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// Package randomart generates OpenSSH style randomart images.
package randomart
import (
"bytes"
)
// Dimensions of the generated image.
const (
XDim = 17
YDim = 9
)
const (
start = -1
end = -2
)
// Board is a generated randomart board.
type Board struct {
tiles [YDim][XDim]int8
title string
subtitle string
}
// Generate creates a Board to represent the given data by applying the drunken
// bishop algorithm.
func Generate(data []byte, title string) Board {
return GenerateSubtitled(data, title, "")
}
func GenerateSubtitled(data []byte, title, subtitle string) Board {
board := Board{title: title, subtitle: subtitle}
var x, y int
x = XDim / 2
y = YDim / 2
board.tiles[y][x] = start
for _, b := range data {
for s := uint(0); s < 8; s += 2 {
d := (b >> s) & 3
switch d {
case 0, 1:
// Up
if y > 0 {
y--
}
case 2, 3:
// Down
if y < YDim-1 {
y++
}
}
switch d {
case 0, 2:
// Left
if x > 0 {
x--
}
case 1, 3:
// Right
if x < XDim-1 {
x++
}
}
if board.tiles[y][x] >= 0 {
board.tiles[y][x]++
}
}
}
if board.tiles[YDim/2][XDim/2] == 0 {
board.tiles[YDim/2][XDim/2] = start
}
board.tiles[y][x] = end
return board
}
// Returns the string representation of the Board, using the OpenSSH ASCII art
// character set.
func (board Board) String() string {
var chars = []string{
" ", ".", "o", "+", "=",
"*", "B", "O", "X", "@",
"%", "&", "#", "/", "^",
}
var buf bytes.Buffer
if len(board.title) > 15 {
board.title = board.title[:15]
}
writeTitle(&buf, board.title)
for _, row := range board.tiles {
buf.WriteString("|")
for _, c := range row {
var s string
if c == start {
s = "S"
} else if c == end {
s = "E"
} else if int(c) < len(chars) {
s = chars[c]
} else {
s = chars[len(chars)-1]
}
buf.WriteString(s)
}
buf.WriteString("|\n")
}
writeTitle(&buf, board.subtitle)
return buf.String()
}
func writeTitle(buf *bytes.Buffer, title string) {
if title != "" {
extraChars := len(title) + 2 - XDim
if extraChars > 0 {
title = title[:XDim-extraChars]
}
title = "[" + title + "]"
}
leftLen := (XDim - len(title)) / 2
rightLen := XDim - len(title) - leftLen
buf.WriteString("+")
for i := 0; i < leftLen; i++ {
buf.WriteString("-")
}
buf.WriteString(title)
for i := 0; i < rightLen; i++ {
buf.WriteString("-")
}
buf.WriteString("+\n")
}
|
