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Dynamic Lock Screen for Windows Phone 8

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[[Category:Draft]]
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[[Category:Windows Phone]][[Category:Windows Phone 8]][[Category:Silverlight]][[Category:Code Examples]][[Category:UI]]
{{Abstract|This article explains how to change the Lock screen image of Windows phone 8 using application that can be set in Lock screen setting. Going further, this article also explain how we can change the lock screen wallpaper periodically with new image. This article also explains how to add text or image at runtime over Jpeg image to add more information on Lock screen wallpaper and compose image at runtime. }}
+
{{Abstract|This article explains how to change the Lock screen image of Windows phone 8 using application that can be set in Lock screen setting. Going further, this article also explains how we can change the lock screen periodically with new image which can located on app folder or over internet. We will also see code demo for each method to set lock screen. }}
 
+
 
{{Note|This is a community entry in the [[Windows Phone 8 Wiki Competition 2012Q4]].}}
 
{{Note|This is a community entry in the [[Windows Phone 8 Wiki Competition 2012Q4]].}}
 
 
{{ArticleMetaData <!-- v1.2 -->
 
{{ArticleMetaData <!-- v1.2 -->
|sourcecode= <!-- Link to example source code e.g. [[Media:The Code Example ZIP.zip]] -->
+
|sourcecode= [[Media:DynamicLockScreen.zip]]
 
|installfile= <!-- Link to installation file (e.g. [[Media:The Installation File.sis]]) -->
 
|installfile= <!-- Link to installation file (e.g. [[Media:The Installation File.sis]]) -->
 
|devices= Windows Phone 8 device, Nokia Lumia 920, 820
 
|devices= Windows Phone 8 device, Nokia Lumia 920, 820
Line 25: Line 23:
 
|creationdate= 20121106
 
|creationdate= 20121106
 
|author= [[User:Chintandave er]]
 
|author= [[User:Chintandave er]]
 +
}}
 +
 +
{{ SeeAlso |
 +
* [http://bit.ly/T4JKL1 Lock screen background for Windows Phone 8]
 +
* [http://bit.ly/QhyXyQ Lock screen notifications for Windows Phone 8]
 +
* [http://bit.ly/T5J4Wy Background Agent]
 +
* [http://www.developer.nokia.com/Community/Wiki/What%27s_new_in_Windows_Phone_8#Lock_Screen:_Background_image.2C_counter.2C_and_text ND What's New in WP8]
 
}}
 
}}
  
 
== Introduction ==
 
== Introduction ==
Windows phone 8 has awesome features like new personalised home screen, Dynamic Lock screen, Integrated VOIP Skype etc. In Windows Phone 8, a user can choose to use an app as its lock screen background image provider. I think best feature is Dynamic Lock Screen as user first see phone is Lock screen image and which can have lots of information.
+
Windows phone 8 has awesome features like new personalised home screen, Dynamic Lock screen, Integrated VOIP Skype etc. In Windows Phone 8, a user can choose to use an app as its lock screen background image provider. I think best feature is Dynamic Lock Screen as user first see Lock screen on his/her phone.
  
This article explains how to change the Lock screen image of Windows phone 8 using {{Icode|LockScreenManager}}. We will also show you how to change the Lockscreen wallpaper in background periodically using {{Icode|Background Agent}} Scheduler. This article also explains how to compose image dynamically by adding text or image at runtime over Jpeg image to add more information on Lock screen wallpaper.
+
This article explains how to change the Lock screen image of Windows phone 8 using [http://msdn.microsoft.com/en-us/library/windowsphone/develop/windows.phone.system.userprofile.lockscreenmanager LockScreenManager]. We will also show you how to change the Lockscreen wallpaper in background periodically using [http://bit.ly/T5J4Wy Background Agent Scheduler].  
  
To provide the lock screen background image in the phone, we need to declare the app's intent in the app manifest file, and add code to handle changing the background image and then to change image periodically need to use Windows phone Scheduler as Background Agent.  
+
To provide the lock screen background image in the phone, we need to declare the app's intent in the app manifest file '''WMAppManifest.xml''', and add code to handle changing the background image and then to change image periodically we need to use [http://bit.ly/T5J4Wy Windows phone Scheduler] as {{Icode|Background Agent}}.  
  
