package main
import (
"fmt"
"log"
"math/rand"
"net"
"net/http"
"time"
"github.com/zserge/webview"
)
const (
windowWidth = 480
windowHeight = 320
)
var indexHTML = fmt.Sprintf(`
`, windowWidth, windowHeight)
func startServer() string {
ln, err := net.Listen("tcp", "127.0.0.1:0")
if err != nil {
log.Fatal(err)
}
go func() {
defer ln.Close()
http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
w.Write([]byte(indexHTML))
})
log.Fatal(http.Serve(ln, nil))
}()
return "http://" + ln.Addr().String()
}
var (
numFrames int
prevTime time.Time
totalTime time.Duration
)
func handleRPC(w webview.WebView, data string) {
numFrames++
if !prevTime.IsZero() {
totalTime = totalTime + time.Since(prevTime)
}
prevTime = time.Now()
if numFrames%100 == 0 {
d := totalTime / time.Duration(numFrames)
log.Println("time per frame:", d, " fps:", int(time.Second/d))
}
s := fmt.Sprintf(`drawData = {x1:%d,y1:%d,x2:%d,y2:%d}`,
rand.Intn(windowWidth), rand.Intn(windowHeight),
rand.Intn(windowWidth), rand.Intn(windowHeight))
w.Eval(s)
}
func main() {
url := startServer()
w := webview.New(webview.Settings{
Width: windowWidth,
Height: windowHeight,
Title: "Simple canvas demo",
URL: url,
ExternalInvokeCallback: handleRPC,
})
defer w.Exit()
w.Run()
}