Live reload for Qt QML development on go with QQmlApplicationEngine

qml_live_reload.go

package main

import (
	"log"
	"os"

	"github.com/fsnotify/fsnotify"
	"github.com/therecipe/qt/core"
	"github.com/therecipe/qt/gui"
	"github.com/therecipe/qt/qml"
)

func main() {
	core.QCoreApplication_SetAttribute(core.Qt__AA_EnableHighDpiScaling, true)
	gui.NewQGuiApplication(len(os.Args), os.Args)

	engine := qml.NewQQmlApplicationEngine(nil)
	engine.Load(core.NewQUrl3("./qml/main.qml", 0))

	watcher, err := fsnotify.NewWatcher()
	if err != nil {
		log.Fatal(err)
	}
	defer watcher.Close()

	go func() {
		for {
			select {
			case event, ok := <-watcher.Events:
				if !ok {
					return
				}
				if event.Op&fsnotify.Write == fsnotify.Write {
					log.Println("modified file:", event.Name)
          
					objs := engine.RootObjects()
					if obj := objs[len(objs)-1]; obj != nil {
						window := gui.NewQWindowFromPointer(obj.Pointer())
            					window.DeleteLater()
            
						engine.ClearComponentCache()
						engine.Load(core.NewQUrl3("./qml/main.qml", 0))
					}
				}
			case err, ok := <-watcher.Errors:
				if !ok {
					return
				}
				log.Println("error:", err)
			}
		}
	}()

	err = watcher.Add("./qml")
	if err != nil {
		log.Fatal(err)
	}

	gui.QGuiApplication_Exec()
}