First we will show you how to set a default image to lock screen by app acting as Background image provide.  
+
== Video Demo ==
 +
Here you can see the app in action changing lock screen image every 30 sec. {{#ev:youtube|6151VMkioT0}}
 +
 
 +
 
 +
We are going to create this app. So '''let's get started'''! First we will show you how to set a default image to lock screen by app acting as Background image provide.  
  
 
== Setting up a default lock screen background image ==
 
== Setting up a default lock screen background image ==
To provide the lock screen background image for the phone, first we need to update the app manifest file to declare your app as a lock screen background provider.  
+
To provide the lock screen background image on Windows phone 8, first we need to update the app manifest file to declare your app as a lock screen background provider so that app can get permission to access the lock screen of the phone.
  
 
=== Updating the app manifest file ===
 
=== Updating the app manifest file ===
Line 43: Line 52:
  
 
# In '''Solution Explorer''', expand Properties, right-click '''WMAppManifest.xml''', click '''Open With''', and then click '''Source Code (Text Editor) With Encoding'''.
 
# In '''Solution Explorer''', expand Properties, right-click '''WMAppManifest.xml''', click '''Open With''', and then click '''Source Code (Text Editor) With Encoding'''.
# Add the lock screen background '''<Extension>''' element in the '''<Extensions>''' element. If the '''<Extensions>''' element doesn’t appear in the file, place the entire code example below into the file. The '''<Extensions>''' element must be placed below the '''<Tokens>''' element.<br />
+
# Add the lock screen background '''<Extension>''' element in the '''<Extensions>''' element. If the '''<Extensions>''' element doesn’t appear in the file, place the entire code example below into the file. The '''<Extensions>''' element must be placed below the '''<Tokens>''' element.
 +
Here in '''<Extension>''' element, we need to define '''ExtensionName''', '''ConsumerID''' and '''TaskID'''. In your application, you can use same '''ConsumerID''' and '''TaskID''' as below.
  
 
<code xml>
 
<code xml>
Line 52: Line 62:
  
 
Now users can see the app in the Lock Screen Settings and choose to let the app change the lock screen.
 
Now users can see the app in the Lock Screen Settings and choose to let the app change the lock screen.
 +
 +
=== DefaultLockScreen.jpg ===
 +
Once, User set our app as default lock screen provide in setting, our default image is set as lock screen as our app service agent is not yet got chance to set image dynamically.So for this reason, we should include a default lock screen background image at the root of your main project's XAP package. Name the image '''DefaultLockScreen.jpg'''.
 +
 +
=== Size of the Lock screen image ===
 +
Recommended image size for lock screen is '''480px X 800px''' or '''960px X 1708px''' but if provided image is too big than it will be automatically cropped from center and set in lock screen. Also if provided image is too small than it will be re-sized to big automatically but it will be blurred/scratched and look odd.
  
 
=== Adding code to change the Lock screen background ===
 
=== Adding code to change the Lock screen background ===
We can change background of Lock screen using {{Icode|Windows.Phone.System.UserProfile.LockScreenManager}} namespace. To change the background, our app must have selected as Lock screen background provide, to check that Go to Setting -> Lock Screen.
+
We can change background of Lock screen using {{Icode|Windows.Phone.System.UserProfile.LockScreenManager}} namespace. To change the background, our app must have selected as Lock screen background provider in Lockscreen setting, to check that Go to Setting -> Lock Screen.
  
[[File:Setting_DL.png|320x540px]]
+
[[File:Setting DL.png|300x480px]]
  
To check that whether our app is selected as Lock screen image provider or not through code, we can do that using below code.
+
To check that whether our app is selected as Lock screen image provider or not through code, we can use [http://msdn.microsoft.com/en-us/library/windowsphone/develop/windows.phone.system.userprofile.lockscreenmanager.isprovidedbycurrentapplication(v=vs.105).aspx LockScreenManager.IsProvidedByCurrentApplication] method. And if it return false, we use [http://msdn.microsoft.com/en-us/library/windowsphone/develop/windows.phone.system.userprofile.lockscreenmanager.requestaccessasync(v=vs.105).aspx LockScreenManager.RequestAccessAsync()] method to ask user to select our app as Provider.  
  
 
<code csharp>
 
<code csharp>
Line 75: Line 91:
 
</code>
 
</code>
  
This code ask user to give permission for the app to provide wallpaper images to the lock screen. Once user click on OK, our app is granted to change the lock screen and become current Lock screen image provider.
+
This code ask user to give permission to our app to access lock screen. Once user click on '''Yes''', our app is granted to change the lock screen and become current Lock screen image provider.
  
