ws_canvas.go

package main

import (
	"fmt"
	"image"
	"io"
	"math"
	"net/http"
	"time"

	"code.google.com/p/go.net/websocket"
	"github.com/gorilla/mux"
)

func GradientHandler(ws *websocket.Conn) {
	width, height := 200, 200
	canvas := NewCanvas(image.Rect(0, 0, width, height))
	canvas.DrawGradient()
	// Warning, slow for large canvases!
	// This is definitely not an efficient way to send an image!
	for x := 0; x < width; x++ {
		for y := 0; y < height; y++ {
			r, g, b, _ := canvas.At(x, y).RGBA()
			color := fmt.Sprintf("#%02x%02x%02x", r/0xFF, g/0xFF, b/0xFF)
			msg := fmt.Sprintf("PIXEL %d %d %s\n", x, y, color)
			io.WriteString(ws, msg)
		}
		time.Sleep(time.Second / 30.0)
	}
}

func GraphHandler(ws *websocket.Conn) {
	width, height := 512, 512
	t := 0.0
	for {
		msg := "CLEAR\n"
		for x := 0; x < width; x++ {
			y := height/2 + int(50*math.Sin(t/10)*math.Sin(float64(x)/10.0+t))
			y2 := height/3 + int(60*math.Sin(t/9)*math.Sin(float64(x)/20.0+2.0*t))
			msg += fmt.Sprintf("PIXEL %d %d %s\n", x, y, "#ff0000")
			msg += fmt.Sprintf("PIXEL %d %d %s\n", x, y2, "#00ff00")
		}
		t += 0.3
		io.WriteString(ws, msg)
		time.Sleep(time.Second / 30.0)
	}
}

func HelloHandler(ws *websocket.Conn) {
	io.WriteString(ws, "HELLO")
}

func main() {
	router := mux.NewRouter()
	//router.Handle("/ws", websocket.Handler(GradientHandler))
	router.Handle("/ws", websocket.Handler(GraphHandler))
	staticHandler := http.FileServer(http.Dir("."))
	router.PathPrefix("/").Handler(staticHandler)
	http.ListenAndServe("localhost:1234", router)
}