openlp/openlp/core/ui/thememanager.py

# -*- coding: utf-8 -*-
# vim: autoindent shiftwidth=4 expandtab textwidth=80 tabstop=4 softtabstop=4

###############################################################################
# OpenLP - Open Source Lyrics Projection                                      #
# --------------------------------------------------------------------------- #
# Copyright (c) 2008-2011 Raoul Snyman                                        #
# Portions copyright (c) 2008-2011 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                          #
###############################################################################

import os
import zipfile
import shutil
import logging

from xml.etree.ElementTree import ElementTree, XML
from PyQt4 import QtCore, QtGui

from openlp.core.ui import FileRenameForm, ThemeForm
from openlp.core.theme import Theme
from openlp.core.lib import OpenLPToolbar, ThemeXML, get_text_file_string, \
    build_icon, Receiver, SettingsManager, translate, check_item_selected, \
    BackgroundType, BackgroundGradientType, check_directory_exists
from openlp.core.utils import AppLocation, get_filesystem_encoding

log = logging.getLogger(__name__)

class ThemeManager(QtGui.QWidget):
    """
    Manages the orders of Theme.
    """
    def __init__(self, mainwindow, parent=None):
        QtGui.QWidget.__init__(self, parent)
        self.mainwindow = mainwindow
        self.settingsSection = u'themes'
        self.themeForm = ThemeForm(self)
        self.fileRenameForm = FileRenameForm(self)
        self.serviceComboBox = self.mainwindow.ServiceManagerContents.themeComboBox
        # start with the layout
        self.layout = QtGui.QVBoxLayout(self)
        self.layout.setSpacing(0)
        self.layout.setMargin(0)
        self.layout.setObjectName(u'layout')
        self.toolbar = OpenLPToolbar(self)
        self.toolbar.addToolbarButton(
            translate('OpenLP.ThemeManager', 'New Theme'),
            u':/themes/theme_new.png',
            translate('OpenLP.ThemeManager', 'Create a new theme.'),
            self.onAddTheme)
        self.toolbar.addToolbarButton(
            translate('OpenLP.ThemeManager', 'Edit Theme'),
            u':/themes/theme_edit.png',
            translate('OpenLP.ThemeManager', 'Edit a theme.'),
            self.onEditTheme)
        self.toolbar.addToolbarButton(
            translate('OpenLP.ThemeManager', 'Delete Theme'),
            u':/general/general_delete.png',
            translate('OpenLP.ThemeManager', 'Delete a theme.'),
            self.onDeleteTheme)
        self.toolbar.addSeparator()
        self.toolbar.addToolbarButton(
            translate('OpenLP.ThemeManager', 'Import Theme'),
            u':/general/general_import.png',
            translate('OpenLP.ThemeManager', 'Import a theme.'),
            self.onImportTheme)
        self.toolbar.addToolbarButton(
            translate('OpenLP.ThemeManager', 'Export Theme'),
            u':/general/general_export.png',
            translate('OpenLP.ThemeManager', 'Export a theme.'),
            self.onExportTheme)
        self.toolbar.setObjectName(u'toolbar')
        self.layout.addWidget(self.toolbar)
        self.themeWidget = QtGui.QWidgetAction(self.toolbar)
        self.themeWidget.setObjectName(u'themeWidget')
        # create theme manager list
        self.themeListWidget = QtGui.QListWidget(self)
        self.themeListWidget.setAlternatingRowColors(True)
        self.themeListWidget.setIconSize(QtCore.QSize(88, 50))
        self.themeListWidget.setContextMenuPolicy(QtCore.Qt.CustomContextMenu)
        self.themeListWidget.setObjectName(u'themeListWidget')
        self.layout.addWidget(self.themeListWidget)
        QtCore.QObject.connect(self.themeListWidget,
            QtCore.SIGNAL('customContextMenuRequested(QPoint)'),
            self.contextMenu)
        # build the context menu
        self.menu = QtGui.QMenu()
        self.editAction = self.menu.addAction(
            translate('OpenLP.ThemeManager', '&Edit Theme'))
        self.editAction.setIcon(build_icon(u':/themes/theme_edit.png'))
        self.copyAction = self.menu.addAction(
            translate('OpenLP.ThemeManager', '&Copy Theme'))
        self.copyAction.setIcon(build_icon(u':/themes/theme_edit.png'))
        self.renameAction = self.menu.addAction(
            translate('OpenLP.ThemeManager', '&Rename Theme'))
        self.renameAction.setIcon(build_icon(u':/themes/theme_edit.png'))
        self.deleteAction = self.menu.addAction(
            translate('OpenLP.ThemeManager', '&Delete Theme'))
        self.deleteAction.setIcon(build_icon(u':/general/general_delete.png'))
        self.separator = self.menu.addSeparator()
        self.globalAction = self.menu.addAction(
            translate('OpenLP.ThemeManager', 'Set As &Global Default'))
        self.globalAction.setIcon(build_icon(u':/general/general_export.png'))
        self.exportAction = self.menu.addAction(
            translate('OpenLP.ThemeManager', '&Export Theme'))
        self.exportAction.setIcon(build_icon(u':/general/general_export.png'))
        # Signals
        QtCore.QObject.connect(self.themeListWidget,
            QtCore.SIGNAL(u'doubleClicked(QModelIndex)'),
            self.changeGlobalFromScreen)
        QtCore.QObject.connect(Receiver.get_receiver(),
            QtCore.SIGNAL(u'theme_update_global'), self.changeGlobalFromTab)
        QtCore.QObject.connect(Receiver.get_receiver(),
            QtCore.SIGNAL(u'config_updated'), self.configUpdated)
        # Variables
        self.themelist = []
        self.path = AppLocation.get_section_data_path(self.settingsSection)
        check_directory_exists(self.path)
        self.thumbPath = os.path.join(self.path, u'thumbnails')
        check_directory_exists(self.thumbPath)
        self.themeForm.path = self.path
        self.oldBackgroundImage = None
        # Last little bits of setting up
        self.configUpdated()

