Re: porting gdk -> cairo

On 11 August 2010 02:14, Allin Cottrell <cottrell wfu edu> wrote:
rid of GdkGC.  I'd imagine that the effect I'm after is something
that many GTP apps have need of, and it's trivial to achieve with
the GDK API.

I've found that XOR rubber banding is quite hard to do reliably in
gdk.  The problem I think is that you are using the screen pixels to
store part of the state, and that gets hard to coordinate between the
various things that can affect the display.

I had mouse movements triggering rect moves, mouse moves with a button
held down causing background scrolling of the canvas, and mouse moves
over other screen objects triggering highlight effects. With all these
things going on at once it became very difficult to get XOR rubber
bands to not leave annoying trails as they moved.

I switched to an update-model / invalidate-widget / redraw-on-idle
scheme as Dov suggests and I got prettier updates with less
complication. Since input and output are decoupled, it'll scale more
gracefully between slower and faster machines as well, which is nice.

Anyway, my 2p.


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