VariablePanel.py
author b.taylor@willowglen.ca
Thu, 17 Sep 2009 14:17:52 -0600
changeset 427 22d16c457d87
parent 425 dbc4a66190a6
child 431 c1c92d068ac5
permissions -rw-r--r--
improved English spelling & grammar
# -*- coding: utf-8 -*-

#This file is part of PLCOpenEditor, a library implementing an IEC 61131-3 editor
#based on the plcopen standard. 
#
#Copyright (C) 2007: Edouard TISSERANT and Laurent BESSARD
#
#See COPYING file for copyrights details.
#
#This library 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 2.1 of the License, or (at your option) any later version.
#
#This library 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 library; if not, write to the Free Software
#Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

import wx, wx.grid

from types import TupleType

from PLCOpenEditor import AppendMenu
from plcopen.structures import LOCATIONDATATYPES, TestIdentifier, IEC_KEYWORDS

#-------------------------------------------------------------------------------
#                            Variables Editor Panel
#-------------------------------------------------------------------------------

def GetVariableTableColnames(location):
    _ = lambda x : x
    if location:
    	return ["#", _("Name"), _("Class"), _("Type"), _("Location"), _("Initial Value"), _("Retain"), _("Constant"), _("Documentation")]
    return ["#", _("Name"), _("Class"), _("Type"), _("Initial Value"), _("Retain"), _("Constant"), _("Documentation")]

def GetAlternativeOptions():
    _ = lambda x : x
    return [_("Yes"), _("No")]
ALTERNATIVE_OPTIONS_DICT = dict([(_(option), option) for option in GetAlternativeOptions()])

def GetFilterChoiceTransfer():
    _ = lambda x : x
    return {_("All"): _("All"), _("Interface"): _("Interface"), 
            _("   Input"): _("Input"), _("   Output"): _("Output"), _("   InOut"): _("InOut"), 
            _("   External"): _("External"), _("Variables"): _("Variables"), _("   Local"): _("Local"),
            _("   Temp"): _("Temp"), _("Global"): _("Global")}#, _("Access") : _("Access")}
VARIABLE_CLASSES_DICT = dict([(_(_class), _class) for _class in GetFilterChoiceTransfer().itervalues()])

class VariableTable(wx.grid.PyGridTableBase):
    
    """
    A custom wx.grid.Grid Table using user supplied data
    """
    def __init__(self, parent, data, colnames):
        # The base class must be initialized *first*
        wx.grid.PyGridTableBase.__init__(self)
        self.data = data
        self.old_value = None
        self.colnames = colnames
        self.Errors = {}
        self.Parent = parent
        # XXX
        # we need to store the row length and collength to
        # see if the table has changed size
        self._rows = self.GetNumberRows()
        self._cols = self.GetNumberCols()
    
    def GetNumberCols(self):
        return len(self.colnames)
        
    def GetNumberRows(self):
        return len(self.data)

    def GetColLabelValue(self, col, translate=True):
        if col < len(self.colnames):
            if translate:
                return _(self.colnames[col])
            return self.colnames[col]

    def GetRowLabelValues(self, row, translate=True):
        return row

    def GetValue(self, row, col):
        if row < self.GetNumberRows():
            if col == 0:
                return self.data[row]["Number"]
            colname = self.GetColLabelValue(col, False)
            value = str(self.data[row].get(colname, ""))
            if colname in ["Class", "Retain", "Constant"]:
                return _(value)
            return value
    
    def SetValue(self, row, col, value):
        if col < len(self.colnames):
            colname = self.GetColLabelValue(col, False)
            if colname == "Name":
                self.old_value = self.data[row][colname]
            elif colname == "Class":
                value = VARIABLE_CLASSES_DICT[value]
            elif colname in ["Retain", "Constant"]:
                value = ALTERNATIVE_OPTIONS_DICT[value]
            self.data[row][colname] = value
    
    def GetValueByName(self, row, colname):
        if row < self.GetNumberRows():
            return self.data[row].get(colname)

    def SetValueByName(self, row, colname, value):
        if row < self.GetNumberRows():
            self.data[row][colname] = value

    def GetOldValue(self):
        return self.old_value
    
    def ResetView(self, grid):
        """
        (wx.grid.Grid) -> Reset the grid view.   Call this to
        update the grid if rows and columns have been added or deleted
        """
        grid.BeginBatch()
        for current, new, delmsg, addmsg in [
            (self._rows, self.GetNumberRows(), wx.grid.GRIDTABLE_NOTIFY_ROWS_DELETED, wx.grid.GRIDTABLE_NOTIFY_ROWS_APPENDED),
            (self._cols, self.GetNumberCols(), wx.grid.GRIDTABLE_NOTIFY_COLS_DELETED, wx.grid.GRIDTABLE_NOTIFY_COLS_APPENDED),
        ]:
            if new < current:
                msg = wx.grid.GridTableMessage(self,delmsg,new,current-new)
                grid.ProcessTableMessage(msg)
            elif new > current:
                msg = wx.grid.GridTableMessage(self,addmsg,new-current)
                grid.ProcessTableMessage(msg)
                self.UpdateValues(grid)
        grid.EndBatch()

        self._rows = self.GetNumberRows()
        self._cols = self.GetNumberCols()
        # update the column rendering scheme
        self._updateColAttrs(grid)

        # update the scrollbars and the displayed part of the grid
        grid.AdjustScrollbars()
        grid.ForceRefresh()

    def UpdateValues(self, grid):
        """Update all displayed values"""
        # This sends an event to the grid table to update all of the values
        msg = wx.grid.GridTableMessage(self, wx.grid.GRIDTABLE_REQUEST_VIEW_GET_VALUES)
        grid.ProcessTableMessage(msg)

    def _updateColAttrs(self, grid):
        """
        wx.grid.Grid -> update the column attributes to add the
        appropriate renderer given the column name.

