[sugar] Pie menus for pygtk and OLPC Sugar!

[Antoine van Gelder]

Don Hopkins wrote:
> Good point! That should be possible, I think. The PieItem objects are 
> not widgets, just objects that are called with a context to draw 
> themselves with, so just the PieMenu and PieMenuDrawingArea classes 
> would have to be reworked a bit. It's the mouse tracking and grabbing 
> stuff that would be different. There should be a way to factor that 
> stuff out so the same class can draw into its own window or a cairo 
> context owned by another window. Presumably it would have to hook into 
> some kind of cairo context based drawing handler, so it knew when to 
> draw itself, instead of responding to window expose events.


With my own custom controls I've taken a very simple approach where I 
added a render_to_cairo() function on each one that takes a cairo 
context and an x&y co-ordinate as arguments.


>  And what
> about handing mouse events inside a cairo context and grabbing the 
> cursor from your application during popup? That's always where the 
> rubber meets the road.


*nod*

Can get heap big ugly very quickly.

There is consensus on using cairo to render a gtk widget, but when 
rendering a widget onto a cairo surface one is still pretty much on 
one's own.

In my own case I wanted to take advantage of Cairo's transformation 
capabilities in order to implement a zoomable user interface.

Ended up with a CairoCanvasLike derived from gtk.DrawingArea which acts 
as a container for my own 'native-cairo' widgets [1], with my canvas 
taking over window management duties such as event-forwarding, clipping, 
coordinate transformation and redraw handling.

[1] Kind of stupid considering that we already have gtk widgets that are 
already being rendered by cairo but I could never bring myself to 
implementing a pixbufblit strategy for rendering gtk widgets such as the 
experimental cairofirefox uses :-P

  - antoine