[[File:AppAsk_DL.png|320x540px]]
+
[[File:AppAsk DL.png|300x480px]]
  
Then, we need to call the {{Icode|LockScreen.SetImageUri}} method with the URI of the picture. The URI must be prefixed by “ms-appx:///if the picture is stored in the resources, or “ms-appdata:///Local/if the picture is stored in root folder.
+
Then, we need to call the [http://msdn.microsoft.com/en-us/library/windowsphone/develop/windows.phone.system.userprofile.lockscreen.setimageuri LockScreen.SetImageUri] method with the URI of the picture. The URI must be prefixed by {{Icode|ms-appx:///}} if the picture is stored in the resources, or {{Icode|ms-appdata:///Local/}} if the picture is stored in root folder.
  
* "ms-appx:///" for resources bundled within the xap
+
* {{Icode|ms-appx:///}} for resources bundled within the .xap
* "ms-appdata:///local/" for local images within the root folder.
+
* {{Icode|ms-appdata:///local/}} for local images within the root folder.
 +
 
 +
 
 +
We can not set image located on server using Image URL directly on [http://msdn.microsoft.com/en-us/library/windowsphone/develop/windows.phone.system.userprofile.lockscreen.setimageuri LockScreen.SetImageUri] method. But we do it by downloading image using {{Icode|WebClient}} and storing it on {{Icode|IsolatedStorage}} and then can use above {{Icode|ms-appx:///}} on  [http://msdn.microsoft.com/en-us/library/windowsphone/develop/windows.phone.system.userprofile.lockscreen.setimageuri LockScreen.SetImageUri] method.  
  
 
The following final code example shows how we can change the lock screen background image. We need to call below function. Here method uses {{Icode|async}} as 'the user for permission can only be done by using an {{Icode|async}} call.
 
The following final code example shows how we can change the lock screen background image. We need to call below function. Here method uses {{Icode|async}} as 'the user for permission can only be done by using an {{Icode|async}} call.
Line 121: Line 140:
 
</code>
 
</code>
  
Once you say 'yes', This app becomes current background image provider of Lock screen and we can see the image set by above method in lock screen by pressing F12 during using in WP8 Simulator.
 
  
[[File:LockscreenSet_Dl.png|320x540px]]
+
Once you say '''Yes''', This app becomes current background image provider of Lock screen and we can see the image set by above method in lock screen by pressing '''F12''' during using in Windows Phone 8 Emulator.  
  
To call set lock screen image, call above method as below. Here we need to pass Image file path that we want to set as Lock screen and whether it is in app resources folder or in root.
+
<gallery widths="300px" heights="480px">
 +
File:LockscreenSet_Dl.png|Image set on Lock screen
 +
File:Home_DL.png|Home page
 +
</gallery>
 +
 
 +
To set lock screen image, call {{Icode|LockScreenChange}} method as below. Here we need to pass Image file path that we want to set as Lock screen and whether it is in app resources folder or in root.
  
 
<code csharp>
 
<code csharp>
 
  LockScreenChange("wallpaper/CustomizedPersonalWalleper_0.jpg", true);
 
  LockScreenChange("wallpaper/CustomizedPersonalWalleper_0.jpg", true);
 
