pub trait PrimitveGFX {
    fn draw_pixel(&mut self,
                  x: u8,
                  y: u8,
                  color: u16);

    fn fill_rect(&mut self,
                 x: u8,
                 y: u8,
                 w: u8,
                 h: u8,
                 color: u16);


    fn draw_fast_vline(&mut self,
                       x: u8,
                       y: u8,
                       h: u8,
                       color: u16);

    fn draw_fast_hline(&mut self,
                       x: u8,
                       y: u8,
                       w: u8,
                       color: u16);
}


pub trait GFX : PrimitveGFX {
    fn draw_line(&mut self, x0 : u8, y0 : u8, x1 : u8, y1 : u8, color : u16) {
    	let steep_dir_vertical = ((y1 as i16) - (y0 as i16)).abs() > ((x1 as i16) - (x0 as i16)).abs();


    	let (x0, y0, x1, y1) = if (steep_dir_vertical) {
    	    (y0, x0, y1, x1)
    	}
        else {
            (x0, y0, x1, y1)
        };

    	let (x0, y0, x1, y1) = if (x0 > x1) {
            (x1, y1, x0, y0)
    	}
        else {
            (x0, y0, x1, y1)
        };


      	let dx = (x1 as i16) - (x0 as i16);
      	let dy = ((y1 as i16) - (y0 as i16)).abs();

    	let mut err = dx / 2;

    	let y_step : i16 = if (y0 < y1) {
    		1
    	} else {
    		-1
    	};


    	let mut seg = x0;
        let mut cur_y = y0 as i16;
    	for cur_x in x0..(x1 + 1) {
    		err -= dy;
    		if (err < 0) {
    			if (steep_dir_vertical) {
    				self.draw_fast_vline(cur_y as u8, seg, cur_x - seg + 1, color);
    			} else {
    				self.draw_fast_hline(seg, cur_y as u8, cur_x - seg + 1, color);
    			}
    			cur_y += y_step;
    			err += dx;
    			seg = cur_x + 1;
    		}
    	}

        // Finish line case there is a piece missing
        let cur_y = cur_y as u8;
        let last_len = ((x1 as i16) - (seg as i16) + 1) as u8;

    	if steep_dir_vertical {
    		self.draw_fast_vline(cur_y, seg, last_len, color);
    	} else {
    		self.draw_fast_hline(seg, cur_y, last_len, color);
    	}

    }
}