Re: suitable toolbox for drawing toons on a screen.

["Jasper St. Pierre" <jstpierre mecheye net>]

On Thu, May 10, 2012 at 11:00 PM, Amy C <mathematical coffee gmail com> wrote:
> Hi all,
>
> As something fun I'd like to try writing a gnome shell extension that
> draws things on the user's screen. Entirely useless, but I think it'll
> be fun to write (OK OK, the vague idea I have is to port xpenguins to
> gjs :P).

Right off the bat, GTK+/GDK is mostly out. You have to use Clutter,
because GNOME Shell uses Clutter. You should draw vector graphics
using Cairo. StDrawingArea will give you a cairo canvas on which you
can draw on.

> I've done a bit of X11 programming before as in a previous life I
> spent quite a while in the XPenguins source tweaking it to my
> preference, but now that it comes to GJS I'm not sure what tools are
> available/which to use.
>
> Features I'd like:
> 1) draw animated toons (by displaying a particular snippet of a
> pixmap) : Gtk? Gdk?
> 2) window features - calculate where windows are to build up regions
> toons are/aren't allowed to walk on (XRegions, XRectangles) : mutter?
> clutter?
> 3) draw onto either a particular window that I choose, or the 'root' window.
>
> Does anyone have a feel for what toolkit(s) are suitable for this? I
> guess it would be ideal to use the one toolkit for most things, to
> avoid having to translate (e.g.) a Meta.Rectangle to some sort of Gdk
> region all the time.
>
> I have no idea what toolkit to use for 1), but I have the vague
> feeling it's G[dt]k.
> As for window features, I know I can get window rectangles via
> Meta.Rectangle and union them together to build up regions.
>
> However, does one draw *directly* onto the target window (this is what
> Xlib XPenguins does), or does one create a transparent, clickthrough
> window over the top of the target window and draw onto that? Or one
> small window per toon??
>
> Or can everything be done with Clutter (I must confess I know very
> little about Clutter)? Do I make a "stage" and each "actor" is a toon,
> and use a ClutterTexture (ClutterImage? ClutterCanvas?) for displaying
> the toon's picture, updating it every frame?
>
> I apologise for the somewhat confused nature of this email, but I feel
> like there's so many ways to skin this cat, and I just want to pick
> the "right" one from the get go rather than doing lots of switching
> and changing after starting with a toolkit that turned out to be
> inappropriate.
>
> cheers!
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-- 
  Jasper