Re: Heads-up: Potentially breaking changes to the GDK drawing model pushed

[Jean Brefort <jean brefort normalesup org>]

Le samedi 21 juin 2014 à 11:05 -0400, Paul Davis a écrit :
> On Sat, Jun 21, 2014 at 10:35 AM, Jean Brefort
> <jean brefort normalesup org> wrote:
>         In gnumeric this arised when we draw an animated rectangle
>         around the
>         selected rectangle. When using the draw event, we need to
>         repaint
>         everything inside the rectangle and this made gnumeric quite
>         unresponsive when there were many cells displayed at once.
>
>
> i don't believe that this is true, but thanks for the explanation. 
>
>
> A draw/expose event contains a list of rectangles which need not be
> contiguous. It is only a matter of convenience to use the GdkRectangle
> that is also supplied. You can invalidate the "border" around the
> cell. We do this in ardour, especially in our new canvas, where we
> frequently queue discontiguous areas of the screen for drawing - when
> we render we do not draw the union of all these areas, just each
> rectangle in the list of regions.
I know that an expose event contains a region, but this does not help,
we use the draw event, and I don't know how to reliably access the
region. More, it is not really easy to determine what needs to be
redrawn from inside a draw event.