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package main
import (
"encoding/json"
"fmt"
"image"
"image/draw"
"image/png"
"io/ioutil"
"log"
"net/http"
"os"
"os/exec"
"time"
)
var level = 4
var width = 550
var delay = 8 // delay in hours, so that I can see daylight on my wallpaper during the day!
type latestData struct {
Date string `json:"date"`
File string `json:"file"`
}
func main() {
// Define work directory and files
var home = os.Getenv("HOME")
var work_dir = home + "/.himawari"
var image_file = work_dir + "/latest.png"
var dat_file = work_dir + "/data"
// Read the last date from dat_file if it exists
data, err := ioutil.ReadFile(dat_file)
oldData := new(latestData)
if err != nil {
data = nil
} else {
err = json.Unmarshal(data, oldData)
if err != nil {
oldData = nil
}
}
// Get the data about the last image
initData := new(latestData)
err = getJson("http://himawari8-dl.nict.go.jp/himawari8/img/D531106/latest.json", initData)
if err != nil {
log.Fatal("error getting json :", err)
}
location, _ := time.LoadLocation("Asia/Tokyo")
t, _ := time.ParseInLocation("2006-01-02 15:04:05", initData.Date, location)
if oldData != nil && oldData.Date == initData.Date {
log.Print("No new image, keeping the old one")
os.Exit(0)
}
t = t.Add(time.Duration(-delay) * time.Hour)
// Get all the chunks from the latest image and assemble them
output := image.NewRGBA(image.Rect(0, 0, level*width, level*width))
for x := 0; x < level; x++ {
for y := 0; y < level; y++ {
url := fmt.Sprintf("http://himawari8.nict.go.jp/img/D531106/%dd/%d/%s_%d_%d.png",
level, width, t.Format("2006/01/02/150405"), x, y)
var buff image.Image
err = getPng(url, &buff)
if err != nil {
err = getPng(url, &buff)
if err != nil {
log.Fatal("Error getting png :", url)
}
}
draw.Draw(output, image.Rect(x*width, y*width, (x+1)*width, (y+1)*width), buff, image.Point{0, 0}, draw.Src)
}
}
// Write output to file
out, err := os.Create(image_file)
if err != nil {
err := os.Mkdir(work_dir, 0755)
if err != nil {
log.Fatal("error creating :", err)
}
out, err = os.Create(image_file)
if err != nil {
log.Fatal("error creating :", err)
}
}
defer out.Close()
err = png.Encode(out, output)
if err != nil {
log.Fatal("Error writing output:", err)
}
// Write dat file
buff, err := json.Marshal(initData)
ioutil.WriteFile(dat_file, buff, 0644)
// Exec feh
cmd := exec.Command("feh", "--bg-max", image_file)
err = cmd.Run()
if err != nil {
log.Fatal("Error launching feh :", err)
}
}
func getJson(url string, target interface{}) error {
r, err := http.Get(url)
if err != nil {
return err
}
defer r.Body.Close()
return json.NewDecoder(r.Body).Decode(target)
}
func getPng(url string, image *image.Image) error {
r, err := http.Get(url)
if err != nil {
return err
}
defer r.Body.Close()
*image, err = png.Decode(r.Body)
return err
}
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