Re: How wide can a widget get ?

[Paul Pogonyshev <pogonyshev gmx net>]

John Cupitt wrote (on 23 November):
> Hi,
>
> On Tue, 23 Nov 2004 02:51:25 -0700, Nix N. Nix <nix go-nix ca> wrote:
> > What's the maximum width I can set a widget to ? I end up attempting to
> > set the width of one of my drawing area widgets to 66327, and it doesn't
> > seem to want to go that wide. Is there an inherent limit to the width of
> > a widget ?
>
> There was in gtk+-1.2, but gtk2 (pretty much) removed this. I have
> drawing areas in my app which go up to several million pixels in each
> axis and gtk scrolls them fine. Memory isn't allocated for invisible
> pixels, so there's no limit there either.
>
> You can have problems with a 16 bit coordinate limit on drawing
> operations on very large drawing areas: you may need to do some
> clipping yourself.

Can you please explain this further?  (Sample code would be especially
helpful.)  Here is one particular example that causes problems:

        gdk_draw_line (window, gc, 20, 20, 20, 40000);

Instead of going downwards, the line goes upwards (seems like X
considers 40000 to be a negative 16-bit number.)

I can cope with this particular example just fine, but what if the
user scrolls the window right to the "sign flip frontier"?

The very reason why I use such horribly large windows is that they
have a pixmap background and I like it to be scrolled.  I couldn't
find a way to adjust background origin instead of scrolling the
window... :(

Paul