    def configUpdated(self, firstTime=False):
        """
        Triggered when Config dialog is updated.
        """
        self.global_theme = unicode(QtCore.QSettings().value(
            self.settingsSection + u'/global theme',
            QtCore.QVariant(u'')).toString())

    def contextMenu(self, point):
        """
        Build the Right Click Context menu and set state depending on
        the type of theme.
        """
        item = self.themeListWidget.itemAt(point)
        if item is None:
            return
        realThemeName = unicode(item.data(QtCore.Qt.UserRole).toString())
        themeName = unicode(item.text())
        self.deleteAction.setVisible(False)
        self.renameAction.setVisible(False)
        self.globalAction.setVisible(False)
        # If default theme restrict actions
        if realThemeName == themeName:
            self.deleteAction.setVisible(True)
            self.renameAction.setVisible(True)
            self.globalAction.setVisible(True)
        action = self.menu.exec_(self.themeListWidget.mapToGlobal(point))
        if action == self.editAction:
            self.onEditTheme()
        if action == self.copyAction:
            self.onCopyTheme()
        if action == self.renameAction:
            self.onRenameTheme()
        if action == self.deleteAction:
            self.onDeleteTheme()
        if action == self.globalAction:
            self.changeGlobalFromScreen()
        if action == self.exportAction:
            self.onExportTheme()

    def changeGlobalFromTab(self, themeName):
        """
        Change the global theme when it is changed through the Themes settings
        tab
        """
        log.debug(u'changeGlobalFromTab %s', themeName)
        for count in range (0, self.themeListWidget.count()):
            # reset the old name
            item = self.themeListWidget.item(count)
            oldName = item.text()
            newName = unicode(item.data(QtCore.Qt.UserRole).toString())
            if oldName != newName:
                self.themeListWidget.item(count).setText(newName)
            # Set the new name
            if themeName == newName:
                name = unicode(translate('OpenLP.ThemeManager',
                    '%s (default)')) % newName
                self.themeListWidget.item(count).setText(name)

