Added QR code scanner on when adding node (closes #39).

This uses intents, not a built-in scanner, so a seperate app is
required (eg "Barcode Scanner").

src/main/java/com/nutomic/syncthingandroid/gui/NodeSettingsActivity.java

@@ -2,6 +2,7 @@ package com.nutomic.syncthingandroid.gui;
 
 import android.annotation.SuppressLint;
 import android.annotation.TargetApi;
+import android.app.Activity;
 import android.app.AlertDialog;
 import android.content.ComponentName;
 import android.content.Context;
@@ -16,6 +17,7 @@ import android.preference.Preference;
 import android.preference.PreferenceActivity;
 import android.view.Menu;
 import android.view.MenuItem;
+import android.view.View;
 import android.widget.Toast;
 
 import com.nutomic.syncthingandroid.R;
@@ -39,6 +41,8 @@ public class NodeSettingsActivity extends PreferenceActivity implements
 
 	public static final String KEY_NODE_ID = "node_id";
 
+	private static final int SCAN_QR_REQUEST_CODE = 235;
+
 	private SyncthingService mSyncthingService;
 
 	private final ServiceConnection mSyncthingServiceConnection = new ServiceConnection() {
@@ -254,4 +258,27 @@ public class NodeSettingsActivity extends PreferenceActivity implements
 		}
 	}
 
+	/**
+	 * Sends QR code scanning intent when clicking the qrcode icon.
+	 */
+	public void onClick(View view) {
+		Intent intentScan = new Intent("com.google.zxing.client.android.SCAN");
+		intentScan.addCategory(Intent.CATEGORY_DEFAULT);
+		intentScan.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
+		intentScan.addFlags(Intent.FLAG_ACTIVITY_CLEAR_WHEN_TASK_RESET);
+		startActivityForResult(intentScan, SCAN_QR_REQUEST_CODE);
+	}
+
+	/**
+	 * Receives value of scanned QR code and sets it as node ID.
+	 */
+	@Override
+	protected void onActivityResult(int requestCode, int resultCode, Intent data) {
+		if (requestCode == SCAN_QR_REQUEST_CODE && resultCode == Activity.RESULT_OK) {
+			mNode.NodeID = data.getStringExtra("SCAN_RESULT");
+			((EditTextPreference) mNodeId).setText(mNode.NodeID);
+			mNodeId.setSummary(mNode.NodeID);
+		}
+	}
+
 }

src/main/res/layout/scan_qr_code_widget.xml

@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="utf-8"?>
+
+<ImageView xmlns:android="http://schemas.android.com/apk/res/android"
+		android:layout_width="48dip"
+		android:layout_height="48dip"
+		android:src="@drawable/ic_qrcode"
+		android:onClick="onClick" />

src/main/res/xml/node_settings_create.xml

@@ -4,7 +4,8 @@
 
 	<EditTextPreference
 			android:key="node_id"
-			android:title="@string/node_id" />
+			android:title="@string/node_id"
+			android:widgetLayout="@layout/scan_qr_code_widget" />
 
 	<EditTextPreference
 			android:key="name"