[cairo] recursive quad-tree, or bounding box of changed area during drawing?

[Federico Mena Quintero]

On Thu, 2006-06-01 at 21:35 +0200, Leon Woestenberg wrote:
> It is very interesting to read about canvas (retained mode) 
> optimizations, but I am using cairo (direct mode) where I have no notion 
> of paint objects. I start painting, stop painting, and want to know if I 
> can get a cheap bounded box (or a recursive variant thereof) of the 
> region being dirtied in the paint process.

Oh, I always assumed you were writing something like a canvas.

So do you want something like this?

  surf = cairo_image_surface_new (big_enough_for_the_screen);
  paint_everything (surf);
  bbox = bounding_box_for_pixels_that_were_painted (surf);
  bit_blt (surf, bbox, screen); <- you want to minimize this

Blitting is not going to be your main performance problem, unless your
blitter is absolutely horrible.  You need to do profiling on the whole
pipeline.

  Federico