scroll a frame to display several lines of widgets at a time

[William Gill]

Matt Hammond wrote:
> I don't quite understand (if I'm interpreting you correctly) why you 
> want  separate widgets, all displayed at once, for several hundred 
> records -  surely better to just reuse the one set of widgets and have 
> the scrollbar  or back-forward buttons change which record is being 
> displayed in the  widgets.

I need to re-think things a little.  I wanted to be able to quickly 
scroll through several hundred entries in the db, and check off (yes/no) 
which have been reviewed, updated, or whatever.

I will look at having a fixed number of display widgets and scrolling 
through the underlying data to determine which records are currently 
displayed/editable.

My first pass was db -> display/edit widgets -> db.  So I jumped 
(incorrectly) to wanting to 'hold' all record in widgets for 
editing.There's no reason I can't use:

db -> master list -> slice -> display/edit widgets -> master list -> db.

i.e. a list holding all the data, display/edit slices controlled by a 
scrollbar, and storing the final list when done.

> 
> If you're after replacing widgets, then you need to destroy them first.  
> Use the self.destroy method and unset/change any variables referencing 
> the  widget so it get a chance to be garbage collected.
> 
> However, if you want a scrollable view onto a larger area, what you 
> need  to do is use a Canvas, with a window shape on it. You then put a 
> frame  into that window.
> 
>    canvas = Tkinter.Canvas( <parent> )
>    canvas.grid( ... )
>    winID = self.canvas.create_window(0,0, anchor=Tkinter.NW)
> 
> Then later you can add a frame to that window on the canvas:
> 
>    canvas.itemconfigure( winID, window = <my frame> )
>    canvas['scrollregion'] = canvas.bbox('all')
> 
> Make sure you've created the frame and perhaps called 
> update_idletasks()  to give it a chance to size itself before shoving it 
> onto the canvas.
> 
> And of course, the scrollbar!
> 
>    yscroll = Tkinter.Scrollbar( <parent>, orient=Tkinter.VERTICAL)
>    yscroll.grid( ... )
>    yscroll['command'] = canvas.yview
>    canvas['yscrollcommand'] = yscroll.set
>
Probably, not needed now that I have re-thought the situation, but I do 
have several occasions where i need to view and select/deselect 50 or 60 
  options (checkbuttons).  So this will make them much more manageable.

Thanks,

Bill

> 
> On Thu, 01 Sep 2005 14:33:36 +0100, William Gill <noreply at gcgroup.net>  
> wrote:
> 
>> I need to display a couple of labels and a checkbox from each entry 
>> in  my database.  Simple enough, but there are several hundred 
>> records, and  I only want to display 5 or 10 at a time.  Can this be 
>> accomplished by  putting everything in a Frame(), using width, height, 
>> grid_propagate(0)  , and a scrollbar?  or do I have to grid 5 rows at 
>> a time?  If the  latter, can I just grid over the previous 5 or do 
>> they have to be  explicitly removed first.
>>
>> Thanks.
>>
>> Bill
> 
> 
> 
>