Move Drawer to separate file

- Now consistent drawer is accessible across all views

lib/main.dart

@@ -1,6 +1,7 @@
 import 'package:InvenTree/inventree/stock.dart';
 import 'package:InvenTree/widget/category_display.dart';
 import 'package:InvenTree/widget/location_display.dart';
+import 'package:InvenTree/widget/drawer.dart';
 import 'package:flutter/cupertino.dart';
 import 'package:flutter/material.dart';
 import 'package:shared_preferences/shared_preferences.dart';
@@ -103,28 +104,6 @@ class _MyHomePageState extends State<MyHomePage> {
 
   _MyHomePageState() : super();
 
-  void _login() {
-    Navigator.push(context, MaterialPageRoute(builder: (context) => InvenTreeSettingsWidget()));
-  }
-
-  void _goHome() {
-    // Reset the stack, go to "home"
-    Navigator.pushNamedAndRemoveUntil(context, "/", (r) => false);
-  }
-
-  void _showParts() {
-    // Construct a top-level category display (initialize with a null category)
-    Navigator.push(context, MaterialPageRoute(builder: (context) => CategoryDisplayWidget(null)));
-  }
-
-  void _scanCode() async {
-    scanQrCode(context);
-  }
-
-  void _showStock() {
-    Navigator.push(context, MaterialPageRoute(builder: (context) => LocationDisplayWidget(null)));
-  }
-
   @override
   Widget build(BuildContext context) {
     // This method is rerun every time setState is called, for instance as done
@@ -138,46 +117,15 @@ class _MyHomePageState extends State<MyHomePage> {
         // Here we take the value from the MyHomePage object that was created by
         // the App.build method, and use it to set our appbar title.
         title: Text(widget.title),
-        /*
-        leading: IconButton(
-          icon: Icon(Icons.menu),
-          tooltip: "Menu",
+        actions: <Widget>[
+          IconButton(
+            icon: Icon(Icons.search),
+            tooltip: 'Search',
             onPressed: null,
-        )
-        */
-      ),
-      drawer: new Drawer(
-          child: new ListView(
-            children: <Widget>[
-              new ListTile(
-                leading: new Image.asset("assets/image/icon.png",
-                  fit: BoxFit.scaleDown,
-                 ),
-                  title: new Text("InvenTree"),
-                  onTap: _goHome,
-              ),
-              new Divider(),
-              new ListTile(
-                title: new Text("Scan"),
-                onTap: _scanCode,
-              ),
-              new ListTile(
-                title: new Text("Parts"),
-                onTap: _showParts,
-              ),
-              new ListTile(
-                title: new Text("Stock"),
-                onTap: _showStock,
-              ),
-              new Divider(),
-              new ListTile(
-                title: new Text("Settings"),
-                leading: new Icon(Icons.settings),
-                onTap: _login,
           ),
         ],
-          )
       ),
+      drawer: new InvenTreeDrawer(context),
       body: Center(
         // Center is a layout widget. It takes a single child and positions it
         // in the middle of the parent.

lib/widget/category_display.dart

@@ -1,6 +1,9 @@
 
 import 'package:InvenTree/inventree/part.dart';
+
 import 'package:InvenTree/widget/part_display.dart';
+import 'package:InvenTree/widget/drawer.dart';
+
 import 'package:flutter/cupertino.dart';
 import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
@@ -82,6 +85,7 @@ class _CategoryDisplayState extends State<CategoryDisplayWidget> {
       appBar: AppBar(
         title: Text(_titleString),
       ),
+      drawer: new InvenTreeDrawer(context),
       body: Center(
         child: Column(
           mainAxisAlignment: MainAxisAlignment.center,

