//! QuickDraw PICT color lookup tables.

use crate::{err::*, image::*};

/// Read a `ColorTable` structure.
pub fn read(b: &[u8]) -> ResultS<(Vec<Color8>, usize)>
{
   read_data! {
      endian: BIG, buf: b, size: 8, start: 0, data {
         let dev = u16[4];
         let num = u16[6] usize;
      }
   }

   let dev = dev & 0x8000 != 0;
   let num = num + 1;

   let mut p = 8;
   let mut clut = vec![Color8::new(0, 0, 0); num];

   for i in 0..num {
      read_data! {
         endian: BIG, buf: b, size: 8, start: p, data {
            let n = u16[0] usize;
            let r = u8[2];
            let g = u8[4];
            let b = u8[6];
         }
      }

      // with device mapping, we ignore the index entirely
      let n = if dev {i} else {n};

      *ok!(clut.get_mut(n), "invalid index")? = Color8::new(r, g, b);

      p += 8;
   }

   Ok((clut, p))
}

// EOF