Helpviewer/ZoomManager/ZoomManager.py

# -*- coding: utf-8 -*-

# Copyright (c) 2015 - 2018 Detlev Offenbach <detlev@die-offenbachs.de>
#

"""
Module implementing a manager for site specific zoom level settings.
"""

from __future__ import unicode_literals

import json

from PyQt5.QtCore import pyqtSignal, QObject

from Utilities.AutoSaver import AutoSaver
import Preferences


class ZoomManager(QObject):
    """
    Class implementing a manager for site specific zoom level settings.
    
    @signal changed() emitted to indicate a change of the zoom level
    """
    changed = pyqtSignal()
    
    def __init__(self, parent=None):
        """
        Constructor
        
        @param parent reference to the parent object (QObject)
        """
        super(ZoomManager, self).__init__(parent)
        
        self.__zoomDB = {}
        
        self.__saveTimer = AutoSaver(self, self.save)
        
        self.changed.connect(self.__saveTimer.changeOccurred)
        
        self.__loaded = False
    
    def close(self):
        """
        Public method to close the bookmark manager.
        """
        self.__saveTimer.saveIfNeccessary()
    
    def load(self):
        """
        Public method to load the bookmarks.
        """
        if self.__loaded:
            return
        
        dbString = Preferences.getHelp("ZoomValuesDB")
        if dbString:
            try:
                db = json.loads(dbString)
                self.__zoomDB = db
            except ValueError:
                # ignore silently
                pass
        
        self.__loaded = True
    
    def save(self):
        """
        Public method to save the bookmarks.
        """
        if not self.__loaded:
            return
        
        dbString = json.dumps(self.__zoomDB)
        Preferences.setHelp("ZoomValuesDB", dbString)
    
    def __keyFromUrl(self, url):
        """
        Private method to generate a DB key for an URL.
        
        @param url URL to generate a key for
        @type QUrl
        @return key for the given URL
        @rtype str
        """
        if url.isEmpty():
            key = ""
        else:
            scheme = url.scheme()
            host = url.host()
            if host:
                key = host
            elif scheme == "file":
                path = url.path()
                key = path.rsplit("/", 1)[0]
            else:
                key = ""
        
        return key
    
    def setZoomValue(self, url, zoomValue):
        """
        Public method to record the zoom value for the given URL.
        
        Note: Only zoom values not equal 100% are recorded.
        
        @param url URL of the page to remember the zoom value for
        @type QUrl
        @param zoomValue zoom value for the URL
        @type int
        """
        self.load()
        
        key = self.__keyFromUrl(url)
        if not key:
            return
        
        if ((zoomValue == 100 and key not in self.__zoomDB) or
                (key in self.__zoomDB and self.__zoomDB[key] == zoomValue)):
            return
        
        if zoomValue == 100:
            del self.__zoomDB[key]
        else:
            self.__zoomDB[key] = zoomValue
        
        self.changed.emit()
    
    def zoomValue(self, url):
        """
        Public method to get the zoom value for an URL.
        
        @param url URL of the page to get the zoom value for
        @type QUrl
        @return zoomValue zoom value for the URL
        @rtype int
        """
        self.load()
        
        key = self.__keyFromUrl(url)
        if not key:
            zoom = 100
        
        if key in self.__zoomDB:
            zoom = self.__zoomDB[key]
        else:
            # default zoom value (i.e. no zoom)
            zoom = 100
        
        return zoom
    
    def clear(self):
        """
        Public method to clear the saved zoom values.
        """
        self.__zoomDB = {}
        self.__loaded = True
        
        self.changed.emit()
    
    def removeZoomValue(self, site):
        """
        Public method to remove a zoom value entry.
        
        @param site web site name
        @type str
        """
        self.load()
        
        if site in self.__zoomDB:
            del self.__zoomDB[site]
            self.changed.emit()
    
    def allSiteNames(self):
        """
        Public method to get a list of all site names.
        
        @return sorted list of all site names
        @rtype list of str
        """
        self.load()
        
        return sorted(self.__zoomDB.keys())
    
    def sitesCount(self):
        """
        Public method to get the number of available sites.
        
        @return number of sites
        @rtype int
        """
        self.load()
        
        return len(self.__zoomDB)
    
    def siteInfo(self, site):
        """
        Public method to get the zoom value for the site.
        
        @param site web site name
        @type str
        @return zoom value for the site
        @rtype int
        """
        self.load()
        
        if site not in self.__zoomDB:
            return None
        
        return self.__zoomDB[site]