</code>
 
</code>
 +
 +
 +
You can see new lock screen image in below image.
 +
 +
<gallery widths="300px" heights ="480px">
 +
File:Lockscreen_DL.png|New Lock Screen Image
 +
</gallery>
 +
 +
=== Linking to the lock screen settings screen from within your app ===
 +
We can’t programmatically turn off our app as a lock screen background image provider from within the app. The user will need to visit the phone's settings screen and make the change themselves. Providing a link to the settings screen makes this useful and easy for user.
 +
The following code example shows you how you can route a button click to the phone's lock screen settings screen using [http://bit.ly/Wb7PTn URI of setting page] in Windows Phone 8 .
 +
 +
<Code csharp>
 +
private async void btnGoToLockSettings_Click(object sender, RoutedEventArgs e)
 +
{
 +
    // Launch URI for the lock screen settings screen.
 +
    var op = await Windows.System.Launcher.LaunchUriAsync(new Uri("ms-settings-lock:"));
 +
}
 +
</code>
 +
 +
== Dynamic Lock screen ==
 +
We saw above how we can change the lock screen image. Now We want to make app that change the lock screen periodically like in built 'Bing' app of Windows Phone 8. To change the lock screen after some period, we need to use [http://bit.ly/T5J4Wy Windows Phone Scheduled Task Agent]', also known as [http://bit.ly/T5J4Wy Background Agent].
 +
 +
=== Change Lock screen image Dynamically using Background Agent ===
 +
First we need to add Scheduled Task Agent to our solution from "New Project" as seen below. To do that go to '''New Project''' ->  '''Windows Phone Scheduled Task Agent'''.
 +
 +
<gallery widths="760px" heights="460px">
 +
File:ScheduledTaskProject_DL.png|Windows Phone Scheduled Task Agent
 +
</gallery>
 +
 +
In '''MainPage.xaml.cs''' class, we need to add [http://msdn.microsoft.com/en-us/library/microsoft.phone.scheduler.periodictask(v=vs.92).aspx PeriodicTask] type [http://msdn.microsoft.com/en-us/library/microsoft.phone.scheduler.scheduledtaskagent(v=vs.92).aspx ScheduleAgentTask] as shown below which run after some time (normally after 30 min). But to test this in simulator we cant wait 30 min, so we have made it to run after every 30 sec using [http://bit.ly/T5Jpsl LaunchForTest(String, TimeSpan)] method which run only on device/simulator when application is in debug mode. You can see we have defined {{Icode|#define DEBUG_AGENT}} before calling [http://bit.ly/T5Jpsl LaunchForTest(String, TimeSpan)] method.
 +
 +
Here we also defined [http://bit.ly/Tlzm2y ExpirationTime] of this PeriodicTask by  {{Icode|periodicTask.ExpirationTime}} to 14 days or less from the current date. The default value is 14 days from the current date. Applications that use [http://msdn.microsoft.com/en-us/library/microsoft.phone.scheduler.scheduledtask(v=vs.92).aspx ScheduledTask] must renew their schedule at least once every two weeks by calling [http://msdn.microsoft.com/en-us/library/microsoft.phone.scheduler.scheduledactionservice.remove(v=vs.92).aspx Remove(String)] and then [http://msdn.microsoft.com/en-us/library/microsoft.phone.scheduler.scheduledactionservice.add(v=vs.92).aspx Add(ScheduledAction)] to add the task when the main application is running in the foreground. This helps to ensure that unused applications are not draining device resources.
 +
 +
{{Note| The [http://bit.ly/T5Jpsl LaunchForTest(String, TimeSpan)] method is provided so that you can run your agent on a more frequent schedule than it will run on an actual device. This method is only for application development. It will not function except for in applications that are deployed using the development tools. You should remove calls to this method from your production application. In this example, the call is placed in an '''#if''' block to enable you to easily switch between debugging and production functionality. To enable the call, put the following line at the top of the '''ScheduledAgent.cs''' file. {{Icode|#define DEBUG_AGENT}}  }}
 +
 +
First we need to define [http://msdn.microsoft.com/en-us/library/microsoft.phone.scheduler.periodictask(v=vs.92).aspx PeriodicTask] in '''MainPage.xaml.cs''' as below.
 +
 +
<code csharp>
 +
PeriodicTask periodicTask;
 +
string periodicTaskName = "PeriodicAgent";
 +
</code>
 +
 +
Here is the Method which add our [http://msdn.microsoft.com/en-us/library/microsoft.phone.scheduler.periodictask(v=vs.92).aspx PeriodicTask] to {{Icode|ScheduledActionService}}.
