Re: [Inkscape-devel] [Recolor] Re-painting the 'gimpcolorwheel'

Okay guys, no need for the above said approaches, I took care of it using saturation adjustment itself. :) Here's a snapshot: [image: Inline image 1]

On Sat, Jun 15, 2013 at 11:10 PM, Arshdeep Singh <moduli16@...400...> wrote:

Hello devs, My current state of the wheel looks like this: [image: Inline image 1]

I want a white center that blends into the respective colors towards the circumference. Here's a snippet from gimpcolorwheel.c *Function :* static void paint_ring (GimpColorWheel *wheel, cairo_t *cr) { ...}

Snippet: *for (yy = 0; yy < height; yy++)*

• {*

•  p = buf + yy * width;*
  

•  dy = -(yy - center_y);*
  

•  for (xx = 0; xx < width; xx++)*
  

•    {*
  

•      dx = xx - center_x;*
  

•      dist = dx * dx + dy * dy;*
  

•      if (dist < ((inner-1) * (inner-1)) || dist > ((outer+1) *
  

(outer+1)))*

•        {*
  

•          *p++ = 0;*
  

•          continue;*
  

•        }*
  

•      angle = atan2 (dy, dx);*
  

•      if (angle < 0.0)*
  

•        angle += 2.0 * G_PI;*
  

•      hue = angle / (2.0 * G_PI);*
  

•      r = hue;*
  

•      g = 1.0;*
  

•      b = 1.0;*
  

•      hsv_to_rgb (&r, &g, &b);*
  

•      *p++ = (((int)floor (r * 255 + 0.5) << 16) |*
  

•              ((int)floor (g * 255 + 0.5) << 8) |*
  

•              (int)floor (b * 255 + 0.5));*
  

•    }*
  

• }*

this paints the colors of the wheel. Because we need to paint the center white, we have two options: ( I suppose ? ) One is to include a distance from the center that shall be the faintest white from the center We can choose this distance to be 20% of the radius allocated. This white coloration can be accommodated into the above snippet but what I fail to solve is how to add the transparency ? Should I calculate a separate 'buf' that is then OR-ed (overlaid) with the 'p' buffer to create that effect ?

OR

I can create a smaller circular arc and use radial gradient (white at center and transparent at circumference , radius again 20% ) and overlay onto the same surface used to draw the initial color wheel as shown in the picture above.

I personally feel, the second option is easier because the first option would require to know how rgb changes when a certain degree of white is added to it. Your views are looked forward to. Thanks.

-- Arshdeep Singh Third Year, Computer Engineering Delhi Technological University Ph: +91-9654115614 https://sites.google.com/site/adsingh1729/home