gopaper/slideshow.go

package main

import (
	"fmt"
	"log"
	"os/exec"
	"time"
)

func slideshow(ch <-chan string) {
	dir := <-ch
	ticker := time.NewTicker(time.Duration(config.Duration) * time.Minute)

	//set a flat background color based on config defaults
	fillReady := make(chan bool)
	go func() {
		fillCmd := exec.Command("swaybg", "-c", "#232136")
		err := fillCmd.Start()
		if err != nil {
			fmt.Println("could not set background color", err)
		}
		fmt.Println("bg color set!")
		fillReady <- true
		fillCmd.Wait()
	}()

	var cmd *exec.Cmd
	go func() {
		for {
			<-fillReady
			newCmd := setRandomWallpaper(dir)
			if cmd != nil {
				err := cmd.Process.Kill()
				if err != nil {
					log.Fatal("could not kill process", err)
				}
			}
			cmd = newCmd
			select {
			case dir = <-ch:
				log.Println("directory set!")
				continue
			case <-ticker.C:
				continue
			}
		}
	}()
}

func setRandomWallpaper(dir string) *exec.Cmd {
	img, err := pickRandomImage(dir)
	if err != nil {
		panic(err)
	}

	cmd := exec.Command("swaybg", "-i", img, "--mode", "fit")
	fmt.Printf("setting wallpaper: %v\n", img)
	err = cmd.Start()
	if err != nil {
		log.Fatal("failed to set wallpaper!", err)
	}
	go cmd.Wait()
	return cmd
}