[WIP] Add hsv to rgb conversion function in restricted list

[ohthehugemanatee]

So far the only functions that return RGB colors are ones that ignore the palette. This PR adds a function (shamelessly learned from stackoverflow) for converting HSV to RGB. I don't think the reverse is necessary, since the palette functions return HSV and the whole primary pattern can return RGB without problem.

One thing I'm not sure about though: does prev_state always come in HSV? Or if the previous loop returned RGB, will we get RGB on the second loop? If it's the latter case, this PR needs some work to either:

• identify if prev_state is HSV vs RGB, or
• ensure prev_state always comes in as HSV.

[ohthehugemanatee]

Marking this as Work In Progress because on testing, it looks like prev_state does preserve whatever the previous return type was. Still usable if you do the conversion inside an if t==0: block but that's not nice.

[jackw01]

This would be much faster if implemented in C (add this to led_render.h):

color_rgb_float hsv_to_rgb(float h, float s, float v) {
  if (s == 0.0) return (color_rgb_float){v, v, v};
  float f = h * 6.0;
  int i = (int)f;
  f -= i;
  i %= 6;
  float p = v * (1.0 - s);
  float q = v * (1.0 - s * f);
  float t = v * (1.0 - s * (1.0 - f));
  if (i == 0) return (color_rgb_float){v, t, p};
  else if (i == 1) return (color_rgb_float){q, v, p};
  else if (i == 2) return (color_rgb_float){p, v, t};
  else if (i == 3) return (color_rgb_float){p, q, v};
  else if (i == 4) return (color_rgb_float){t, p, v};
  else return (color_rgb_float){v, p, q};
}

Just run swig -python ./ledcontrol/driver/ledcontrol_rpi_ws281x_driver.i && sudo python3 setup.py develop to rebuild the extension module and add driver.hsv_to_rgb to the restricted_globals dictionary.