__(self, manager):
+        QtCore.QThread.__init__(self, None)
+        self.image_mamager = manager
+
+    def run(self):
+        """
+        Run the thread.
+        """
+        self.image_mamager.process()
+
+
+class Image(object):
+    name = ''
+    path = ''
+    dirty = True
+    image = None
+    image_bytes = None
+
+class ImageManager(QtCore.QObject):
+    """
+    Image Manager handles the conversion and sizing of images.
+
+    """
+    log.info(u'Image Manager loaded')
+
+    def __init__(self):
+        self._cache = {}
+        self._thread_running = False
+        self._cache_dirty = False
+        self.image_thread = ImageThread(self)
+
+    def update_display(self, width, height):
+        """
+        Screen has changed size so rebuild the cache to new size
+        """
+        log.debug(u'update_display')
+        self.width = width
+        self.height = height
+        # mark the images as dirty for a rebuild
+        for key in self._cache.keys():
+            image = self._cache[key]
+            image.dirty = True
+            fullpath = os.path.join(image.path, image.name)
+            image.image = resize_image(fullpath,
+                self.width, self.height)
+        self._cache_dirty = True
+        # only one thread please
+        if not self._thread_running:
+            self.image_thread.start()
+
+    def get_image(self, name):
+        return self._cache[name].image
+
+    def get_image_bytes(self, name):
+        return self._cache[name].image_bytes
+
+    def add_image(self, name, path):
+        """
+        Add image to cache if it is not already there
+        """
+        log.debug(u'add_image')
+        if not name in self._cache:
+            image = Image()
+            image.name = name
+            image.path = path
+            fullpath = os.path.join(image.path, image.name)
+            image.image = resize_image(fullpath,
+                self.width, self.height)
+            self._cache[name] = image
+        self._cache_dirty = True
+        # only one thread please
+        if not self._thread_running:
+            self.image_thread.start()
+
+    def process(self):
+        """
+        Controls the processing called from a QThread
+        """
+        log.debug(u'process - started')
+        self._thread_running = True
+        self.clean_cache()
+        # data loaded since we started ?
+        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):
+        """
+        Actually does the work.
+        """
+        log.debug(u'clean_cache')
+        # we will clean the cache now
+        self._cache_dirty = False
+        for key in self._cache.keys():
+            image = self._cache[key]
+            if image.dirty:
+                image.image_bytes = image_to_byte(image.image)
+                image.dirty = False