Date: Tue, 9 Jan 2001 18:53:00 +0100
To: Chris Hecker <checker at d6.com>
Cc: lablgtk at kaba.or.jp
Subject: Re: resize event?
Message-ID: <20010109185300.A888 at lambda.u-strasbg.fr>
References: <4.3.2.7.2.20010105002151.00baf5c0 at shell16.ba.best.com>
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In-Reply-To: <4.3.2.7.2.20010105002151.00baf5c0 at shell16.ba.best.com>; from checker at d6.com on Fri, Jan 05, 2001 at 12:23:18AM -0800
From: Sven LUTHER <luther at dpt-info.u-strasbg.fr>
Sender: Sven LUTHER <luther at lambda.u-strasbg.fr>

On Fri, Jan 05, 2001 at 12:23:18AM -0800, Chris Hecker wrote:
> 
> [Resent to the list to keep people updated...Jacques and I had a private thread going.]
> 
> >It is possible that events work differently on windows and X11.
> >Try using other events, like configure,  in place of expose, this may
> >work better.
> 
> I tried configure, but that didn't work either.  Which one is supposed to be called on resize?
> 
> Now that I've looked at it closer, it looks like the image does get repainted on resize, it's just that the window gets cleared immediately afterwards.

I may be a bit ate on this one, but in my experience, and from the gtk+
tutorial on gtk_drawing_area and such : 

  * the configure event is the one called when the object gets resized,
    created and such.

  * the expose event is the one called when part of the window is again
    redrawn.

i nthe mlgtk tutorial 3 example, i use a drawingarea widget whit an offscreen
pixmap in which i do normal drawing, and which i draw to the drawingarea after
a bunch of drawing. 

I have to redraw the part of the pixmap that was obscured at the expose event
and have to create a new offscreen pixmap of the new size at each expose
event, thus loosing all drawings i have done in the previous one. Hope this
helps.

Now, i have also a question :

i am using a GlArea widget to do OpenGL drawing into, i create it with :

    let area = GlGtk.area [`DOUBLEBUFFER;`RGBA;`DEPTH_SIZE 1]
      ~width:600 ~height:400 ()

and do some matrix stuff in it like it is done in the GL examples :

    ignore (area#event#connect#after#configure ~callback:
      begin function _ ->
        GlMat.mode `projection;
        GlMat.load_identity ();
        GlMat.ortho ~x:(-1.0,1.0) ~y:(-1.0,1.0) ~z:(-1.0,1.0);
        false
      end);

now, if i understood it well, (fst ~x, fst ~y) is the coordinate of the lower
left corner of the glArea and (snd ~x, snd ~y) is the coordinate of the upper
right corner of the GLArrea.

The problem with this is that :

  - the glarea being 600x400, this gives me an non-orthogonal view, which
    don't have correct 90° angles.
  - when i use the button_press callback, i get coordinates in the -1,1 range.
  - when i resize window, i get a larger window, but the button_press event
    still seem to be providing me the older values, not sure though.

if i provide the area with a 400x400 size, everything works well.

if i do :

        GlMat.ortho ~x:(-1.5,1.5) ~y:(-1.0,1.0) ~z:(-1.0,1.0);

i think i will preserver the correct ratio, but nothing happens.

if i do 
    
        GlMat.ortho ~x:(-300.0,300.0) ~y:(-200.0,200.0) ~z:(-1.0,1.0);

i think i will get coordinates in the -300/300,-200/200 range, but it is not
the case ...


mmm, ...

openGL is doing some strange tricks to me here, 

any help would be welcome ...

Friendly,

Sven Luther