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// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
//go:build darwin || linux || windows
// An app that paints green if golang.org is reachable when the app first
// starts, or red otherwise.
//
// In order to access the network from the Android app, its AndroidManifest.xml
// file must include the permission to access the network.
//
// http://developer.android.com/guide/topics/manifest/manifest-intro.html#perms
//
// The gomobile tool auto-generates a default AndroidManifest file by default
// unless the package directory contains the AndroidManifest.xml. Users can
// customize app behavior, such as permissions and app name, by providing
// the AndroidManifest file. This is irrelevant to iOS.
//
// Note: This demo is an early preview of Go 1.5. In order to build this
// program as an Android APK using the gomobile tool.
//
// See http://godoc.org/golang.org/x/mobile/cmd/gomobile to install gomobile.
//
// Get the network example and use gomobile to build or install it on your device.
//
// $ go get -d golang.org/x/mobile/example/network
// $ gomobile build golang.org/x/mobile/example/network # will build an APK
//
// # plug your Android device to your computer or start an Android emulator.
// # if you have adb installed on your machine, use gomobile install to
// # build and deploy the APK to an Android target.
// $ gomobile install golang.org/x/mobile/example/network
//
// Switch to your device or emulator to start the network application from
// the launcher.
// You can also run the application on your desktop by running the command
// below. (Note: It currently doesn't work on Windows.)
//
// $ go install golang.org/x/mobile/example/network && network
package main
import (
"net/http"
"golang.org/x/mobile/app"
"golang.org/x/mobile/event/lifecycle"
"golang.org/x/mobile/event/paint"
"golang.org/x/mobile/event/size"
"golang.org/x/mobile/gl"
)
func main() {
// checkNetwork runs only once when the app first loads.
go checkNetwork()
app.Main(func(a app.App) {
var glctx gl.Context
det, sz := determined, size.Event{}
for {
select {
case <-det:
a.Send(paint.Event{})
det = nil
case e := <-a.Events():
switch e := a.Filter(e).(type) {
case lifecycle.Event:
glctx, _ = e.DrawContext.(gl.Context)
case size.Event:
sz = e
case paint.Event:
if glctx == nil {
continue
}
onDraw(glctx, sz)
a.Publish()
}
}
}
})
}
var (
determined = make(chan struct{})
ok = false
)
func checkNetwork() {
defer close(determined)
_, err := http.Get("http://golang.org/")
if err != nil {
return
}
ok = true
}
func onDraw(glctx gl.Context, sz size.Event) {
select {
case <-determined:
if ok {
glctx.ClearColor(0, 1, 0, 1)
} else {
glctx.ClearColor(1, 0, 0, 1)
}
default:
glctx.ClearColor(0, 0, 0, 1)
}
glctx.Clear(gl.COLOR_BUFFER_BIT)
}
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