        Otherwise default to the default renderer.
        """
        
        for row in range(self.GetNumberRows()):
            for col in range(self.GetNumberCols()):
                editor = None
                renderer = None
                colname = self.GetColLabelValue(col, False)
                if col != 0 and self.GetValueByName(row, "Edit"):
                    grid.SetReadOnly(row, col, False)
                    if colname == "Name":
                        if self.Parent.PouIsUsed and self.GetValueByName(row, "Class") in ["Input", "Output", "InOut"]:
                            grid.SetReadOnly(row, col, True)
                        else:
                            editor = wx.grid.GridCellTextEditor()
                            renderer = wx.grid.GridCellStringRenderer()
                    elif colname == "Initial Value":
                        editor = wx.grid.GridCellTextEditor()
                        renderer = wx.grid.GridCellStringRenderer()
                    elif colname == "Location":
                        if self.GetValueByName(row, "Class") in ["Local", "Global"]:
                            editor = LocationCellEditor(self.Parent)
                            renderer = wx.grid.GridCellStringRenderer()
                        else:
                            grid.SetReadOnly(row, col, True)
                    elif colname == "Class":
                        if len(self.Parent.ClassList) == 1 or self.Parent.PouIsUsed and self.GetValueByName(row, "Class") in ["Input", "Output", "InOut"]:
                            grid.SetReadOnly(row, col, True)
                        else:
                            editor = wx.grid.GridCellChoiceEditor()
                            excluded = []
                            if self.Parent.PouIsUsed:
                                excluded.extend(["Input","Output","InOut"])
                            if self.Parent.IsFunctionBlockType(self.data[row]["Type"]):
                                excluded.extend(["Local","Temp"])
                            editor.SetParameters(",".join([_(choice) for choice in self.Parent.ClassList if choice not in excluded]))
                    elif colname in ["Retain", "Constant"]:
                        editor = wx.grid.GridCellChoiceEditor()
                        editor.SetParameters(",".join(map(_, self.Parent.OptionList)))
                    elif colname == "Type":
                        editor = wx.grid.GridCellTextEditor()
                else:
                    grid.SetReadOnly(row, col, True)
                
                grid.SetCellEditor(row, col, editor)
                grid.SetCellRenderer(row, col, renderer)
                
                if row in self.Errors and self.Errors[row][0] == colname.lower():
                    grid.SetCellBackgroundColour(row, col, wx.Colour(255, 255, 0))
                    grid.SetCellTextColour(row, col, wx.RED)
                    grid.MakeCellVisible(row, col)
                else:
                    grid.SetCellTextColour(row, col, wx.BLACK)
                    grid.SetCellBackgroundColour(row, col, wx.WHITE)
    
    def SetData(self, data):
        self.data = data
    
    def GetData(self):
        return self.data
    
    def GetCurrentIndex(self):
        return self.CurrentIndex
    
    def SetCurrentIndex(self, index):
        self.CurrentIndex = index
    
    def AppendRow(self, row_content):
        self.data.append(row_content)

    def RemoveRow(self, row_index):
        self.data.pop(row_index)

    def GetRow(self, row_index):
        return self.data[row_index]

    def Empty(self):
        self.data = []
        self.editors = []

    def AddError(self, infos):
        self.Errors[infos[0]] = infos[1:]

    def ClearErrors(self):
        self.Errors = {}

class VariableDropTarget(wx.TextDropTarget):
    '''
    This allows dragging a variable location from somewhere to the Location
    column of a variable row.
    
    The drag source should be a TextDataObject containing a Python tuple like:
        ('%ID0.0.0', 'location', 'REAL')
    
    c_ext/CFileEditor.py has an example of this (you can drag a C extension
    variable to the Location column of the variable panel).
    '''
    def __init__(self, parent):
        wx.TextDropTarget.__init__(self)
        self.ParentWindow = parent
    
    def OnDropText(self, x, y, data):
        x, y = self.ParentWindow.VariablesGrid.CalcUnscrolledPosition(x, y)
        col = self.ParentWindow.VariablesGrid.XToCol(x)
        row = self.ParentWindow.VariablesGrid.YToRow(y - self.ParentWindow.VariablesGrid.GetColLabelSize())
        if col != wx.NOT_FOUND and row != wx.NOT_FOUND:
            if self.ParentWindow.Table.GetColLabelValue(col, False) != "Location":
                return
            message = None
            if not self.ParentWindow.Table.GetValueByName(row, "Edit"):
                message = _("Can't give a location to a function block instance")
            elif self.ParentWindow.Table.GetValueByName(row, "Class") not in ["Local", "Global"]:
                message = _("Can only give a location to local or global variables")
            else:
                try:
                    values = eval(data)    
                except:
                    message = _("Invalid value \"%s\" for location")%data
                    values = None
                if not isinstance(values, TupleType):
                    message = _("Invalid value \"%s\" for location")%data
                    values = None
                if values is not None and values[1] == "location":
                    location = values[0]
                    variable_type = self.ParentWindow.Table.GetValueByName(row, "Type")
                    base_type = self.ParentWindow.Controler.GetBaseType(variable_type)
                    message = None
                    if location.startswith("%"):
                        if base_type != values[2]:
                            message = _("Incompatible data types between \"%s\" and \"%s\"")%(values[2], variable_type)
                        else:
                            self.ParentWindow.Table.SetValue(row, col, location)
                            self.ParentWindow.Table.ResetView(self.ParentWindow.VariablesGrid)
                            self.ParentWindow.SaveValues()
                    else:
                        if location[0].isdigit() and base_type != "BOOL":
                            message = _("Incompatible size of data between \"%s\" and \"BOOL\"")%location
                        elif location[0] not in LOCATIONDATATYPES:
                            message = _("Unrecognized data size \"%s\"")%location[0]
                        elif base_type not in LOCATIONDATATYPES[location[0]]:
                            message = _("Incompatible size of data between \"%s\" and \"%s\"")%(location, variable_type)
                        else:
                            dialog = wx.SingleChoiceDialog(self.ParentWindow, _("Select a variable class:"), _("Variable class"), ["Input", "Output", "Memory"], wx.OK|wx.CANCEL)
                            if dialog.ShowModal() == wx.ID_OK:
                                selected = dialog.GetSelection()
                                if selected == 0:
                                    location = "%I" + location
                                elif selected == 1:
                                    location = "%Q" + location
                                else:
                                    location = "%M" + location
                                self.ParentWindow.Table.SetValue(row, col, location)
                                self.ParentWindow.Table.ResetView(self.ParentWindow.VariablesGrid)
                                self.ParentWindow.SaveValues()
                            dialog.Destroy()
            if message is not None:
                wx.CallAfter(self.ShowMessage, message)
            
    def ShowMessage(self, message):
        message = wx.MessageDialog(self.ParentWindow, message, _("Error"), wx.OK|wx.ICON_ERROR)
        message.ShowModal()
        message.Destroy()

