added get endpoint for image

go/server.go

@@ -8,9 +8,11 @@
 package main
 
 import (
+	"encoding/json"
 	"flag"
 	"log"
 	"net/http"
+	"time"
 
 	"github.com/gorilla/websocket"
 )
@@ -19,9 +21,9 @@ var upgrader = websocket.Upgrader{
 	ReadBufferSize:  2048,
 	WriteBufferSize: 2048,
 }
-var img = GetImage(10, 10)
+var img = GetImage(1000, 1000)
 
-func serve(w http.ResponseWriter, r *http.Request) {
+func set(w http.ResponseWriter, r *http.Request) {
 	c, err := upgrader.Upgrade(w, r, nil)
 	if err != nil {
 		log.Print("error while upgrading", err)
@@ -47,11 +49,38 @@ func serve(w http.ResponseWriter, r *http.Request) {
 	}
 }
 
+func get(w http.ResponseWriter, r *http.Request) {
+	c, err := upgrader.Upgrade(w, r, nil)
+	if err != nil {
+		log.Print("error while upgrading", err)
+		return
+	}
+	defer c.Close()
+	log.Println("Client Connected")
+	ticker := time.NewTicker(1 * time.Second)
+	go func() {
+		for range ticker.C {
+			tmpImage := GetImage(img.width, img.height)
+			diff := tmpImage.GetDiff(&img)
+			msg, err := json.Marshal(diff)
+			err = c.WriteMessage(1, msg)
+			if err != nil {
+				log.Print("error while writing image", err)
+			}
+			copy(tmpImage.pixels, img.pixels)
+		}
+	}()
+	if err != nil {
+		log.Println(err)
+	}
+}
+
 func main() {
 	var addr = flag.String("addr", "localhost:8080", "http service address")
 
 	flag.Parse()
 	log.SetFlags(0)
-	http.HandleFunc("/", serve)
+	http.HandleFunc("/set", set)
+	http.HandleFunc("/get", get)
 	log.Fatal(http.ListenAndServe(*addr, nil))
 }

go/util.go

@@ -32,6 +32,25 @@ type image struct {
 	pixels []pixel
 }
 
+type messagePixel struct {
+	Color     uint8  `json:"color"`
+	Timestamp int64  `json:"timestamp"`
+	UserID    uint64 `json:"userid"`
+}
+type messageImage struct {
+	Width  uint16         `json:"width"`
+	Height uint16         `json:"height"`
+	Pixels []messagePixel `json:"pixel"`
+}
+
+func GetMessageImage(w uint16, h uint16) messageImage {
+	pixels := make([]messagePixel, w*h)
+	for i := 0; i < int(w*h); i++ {
+		pixels[i] = messagePixel{Color: 0, Timestamp: 0, UserID: 0}
+	}
+	return messageImage{Width: w, Height: h, Pixels: pixels}
+}
+
 func GetImage(w uint16, h uint16) image {
 	pixels := make([]pixel, w*h)
 	for i := 0; i < int(w*h); i++ {
@@ -63,3 +82,19 @@ func (img *image) SetPixel(message Message) *image {
 	img.pixels[pos].setColor(message.Color, message.Timestamp, message.UserID)
 	return img
 }
+
+func comparePixels(pixel1 *pixel, pixel2 *pixel) bool {
+	return pixel1.Color == pixel2.Color && pixel1.Timestamp == pixel2.Timestamp && pixel1.UserID == pixel2.UserID
+}
+
+func (img *image) GetDiff(img2 *image) messageImage {
+	diff := GetMessageImage(img.width, img.height)
+	for i := 0; i < int(img.width*img.height); i++ {
+		if comparePixels(&img.pixels[i], &img2.pixels[i]) {
+			diff.Pixels[i].Color = img2.pixels[i].Color
+			diff.Pixels[i].UserID = img2.pixels[i].UserID
+			diff.Pixels[i].Timestamp = img2.pixels[i].Timestamp
+		}
+	}
+	return diff
+}

python/clients.py

@@ -27,7 +27,7 @@ async def main():
         timestamp=int(time.time()),
         userid=1,
     )
-    async with websockets.connect("ws://localhost:8080") as websocket:
+    async with websockets.connect("ws://localhost:8080/set") as websocket:
         print(message)
         await websocket.send(json.dumps(message.__dict__))
         await websocket.recv()