qpreferences.py

import os
from PyQt4 import QtCore, QtGui, uic

def fromVariant(v):
    _cvrts = {0: lambda x:None,
              1: lambda x:x.toBool(),
              2: lambda x:x.toInt()[0],
              6: lambda x:x.toDouble()[0],
              10: lambda x:unicode(x.toString()),
              12: lambda x:x.toByteArray(),
              21: lambda x:x.toSize(),
              22: lambda x:x.toSizeF(),
              25: lambda x:x.toPoint(),
              26: lambda x:x.toPointF(),
              
              }
    t = v.userType()
    return _cvrts[t](v)
    
class PreferenceItem(object):
    _id = 0
    def __init__(self, default=None, basetype=None, name=None, description=None):
        self._default = default
        self._basetype = basetype
        if self._basetype is None:
            self._basetype = self._default.__class__
        self._id = "_pref%X"%self.__class__._id
        self._name = name
        self._description = description
        self.__class__._id += 1

    def __get__(self, obj, cls):
        if obj is None:
            return self
        try:
            return obj.getPref(self._id)
        except Exception, e:
            #print "humm", e
            return None

    def __set__(self, obj, value):
        obj.setPref(self._id, value)
        
class AbstractPreferences(QtCore.QObject):
    def __init__(self):
        QtCore.QObject.__init__(self)
        self._settings = QtCore.QSettings(QtCore.QSettings.UserScope,
                                          self.ORGANISATION, self.APPLICATION)
        self._prefs = {}
        for k in dir(self.__class__):
            item = getattr(self.__class__, k)
            if isinstance(item, PreferenceItem):
                self._prefs[item._id] = k            
        
    def getPref(self, key):
        key = self._prefs.get(key, key)
        default = getattr(self.__class__, key)._default
        if default is not None:
            default = QtCore.QVariant(default)
        else:
            default = QtCore.QVariant()
        val = self._settings.value(key, default)
        return fromVariant(val)
    
    def setPref(self, key, value):
        key = self._prefs.get(key, key)
        self._settings.setValue(key, QtCore.QVariant(value))

    def keys(self):
        return [k for k in self._prefs.values() if not k.startswith('_')]

    def getName(self, key):
        item = getattr(self.__class__, key)
        return item._name

    def getDescription(self, key):
        item = getattr(self.__class__, key)
        return item._description
    
form_class, base_class = uic.loadUiType(os.path.join(os.path.dirname(__file__), "qpreferences_dialog.ui"))

class PreferencesEditor(QtGui.QDialog, form_class):
    def __init__(self, preferences, parent=None):
        QtGui.QDialog.__init__(self, parent)
        self.setupUi(self)
        self._prefs = preferences
        self.buildUI()

    def buildUI(self):
        w = self.centralFrame
        g = QtGui.QGridLayout(w)
        p = self._prefs
        eds = {}
        self._editors = eds
        for i, k in enumerate(p.keys()):
            name = p.getName(k)
            if not name:
                name = k
            l = QtGui.QLabel(name, w)
            g.addWidget(l, i, 0)
            if p.getDescription(k):
                l.setToolTip(p.getDescription(k))
            
            e = QtGui.QLineEdit(w)
            eds[k] = e
            g.addWidget(e, i, 1)
            val = p.getPref(k)
            if val is None:
                val = ''
            if not isinstance(val, basestring):
                val = unicode(val)
            e.setText(val)
            
        g.addWidget(QtGui.QWidget(w), i+1, 0)
        g.setRowStretch(i+1,1)
        g.setColumnStretch(1,1)

    def accept(self):
        p=self._prefs
        for k in p.keys():
            newval = unicode(self._editors[k].text())
            p.setPref(k, newval)            
        return QtGui.QDialog.accept(self)
            
if __name__ == '__main__':
    class TestPreferences(AbstractPreferences):
        ORGANISATION="Logilab"
        APPLICATION="test_qpref_editor"

        device = PreferenceItem('/dev/ttyUSB0', name="the device")
        address = PreferenceItem(5, description="GPIB address of the plotter")
        _pos = PreferenceItem(None)
        _size = PreferenceItem(None)
        _appState = PreferenceItem(None)
        
    a = QtGui.QApplication([])

    prefs = TestPreferences()
    w = PreferencesEditor(prefs)
    w.show()
    a.exec_()