[ID_VARIABLEEDITORPANEL, ID_VARIABLEEDITORPANELVARIABLESGRID, 
 ID_VARIABLEEDITORCONTROLPANEL, ID_VARIABLEEDITORPANELRETURNTYPE, 
 ID_VARIABLEEDITORPANELCLASSFILTER, ID_VARIABLEEDITORPANELADDBUTTON, 
 ID_VARIABLEEDITORPANELDELETEBUTTON, ID_VARIABLEEDITORPANELUPBUTTON, 
 ID_VARIABLEEDITORPANELDOWNBUTTON, ID_VARIABLEEDITORPANELSTATICTEXT1, 
 ID_VARIABLEEDITORPANELSTATICTEXT2, ID_VARIABLEEDITORPANELSTATICTEXT3,
] = [wx.NewId() for _init_ctrls in range(12)]

class VariablePanel(wx.Panel):
    
    if wx.VERSION < (2, 6, 0):
        def Bind(self, event, function, id = None):
            if id is not None:
                event(self, id, function)
            else:
                event(self, function)
    
    def _init_coll_MainSizer_Items(self, parent):
        parent.AddWindow(self.VariablesGrid, 0, border=0, flag=wx.GROW)
        parent.AddWindow(self.ControlPanel, 0, border=5, flag=wx.GROW|wx.ALL)
    
    def _init_coll_MainSizer_Growables(self, parent):
        parent.AddGrowableCol(0)
        parent.AddGrowableRow(0)
    
    def _init_coll_ControlPanelSizer_Items(self, parent):
        parent.AddSizer(self.ChoicePanelSizer, 0, border=0, flag=wx.GROW)
        parent.AddSizer(self.ButtonPanelSizer, 0, border=0, flag=wx.ALIGN_CENTER)

    def _init_coll_ControlPanelSizer_Growables(self, parent):
        parent.AddGrowableCol(0)
        parent.AddGrowableRow(0)
        parent.AddGrowableRow(1)

    def _init_coll_ChoicePanelSizer_Items(self, parent):
        parent.AddWindow(self.staticText1, 0, border=0, flag=wx.ALIGN_BOTTOM)
        parent.AddWindow(self.ReturnType, 0, border=0, flag=0)
        parent.AddWindow(self.staticText2, 0, border=0, flag=wx.ALIGN_BOTTOM)
        parent.AddWindow(self.ClassFilter, 0, border=0, flag=0)

    def _init_coll_ButtonPanelSizer_Items(self, parent):
        parent.AddWindow(self.UpButton, 0, border=0, flag=0)
        parent.AddWindow(self.AddButton, 0, border=0, flag=0)
        parent.AddWindow(self.DownButton, 0, border=0, flag=0)
        parent.AddWindow(self.DeleteButton, 0, border=0, flag=0)
        
    def _init_coll_ButtonPanelSizer_Growables(self, parent):
        parent.AddGrowableCol(0)
        parent.AddGrowableCol(1)
        parent.AddGrowableCol(2)
        parent.AddGrowableCol(3)
        parent.AddGrowableRow(0)

    def _init_sizers(self):
        self.MainSizer = wx.FlexGridSizer(cols=2, hgap=10, rows=1, vgap=0)
        self.ControlPanelSizer = wx.FlexGridSizer(cols=1, hgap=0, rows=2, vgap=5)
        self.ChoicePanelSizer = wx.GridSizer(cols=1, hgap=5, rows=4, vgap=5)
        self.ButtonPanelSizer = wx.FlexGridSizer(cols=2, hgap=5, rows=2, vgap=5)
        
        self._init_coll_MainSizer_Items(self.MainSizer)
        self._init_coll_MainSizer_Growables(self.MainSizer)
        self._init_coll_ControlPanelSizer_Items(self.ControlPanelSizer)
        self._init_coll_ControlPanelSizer_Growables(self.ControlPanelSizer)
        self._init_coll_ChoicePanelSizer_Items(self.ChoicePanelSizer)
        self._init_coll_ButtonPanelSizer_Items(self.ButtonPanelSizer)
        self._init_coll_ButtonPanelSizer_Growables(self.ButtonPanelSizer)
        
        self.SetSizer(self.MainSizer)
        self.ControlPanel.SetSizer(self.ControlPanelSizer)

    def _init_ctrls(self, prnt):
        wx.Panel.__init__(self, id=ID_VARIABLEEDITORPANEL,
              name='VariableEditorPanel', parent=prnt, pos=wx.Point(0, 0),
              size=wx.Size(0, 0), style=wx.TAB_TRAVERSAL)

        self.VariablesGrid = wx.grid.Grid(id=ID_VARIABLEEDITORPANELVARIABLESGRID,
              name='VariablesGrid', parent=self, pos=wx.Point(0, 0), 
              size=wx.Size(0, 0), style=wx.VSCROLL)
        self.VariablesGrid.SetFont(wx.Font(12, 77, wx.NORMAL, wx.NORMAL, False,
              'Sans'))
        self.VariablesGrid.SetLabelFont(wx.Font(10, 77, wx.NORMAL, wx.NORMAL,
              False, 'Sans'))
        self.VariablesGrid.SetSelectionBackground(wx.WHITE)
        self.VariablesGrid.SetSelectionForeground(wx.BLACK)
        if wx.VERSION >= (2, 6, 0):
            self.VariablesGrid.Bind(wx.grid.EVT_GRID_CELL_CHANGE, self.OnVariablesGridCellChange)
            self.VariablesGrid.Bind(wx.grid.EVT_GRID_SELECT_CELL, self.OnVariablesGridSelectCell)
            self.VariablesGrid.Bind(wx.grid.EVT_GRID_CELL_LEFT_CLICK, self.OnVariablesGridCellLeftClick)
            self.VariablesGrid.Bind(wx.grid.EVT_GRID_EDITOR_SHOWN, self.OnVariablesGridEditorShown)
            #self.VariablesGrid.Bind(wx.EVT_KEY_DOWN, self.OnChar)
        else:
            wx.grid.EVT_GRID_CELL_CHANGE(self.VariablesGrid, self.OnVariablesGridCellChange)
            wx.grid.EVT_GRID_SELECT_CELL(self.VariablesGrid, self.OnVariablesGridSelectCell)
            wx.grid.EVT_GRID_CELL_LEFT_CLICK(self.VariablesGrid, self.OnVariablesGridCellLeftClick)
            wx.grid.EVT_GRID_EDITOR_SHOWN(self.VariablesGrid, self.OnVariablesGridEditorShown)
            #wx.EVT_KEY_DOWN(self.VariablesGrid, self.OnChar)
        self.VariablesGrid.SetDropTarget(VariableDropTarget(self))
        
