android-go/examples/jni/main.go

// +build darwin linux

package main

import (
	"log"

	"gioui.org/app"
	"gioui.org/io/system"
	"gioui.org/layout"
	"gioui.org/op"
	"gioui.org/unit"
	"gioui.org/widget/material"

	"gioui.org/font/gofont"
)

var (
	labchan chan string
)

type (
	D = layout.Dimensions
	C = layout.Context
)

func main() {
	labchan = make(chan string)
	log.Print("Staring event loop")
	go eventloop()
	app.Main()
	log.Print("app.Main() returned")
}

func eventloop() {
	w := app.NewWindow(
		app.Size(unit.Dp(400), unit.Dp(400)),
		app.Title("Hello"))
	th := material.NewTheme(gofont.Collection())
	var ops op.Ops

	sysinset := &layout.Inset{}
	margin := layout.UniformInset(unit.Dp(10))
	labels := []material.LabelStyle{}
	list := &layout.List{Axis: layout.Vertical}

	resetSysinset := func(x system.Insets) {
		sysinset.Top = x.Top
		sysinset.Bottom = x.Bottom
		sysinset.Left = x.Left
		sysinset.Right = x.Right
	}
	go func() {
		labchan <- "Starting"
		callJni()
	}()
	for {
		select {
		case x := <-labchan:
			labels = append(labels, material.Body1(th, x))
			w.Invalidate()
		case e := <-w.Events():
			switch e := e.(type) {
			case system.DestroyEvent:
				return
			case system.FrameEvent:
				gtx := layout.NewContext(&ops, e)
				resetSysinset(e.Insets)
				sysinset.Layout(gtx, func(gtx C) D {
					return margin.Layout(gtx, func(gtx C) D {
						return list.Layout(gtx, len(labels), func(gtx C, i int) D {
							return labels[i].Layout(gtx)
						})
					})
				})
				e.Frame(gtx.Ops)
			}
		}
	}
}