Re: fixed position, fixed size

[Joe Van Dyk <joevandyk gmail com>]

On Wed, 16 Mar 2005 19:42:03 -0500, Paul Davis
<paul linuxaudiosystems com> wrote:
> >I have a gnomecanvas object (is this the right list?).  The user can
> >move around in the object by pressing arrows that are drawn in the
> >lower right hand corner of the object.
> >
> >I'm guessing when the user clicks a move arrow, I'd use
> >gnome_canvas_scroll_to(cx, cy) to scroll on the canvas.
> >
> >The user can also zoom in and out on the canvas.
> >
> >So each time the user moves or zooms, I'd need to rerdraw those
> >movement arrows so they stay in the same place and say the same size
> >(in pixels on the user's screen).
> >
> >Is there an easy way to do this?  Or do I need to delete the old
> >arrows, figure out where in the world coordinates to draw the new
> >arrows, and query the current zooming level to figure out how large
> >the arrows should be?
> 
> my experience of canvas zooming is that its mostly useless.
> 
> as soon as you put multiple objects on the canvas whose behaviour
> under zoom differs from each other, using the affine transform method
> of zooming the whole canvas becomes more of an impediment than a
> benefit.
> 
> your mileage may vary. and check out http://ardour.org/ for a very,
> very heavyduty canvas application (though we're still stuck using
> GtkCanvas for the next month or so).
> 

I'm using gnome_canvas_set_pixels_per_unit () to zoom in and out. 
That's not an affine transformation, is it?