refactor pixelflut package into proper API

main.go

@@ -49,38 +49,15 @@ func main() {
 
 	offset := image.Pt(*image_offsetx, *image_offsety)
 	img := readImage(*image_path)
-	fetchedImg := image.NewNRGBA(img.Bounds().Add(offset))
 
+	var fetchedImg *image.NRGBA
 	if *fetchImgPath != "" {
-		fetchCmds := pixelflut.CmdsFetchImage(fetchedImg.Bounds())
-		fetchMessages := fetchCmds.Chunk(1)
-
-		{
-			// @cleanup: encapsulate this in separate function exported from pixelflut
-			conn, err := net.Dial("tcp", *address)
-			if err != nil {
-				log.Fatal(err)
-			}
-			// defer conn.Close()
-
-			go pixelflut.FetchPixels(fetchedImg, conn)
-			go pixelflut.Bomb2(fetchMessages[0], conn)
-		}
+		fetchedImg = pixelflut.FetchImage(img.Bounds().Add(offset), *address, 1)
 		*connections -= 1
 	}
 
-	// Generate and split messages into equal chunks
-	commands := pixelflut.CommandsFromImage(img, offset)
-	if *shuffle {
-		commands.Shuffle()
-	}
-
-	if *connections > 0 {
-		commandGroups := commands.Chunk(*connections)
-		for _, messages := range commandGroups {
-			go pixelflut.Bomb(messages, *address)
-		}
-	}
+	// 🌊🌊🌊🌊🌊🌊🌊🌊🌊🌊🌊🌊🌊🌊🌊
+	pixelflut.Flut(img, offset, *shuffle, *address, *connections)
 
 	// Terminate after timeout to save resources
 	timer, err := time.ParseDuration(*runtime)

pixelflut/api.go

@@ -0,0 +1,77 @@
+package pixelflut
+
+import (
+	"bufio"
+	"encoding/hex"
+	"image"
+	"image/color"
+	"log"
+	"net"
+	"net/textproto"
+	"strconv"
+	"strings"
+)
+
+// Flut asynchronously sends the given image to pixelflut server at `address`
+//   using `conns` connections. Pixels are sent row wise, unless `shuffle` is set.
+func Flut(img image.Image, position image.Point, shuffle bool, address string, conns int) {
+	cmds := commandsFromImage(img, position)
+	if shuffle {
+		cmds.Shuffle()
+	}
+
+	messages := cmds.Chunk(conns)
+	for _, msg := range messages {
+		go bombAddress(msg, address)
+	}
+}
+
+// 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) (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)
+		}
+
+		// @cleanup: parsePixels calls conn.Close(), as deferring it here would
+		//   instantly close it
+		go parsePixels(img, conn)
+		go bombConn(cmds[i], conn)
+	}
+
+	return img
+}
+
+func parsePixels(target *image.NRGBA, conn net.Conn) {
+	reader := bufio.NewReader(conn)
+	tp := textproto.NewReader(reader)
+	defer conn.Close()
+
+	for {
+		// @speed: textproto seems not the fastest, buffer text manually & split at \n ?
+		res, err := tp.ReadLine()
+		if err != nil {
+			log.Fatal(err)
+		}
+
+		// @speed: Split is ridiculously slow due to mallocs!
+		//   chunk last 6 chars off -> color, remove first 3 chars, find space in
+		//   remainder, then Atoi() xy?
+		res2 := strings.Split(res, " ")
+		x, _ := strconv.Atoi(res2[1])
+		y, _ := strconv.Atoi(res2[2])
+		col, _ := hex.DecodeString(res2[3])
+
+		target.Set(x, y, color.NRGBA{
+			uint8(col[0]),
+			uint8(col[1]),
+			uint8(col[2]),
+			255,
+		})
+	}
+}

pixelflut/commands.go

@@ -1,15 +1,18 @@
 package pixelflut
 
 import (
+	"fmt"
+	"image"
+	"image/color"
 	"math/rand"
 )
 
 // Commands represent a list of messages to be sent to a pixelflut server.
-type Commands [][]byte
+type commands [][]byte
 
 // Chunk splits commands into equally sized chunks, while flattening each chunk
 // so that all commands are concatenated as a single `[]byte`.
-func (c Commands) Chunk(numChunks int) [][]byte {
+func (c commands) Chunk(numChunks int) [][]byte {
 	chunks := make([][]byte, numChunks)
 	chunkLength := len(c) / numChunks
 	for i := 0; i < numChunks; i++ {
@@ -22,9 +25,49 @@ func (c Commands) Chunk(numChunks int) [][]byte {
 }
 