        self.ControlPanel = wx.ScrolledWindow(id=ID_VARIABLEEDITORCONTROLPANEL,
              name='ControlPanel', parent=self, pos=wx.Point(0, 0),
              size=wx.Size(0, 0), style=wx.TAB_TRAVERSAL)
        self.ControlPanel.SetScrollRate(0, 10)
        
        self.staticText1 = wx.StaticText(id=ID_VARIABLEEDITORPANELSTATICTEXT1,
              label=_('Return Type:'), name='staticText1', parent=self.ControlPanel,
              pos=wx.Point(0, 0), size=wx.Size(145, 17), style=0)

        self.ReturnType = wx.ComboBox(id=ID_VARIABLEEDITORPANELRETURNTYPE,
              name='ReturnType', parent=self.ControlPanel, pos=wx.Point(0, 0),
              size=wx.Size(145, 28), style=wx.CB_READONLY)
        self.Bind(wx.EVT_COMBOBOX, self.OnReturnTypeChanged, id=ID_VARIABLEEDITORPANELRETURNTYPE)

        self.staticText2 = wx.StaticText(id=ID_VARIABLEEDITORPANELSTATICTEXT2,
              label=_('Class Filter:'), name='staticText2', parent=self.ControlPanel,
              pos=wx.Point(0, 0), size=wx.Size(145, 17), style=0)

        self.ClassFilter = wx.ComboBox(id=ID_VARIABLEEDITORPANELCLASSFILTER,
              name='ClassFilter', parent=self.ControlPanel, pos=wx.Point(0, 0),
              size=wx.Size(145, 28), style=wx.CB_READONLY)
        self.Bind(wx.EVT_COMBOBOX, self.OnClassFilter, id=ID_VARIABLEEDITORPANELCLASSFILTER)

        self.AddButton = wx.Button(id=ID_VARIABLEEDITORPANELADDBUTTON, label=_('Add'),
              name='AddButton', parent=self.ControlPanel, pos=wx.Point(0, 0),
              size=wx.DefaultSize, style=0)
        self.Bind(wx.EVT_BUTTON, self.OnAddButton, id=ID_VARIABLEEDITORPANELADDBUTTON)

        self.DeleteButton = wx.Button(id=ID_VARIABLEEDITORPANELDELETEBUTTON, label=_('Delete'),
              name='DeleteButton', parent=self.ControlPanel, pos=wx.Point(0, 0),
              size=wx.DefaultSize, style=0)
        self.Bind(wx.EVT_BUTTON, self.OnDeleteButton, id=ID_VARIABLEEDITORPANELDELETEBUTTON)

        self.UpButton = wx.Button(id=ID_VARIABLEEDITORPANELUPBUTTON, label='^',
              name='UpButton', parent=self.ControlPanel, pos=wx.Point(0, 0),
              size=wx.Size(32, 32), style=0)
        self.Bind(wx.EVT_BUTTON, self.OnUpButton, id=ID_VARIABLEEDITORPANELUPBUTTON)

        self.DownButton = wx.Button(id=ID_VARIABLEEDITORPANELDOWNBUTTON, label='v',
              name='DownButton', parent=self.ControlPanel, pos=wx.Point(0, 0),
              size=wx.Size(32, 32), style=0)
        self.Bind(wx.EVT_BUTTON, self.OnDownButton, id=ID_VARIABLEEDITORPANELDOWNBUTTON)

        self._init_sizers()

    def __init__(self, parent, window, controler, element_type):
        self._init_ctrls(parent)
        self.ParentWindow = window
        self.Controler = controler
        self.ElementType = element_type
        
        self.Filter = "All"
        self.FilterChoices = []
        self.FilterChoiceTransfer = GetFilterChoiceTransfer()
        
        self.DefaultValue = {   "Name" : "", "Class" : "", "Type" : "INT", "Location" : "",
                                "Initial Value" : "", "Retain" : "No", "Constant" : "No",
                                "Documentation" : "", "Edit" : True
                            }

        if element_type in ["config", "resource"]:
            self.DefaultTypes = {"All" : "Global"}
        else:
            self.DefaultTypes = {"All" : "Local", "Interface" : "Input", "Variables" : "Local"}

        if element_type in ["config", "resource"] \
        or element_type in ["program", "transition", "action"]:
            # this is an element that can have located variables
            self.Table = VariableTable(self, [], GetVariableTableColnames(True))

            if element_type in ["config", "resource"]:
                self.FilterChoices = ["All", "Global"]#,"Access"]
            else:
                self.FilterChoices = ["All",
                                        "Interface", "   Input", "   Output", "   InOut", "   External",
                                        "Variables", "   Local", "   Temp"]#,"Access"]

            # these condense the ColAlignements list
            l = wx.ALIGN_LEFT
            c = wx.ALIGN_CENTER 

            #                      Num  Name    Class   Type    Loc     Init    Retain  Const   Doc
            self.ColSizes       = [40,  80,     70,     80,     80,     80,     60,     70,     80]
            self.ColAlignements = [c,   l,      l,      l,      l,      l,      c,      c,      l]

        else:
            # this is an element that cannot have located variables
            self.Table = VariableTable(self, [], GetVariableTableColnames(False))

            if element_type == "function":
                self.FilterChoices = ["All",
                                        "Interface", "   Input", "   Output", "   InOut",
                                        "Variables", "   Local", "   Temp"]
            else:
                self.FilterChoices = ["All",
                                        "Interface", "   Input", "   Output", "   InOut", "   External",
                                        "Variables", "   Local", "   Temp"]

