1//
 2// Copyright (c) 2019 Ted Unangst <tedu@tedunangst.com>
 3//
 4// Permission to use, copy, modify, and distribute this software for any
 5// purpose with or without fee is hereby granted, provided that the above
 6// copyright notice and this permission notice appear in all copies.
 7//
 8// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 9// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
10// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
11// ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
12// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
13// ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
14// OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
15
16package main
17
18import (
19	"bytes"
20	"crypto/sha512"
21	"image"
22	"image/png"
23)
24
25func avatar(name string) []byte {
26	h := sha512.New()
27	h.Write([]byte(name))
28	s := h.Sum(nil)
29	img := image.NewNRGBA(image.Rect(0, 0, 64, 64))
30	for i := 0; i < 64; i++ {
31		for j := 0; j < 64; j++ {
32			p := i*img.Stride + j*4
33			xx := i/16*16 + j/16
34			x := s[xx]
35			if x < 64 {
36				img.Pix[p+0] = 16
37				img.Pix[p+1] = 0
38				img.Pix[p+2] = 48
39				img.Pix[p+3] = 255
40			} else if x < 128 {
41				img.Pix[p+0] = 48
42				img.Pix[p+1] = 0
43				img.Pix[p+2] = 96
44				img.Pix[p+3] = 255
45			} else if x < 192 {
46				img.Pix[p+0] = 72
47				img.Pix[p+1] = 0
48				img.Pix[p+2] = 144
49				img.Pix[p+3] = 255
50			} else {
51				img.Pix[p+0] = 96
52				img.Pix[p+1] = 0
53				img.Pix[p+2] = 192
54				img.Pix[p+3] = 255
55			}
56		}
57	}
58	var buf bytes.Buffer
59	png.Encode(&buf, img)
60	return buf.Bytes()
61}