 +
 +
<code csharp>
 +
private void StartPeriodicAgent()
 +
{
 +
    // is old task running, remove it
 +
    periodicTask = ScheduledActionService.Find(periodicTaskName) as PeriodicTask;
 +
    if (periodicTask != null)
 +
    {
 +
        try
 +
        {
 +
            ScheduledActionService.Remove(periodicTaskName);
 +
        }
 +
        catch (Exception)
 +
        {
 +
        }
 +
    }
 +
    // create a new task
 +
    periodicTask = new PeriodicTask(periodicTaskName);
 +
    // load description from localized strings
 +
    periodicTask.Description = "This is Lockscreen image provider app.";
 +
    // set expiration days
 +
    periodicTask.ExpirationTime = DateTime.Now.AddDays(14);
 +
    try
 +
    {
 +
        // add this to scheduled action service
 +
        ScheduledActionService.Add(periodicTask);
 +
        // debug, so run in every 30 secs
 +
#if(DEBUG_AGENT)
 +
        ScheduledActionService.LaunchForTest(periodicTaskName, TimeSpan.FromSeconds(30));
 +
        System.Diagnostics.Debug.WriteLine("Periodic task is started: " + periodicTaskName);
 +
#endif
 +
 +
    }
 +
    catch (InvalidOperationException exception)
 +
    {
 +
        if (exception.Message.Contains("BNS Error: The action is disabled"))
 +
        {
 +
            // load error text from localized strings
 +
            MessageBox.Show("Background agents for this application have been disabled by the user.");
 +
        }
 +
        if (exception.Message.Contains("BNS Error: The maximum number of ScheduledActions of this type have already been added."))
 +
        {
 +
            // No user action required. The system prompts the user when the hard limit of periodic tasks has been reached.
 +
        }
 +
    }
 +
    catch (SchedulerServiceException)
 +
    {
 +
        // No user action required.
 +
    }
 +
}
 +
</code>
 +
 +
 +
In '''ScheduledTaskAgent1''' Project, '''ScheduledAgent.cs''' file, in [http://msdn.microsoft.com/en-us/library/microsoft.phone.scheduler.scheduledtaskagent.oninvoke(v=vs.92).aspx OnInvoke(ScheduledTask)] method which call periodically we need to write code that change the lock screen image periodically. We want to set 10 image one by one periodically in this sample application.
 +
 +
We have 10 images in wallpaper folder. Each images name is start with ''CustomizedPersonalWalleper_'' and ends with image number(0 to 9). Here we first check which image is currently set as lock screen by [http://msdn.microsoft.com/en-us/library/windowsphone/develop/windows.phone.system.userprofile.lockscreen.getimageuri(v=vs.105).aspx LockScreen.GetImageUri] method.
 +
 +
<code csharp>
 +
// Get the URI of the lock screen background image.
 +
var currentImage = LockScreen.GetImageUri();
 +
</code>
 +
 +
 +
Then we find image number from it by using [http://msdn.microsoft.com/en-us/library/ms187748.aspx Substring] and [http://msdn.microsoft.com/en-us/library/system.string.indexof.aspx String.IndexOf] method as below and create the image name that we want to set next and pass it to {{Icode|LockScreenChange}} method. So logic becomes as shown in code below.
 +
 +
<code csharp>
 +
string imgCount = currentImage.ToString().Substring(currentImage.ToString().IndexOf('_') + 1, currentImage.ToString().Length - (currentImage.ToString().IndexOf('_') + 1)).Replace(".jpg", "");
 +
 +
if (imgCount != "9")
 +
    Imagename = "wallpaper/CustomizedPersonalWalleper_" + Convert.ToString(Convert.ToUInt32(imgCount) + 1) + ".jpg";
 +
else
 +
    Imagename = "wallpaper/CustomizedPersonalWalleper_0.jpg";
 +
 +
LockScreenChange(Imagename, true);
 +
</code>
 +
 +
=== ScheduledAgent.cs ===
 +
So Final code of  [http://msdn.microsoft.com/en-us/library/microsoft.phone.scheduler.scheduledtaskagent.oninvoke(v=vs.92).aspx OnInvoke(ScheduledTask)] Method is as below.
 +
<code csharp>
 +
protected override void OnInvoke(ScheduledTask task)
 +
{
 +
 +
    // Get the URI of the lock screen background image.
 +
    var currentImage = LockScreen.GetImageUri();
 +
    string Imagename = string.Empty;
 +
 +
    string imgCount = currentImage.ToString().Substring(currentImage.ToString().IndexOf('_') + 1, currentImage.ToString().Length - (currentImage.ToString().IndexOf('_') + 1)).Replace(".jpg", "");
 +
 +
    if (imgCount != "9")
 +
        Imagename = "wallpaper/CustomizedPersonalWalleper_" + Convert.ToString(Convert.ToUInt32(imgCount) + 1) + ".jpg";
 +
    else
 +
