Re: GtkTree and GtkThread: update and refresh

[Olivier Sessink <oliviersessink gmail com>]

On 09/21/2011 10:53 PM, Paolo wrote:
> Hi! I have a problem about the update and refresh of a tree. This is the
> situation: I have a populated tree and a button that update the tree. The
> button's event calls a function that permorfs the following things:
> 1) Reset the treemodel appending a single text row "Loading"
> 2) Execute a db query
> 3) Reset the treemodel appending the results of the query
> No errors, but a refresh problem. I can't see the text row "Loading" (1st
> step); I can just see the new populated tree (3th step).
>
> I could put the following code between the step 1 and 2:
>
>            while(gtk_events_pending())
>                gtk_main_iteration();

or start step 2 from an idle callback, use g_idle_add_full() to register 
a function that will call step 2.

> This solution works but it blocks the whole GUI.
> A thread can help me for the GUI block and the pending events, but I have
> another problem: after several clicks of the button the program blocks. I
> don't know what happen: no errors, no segmentation fault.
>
> Is it correct create a thread for each event of the button in that way?
>
>              g_thread_create((GThreadFunc) loading_tree_and_the_fill_tree,
> NULL, FALSE,&err)

as suggested elsewhere read about gtk and threads. GTK calls should be 
made from the main thread, so do your db query in a thread, load the 
results in a datastructure, use g_idle_add() again to register a 
function that will be called from the mean thread and in *that* function 
load the data in the treemodel.

Olivier