Re: Canvas framework

[Nicolas Roard]

On 2/1/06, Guilhem BONNEFILLE <Guilhem.Bonnefille@laposte.net> wrote:
> Hi,
>
> For my first application is an image as background and some reference
> points. I wish to allow the user selecting, moving, erasing easily these
> points.
>
> Is there any canvas framework on GNUStep? By canvas, I mean a framework
> that assume the management of the graphical objects: I give it graphical
> object, with coords and layer level, and it called me back when an
> object is selected, moved...
>
> I've looked for such thing on internet with "canvas" keyword, but it is
> unsuccessful.

It's because the whole -gui on GNUstep is mostly done with what you'd
call a canvas.
The display is vectoriel, and using NSView give you discrete objects.
So in fact for a canvas,
you could simply define NSViews, add them as subview to a NSView you'd
use as a "board".
Now to let the user manipulate the NSViews (eg, move them), and in
your NSViews, simply intercept mouse events to do whatever you want
(eg move the objects, or do some action, etc)

http://developer.apple.com/documentation/Cocoa/Conceptual/DrawViews/index.html#//apple_ref/doc/uid/10000079i

--
Nicolas Roard
"Any sufficiently advanced technology is indistinguishable from magic."
  -Arthur C. Clarke