            # these condense the ColAlignements list
            l = wx.ALIGN_LEFT
            c = wx.ALIGN_CENTER 

            #                      Num  Name    Class   Type    Init    Retain  Const   Doc
            self.ColSizes       = [40,  80,     70,     80,     80,     60,     70,     160]
            self.ColAlignements = [c,   l,      l,      l,      l,      c,      c,      l]

        for choice in self.FilterChoices:
            self.ClassFilter.Append(_(choice))

        reverse_transfer = {}
        for filter, choice in self.FilterChoiceTransfer.items():
            reverse_transfer[choice] = filter
        self.ClassFilter.SetStringSelection(_(reverse_transfer[self.Filter]))
        self.RefreshTypeList()

        self.OptionList = GetAlternativeOptions()
        
        if element_type == "function":
            for base_type in self.Controler.GetBaseTypes():
                self.ReturnType.Append(base_type)
            self.ReturnType.Enable(True)
        else:
            self.ReturnType.Enable(False)
            self.staticText1.Hide()
            self.ReturnType.Hide()
            
        self.VariablesGrid.SetTable(self.Table)
        self.VariablesGrid.SetRowLabelSize(0)
        for col in range(self.Table.GetNumberCols()):
            attr = wx.grid.GridCellAttr()
            attr.SetAlignment(self.ColAlignements[col], wx.ALIGN_CENTRE)
            self.VariablesGrid.SetColAttr(col, attr)
            self.VariablesGrid.SetColMinimalWidth(col, self.ColSizes[col])
            self.VariablesGrid.AutoSizeColumn(col, False)
    
    def SetTagName(self, tagname):
        self.TagName = tagname
    
    def IsFunctionBlockType(self, name):
        bodytype = self.Controler.GetEditedElementBodyType(self.TagName, self.ParentWindow.Debug)
        pouname, poutype = self.Controler.GetEditedElementType(self.TagName, self.ParentWindow.Debug)
        if poutype != "function" and bodytype in ["ST", "IL"]:
            return False
        else:
            return name in self.Controler.GetFunctionBlockTypes(self.TagName, self.ParentWindow.Debug)
    
    def RefreshView(self):
        self.PouNames = self.Controler.GetProjectPouNames(self.ParentWindow.Debug)
        
        words = self.TagName.split("::")
        if self.ElementType == "config":
            self.PouIsUsed = False
            returnType = None
            self.Values = self.Controler.GetConfigurationGlobalVars(words[1], self.ParentWindow.Debug)
        elif self.ElementType == "resource":
            self.PouIsUsed = False
            returnType = None
            self.Values = self.Controler.GetConfigurationResourceGlobalVars(words[1], words[2], self.ParentWindow.Debug)
        else:
            self.PouIsUsed = self.Controler.PouIsUsed(words[1], self.ParentWindow.Debug)
            returnType = self.Controler.GetEditedElementInterfaceReturnType(self.TagName, self.ParentWindow.Debug)
            self.Values = self.Controler.GetEditedElementInterfaceVars(self.TagName, self.ParentWindow.Debug)
        
        if returnType and self.ReturnType.IsEnabled():
            self.ReturnType.SetStringSelection(returnType)
        
        self.RefreshValues()
        self.RefreshButtons()
    
    def OnReturnTypeChanged(self, event):
        words = self.TagName.split("::")
        self.Controler.SetPouInterfaceReturnType(words[1], self.ReturnType.GetStringSelection())
        self.Controler.BufferProject()
        self.ParentWindow.RefreshEditor(variablepanel = False)
        self.ParentWindow.RefreshTitle()
        self.ParentWindow.RefreshEditMenu()
        self.ParentWindow.RefreshInstancesTree()
        self.ParentWindow.RefreshLibraryTree()
        event.Skip()
    
    def OnClassFilter(self, event):
        self.Filter = self.FilterChoiceTransfer[self.ClassFilter.GetStringSelection()]
        self.RefreshTypeList()
        self.RefreshValues()
        self.RefreshButtons()
        event.Skip()

    def RefreshTypeList(self):
        if self.Filter == "All":
            self.ClassList = [self.FilterChoiceTransfer[choice] for choice in self.FilterChoices if self.FilterChoiceTransfer[choice] not in ["All","Interface","Variables"]]
        elif self.Filter == "Interface":
            self.ClassList = ["Input","Output","InOut","External"]
        elif self.Filter == "Variables":
            self.ClassList = ["Local","Temp"]
        else:
            self.ClassList = [self.Filter]

    def RefreshButtons(self):
        if getattr(self, "Table", None):
            table_length = len(self.Table.data)
            row_class = None
            row_edit = True
            if table_length > 0:
                row = self.VariablesGrid.GetGridCursorRow()
                row_edit = self.Table.GetValueByName(row, "Edit")
                if self.PouIsUsed:
                    row_class = self.Table.GetValueByName(row, "Class")
            self.AddButton.Enable(not self.PouIsUsed or self.Filter not in ["Interface", "Input", "Output", "InOut"])
            self.DeleteButton.Enable(table_length > 0 and row_edit and row_class not in ["Input", "Output", "InOut"])
            self.UpButton.Enable(table_length > 0 and self.Filter == "All" and row_class not in ["Input", "Output", "InOut"])
            self.DownButton.Enable(table_length > 0 and self.Filter == "All" and row_class not in ["Input", "Output", "InOut"])

    def OnAddButton(self, event):
        new_row = self.DefaultValue.copy()
        if self.Filter in self.DefaultTypes:
            new_row["Class"] = self.DefaultTypes[self.Filter]
        else:
            new_row["Class"] = self.Filter
        if self.Filter == "All" and len(self.Values) > 0:
            row_index = self.VariablesGrid.GetGridCursorRow() + 1
            self.Values.insert(row_index, new_row)
        else:
            row_index = -1
            self.Values.append(new_row)
        self.SaveValues()
        self.RefreshValues(row_index)
        self.RefreshButtons()
        event.Skip()

    def OnDeleteButton(self, event):
        row = self.Table.GetRow(self.VariablesGrid.GetGridCursorRow())
        self.Values.remove(row)
        self.SaveValues()
        self.RefreshValues()
        self.RefreshButtons()
        event.Skip()

    def OnUpButton(self, event):
        self.MoveValue(self.VariablesGrid.GetGridCursorRow(), -1)
        self.RefreshButtons()
        event.Skip()

    def OnDownButton(self, event):
        self.MoveValue(self.VariablesGrid.GetGridCursorRow(), 1)
        self.RefreshButtons()
        event.Skip()

    def OnVariablesGridCellChange(self, event):
        row, col = event.GetRow(), event.GetCol()
        colname = self.Table.GetColLabelValue(col)
        value = self.Table.GetValue(row, col)