    def changeGlobalFromScreen(self, index=-1):
        """
        Change the global theme when a theme is double clicked upon in the
        Theme Manager list
        """
        log.debug(u'changeGlobalFromScreen %s', index)
        selected_row = self.themeListWidget.currentRow()
        for count in range (0, self.themeListWidget.count()):
            item = self.themeListWidget.item(count)
            oldName = item.text()
            # reset the old name
            if oldName != unicode(item.data(QtCore.Qt.UserRole).toString()):
                self.themeListWidget.item(count).setText(
                    unicode(item.data(QtCore.Qt.UserRole).toString()))
            # Set the new name
            if count == selected_row:
                self.global_theme = unicode(
                    self.themeListWidget.item(count).text())
                name = unicode(translate('OpenLP.ThemeManager',
                    '%s (default)')) % self.global_theme
                self.themeListWidget.item(count).setText(name)
                QtCore.QSettings().setValue(
                    self.settingsSection + u'/global theme',
                    QtCore.QVariant(self.global_theme))
                Receiver.send_message(u'theme_update_global',
                    self.global_theme)
                self.pushThemes()

    def onAddTheme(self):
        """
        Loads a new theme with the default settings and then launches the theme
        editing form for the user to make their customisations.
        """
        theme = ThemeXML()
        self.themeForm.theme = theme
        self.themeForm.exec_()

    def onRenameTheme(self):
        """
        Renames an existing theme to a new name
        """
        if self._validate_theme_action(unicode(translate('OpenLP.ThemeManager',
            'You must select a theme to rename.')),
            unicode(translate('OpenLP.ThemeManager', 'Rename Confirmation')),
            unicode(translate('OpenLP.ThemeManager', 'Rename %s theme?')),
            False):
            item = self.themeListWidget.currentItem()
            oldThemeName = unicode(item.data(QtCore.Qt.UserRole).toString())
            self.fileRenameForm.fileNameEdit.setText(oldThemeName)
            if self.fileRenameForm.exec_():
                newThemeName =  unicode(self.fileRenameForm.fileNameEdit.text())
                if self.checkIfThemeExists(newThemeName):
                    oldThemeData = self.getThemeData(oldThemeName)
                    self.deleteTheme(oldThemeName)
                    self.cloneThemeData(oldThemeData, newThemeName)
                    for plugin in self.mainwindow.pluginManager.plugins:
                        if plugin.usesTheme(oldThemeName):
                            plugin.renameTheme(oldThemeName, newThemeName)

    def onCopyTheme(self):
        """
        Copies an existing theme to a new name
        """
        item = self.themeListWidget.currentItem()
        oldThemeName = unicode(item.data(QtCore.Qt.UserRole).toString())
        self.fileRenameForm.fileNameEdit.setText(oldThemeName)
        if self.fileRenameForm.exec_(True):
            newThemeName =  unicode(self.fileRenameForm.fileNameEdit.text())
            if self.checkIfThemeExists(newThemeName):
                themeData = self.getThemeData(oldThemeName)
                self.cloneThemeData(themeData, newThemeName)
                self.loadThemes()

    def cloneThemeData(self, themeData, newThemeName):
        """
        Takes a theme and makes a new copy of it as well as saving it.
        """
        log.debug(u'cloneThemeData')
        saveTo = None
        saveFrom = None
        if themeData.background_type == u'image':
            saveTo = os.path.join(self.path, newThemeName,
                os.path.split(unicode(themeData.background_filename))[1])
            saveFrom = themeData.background_filename
        themeData.theme_name = newThemeName
        self.saveTheme(themeData, saveFrom, saveTo)

    def onEditTheme(self):
        """
        Loads the settings for the theme that is to be edited and launches the
        theme editing form so the user can make their changes.
        """
        if check_item_selected(self.themeListWidget,
            translate('OpenLP.ThemeManager',
            'You must select a theme to edit.')):
            item = self.themeListWidget.currentItem()
            themeName = unicode(item.text())
            theme = self.getThemeData(
                unicode(item.data(QtCore.Qt.UserRole).toString()))
            if theme.background_type == u'image':
                self.oldBackgroundImage = theme.background_filename
            self.themeForm.theme = theme
            self.themeForm.exec_(True)

    def onDeleteTheme(self):
        """
        Delete a theme
        """
        if self._validate_theme_action(unicode(translate('OpenLP.ThemeManager',
            'You must select a theme to delete.')),
            unicode(translate('OpenLP.ThemeManager', 'Delete Confirmation')),
            unicode(translate('OpenLP.ThemeManager', 'Delete %s theme?'))):
            item = self.themeListWidget.currentItem()
            theme = unicode(item.text())
            row = self.themeListWidget.row(item)
            self.themeListWidget.takeItem(row)
            self.deleteTheme(theme)

    def deleteTheme(self, theme):
        """
        Delete a theme.

