//! TARGA format images.

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

/// Writes a TGA file from an image.
///
/// # Errors
///
/// Errors if `out` cannot be written to.
pub fn write_tga(out: &mut impl io::Write, im: &impl Image) -> ResultS<()>
{
   // id len, color map type, image type
   out.write_all(&[0, 0, 2])?;
   // color map spec
   out.write_all(&[0, 0, 0, 0, 0])?;
   // x origin
   out.write_all(&[0, 0])?;
   // y origin
   out.write_all(&[0, 0])?;
   // width
   out.write_all(&u16::to_le_bytes(im.w() as u16))?;
   // height
   out.write_all(&u16::to_le_bytes(im.h() as u16))?;
   // depth, descriptor
   out.write_all(&[32, 0])?;

   for y in (0..im.h()).rev() {
      for x in 0..im.w() {
         let cr = im.index(x, y);
         out.write_all(&[(cr.b() >> 8) as u8,
                         (cr.g() >> 8) as u8,
                         (cr.r() >> 8) as u8,
                         (cr.a() >> 8) as u8])?;
      }
   }

   Ok(())
}

// EOF