Message-ID: <43E0BB69.9080509 at crans.org>
Date: Wed, 01 Feb 2006 14:45:13 +0100
From: =?ISO-8859-1?Q?=22Sayan_=28S=E9bastien_Li-Thiao-T=E9=29=22?=
 <sayan@crans.org>
MIME-Version: 1.0
To: lablgtk at math.nagoya-u.ac.jp
Subject: Drawing curves in a GPack.layout
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Hi,

I am trying to program an application to display and edit a tree with 
nodes containing text.

I use a GPack.layout container and I add each node of the tree to the 
container in a GText.view. This gives multiline text nodes and one can 
distinguish the tree structure thanks to careful positionning of the nodes.

However, I have had no success so far with drawing the edges of the 
tree. Using a drawable area created from layout#misc#window does not 
work, and the gtk2+ manual states:
"When handling expose events on a GtkLayout, you must draw to GTK_LAYOUT 
(layout)->bin_window, rather than to GTK_WIDGET (layout)->window, as you 
would for a drawing area."

Could someone help me with drawing in the GPack.layout or suggest 
another program structure?



Here is a simple example where drawing in a GPack.layout does not work.

let locale = GtkMain.Main.init ();;
let window = GWindow.window ~title:"OcamlMMap" () ;;
    window#connect#destroy ~callback:GMain.Main.quit;;
    window#event#connect#delete ~callback:(fun _ -> GMain.Main.quit (); 
true);;

(*let drawing_area = GMisc.drawing_area ~packing:window#add ();;*) (*works*)
let drawing_area = GPack.layout ~packing:window#add ();; (*does not work *)

let drawing = drawing_area#misc#realize (); new GDraw.drawable
(drawing_area#misc#window) ;;
drawing#set_foreground `BLACK;;
drawing#set_line_attributes ~width:5 ();;

let redraw _ =
     drawing#rectangle ~x:(-10) ~y:(-10) ~width:200 ~height:200 
~filled:true () ;
     drawing#line ~x:0 ~y:0 ~x:200 ~y:300;
    false;;

drawing_area#event#connect#expose ~callback:redraw;;
window#misc#show ();;
Printexc.print GMain.Main.main ();;

-- 
Li-Thiao-Té Sébastien