        ``theme``
            The theme to delete.
        """
        self.themelist.remove(theme)
        thumb = theme + u'.png'
        try:
            os.remove(os.path.join(self.path, thumb))
            os.remove(os.path.join(self.thumbPath, thumb))
            encoding = get_filesystem_encoding()
            shutil.rmtree(os.path.join(self.path, theme).encode(encoding))
        except OSError:
            log.exception(u'Error deleting theme %s', theme)
        # As we do not reload the themes push out the change
        # Reaload the list as the internal lists and events need
        # to be triggered
        self.pushThemes()

    def onExportTheme(self):
        """
        Save the theme in a zip file
        """
        item = self.themeListWidget.currentItem()
        if item is None:
            QtGui.QMessageBox.critical(self,
                translate('OpenLP.ThemeManager', 'Error'),
                translate('OpenLP.ThemeManager',
                'You have not selected a theme.'))
            return
        theme = unicode(item.data(QtCore.Qt.UserRole).toString())
        path = QtGui.QFileDialog.getExistingDirectory(self,
            unicode(translate('OpenLP.ThemeManager',
            'Save Theme - (%s)')) % theme,
            SettingsManager.get_last_dir(self.settingsSection, 1))
        path = unicode(path)
        if path:
            SettingsManager.set_last_dir(self.settingsSection, path, 1)
            themePath = os.path.join(path, theme + u'.otz')
            zip = None
            try:
                zip = zipfile.ZipFile(themePath, u'w')
                source = os.path.join(self.path, theme)
                for files in os.walk(source):
                    for name in files[2]:
                        zip.write(
                            os.path.join(source, name).encode(u'utf-8'),
                            os.path.join(theme, name).encode(u'utf-8'))
                QtGui.QMessageBox.information(self,
                    translate('OpenLP.ThemeManager', 'Theme Exported'),
                    translate('OpenLP.ThemeManager',
                        'Your theme has been successfully exported.'))
            except (IOError, OSError):
                log.exception(u'Export Theme Failed')
                QtGui.QMessageBox.critical(self,
                    translate('OpenLP.ThemeManager', 'Theme Export Failed'),
                    translate('OpenLP.ThemeManager',
                        'Your theme could not be exported due to an error.'))
            finally:
                if zip:
                    zip.close()

    def onImportTheme(self):
        """
        Opens a file dialog to select the theme file(s) to import before
        attempting to extract OpenLP themes from those files.  This process
        will load both OpenLP version 1 and version 2 themes.
        """
        files = QtGui.QFileDialog.getOpenFileNames(self,
            translate('OpenLP.ThemeManager', 'Select Theme Import File'),
            SettingsManager.get_last_dir(self.settingsSection),
            translate('OpenLP.ThemeManager', 'Theme v1 (*.theme);;'
            'Theme v2 (*.otz);;All Files (*.*)'))
        log.info(u'New Themes %s', unicode(files))
        if files:
            for file in files:
                SettingsManager.set_last_dir(
                    self.settingsSection, unicode(file))
                self.unzipTheme(file, self.path)
        self.loadThemes()

