Hochwasser/pixelflut/api.go

92 lines
2.0 KiB
Go

package pixelflut
import (
"bufio"
"encoding/hex"
"image"
"image/color"
"log"
"net"
"sync"
)
// Flut asynchronously sends the given image to pixelflut server at `address`
// using `conns` connections. Pixels are sent column wise, unless `shuffle`
// is set. Stops when stop is closed.
// @cleanup: use FlutTask{} as arg
func Flut(img *image.NRGBA, position image.Point, shuffle bool, address string, conns int, stop chan bool, wg *sync.WaitGroup) {
cmds := commandsFromImage(img, position)
if shuffle {
cmds.Shuffle()
}
messages := cmds.Chunk(conns)
bombWg := sync.WaitGroup{}
for _, msg := range messages {
bombWg.Add(1)
go bombAddress(msg, address, stop, &bombWg)
}
bombWg.Wait()
if wg != nil {
wg.Done()
}
}
// FetchImage asynchronously uses `conns` to fetch pixels within `bounds` from
// a pixelflut server at `address`, and writes them into the returned Image.
func FetchImage(bounds image.Rectangle, address string, conns int, stop chan bool) (img *image.NRGBA) {
img = image.NewNRGBA(bounds)
cmds := cmdsFetchImage(bounds).Chunk(conns)
for i := 0; i < conns; i++ {
conn, err := net.Dial("tcp", address)
if err != nil {
log.Fatal(err)
}
go readPixels(img, conn, stop)
go bombConn(cmds[i], conn, stop)
}
return img
}
func readPixels(target *image.NRGBA, conn net.Conn, stop chan bool) {
reader := bufio.NewReader(conn)
col := make([]byte, 3)
for {
select {
case <-stop:
return
default:
res, err := reader.ReadSlice('\n')
if err != nil {
log.Fatal(err)
}
// parse response ("PX <x> <y> <col>\n")
colorStart := len(res) - 7
xy := res[3 : colorStart-1]
yStart := 0
for yStart = len(xy) - 2; yStart >= 0; yStart-- {
if xy[yStart] == ' ' {
break
}
}
x := asciiToInt(xy[:yStart])
y := asciiToInt(xy[yStart+1:])
hex.Decode(col, res[colorStart:len(res)-1])
target.SetNRGBA(x, y, color.NRGBA{col[0], col[1], col[2], 255})
}
}
}
func asciiToInt(buf []byte) (v int) {
for _, c := range buf {
v = v*10 + int(c-'0')
}
return v
}