github.com/SkycoinProject/gomobile@v0.0.0-20190312151609-d3739f865fa6/example/network/main.go (about)

     1  // Copyright 2015 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  // +build darwin linux windows
     6  
     7  // An app that paints green if golang.org is reachable when the app first
     8  // starts, or red otherwise.
     9  //
    10  // In order to access the network from the Android app, its AndroidManifest.xml
    11  // file must include the permission to access the network.
    12  //
    13  //   http://developer.android.com/guide/topics/manifest/manifest-intro.html#perms
    14  //
    15  // The gomobile tool auto-generates a default AndroidManifest file by default
    16  // unless the package directory contains the AndroidManifest.xml. Users can
    17  // customize app behavior, such as permissions and app name, by providing
    18  // the AndroidManifest file. This is irrelevent to iOS.
    19  //
    20  // Note: This demo is an early preview of Go 1.5. In order to build this
    21  // program as an Android APK using the gomobile tool.
    22  //
    23  // See http://godoc.org/golang.org/x/mobile/cmd/gomobile to install gomobile.
    24  //
    25  // Get the network example and use gomobile to build or install it on your device.
    26  //
    27  //   $ go get -d golang.org/x/mobile/example/network
    28  //   $ gomobile build golang.org/x/mobile/example/network # will build an APK
    29  //
    30  //   # plug your Android device to your computer or start an Android emulator.
    31  //   # if you have adb installed on your machine, use gomobile install to
    32  //   # build and deploy the APK to an Android target.
    33  //   $ gomobile install golang.org/x/mobile/example/network
    34  //
    35  // Switch to your device or emulator to start the network application from
    36  // the launcher.
    37  // You can also run the application on your desktop by running the command
    38  // below. (Note: It currently doesn't work on Windows.)
    39  //   $ go install golang.org/x/mobile/example/network && network
    40  package main
    41  
    42  import (
    43  	"net/http"
    44  
    45  	"golang.org/x/mobile/app"
    46  	"golang.org/x/mobile/event/lifecycle"
    47  	"golang.org/x/mobile/event/paint"
    48  	"golang.org/x/mobile/event/size"
    49  	"golang.org/x/mobile/gl"
    50  )
    51  
    52  func main() {
    53  	// checkNetwork runs only once when the app first loads.
    54  	go checkNetwork()
    55  
    56  	app.Main(func(a app.App) {
    57  		var glctx gl.Context
    58  		det, sz := determined, size.Event{}
    59  		for {
    60  			select {
    61  			case <-det:
    62  				a.Send(paint.Event{})
    63  				det = nil
    64  
    65  			case e := <-a.Events():
    66  				switch e := a.Filter(e).(type) {
    67  				case lifecycle.Event:
    68  					glctx, _ = e.DrawContext.(gl.Context)
    69  				case size.Event:
    70  					sz = e
    71  				case paint.Event:
    72  					if glctx == nil {
    73  						continue
    74  					}
    75  					onDraw(glctx, sz)
    76  					a.Publish()
    77  				}
    78  			}
    79  		}
    80  	})
    81  }
    82  
    83  var (
    84  	determined = make(chan struct{})
    85  	ok         = false
    86  )
    87  
    88  func checkNetwork() {
    89  	defer close(determined)
    90  
    91  	_, err := http.Get("http://golang.org/")
    92  	if err != nil {
    93  		return
    94  	}
    95  	ok = true
    96  }
    97  
    98  func onDraw(glctx gl.Context, sz size.Event) {
    99  	select {
   100  	case <-determined:
   101  		if ok {
   102  			glctx.ClearColor(0, 1, 0, 1)
   103  		} else {
   104  			glctx.ClearColor(1, 0, 0, 1)
   105  		}
   106  	default:
   107  		glctx.ClearColor(0, 0, 0, 1)
   108  	}
   109  	glctx.Clear(gl.COLOR_BUFFER_BIT)
   110  }