    def loadThemes(self):
        """
        Loads the theme lists and triggers updates accross the whole system
        using direct calls or core functions and events for the plugins.
        The plugins will call back in to get the real list if they want it.
        """
        log.debug(u'Load themes from dir')
        self.themelist = []
        self.themeListWidget.clear()
        dirList = os.listdir(self.path)
        dirList.sort()
        for name in dirList:
            if name.endswith(u'.png'):
                # check to see file is in theme root directory
                theme = os.path.join(self.path, name)
                if os.path.exists(theme):
                    textName = os.path.splitext(name)[0]
                    if textName == self.global_theme:
                        name = unicode(translate('OpenLP.ThemeManager',
                            '%s (default)')) % textName
                    else:
                        name = textName
                    thumb = os.path.join(self.thumbPath, u'%s.png' % textName)
                    item_name = QtGui.QListWidgetItem(name)
                    if os.path.exists(thumb):
                        icon = build_icon(thumb)
                    else:
                        icon = build_icon(theme)
                        pixmap = icon.pixmap(QtCore.QSize(88, 50))
                        pixmap.save(thumb, u'png')
                    item_name.setIcon(icon)
                    item_name.setData(QtCore.Qt.UserRole,
                        QtCore.QVariant(textName))
                    self.themeListWidget.addItem(item_name)
                    self.themelist.append(textName)
        self.pushThemes()

    def pushThemes(self):
        """
        Notify listeners that the theme list has been updated
        """
        Receiver.send_message(u'theme_update_list', self.getThemes())

    def getThemes(self):
        """
        Return the list of loaded themes
        """
        return self.themelist

    def getThemeData(self, themeName):
        """
        Returns a theme object from an XML file

        ``themeName``
            Name of the theme to load from file
        """
        log.debug(u'getthemedata for theme %s', themeName)
        xmlFile = os.path.join(self.path, unicode(themeName),
            unicode(themeName) + u'.xml')
        xml = get_text_file_string(xmlFile)
        if not xml:
            return self._baseTheme()
        else:
            return self._createThemeFromXml(xml, self.path)

    def unzipTheme(self, filename, dir):
        """
        Unzip the theme, remove the preview file if stored
        Generate a new preview fileCheck the XML theme version and upgrade if
        necessary.
        """
        log.debug(u'Unzipping theme %s', filename)
        filename = unicode(filename)
        zip = None
        outfile = None
        try:
            zip = zipfile.ZipFile(filename)
            filexml = None
            themename = None
            for file in zip.namelist():
                try:
                    ucsfile = file.decode(u'utf-8')
                except UnicodeDecodeError:
                    QtGui.QMessageBox.critical(
                        self, translate('OpenLP.ThemeManager', 'Error'),
                        translate('OpenLP.ThemeManager',
                            'File is not a valid theme.\n'
                            'The content encoding is not UTF-8.'))
                    log.exception(u'Filename "%s" is not valid UTF-8' %
                        file.decode(u'utf-8', u'replace'))
                    continue
                osfile = unicode(QtCore.QDir.toNativeSeparators(ucsfile))
                theme_dir = None
                if osfile.endswith(os.path.sep):
                    theme_dir = os.path.join(dir, osfile)
                    check_directory_exists(theme_dir)
                else:
                    fullpath = os.path.join(dir, osfile)
                    names = osfile.split(os.path.sep)
                    if len(names) > 1:
                        # not preview file
                        if themename is None:
                            themename = names[0]
                        if theme_dir is None:
                            theme_dir = os.path.join(dir, names[0])
                            check_directory_exists(theme_dir)
                        if os.path.splitext(ucsfile)[1].lower() in [u'.xml']:
                            xml_data = zip.read(file)
                            try:
                                xml_data = xml_data.decode(u'utf-8')
                            except UnicodeDecodeError:
                                log.exception(u'Theme XML is not UTF-8 '
                                    u'encoded.')
                                break
                            filexml = self.checkVersionAndConvert(xml_data)
                            outfile = open(fullpath, u'w')
                            outfile.write(filexml.encode(u'utf-8'))
                        else:
                            outfile = open(fullpath, u'wb')
                            outfile.write(zip.read(file))
            if filexml:
                theme = self._createThemeFromXml(filexml, self.path)
                self.generateAndSaveImage(dir, themename, theme)
            else:
                Receiver.send_message(u'openlp_error_message', {
                    u'title': translate('OpenLP.ThemeManager',
                    'Validation Error'),
                    u'message':translate('OpenLP.ThemeManager',
                    'File is not a valid theme.')})
                log.exception(u'Theme file does not contain XML data %s' %
                    filename)
        except (IOError, NameError):
            Receiver.send_message(u'openlp_error_message', {
                u'title': translate('OpenLP.ThemeManager',
                'Validation Error'),
                u'message':translate('OpenLP.ThemeManager',
                'File is not a valid theme.')})
            log.exception(u'Importing theme from zip failed %s' % filename)
        finally:
            if zip:
                zip.close()
            if outfile:
                outfile.close()

    def checkVersionAndConvert(self, xml_data):
        """
        Check if a theme is from OpenLP version 1

