FocusingControlsWithTheirLabels

Accelerator keys are often a more efficient way of interacting with a GUI that are mouse gestures. However, wxPython does not appear to offer a direct way of associating the label of a textbox, or of another control, with the control itself.

This recipe shows how to associate the accelerator keys implied by a collection of static labels with the appropriate controls in such a way that, when an accelerator key is pressed the associated control gains focus.

What Objects are Involved

wxAcceleratorTable, which is wxPython's container for information about accelerators and their associated controls.

Process Overview

Note that the method called focusHandler uses information that is accumulated in a dictionary to decide which control is to receive focus based on incoming menu event information.

Special Concerns

My main concern is that I might have failed to notice machinery that is already available in wxPython for doing this.

Code Sample

   1 from wxPython.wx import *
   2 
   3 from re import compile,IGNORECASE
   4 
   5 class mainWindow(wxFrame):
   6     def __init__(self,parent,id,title):
   7         wxFrame.__init__(self,parent,-1,title,size=(500,200),
   8                         style=wxDEFAULT_FRAME_STYLE | wxNO_FULL_REPAINT_ON_RESIZE)
   9 
  10         self.mainPanel=wxPanel(self,-1)
  11 
  12         # create controls to be subsequently associated with accelerator keys
  13         self.dateEdit=wxTextCtrl(self.mainPanel,wxNewId(),'',(100,20))
  14         self.comboBox=wxComboBox(self.mainPanel,wxNewId() ,'',(100,40),(-1,-1),[],wxCB_DROPDOWN)
  15         self.activityEdit=wxTextCtrl(self.mainPanel,wxNewId(),'',(100,60))
  16         self.hoursEdit=wxTextCtrl(self.mainPanel,wxNewId(),'',(100,80))
  17         self.visitedBox=wxCheckBox(self.mainPanel,wxNewId(),'',(100,100))
  18 
  19         # instance a class that accummulates information about controls and accelerators
  20         accumAcceleratorTable=self.AccumAcceleratorTable(self,self.focusHandler)
  21 
  22         # as each label is created associate appropriate accelerator key with a control
  23         dateEditLabel=wxStaticText(self.mainPanel,-1,accumAcceleratorTable ('&Date',self.dateEdit),(10,20))
  24         clientEditLabel=wxStaticText(self.mainPanel,-1,accumAcceleratorTable ('&Client',self.comboBox),(10,40))
  25         activityEditLabel=wxStaticText(self.mainPanel,-1,accumAcceleratorTable ('&Activity',self.activityEdit),(10,60))
  26         hoursEditLabel=wxStaticText(self.mainPanel,-1,accumAcceleratorTable ('&Hours',self.hoursEdit),(10,80))
  27         visitedEditLabel=wxStaticText(self.mainPanel,-1,accumAcceleratorTable ('&Visited',self.visitedBox),(10,100))
  28 
  29         # put the accummulated accelerator table and associations to use
  30         self.SetAcceleratorTable(wxAcceleratorTable(accumAcceleratorTable.acceleratorTable))
  31         self.idControlDict=accumAcceleratorTable.idControlDict
  32 
  33         self.Show(True)
  34 
  35     def focusHandler(self,event):
  36         self.idControlDict[event.GetId()].SetFocus()
  37 
  38     class AccumAcceleratorTable:
  39         def __init__(self,parent,focusHandler):
  40             self.acceleratorTable=[]
  41             self.idControlDict={ }
  42             self.patt=compile(r'&([a-z])',IGNORECASE)
  43             self.focusHandler=focusHandler
  44             self.parent=parent
  45 
  46         def __call__(self,labelText,controlToFocus):
  47             # find the accelerator key,if any,in the label
  48             result=self.patt.search(labelText)
  49             if result:
  50                 anId=wxNewId()
  51                 self.acceleratorTable.append(( wxACCEL_ALT,ord(result.group(1).upper()),anId))
  52                 self.idControlDict[anId]=controlToFocus
  53                 EVT_MENU(self.parent,anId,self.focusHandler)
  54             return labelText
  55 
  56 class App(wxApp):
  57     def OnInit(self):
  58         frame=mainWindow(None,-1,"Associating labels with controls")
  59         self.SetTopWindow(frame)
  60         return True
  61 
  62 if __name__=="__main__":
  63     app=App(0)
  64     app.MainLoop()

Comments