lib/widget/drawer.dart

@@ -0,0 +1,111 @@
+import 'package:InvenTree/barcode.dart';
+import 'package:flutter/material.dart';
+
+import 'package:InvenTree/widget/category_display.dart';
+import 'package:InvenTree/widget/location_display.dart';
+
+import 'package:InvenTree/settings.dart';
+
+class InvenTreeDrawer extends StatelessWidget {
+
+  final BuildContext context;
+
+  InvenTreeDrawer(this.context);
+
+  void _closeDrawer() {
+    // Close the drawer
+    Navigator.of(context).pop();
+  }
+
+  /*
+   * Return to the 'home' screen.
+   * This will empty the navigation stack.
+   */
+  void _home() {
+    _closeDrawer();
+
+    Navigator.pushNamedAndRemoveUntil(context, "/", (r) => false);
+  }
+
+  /*
+   * Launch the camera to scan a QR code.
+   * Upon successful scan, data are passed off to be decoded.
+   */
+  void _scan() async {
+
+    _closeDrawer();
+    scanQrCode(context);
+  }
+
+  /*
+   * Display the top-level PartCategory list
+   */
+  void _showParts() {
+
+    _closeDrawer();
+    Navigator.push(context, MaterialPageRoute(builder: (context) => CategoryDisplayWidget(null)));
+  }
+
+  /*
+   * Display the top-level StockLocation list
+   */
+  void _showStock() {
+    _closeDrawer();
+    Navigator.push(context, MaterialPageRoute(builder: (context) => LocationDisplayWidget(null)));
+  }
+
+  /*
+   * Load settings widget
+   */
+  void _settings() {
+    _closeDrawer();
+    Navigator.push(context, MaterialPageRoute(builder: (context) => InvenTreeSettingsWidget()));
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return  Drawer(
+        child: new ListView(
+            children: <Widget>[
+              new ListTile(
+                leading: new Image.asset(
+                  "assets/image/icon.png",
+                  fit: BoxFit.scaleDown,
+                ),
+                title: new Text("InvenTree"),
+                onTap: _home,
+              ),
+              new Divider(),
+              new ListTile(
+                title: new Text("Search"),
+                leading: new Icon(Icons.search),
+                onTap: null,
+              ),
+              new ListTile(
+                title: new Text("Scan"),
+                onTap: _scan,
+              ),
+              new Divider(),
+              new ListTile(
+                title: new Text("Parts"),
+                onTap: _showParts,
+              ),
+              new ListTile(
+                title: new Text("Stock"),
+                onTap: _showStock,
+              ),
+              new ListTile(
+                title: new Text("Suppliers"),
+                onTap: null,
+              ),
+              new Divider(),
+              new ListTile(
+                title: new Text("Settings"),
+                leading: new Icon(Icons.settings),
+                onTap: _settings,
+              ),
+            ]
+        )
+    );
+  }
+}

lib/widget/location_display.dart

@@ -1,5 +1,6 @@
 
 import 'package:InvenTree/inventree/stock.dart';
+import 'package:InvenTree/widget/drawer.dart';
 import 'package:InvenTree/widget/stock_display.dart';
 import 'package:flutter/cupertino.dart';
 import 'package:flutter/material.dart';
@@ -88,6 +89,7 @@ class _LocationDisplayState extends State<LocationDisplayWidget> {
       appBar: AppBar(
         title: Text(_title),
       ),
+      drawer: new InvenTreeDrawer(context),
       body: Center(
         child: Column(
           mainAxisAlignment: MainAxisAlignment.center,

lib/widget/part_display.dart

@@ -4,6 +4,8 @@ import 'package:flutter/cupertino.dart';
 import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 
+import 'package:InvenTree/widget/drawer.dart';
+
 class PartDisplayWidget extends StatefulWidget {
 
   PartDisplayWidget(this.part, {Key key}) : super(key: key);
@@ -38,6 +40,7 @@ class _PartDisplayState extends State<PartDisplayWidget> {
       appBar: AppBar(
         title: Text(_title),
       ),
+      drawer: new InvenTreeDrawer(context),
       body: Center(
         child: Column(
           mainAxisAlignment: MainAxisAlignment.center,

lib/widget/stock_display.dart

@@ -4,6 +4,8 @@ import 'package:InvenTree/inventree/stock.dart';
 import 'package:flutter/cupertino.dart';
 import 'package:flutter/material.dart';
 
+import 'package:InvenTree/widget/drawer.dart';
+
 class StockItemDisplayWidget extends StatefulWidget {
 
   StockItemDisplayWidget(this.item, {Key key}) : super(key: key);
@@ -37,6 +39,7 @@ class _StockItemDisplayState extends State<StockItemDisplayWidget> {
       appBar: AppBar(
         title: Text(_title),
       ),
+      drawer: new InvenTreeDrawer(context),
       body: Center(
         child: Column(
           mainAxisAlignment: MainAxisAlignment.center,