Re: GtkCanvas requirements?

[Havoc Pennington <hp redhat com>]

Hi,

Carlos Garnacho wrote:
> First of all we need to specify the feature requirements for the  
> canvas.

I'd step back first and do use-cases instead, and also talk about at a 
high level what the canvas is for and when it would be used, i.e.:

 - when is a canvas item used vs. a widget? what current widgets would
   be "replicated" as canvas items?
 - when is a canvas used vs. just drawing to a drawable with Cairo and
   Pango?
 - is the canvas essentially a fixed-up replacement for
   GtkWidget/GtkContainer (the GTK widget core) or does it have some
   other purpose? If it has another purpose, what is it?
 - can a list of use cases be spelled out?
 - how are existing canvases being used? which apps seem to be
   using canvases and why and for what?

I bet everyone would think more clearly if we put a bullet in the word 
"canvas" and instead thought about "next-gen widget system core" or 
"simplified drawing API" or something of that nature. If you start 
thinking this way, perhaps there's even more than one new API that's 
needed, i.e. maybe there's a next-gen widget core, but *also* a 
simplified drawing API used to *write* complex widgets/canvas-items.
I don't know.

The word "canvas" is especially misleading because GnomeCanvas is such a 
bad model; the big problems GnomeCanvas used to solve no longer exist, 
so the GnomeCanvas design really has little or nothing to do with 
anything. GnomeCanvas was based on TkCanvas, which has even less to 
offer as a model I'd say.

Havoc