github.com/SahandAslani/gomobile@v0.0.0-20210909130135-2cb2d44c09b2/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  //go:build darwin || linux || windows
     6  // +build darwin linux windows
     7  
     8  // An app that paints green if golang.org is reachable when the app first
     9  // starts, or red otherwise.
    10  //
    11  // In order to access the network from the Android app, its AndroidManifest.xml
    12  // file must include the permission to access the network.
    13  //
    14  //   http://developer.android.com/guide/topics/manifest/manifest-intro.html#perms
    15  //
    16  // The gomobile tool auto-generates a default AndroidManifest file by default
    17  // unless the package directory contains the AndroidManifest.xml. Users can
    18  // customize app behavior, such as permissions and app name, by providing
    19  // the AndroidManifest file. This is irrelevent to iOS.
    20  //
    21  // Note: This demo is an early preview of Go 1.5. In order to build this
    22  // program as an Android APK using the gomobile tool.
    23  //
    24  // See http://godoc.org/github.com/SahandAslani/gomobile/cmd/gomobile to install gomobile.
    25  //
    26  // Get the network example and use gomobile to build or install it on your device.
    27  //
    28  //   $ go get -d github.com/SahandAslani/gomobile/example/network
    29  //   $ gomobile build github.com/SahandAslani/gomobile/example/network # will build an APK
    30  //
    31  //   # plug your Android device to your computer or start an Android emulator.
    32  //   # if you have adb installed on your machine, use gomobile install to
    33  //   # build and deploy the APK to an Android target.
    34  //   $ gomobile install github.com/SahandAslani/gomobile/example/network
    35  //
    36  // Switch to your device or emulator to start the network application from
    37  // the launcher.
    38  // You can also run the application on your desktop by running the command
    39  // below. (Note: It currently doesn't work on Windows.)
    40  //   $ go install github.com/SahandAslani/gomobile/example/network && network
    41  package main
    42  
    43  import (
    44  	"net/http"
    45  
    46  	"github.com/SahandAslani/gomobile/app"
    47  	"github.com/SahandAslani/gomobile/event/lifecycle"
    48  	"github.com/SahandAslani/gomobile/event/paint"
    49  	"github.com/SahandAslani/gomobile/event/size"
    50  	"github.com/SahandAslani/gomobile/gl"
    51  )
    52  
    53  func main() {
    54  	// checkNetwork runs only once when the app first loads.
    55  	go checkNetwork()
    56  
    57  	app.Main(func(a app.App) {
    58  		var glctx gl.Context
    59  		det, sz := determined, size.Event{}
    60  		for {
    61  			select {
    62  			case <-det:
    63  				a.Send(paint.Event{})
    64  				det = nil
    65  
    66  			case e := <-a.Events():
    67  				switch e := a.Filter(e).(type) {
    68  				case lifecycle.Event:
    69  					glctx, _ = e.DrawContext.(gl.Context)
    70  				case size.Event:
    71  					sz = e
    72  				case paint.Event:
    73  					if glctx == nil {
    74  						continue
    75  					}
    76  					onDraw(glctx, sz)
    77  					a.Publish()
    78  				}
    79  			}
    80  		}
    81  	})
    82  }
    83  
    84  var (
    85  	determined = make(chan struct{})
    86  	ok         = false
    87  )
    88  
    89  func checkNetwork() {
    90  	defer close(determined)
    91  
    92  	_, err := http.Get("http://golang.org/")
    93  	if err != nil {
    94  		return
    95  	}
    96  	ok = true
    97  }
    98  
    99  func onDraw(glctx gl.Context, sz size.Event) {
   100  	select {
   101  	case <-determined:
   102  		if ok {
   103  			glctx.ClearColor(0, 1, 0, 1)
   104  		} else {
   105  			glctx.ClearColor(1, 0, 0, 1)
   106  		}
   107  	default:
   108  		glctx.ClearColor(0, 0, 0, 1)
   109  	}
   110  	glctx.Clear(gl.COLOR_BUFFER_BIT)
   111  }