example/network: a simple example to show AndroidManifest customization

Change-Id: I558925eca6be12772726cfff96b48fd4c6bbc303
Reviewed-on: https://go-review.googlesource.com/11892
Reviewed-by: Burcu Dogan <jbd@google.com>

example/network/AndroidManifest.xml

@@ -0,0 +1,33 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+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.
+-->
+<manifest
+	xmlns:android="http://schemas.android.com/apk/res/android"
+	package="org.golang.todo.network"
+	android:versionCode="1"
+	android:versionName="1.0">
+
+	<uses-sdk android:minSdkVersion="9" />
+
+	<!-- In order to access the network, your application manifest must
+	     specify the permission requirement. See the following page for
+	     details.
+	     http://developer.android.com/guide/topics/manifest/manifest-intro.html#perms -->
+	<uses-permission android:name="android.permission.INTERNET" />
+
+	<application android:label="network" android:hasCode="false" android:debuggable="true">
+
+	<activity android:name="android.app.NativeActivity"
+		android:label="network"
+		android:configChanges="orientation|keyboardHidden">
+		<meta-data android:name="android.app.lib_name" android:value="network" />
+		<intent-filter>
+			<action android:name="android.intent.action.MAIN" />
+			<category android:name="android.intent.category.LAUNCHER" />
+		</intent-filter>
+	</activity>
+	</application>
+</manifest>

example/network/main.go

@@ -0,0 +1,87 @@
+// 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.
+
+// 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 irrelevent 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"
+	"golang.org/x/mobile/exp/app/debug"
+	"golang.org/x/mobile/gl"
+)
+
+func main() {
+	// checkNetwork runs only once when the app first loads.
+	go checkNetwork()
+
+	app.Run(app.Callbacks{
+		Draw: draw,
+	})
+}
+
+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 draw(c event.Config) {
+	select {
+	case <-determined:
+		if ok {
+			gl.ClearColor(0, 1, 0, 1)
+		} else {
+			gl.ClearColor(1, 0, 0, 1)
+		}
+	default:
+		gl.ClearColor(0, 0, 0, 1)
+	}
+	gl.Clear(gl.COLOR_BUFFER_BIT)
+
+	debug.DrawFPS(c)
+}