Windows Phone 8.0 improvements and bugfixes:

#615 Adds Cancel button to UI, handle backbutton event
#617 Adds redline focus helper to UI
#618 Adds continuous focusing

plugin.xml

@@ -303,7 +303,6 @@
 
     <!-- Windows Phone 8 -->
     <platform name="wp8">
-
         <config-file target="config.xml" parent="/*">
             <feature name="BarcodeScanner">
                 <param name="wp-package" value="BarcodeScanner"/>
@@ -316,11 +315,12 @@
 
         <framework src="src/wp8/lib/zxing.wp8.0.dll" custom="true" />
 
+        <asset src="src/wp8/assets/cancel.png" target="Images/appbar.cancel.png" />
+
         <source-file src="src/wp8/BarcodeScanner.cs" />
         <source-file src="src/wp8/BarcodeScannerTask.cs" />
         <source-file src="src/wp8/BarcodeScannerUI.xaml" />
         <source-file src="src/wp8/BarcodeScannerUI.xaml.cs" />
-
     </platform>
 
     <!-- browser -->

src/wp8/BarcodeScannerUI.xaml

@@ -20,7 +20,12 @@
     Foreground="{StaticResource PhoneForegroundBrush}"
     SupportedOrientations="Portrait" Orientation="Portrait"
     mc:Ignorable="d"
-    shell:SystemTray.IsVisible="True">
+    shell:SystemTray.IsVisible="True" CacheMode="BitmapCache" >
+    <phone:PhoneApplicationPage.ApplicationBar>
+        <shell:ApplicationBar IsVisible="True" IsMenuEnabled="False" Mode="Minimized">
+            <shell:ApplicationBarIconButton IconUri="/www/Images/appbar.cancel.png" IsEnabled="True" Text="Cancel" Click="CancelScan"/>
+        </shell:ApplicationBar>
+    </phone:PhoneApplicationPage.ApplicationBar>
 
     <Grid Background="Transparent">
         <Canvas x:Name="CameraCanvas">
@@ -35,6 +40,7 @@
                 </VideoBrush>
             </Canvas.Background>
         </Canvas>
+        <Rectangle Margin="0" Stroke="Red" Height="2"/>
     </Grid>
 
 </phone:PhoneApplicationPage>

src/wp8/BarcodeScannerUI.xaml.cs

@@ -12,11 +12,13 @@ namespace WPCordovaClassLib.Cordova.Commands
 {
     using System;
     using System.Windows;
+    using System.Windows.Controls;
+    using System.Windows.Input;
     using System.Windows.Media.Imaging;
     using System.Windows.Navigation;
+    using System.Windows.Threading;
 
     using Microsoft.Devices;
-    using Microsoft.Phone.Controls;
     using Microsoft.Phone.Tasks;
 
     using ZXing;
@@ -41,6 +43,8 @@ public partial class BarcodeScannerUI
         /// </summary>
         private PhotoCamera camera;
 
+        private DispatcherTimer timer;
+
         /// <summary>
         /// Initializes a new instance of the <see cref="BarcodeScannerUI"/> class.
         /// This implementation not use camera autofocus.
@@ -57,6 +61,20 @@ public BarcodeScannerUI()
             // Bind events
             this.camera.Initialized += this.CameraInitialized;
             this.reader.ResultFound += this.ReaderResultFound;
+
+            this.timer = new DispatcherTimer {Interval = TimeSpan.FromMilliseconds(100)};
+            this.timer.Tick += (sender, args) => ScanForBarcode();
+
+            this.BackKeyPress += CancelScan;
+
+            CameraButtons.ShutterKeyHalfPressed += StartCameraFocus;
+            camera.AutoFocusCompleted += StartCameraFocus;
+
+        }
+
+        private void StartCameraFocus(object sender, EventArgs eventArgs)
+        {
+            camera.Focus();
         }
 
         /// <summary>
@@ -86,22 +104,13 @@ private void CameraInitialized(object sender, CameraOperationCompletedEventArgs
         {
             if (e.Succeeded)
             {
+                if (camera.IsFocusSupported)
+                {
+                    camera.Focus();
+                }
+
                 // Start scan process in separate thread
-                Deployment.Current.Dispatcher.BeginInvoke(
-                    () =>
-                        {
-                            while (result == null)
-                            {
-                                var cameraBuffer = new WriteableBitmap(
-                                    (int)camera.PreviewResolution.Width,
-                                    (int)camera.PreviewResolution.Height);
-
-                                camera.GetPreviewBufferArgb32(cameraBuffer.Pixels);
-                                cameraBuffer.Invalidate();
-
-                                reader.Decode(cameraBuffer);
-                            }
-                        });
+                this.Dispatcher.BeginInvoke(() => timer.Start());
             }
             else
             {
@@ -110,6 +119,18 @@ private void CameraInitialized(object sender, CameraOperationCompletedEventArgs
             }
         }
 
+        private void ScanForBarcode()
+        {
+            var cameraBuffer = new WriteableBitmap(
+                                (int)camera.PreviewResolution.Width,
+                                (int)camera.PreviewResolution.Height);
+
+            camera.GetPreviewBufferArgb32(cameraBuffer.Pixels);
+            cameraBuffer.Invalidate();
+
+            reader.Decode(cameraBuffer);
+        }
+
         /// <summary>
         /// Called when reader find barcode.
         /// </summary>
@@ -126,8 +147,10 @@ private void ReaderResultFound(Result obj)
         /// </summary>
         private void CleanUp()
         {
+            CameraButtons.ShutterKeyHalfPressed -= StartCameraFocus;
             if (this.camera != null)
             {
+                this.camera.AutoFocusCompleted -= StartCameraFocus;
                 this.camera.Initialized -= this.CameraInitialized;
                 this.camera.Dispose();
                 this.camera = null;
@@ -138,6 +161,22 @@ private void CleanUp()
                 this.reader.ResultFound -= this.ReaderResultFound;
                 this.reader = null;
             }
+
+            if (this.timer != null)
+            {
+                this.timer.Stop();
+                this.timer = null;
+            }
+        }
+
+        private void ApplicationBarIconButton_Click(object sender, EventArgs e)
+        {
+            NavigationService.GoBack();
+        }
+
+        private void CancelScan(object sender, EventArgs eventArgs)
+        {
+            NavigationService.GoBack();
         }
     }
 }