        ``xml_data``
            Theme XML to check the version of
        """
        log.debug(u'checkVersion1 ')
        theme = xml_data.encode(u'ascii', u'xmlcharrefreplace')
        tree = ElementTree(element=XML(theme)).getroot()
        # look for old version 1 tags
        if tree.find(u'BackgroundType') is None:
            return xml_data
        else:
            return self._migrateVersion122(xml_data)

    def checkIfThemeExists(self, themeName):
        """
        Check if theme already exists and displays error message

        ``themeName``
            Name of the Theme to test
        """
        theme_dir = os.path.join(self.path, themeName)
        if os.path.exists(theme_dir):
            Receiver.send_message(u'openlp_error_message', {
                u'title': translate('OpenLP.ThemeManager',
                'Validation Error'),
                u'message':translate('OpenLP.ThemeManager',
                'A theme with this name already exists.')})
            return False
        return True

    def saveTheme(self, theme, imageFrom, imageTo):
        """
        Called by thememaintenance Dialog to save the theme
        and to trigger the reload of the theme list
        """
        name = theme.theme_name
        theme_pretty_xml = theme.extract_formatted_xml()
        log.debug(u'saveTheme %s %s', name, theme_pretty_xml)
        theme_dir = os.path.join(self.path, name)
        check_directory_exists(theme_dir)
        theme_file = os.path.join(theme_dir, name + u'.xml')
        if imageTo and self.oldBackgroundImage and \
            imageTo != self.oldBackgroundImage:
            try:
                os.remove(self.oldBackgroundImage)
            except OSError:
                log.exception(u'Unable to remove old theme background')
        outfile = None
        try:
            outfile = open(theme_file, u'w')
            outfile.write(theme_pretty_xml)
        except IOError:
            log.exception(u'Saving theme to file failed')
        finally:
            if outfile:
                outfile.close()
        if imageFrom and imageFrom != imageTo:
            try:
                encoding = get_filesystem_encoding()
                shutil.copyfile(
                    unicode(imageFrom).encode(encoding),
                    unicode(imageTo).encode(encoding))
            except IOError:
                log.exception(u'Failed to save theme image')
        self.generateAndSaveImage(self.path, name, theme)
        self.loadThemes()
        self.pushThemes()

    def generateAndSaveImage(self, dir, name, theme):
        log.debug(u'generateAndSaveImage %s %s', dir, name)
        theme_xml = theme.extract_xml()
        frame = self.generateImage(theme)
        samplepathname = os.path.join(self.path, name + u'.png')
        if os.path.exists(samplepathname):
            os.unlink(samplepathname)
        frame.save(samplepathname, u'png')
        thumb = os.path.join(self.thumbPath, u'%s.png' % name)
        icon = build_icon(frame)
        pixmap = icon.pixmap(QtCore.QSize(88, 50))
        pixmap.save(thumb, u'png')
        log.debug(u'Theme image written to %s', samplepathname)

    def generateImage(self, themeData, forcePage=False):
        """
        Call the RenderManager to build a Sample Image

        ``themeData``
            The theme to generated a preview for.

        ``forcePage``
            Flag to tell message lines per page need to be generated.
        """
        log.debug(u'generateImage \n%s ', themeData)
        return self.mainwindow.renderManager.generate_preview(themeData, forcePage)

    def getPreviewImage(self, theme):
        """
        Return an image representing the look of the theme

        ``theme``
            The theme to return the image for
        """
        log.debug(u'getPreviewImage %s ', theme)
        image = os.path.join(self.path, theme + u'.png')
        return image

    def _baseTheme(self):
        """
        Provide a base theme with sensible defaults
        """
        log.debug(u'base theme created')
        newtheme = ThemeXML()
        return newtheme

    def _createThemeFromXml(self, themeXml, path):
        """
        Return a theme object using information parsed from XML

