Re: liststore questions

[muppet <scott asofyet org>]

On Apr 8, 2005, at 7:38 PM, Dave M wrote:

> 1. I don't understand how the liststore works like this. In Tk, for
> example, I would create an HList, and use something like this to add
> to it:
> $widget->itemCreate( entrypath, column, -text => "foo");
> Is there a dummy's guide to how this works?

you can do

    $model->set ($iter,
                0, $col0_data,
                1, $col1_data,
                2, $col2_data,
                3, $col3_data);

at any time during a tree model's lifetime, and all attached views will 
update automatically.

you can update existing iters as well as add and remove iters at will.

there are other functions that you can use to keep the view scrolled to 
the bottom as you append new rows.

it would help if you describe what you want you app to do, so we can 
give you more specific advice.


if you're going to insert a whole lot of rows at once (more than a 
hundred), it can be a good idea to remove the model from the view, do 
the insertions, then put the model back into the view to avoid a deluge 
of ui updates.



> 2. (Sorry to keep using Tk examples; it's all I know...) Is there a
> gtk2 equivalent to $mw->update to refresh the screen? There are
> various widgets that will need refreshed to create a "real-time" look
> as data gets displayed in the columns.

depends on what $mw->update is supposed to do.

   $toplevel->queue_draw;

will place a complete-redraw event on the queue to be handled at the 
next idle.  you can call this on any widget if you want finer 
granularity.

in a lot of cases, if you have those other widgets listening to the 
right events, it will all just work out; most widgets will call 
queue_draw on themselves after a change.  (using queue draw reduces 
flicker resulting from rapid-fire repaints.)

if your ui isn't updating because you're in a tight loop or blocking on 
a function call, there are other techniques.

something like this at the bottom of a loop can help:

   # flush the event queue
   Gtk2->main_iteration while Gtk2->events_pending;

if you're blocking on IO, then you want to look at 
Glib::IO->add_watch().

if you have a function call that blocks or an intensive algorithm, you 
may want to fork a child process to do that work, and monitor its 
progress over a pipe.


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