[Tutor] Tkinter: Deleting text when clicking in field.

[brandon w]

On 08/20/2011 07:11 PM, Alan Gauld wrote:
> On 20/08/11 20:12, brandon w wrote:
>> I worked on this for a long time. I did many searches to fix the many
>> error messages I was getting and I finally got this to work. I would now
>> just like to have the text disappear when a person clicks in the box to
>> type something. How can I do that?
>>
>
> You need to buind the mouse click event to the event handler method. 
> It will not be called unless you tell Tkinter to call it.
>
>> from Tkinter import *
>>
>> class MyGrid(Frame):
>>    def __init__(self, win=None):
>>       Frame.__init__(self, win)
>>       self.grid()
>>       self.mkWidgets()
>>
>> [...snip...]
>>
>> self.mytext = StringVar()
>> self.mytext.set("Enter text here") # This text needs to be deleted upon
>> clicking in the field.
>> self.e = Entry(bg='orange', textvariable=self.mytext, relief=SUNKEN,
>> width=50)
>> self.e.grid(row=0, column=0)
>
> You need to add a Bind statement to bind a mouse click to a method 
> that clears the text. Remember that everything in a GUI is event 
> driven, so you have to link your code to the events.
>
>>
>> I have created a method to clear the field.
>> This is not working:
>>
>> def clearBox(self):
>> self.mytext.delete(0, END)
>> return
>
> You need to delete the text in the Entry widget not the StringVar
> Alternatively you need to set the StringVar to an empty string and
> wait for the widget to redraw itself. (Or force it to redraw!)
>
> Then you need to add a bind statement to tie that method to a mouse 
> click in the Entry.
>
>> self.mytext = StringVar(None)
>> self.mytext.set("Enter text here")
>> self.e = Entry(bg='orange', textvariable=self.mytext, relief=SUNKEN,
>> width=50, command=self.clearBox)
>
> That binds the event to the command parameter of the Entry.
> BUT the Entry widget does not have a command option - I'm surprised 
> you dont get an error complaining about that?
>
> So you need to use the bind() function.
> The bind function specifies the event type and the method to be 
> called. It expects the method to take an additional event argument:
> It should look something like:
>
> # define an event handler
> def handleEvent(self, event):
>      print "I'm habdling an event"
>
> # bind the button-1 click of the Entry to the handler
> self.e.bind('Button-1', handleEvent)
>
> HTH
>
Thanks again for your help. I'll work on this tomorrow.