        ``themeXml``
            The XML data to load into the theme
        """
        theme = ThemeXML()
        theme.parse(themeXml)
        theme.extend_image_filename(path)
        return theme

    def _validate_theme_action(self, select_text, confirm_title, confirm_text,
        testPlugin=True):
        """
        Check to see if theme has been selected and the destructive action
        is allowed.
        """
        self.global_theme = unicode(QtCore.QSettings().value(
            self.settingsSection + u'/global theme',
            QtCore.QVariant(u'')).toString())
        if check_item_selected(self.themeListWidget, select_text):
            item = self.themeListWidget.currentItem()
            theme = unicode(item.text())
            # confirm deletion
            answer = QtGui.QMessageBox.question(self, confirm_title,
                confirm_text % theme, QtGui.QMessageBox.StandardButtons(
                QtGui.QMessageBox.Yes | QtGui.QMessageBox.No),
                QtGui.QMessageBox.No)
            if answer == QtGui.QMessageBox.No:
                return False
            # should be the same unless default
            if theme != unicode(item.data(QtCore.Qt.UserRole).toString()):
                QtGui.QMessageBox.critical(self,
                    translate('OpenLP.ThemeManager', 'Error'),
                    translate('OpenLP.ThemeManager',
                        'You are unable to delete the default theme.'))
                return False
            # check for use in the system else where.
            if testPlugin:
                for plugin in self.mainwindow.pluginManager.plugins:
                    if plugin.usesTheme(theme):
                        Receiver.send_message(u'openlp_error_message', {
                            u'title': translate('OpenLP.ThemeManager',
                            'Validation Error'),
                            u'message': unicode(translate('OpenLP.ThemeManager',
                            'Theme %s is used in the %s plugin.')) % \
                            (theme, plugin.name)})
                        return False
        return True

    def _migrateVersion122(self, xml_data):
        """
        Convert the xml data from version 1 format to the current format.

        New fields are loaded with defaults to provide a complete, working
        theme containing all compatible customisations from the old theme.

        ``xml_data``
            Version 1 theme to convert
        """
        theme = Theme(xml_data)
        newtheme = ThemeXML()
        newtheme.theme_name = theme.Name
        if theme.BackgroundType == 0:
            newtheme.background_type = \
                BackgroundType.to_string(BackgroundType.Solid)
            newtheme.background_color = \
                unicode(theme.BackgroundParameter1.name())
        elif theme.BackgroundType == 1:
            newtheme.background_type = \
                BackgroundType.to_string(BackgroundType.Gradient)
            newtheme.background_direction = \
                BackgroundGradientType. \
                to_string(BackgroundGradientType.Horizontal)
            if theme.BackgroundParameter3.name() == 1:
                newtheme.background_direction = \
                    BackgroundGradientType. \
                    to_string(BackgroundGradientType.Horizontal)
            newtheme.background_start_color = \
                unicode(theme.BackgroundParameter1.name())
            newtheme.background_end_color = \
                unicode(theme.BackgroundParameter2.name())
        else:
            newtheme.background_type = \
                BackgroundType.to_string(BackgroundType.Image)
            newtheme.background_filename = unicode(theme.BackgroundParameter1)
        newtheme.font_main_name = theme.FontName
        newtheme.font_main_color = unicode(theme.FontColor.name())
        newtheme.font_main_size = theme.FontProportion * 3
        newtheme.font_footer_name = theme.FontName
        newtheme.font_footer_color = unicode(theme.FontColor.name())
        newtheme.font_main_shadow = False
        if theme.Shadow == 1:
            newtheme.font_main_shadow = True
            newtheme.font_main_shadow_color = unicode(theme.ShadowColor.name())
        if theme.Outline == 1:
            newtheme.font_main_outline = True
            newtheme.font_main_outline_color = \
                unicode(theme.OutlineColor.name())
        vAlignCorrection = 0
        if theme.VerticalAlign == 2:
            vAlignCorrection = 1
        elif theme.VerticalAlign == 1:
            vAlignCorrection = 2
        newtheme.display_horizontal_align = theme.HorizontalAlign
        newtheme.display_vertical_align = vAlignCorrection
        return newtheme.extract_xml()