        if colname == "Name" and value != "":
            if not TestIdentifier(value):
                message = wx.MessageDialog(self, _("\"%s\" is not a valid identifier!")%value, _("Error"), wx.OK|wx.ICON_ERROR)
                message.ShowModal()
                message.Destroy()
                event.Veto()
            elif value.upper() in IEC_KEYWORDS:
                message = wx.MessageDialog(self, _("\"%s\" is a keyword. It can't be used!")%value, _("Error"), wx.OK|wx.ICON_ERROR)
                message.ShowModal()
                message.Destroy()
                event.Veto()
            elif value.upper() in self.PouNames:
                message = wx.MessageDialog(self, _("A pou with \"%s\" as name exists!")%value, _("Error"), wx.OK|wx.ICON_ERROR)
                message.ShowModal()
                message.Destroy()
                event.Veto()
            elif value.upper() in [var["Name"].upper() for var in self.Values if var != self.Table.data[row]]:
                message = wx.MessageDialog(self, _("A variable with \"%s\" as name already exists in this pou!")%value, _("Error"), wx.OK|wx.ICON_ERROR)
                message.ShowModal()
                message.Destroy()
                event.Veto()
            else:
                self.SaveValues(False)
                old_value = self.Table.GetOldValue()
                if old_value != "":
                    self.Controler.UpdateEditedElementUsedVariable(self.TagName, old_value, value)
                self.Controler.BufferProject()
                self.ParentWindow.RefreshEditor(variablepanel = False)
                self.ParentWindow.RefreshTitle()
                self.ParentWindow.RefreshEditMenu()
                self.ParentWindow.RefreshInstancesTree()
                self.ParentWindow.RefreshLibraryTree()
                event.Skip()
        else:
            self.SaveValues()
            if colname == "Class":
                self.Table.ResetView(self.VariablesGrid)
            event.Skip()
    
    def OnVariablesGridEditorShown(self, event):
        row, col = event.GetRow(), event.GetCol() 

        label_value = self.Table.GetColLabelValue(col)
        if label_value == "Type":
            debug = self.ParentWindow.Debug
            type_menu = wx.Menu(title='')   # the root menu

            # build a submenu containing standard IEC types
            base_menu = wx.Menu(title='')
            for base_type in self.Controler.GetBaseTypes():
                new_id = wx.NewId()
                AppendMenu(base_menu, help='', id=new_id, kind=wx.ITEM_NORMAL, text=base_type)
                self.Bind(wx.EVT_MENU, self.GetVariableTypeFunction(base_type), id=new_id)

            type_menu.AppendMenu(wx.NewId(), _("Base Types"), base_menu)

            # build a submenu containing user-defined types
            datatype_menu = wx.Menu(title='')
            datatypes = self.Controler.GetDataTypes(basetypes = False, debug = debug)
            for datatype in datatypes:
                new_id = wx.NewId()
                AppendMenu(datatype_menu, help='', id=new_id, kind=wx.ITEM_NORMAL, text=datatype)
                self.Bind(wx.EVT_MENU, self.GetVariableTypeFunction(datatype), id=new_id)

            type_menu.AppendMenu(wx.NewId(), _("User Data Types"), datatype_menu)

            # build a submenu containing function block types
            bodytype = self.Controler.GetEditedElementBodyType(self.TagName, debug)
            pouname, poutype = self.Controler.GetEditedElementType(self.TagName, debug)
            classtype = self.Table.GetValueByName(row, "Class")

            if classtype in ["Input", "Output", "InOut", "External", "Global"] or \
            poutype != "function" and bodytype in ["ST", "IL"]:
                functionblock_menu = wx.Menu(title='')
                fbtypes = self.Controler.GetFunctionBlockTypes(self.TagName, debug)
                for functionblock_type in fbtypes:
                    new_id = wx.NewId()
                    AppendMenu(functionblock_menu, help='', id=new_id, kind=wx.ITEM_NORMAL, text=functionblock_type)
                    self.Bind(wx.EVT_MENU, self.GetVariableTypeFunction(functionblock_type), id=new_id)

                type_menu.AppendMenu(wx.NewId(), _("Function Block Types"), functionblock_menu)

            rect = self.VariablesGrid.BlockToDeviceRect((row, col), (row, col))
            corner_x = rect.x + rect.width
            corner_y = rect.y + self.VariablesGrid.GetColLabelSize()

            # pop up this new menu
            self.VariablesGrid.PopupMenuXY(type_menu, corner_x, corner_y)
            event.Veto()
        else:
            event.Skip()
    
    def GetVariableTypeFunction(self, base_type):
        def VariableTypeFunction(event):
            row = self.VariablesGrid.GetGridCursorRow()
            self.Table.SetValueByName(row, "Type", base_type)
            self.Table.ResetView(self.VariablesGrid)
            self.SaveValues(False)
            self.ParentWindow.RefreshEditor(variablepanel = False)
            self.Controler.BufferProject()
            self.ParentWindow.RefreshTitle()
            self.ParentWindow.RefreshEditMenu()
            self.ParentWindow.RefreshInstancesTree()
            self.ParentWindow.RefreshLibraryTree()
            event.Skip()
        return VariableTypeFunction
    
    def OnVariablesGridCellLeftClick(self, event):
        row = event.GetRow()
        if event.GetCol() == 0 and self.Table.GetValueByName(row, "Edit"):
            row = event.GetRow()
            var_name = self.Table.GetValueByName(row, "Name")
            var_class = self.Table.GetValueByName(row, "Class")
            var_type = self.Table.GetValueByName(row, "Type")
            data = wx.TextDataObject(str((var_name, var_class, var_type, self.TagName)))
            dragSource = wx.DropSource(self.VariablesGrid)
            dragSource.SetData(data)
            dragSource.DoDragDrop()
        event.Skip()
    
    def OnVariablesGridSelectCell(self, event):
        wx.CallAfter(self.RefreshButtons)
        event.Skip()

    def OnChar(self, event):
        keycode = event.GetKeyCode()
        if keycode == wx.WXK_DELETE:
            row = self.Table.GetRow(self.VariablesGrid.GetGridCursorRow())
            self.Values.remove(row)
            self.SaveValues()
            self.RefreshValues()
            self.RefreshButtons()
        event.Skip()

    def MoveValue(self, value_index, move):
        new_index = max(0, min(value_index + move, len(self.Values) - 1))
        if new_index != value_index:
            self.Values.insert(new_index, self.Values.pop(value_index))
            self.SaveValues()
            self.RefreshValues()
            self.VariablesGrid.SetGridCursor(new_index, self.VariablesGrid.GetGridCursorCol())
        
    def RefreshValues(self, select=0):
        if len(self.Table.data) > 0:
            self.VariablesGrid.SetGridCursor(0, 1)
        data = []
        for num, variable in enumerate(self.Values):
            if variable["Class"] in self.ClassList:
                variable["Number"] = num + 1
                data.append(variable)
        self.Table.SetData(data)
        if len(self.Table.data) > 0:
            if select == -1:
                select = len(self.Table.data) - 1
            self.VariablesGrid.SetGridCursor(select, 1)
            self.VariablesGrid.MakeCellVisible(select, 1)
        self.Table.ResetView(self.VariablesGrid)