 // Shuffle reorders commands randomly, in place.
-func (c Commands) Shuffle() {
+func (c commands) Shuffle() {
 	for i := range c {
 		j := rand.Intn(i + 1)
 		c[i], c[j] = c[j], c[i]
 	}
 }
+
+// CommandsFromImage converts an image to the respective pixelflut commands
+func commandsFromImage(img image.Image, offset image.Point) (cmds commands) {
+	b := img.Bounds()
+	cmds = make([][]byte, b.Size().X*b.Size().Y)
+	numCmds := 0
+
+	for x := b.Min.X; x < b.Max.X; x++ {
+		for y := b.Min.Y; y < b.Max.Y; y++ {
+			// ensure we're working with RGBA colors (non-alpha-pre-multiplied)
+			c := color.NRGBAModel.Convert(img.At(x, y)).(color.NRGBA)
+
+			// ignore transparent pixels
+			if c.A == 0 {
+				continue
+			}
+			// @incomplete: also send alpha? -> bandwidth tradeoff
+			// @speed: this sprintf call is quite slow..
+			cmd := fmt.Sprintf("PX %d %d %.2x%.2x%.2x\n",
+				x+offset.X, y+offset.Y, c.R, c.G, c.B)
+			cmds[numCmds] = []byte(cmd)
+			numCmds++
+		}
+	}
+
+	return cmds[:numCmds]
+}
+
+func cmdsFetchImage(bounds image.Rectangle) (cmds commands) {
+	cmds = make([][]byte, bounds.Size().X*bounds.Size().Y)
+	numCmds := 0
+	for x := bounds.Min.X; x < bounds.Max.X; x++ {
+		for y := bounds.Min.Y; y < bounds.Max.Y; y++ {
+			cmd := fmt.Sprintf("PX %d %d\n", x, y)
+			cmds[numCmds] = []byte(cmd)
+			numCmds++
+		}
+	}
+	return cmds
+}

pixelflut/fetch.go

@@ -1,19 +0,0 @@
-package pixelflut
-
-import (
-	"fmt"
-	"image"
-)
-
-func CmdsFetchImage(bounds image.Rectangle) (cmds Commands) {
-	cmds = make([][]byte, bounds.Size().X*bounds.Size().Y)
-	numCmds := 0
-	for x := bounds.Min.X; x < bounds.Max.X; x++ {
-		for y := bounds.Min.Y; y < bounds.Max.Y; y++ {
-			cmd := fmt.Sprintf("PX %d %d\n", x, y)
-			cmds[numCmds] = []byte(cmd)
-			numCmds++
-		}
-	}
-	return cmds
-}

pixelflut/net.go

@@ -1,34 +1,26 @@
 package pixelflut
 
 import (
-	"bufio"
-	"encoding/hex"
-	"image"
-	"image/color"
 	"log"
 	"net"
-	"net/textproto"
-	"strconv"
-	"strings"
 )
 
 // @speed: add some performance reporting mechanism on these functions when
 //   called as goroutines
 
-// Bomb writes the given message via plain TCP to the given address,
+// bombAddress writes the given message via plain TCP to the given address,
 // forever, as fast as possible.
-func Bomb(message []byte, address string) {
+func bombAddress(message []byte, address string) {
 	conn, err := net.Dial("tcp", address)
 	if err != nil {
 		log.Fatal(err)
 	}
 	defer conn.Close()
 
-	Bomb2(message, conn)
+	bombConn(message, conn)
 }
 
-// @cleanup: find common interface instead of Bomb2
-func Bomb2(message []byte, conn net.Conn) {
+func bombConn(message []byte, conn net.Conn) {
 	for {
 		_, err := conn.Write(message)
 		if err != nil {
@@ -36,31 +28,3 @@ func Bomb2(message []byte, conn net.Conn) {
 		}
 	}
 }
-
-func FetchPixels(target *image.NRGBA, conn net.Conn) {
-	reader := bufio.NewReader(conn)
-	tp := textproto.NewReader(reader)
-
-	for {
-		// @speed: textproto seems not the fastest, buffer text manually & split at \n ?
-		res, err := tp.ReadLine()
-		if err != nil {
-			log.Fatal(err)
-		}
-
-		// @speed: Split is ridiculously slow due to mallocs!
-		//   chunk last 6 chars off -> color, remove first 3 chars, find space in
-		//   remainder, then Atoi() xy?
-		res2 := strings.Split(res, " ")
-		x, _ := strconv.Atoi(res2[1])
-		y, _ := strconv.Atoi(res2[2])
-		col, _ := hex.DecodeString(res2[3])
-
-		target.Set(x, y, color.NRGBA{
-			uint8(col[0]),
-			uint8(col[1]),
-			uint8(col[2]),
-			255,
-		})
-	}
-}

pixelflut/send.go

@@ -1,34 +0,0 @@
-package pixelflut
-
-import (
-	"fmt"
-	"image"
-	"image/color"
-)
-
-// CommandsFromImage converts an image to the respective pixelflut commands
-func CommandsFromImage(img image.Image, offset image.Point) (commands Commands) {
-	b := img.Bounds()
-	commands = make([][]byte, b.Size().X*b.Size().Y)
-	numCmds := 0
-
-	for x := b.Min.X; x < b.Max.X; x++ {
-		for y := b.Min.Y; y < b.Max.Y; y++ {
-			// ensure we're working with RGBA colors (non-alpha-pre-multiplied)
-			c := color.NRGBAModel.Convert(img.At(x, y)).(color.NRGBA)
-
-			// ignore transparent pixels
-			if c.A == 0 {
-				continue
-			}
-			// @incomplete: also send alpha? -> bandwidth tradeoff
-			// @speed: this sprintf call is quite slow..
-			cmd := fmt.Sprintf("PX %d %d %.2x%.2x%.2x\n",
-				x+offset.X, y+offset.Y, c.R, c.G, c.B)
-			commands[numCmds] = []byte(cmd)
-			numCmds++
-		}
-	}
-
-	return commands[:numCmds]
-}