Re: [Gimp-developer] [Patch] Speed up blending code

[Daniel Egger <de@xxxxxxxxxx>]

On 27.02.2005, at 20:01, Robert L Krawitz wrote:

> OK.  The code Daniel posted shouldn't be too hard to convert.  The
> only thing it needs is to have the absolute row and column, to index
> into the matrix.

That hasn't made it into CVS because Sven was faster...

Here's the current code:
static void
gradient_fill_single_region_rgb_dither (RenderBlendData *rbd,
                                        PixelRegion     *PR)
{
  GRand  *dither_rand = g_rand_new_with_seed (g_rand_int (rbd->seed));
  guchar *dest        = PR->data;
  gint    endx        = PR->x + PR->w;
  gint    endy        = PR->y + PR->h;
  gint    x, y;

  for (y = PR->y; y < endy; y++)
    for (x = PR->x; x < endx; x++)
      {
        GimpRGB  color;

        gradient_render_pixel (x, y, &color, rbd);

        gradient_dither (dest, dither_rand, color.r);
        gradient_dither (dest, dither_rand, color.g);
        gradient_dither (dest, dither_rand, color.b);
        gradient_dither (dest, dither_rand, color.a);
      }

  g_rand_free (dither_rand);
}

If needed you can setup your LUT globally or create it
on demand and have a pointer in RenderBlendData, depending
on how big and/or complex it is to compute and replace the
inner loop by your code.

Would it make sense to have several (selectable) dither
algorithms?

> Will I be able to compile it against a current (stable) GIMP
> installation?

Huh?

Servus,
      Daniel

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