    def SaveValues(self, buffer = True):
        words = self.TagName.split("::")
        if self.ElementType == "config":
            self.Controler.SetConfigurationGlobalVars(words[1], self.Values)
        elif self.ElementType == "resource":
            self.Controler.SetConfigurationResourceGlobalVars(words[1], words[2], self.Values)
        else:
            if self.ReturnType.IsEnabled():
                self.Controler.SetPouInterfaceReturnType(words[1], self.ReturnType.GetStringSelection())
            self.Controler.SetPouInterfaceVars(words[1], self.Values)
        if buffer:
            self.Controler.BufferProject()
            self.ParentWindow.RefreshTitle()
            self.ParentWindow.RefreshEditMenu()
            self.ParentWindow.RefreshInstancesTree()
            self.ParentWindow.RefreshLibraryTree()

    def AddVariableError(self, infos):
        if isinstance(infos[0], TupleType):
            for i in xrange(*infos[0]):
                self.Table.AddError((i,) + infos[1:])
        else:
            self.Table.AddError(infos)
        self.Table.ResetView(self.VariablesGrid)

    def ClearErrors(self):
        self.Table.ClearErrors()
        self.Table.ResetView(self.VariablesGrid)

class LocationCellControl(wx.PyControl):
    '''
    Custom cell editor control with a text box and a button that launches
    the BrowseVariableLocationsDialog.
    '''
    def __init__(self, parent, var_panel):
        wx.Control.__init__(self, parent, -1)
        self.ParentWindow = parent
        self.VarPanel = var_panel
        self.Row = -1

        self.Bind(wx.EVT_SIZE, self.OnSize)

        # create text control
        self.txt = wx.TextCtrl(self, -1, '')

        # create browse button
        self.btn = wx.Button(self, -1, '...', size=(20,20))
        self.btn.Bind(wx.EVT_BUTTON, self.OnBtnBrowseClick)

        szr = wx.BoxSizer(wx.HORIZONTAL)
        szr.Add(self.txt, proportion=1, flag=wx.EXPAND)
        szr.Add(self.btn, proportion=0, flag=wx.ALIGN_RIGHT)

        szr.SetSizeHints(self)
        self.SetSizer(szr)
        self.Layout()

    def SetRow(self, row):
        '''set the grid row that we're working on'''
        self.Row = row

    def OnSize(self, event):
        '''resize the button and text control to fit'''
        overall_width = self.GetSize()[0]
        btn_width, btn_height = self.btn.GetSize()
        new_txt_width = overall_width - btn_width

        self.txt.SetSize(wx.Size(new_txt_width, -1))
        self.btn.SetDimensions(new_txt_width, -1, btn_width, btn_height)

    def OnBtnBrowseClick(self, event):
        # pop up the location browser dialog
        dia = BrowseVariableLocationsDialog(self.ParentWindow, self.VarPanel)
        dia.ShowModal()

        if dia.Selection:
            loc, iec_type, doc = dia.Selection

            # set the location
            self.SetText(loc)

            # set the variable type and documentation
            # NOTE: this update won't be displayed until editing is complete
            # (when EndEdit is called).
            # we can't call VarPanel.RefreshValues() here because it causes
            # an exception. 
            self.VarPanel.Table.SetValueByName(self.Row, 'Type', iec_type)
            self.VarPanel.Table.SetValueByName(self.Row, 'Documentation', doc)

        self.txt.SetFocus()

    def SetText(self, text):
        self.txt.SetValue(text)

    def SetInsertionPoint(self, i):
        self.txt.SetInsertionPoint(i)

    def GetText(self):
        return self.txt.GetValue()

    def SetFocus(self):
        self.txt.SetFocus()

class LocationCellEditor(wx.grid.PyGridCellEditor):
    '''
    Grid cell editor that uses LocationCellControl to display a browse button.
    '''
    def __init__(self, var_panel):
        wx.grid.PyGridCellEditor.__init__(self)
        self.VarPanel = var_panel

    def Create(self, parent, id, evt_handler):
        self.text_browse = LocationCellControl(parent, self.VarPanel)
        self.SetControl(self.text_browse)
        if evt_handler:
            self.text_browse.PushEventHandler(evt_handler)

    def BeginEdit(self, row, col, grid):
        loc = self.VarPanel.Table.GetValueByName(row, 'Location')
        self.text_browse.SetText(loc)
        self.text_browse.SetRow(row)
        self.text_browse.SetFocus()

    def EndEdit(self, row, col, grid):
        loc = self.text_browse.GetText()
        old_loc = self.VarPanel.Table.GetValueByName(row, 'Location')

        if loc != old_loc:
            self.VarPanel.Table.SetValueByName(row, 'Location', loc)
            
            # NOTE: this is a really lame hack to force this row's
            # 'Type' cell to redraw (since it may have changed). 
            # There's got to be a better way than this.
            self.VarPanel.VariablesGrid.AutoSizeRow(row)
            return True

    def SetSize(self, rect):
        # -2 and +5 give this some extra vertical padding
        self.text_browse.SetDimensions(rect.x, rect.y-2,
                                        rect.width, rect.height+5,
                                        wx.SIZE_ALLOW_MINUS_ONE)

    def Clone(self):
        return LocationCellEditor(self.VarPanel)

class BrowseVariableLocationsDialog(wx.Dialog):
    # turn LOCATIONDATATYPES inside-out
    LOCATION_SIZES = {}
    for size, types in LOCATIONDATATYPES.iteritems():
        for type in types:
            LOCATION_SIZES[type] = size

    class PluginData:
        '''contains a plugin's VariableLocationTree'''
        def __init__(self, plugin):
            self.subtree  = plugin.GetVariableLocationTree()

    class SubtreeData:
        '''contains a subtree of a plugin's VariableLocationTree'''
        def __init__(self, subtree):
            self.subtree = subtree

    class VariableData:
        '''contains all the information about a valid variable location'''
        def __init__(self, type, dir, loc):
            self.type   = type

            loc_suffix = '.'.join([str(x) for x in loc])

            size = BrowseVariableLocationsDialog.LOCATION_SIZES[type]
            self.loc = size + loc_suffix

            # if a direction was given, use it
            # (if not we'll prompt the user to select one)
            if dir:
                self.loc = '%' + dir + self.loc

    def __init__(self, parent, var_panel):
        self.VarPanel   = var_panel
        self.Selection  = None

        # create the dialog
        wx.Dialog.__init__(self, parent=parent, title=_('Browse Variables'),
                            style=wx.DEFAULT_DIALOG_STYLE|wx.RESIZE_BORDER,
                            size=(-1, 400))

        # create the root sizer
        sizer = wx.BoxSizer(wx.VERTICAL)
        self.SetSizer(sizer)

        # create the tree control
        self.tree = wx.TreeCtrl(self, style=wx.TR_DEFAULT_STYLE|wx.TR_HIDE_ROOT)
        sizer.Add(self.tree, 1, wx.EXPAND|wx.ALL, border=20)

        # create the Direction sizer and field
        dsizer = wx.BoxSizer(wx.HORIZONTAL)
        sizer.Add(dsizer, 0, wx.LEFT|wx.RIGHT|wx.BOTTOM|wx.EXPAND, border=20)

        #   direction label
        ltext = wx.StaticText(self, -1, _('Direction:'))
        dsizer.Add(ltext, flag=wx.RIGHT|wx.ALIGN_CENTER_VERTICAL, border=20)

        #   direction choice
        self.DirChoice = wx.Choice(id=-1, parent=self, choices=[_('Input'), _('Output'), _('Memory')])
        dsizer.Add(self.DirChoice, flag=wx.EXPAND)
        #   set a default for the choice   
        self.SetSelectedDirection('I')

        # create the button sizer
        btsizer = wx.BoxSizer(wx.HORIZONTAL)
        sizer.Add(btsizer, 0, wx.LEFT|wx.RIGHT|wx.BOTTOM|wx.ALIGN_RIGHT, border=20)

        # add plugins to the tree
        root = self.tree.AddRoot(_('Plugins'))
        ctrl = self.VarPanel.Controler
        self.AddChildPluginsToTree(ctrl.PluginsRoot, root)

        #       -- buttons --

        # ok button
        self.OkButton = wx.Button(self, wx.ID_OK, _('Use Location'))
        self.OkButton.SetDefault()
        btsizer.Add(self.OkButton, flag=wx.RIGHT, border=5)

        # cancel button
        b = wx.Button(self, wx.ID_CANCEL, _('Cancel'))
        btsizer.Add(b)

        #       -- event handlers --

        # accept the location on doubleclick or clicking the Use Location button
        self.Bind(wx.EVT_BUTTON, self.OnOk, self.OkButton)
        self.Bind(wx.EVT_TREE_ITEM_ACTIVATED, self.OnOk, self.tree)

        # disable the Add button when we're not on a valid variable
        self.Bind(wx.EVT_TREE_SEL_CHANGED, self.OnSelChange, self.tree)

        # handle the Expand event. this lets us create the tree as it's expanded
        # (trying to create it all at once is slow since plugin variable location
        # trees can be big)
        wx.EVT_TREE_ITEM_EXPANDING(self.tree, self.tree.GetId(), self.OnExpand)

    def OnExpand(self, event):
        item = event.GetItem()
        if not item.IsOk():
            item = self.tree.GetSelection()
        
        data = self.tree.GetPyData(item)
        self.ExpandTree(item, data.subtree)

    def AddChildPluginsToTree(self, plugin, root):
        for p in plugin.IECSortedChilds():
            plug_name = p.BaseParams.getName()
            new_item = self.tree.AppendItem(root, plug_name)

            # make it look like the tree item has children (since it doesn't yet)
            self.tree.SetItemHasChildren(new_item) 

            # attach the plugin data to the tree item
            self.tree.SetPyData(new_item, BrowseVariableLocationsDialog.PluginData(p))

            # add child plugins recursively
            self.AddChildPluginsToTree(p, new_item)

    def ExpandTree(self, root, subtree):
            items = subtree.items()
            items.sort()

            for node_name, data in items:
                if isinstance(data, dict):
                    # this is a new subtree

                    new_item = self.tree.AppendItem(root, node_name)
                    self.tree.SetItemHasChildren(new_item)

                    # attach the new subtree's data to the tree item
                    new_data = BrowseVariableLocationsDialog.SubtreeData(data)
                    self.tree.SetPyData(new_item, new_data)
                else:
                    # this is a new leaf.

                    # data is a tuple containing (IEC type, I/Q/M/None, IEC path tuple)
                    type, dir, loc = data

                    node_name = '%s (%s)' % (node_name, type)
                    new_item = self.tree.AppendItem(root, node_name)

                    vd = BrowseVariableLocationsDialog.VariableData(type, dir, loc)
                    self.tree.SetPyData(new_item, vd)

    def OnSelChange(self, event):
        '''updates the text field and the "Use Location"  button.'''
        item = self.tree.GetSelection()
        data = self.tree.GetPyData(item)

        if isinstance(data, BrowseVariableLocationsDialog.VariableData):
            self.OkButton.Enable()

            location = data.loc
            if location[0] == '%':
                # location has a fixed direction
                self.SetSelectedDirection(location[1])
                self.DirChoice.Disable()
            else:
                # this location can have any direction (user selects)
                self.DirChoice.Enable()
        else:
            self.OkButton.Disable()
            self.DirChoice.Disable()

    def GetSelectedDirection(self):
        selected = self.DirChoice.GetSelection()
        if selected == 0:
            return 'I'
        elif selected == 1:
            return 'Q'
        else:
            return 'M'

    def SetSelectedDirection(self, dir_letter):
        if dir_letter == 'I':
            self.DirChoice.SetSelection(0)
        elif dir_letter == 'Q':
            self.DirChoice.SetSelection(1)
        else:
            self.DirChoice.SetSelection(2)

    def OnOk(self, event):
        item = self.tree.GetSelection()
        data = self.tree.GetPyData(item)

        if not isinstance(data, BrowseVariableLocationsDialog.VariableData):
            return

        location = data.loc

        if location[0] != '%':
            # no direction was given, grab the one from the wxChoice
            dir = self.GetSelectedDirection()
            location = '%' + dir + location

        # walk up the tree, building documentation for the variable
        documentation = self.tree.GetItemText(item)
        parent = self.tree.GetItemParent(item)
        root = self.tree.GetRootItem()
        while parent != root:
            text = self.tree.GetItemText(parent)
            documentation = text + ":" + documentation
            parent = self.tree.GetItemParent(parent)

        self.Selection = (location, data.type, documentation)
        self.Destroy()