        Imagename = "wallpaper/CustomizedPersonalWalleper_0.jpg";
 +
 +
    LockScreenChange(Imagename, true);
 +
 +
    // If debugging is enabled, launch the agent again in one minute.
 +
    // debug, so run in every 30 secs
 +
#if(DEBUG_AGENT)
 +
    ScheduledActionService.LaunchForTest(task.Name, TimeSpan.FromSeconds(30));
 +
    System.Diagnostics.Debug.WriteLine("Periodic task is started again: " + task.Name);
 +
#endif
 +
 +
    // Call NotifyComplete to let the system know the agent is done working.
 +
    NotifyComplete();
 +
}
 +
</code>
 +
 +
== Set Lock screen image located over internet (like Bing App) ==
 +
Setting image as Lock screen directly using {{Icode|LockScreen.SetImageUri()}} is not possible currently. So how we can set image which located over internet. There is one way to do that by downloading image on {{Icode|IsolatedStorage}} and then using {{Icode|LockScreen.SetImageUri()}} we can set image as Lock Screen.
 +
 +
Below we will see how to download image from internet and store it in {{Icode|IsolatedStorage}} and then how to set that image as Lock screen.
 +
 +
<code csharp>
 +
private void DownloadImagefromServer()
 +
{
 +
    WebClient client = new WebClient();
 +
    client.OpenReadCompleted += new OpenReadCompletedEventHandler(client_OpenReadCompleted);
 +
    // give the image url that we need to download and store on IsolatedStorage
 +
    client.OpenReadAsync(new Uri("http://ajtroxell.com/wp-content/uploads/2012/02/wp7_vintage.jpg", UriKind.Absolute));
 +
}
 +
void client_OpenReadCompleted(object sender, OpenReadCompletedEventArgs e)
 +
{
 +
    BitmapImage bitmap = new BitmapImage();
 +
    bitmap.SetSource(e.Result);
 +
    //img.Source = bitmap;
 +
 +
    // Create a filename for JPEG file in isolated storage.
 +
    String tempJPEG = "DownloadedWalleper.jpg";
 +
 +
    // Create virtual store and file stream. Check for duplicate tempJPEG files.
 +
    using (IsolatedStorageFile myIsolatedStorage = IsolatedStorageFile.GetUserStoreForApplication())
 +
    {
 +
        if (myIsolatedStorage.FileExists(tempJPEG))
 +
        {
 +
            myIsolatedStorage.DeleteFile(tempJPEG);
 +
        }
 +
 +
        IsolatedStorageFileStream fileStream = myIsolatedStorage.CreateFile(tempJPEG);
 +
 +
        StreamResourceInfo sri = null;
 +
        Uri uri = new Uri(tempJPEG, UriKind.Relative);
 +
        sri = Application.GetResourceStream(uri);
 +
 +
        //BitmapImage bitmap = new BitmapImage();
 +
        //bitmap.SetSource(sri.Stream);
 +
        WriteableBitmap wb = new WriteableBitmap(bitmap);
 +
 +
        // Encode WriteableBitmap object to a JPEG stream.
 +
        Extensions.SaveJpeg(wb, fileStream, wb.PixelWidth, wb.PixelHeight, 0, 85);
 +
 +
        //wb.SaveJpeg(fileStream, wb.PixelWidth, wb.PixelHeight, 0, 85);
 +
        fileStream.Close();
 +
    }
 +
 +
    // call function to set downloaded image as lock screen
 +
    LockScreenChange("DownloadedWalleper.jpg", false);
 +
}
 +
 +
</code>
 +
 +
You can see below in screenshot that a image located over internet is now set as Lock screen.
 +
 +
[[File:ImagefromInternet.png|300x480px]]
 +
 +
=== Dynamic Lock screen image like Bing App ===
 +
We need to upload different image over internet periodically in other platform so that our app in Windows Phone 8 can download it and set it as Lock screen image. To Upload image periodically over internet in other platform, We can create some Windows Service in .net that will run on Windows and upload images to a specific URL over internet by picking image from provided folder path. OR we can have bunch of image URL to set as lock screen periodically.
 +
 +
=== Concept becomes Reality ===
 +
Below concept can now become reality. To make it real, We need to have one image URL path which will have different images periodically with some details written on image and our lock screen app will download image from that Image URL path and set as Lock screen.
 +
We just need to upload different images to specific image URL path. To upload image, we can use Windows Service of other platform or we can upload it manually.
 +
 +
We can not write text over image at runtime in Windows Phone 7 and 8 but we can do that in other platform using imaging API for example in .net and upload composed image to specific Image URL and our lock screen app in windows phone 8 will set it as lock screen.
 +
 +
So this way, below concept becomes real app.
 +
 +
[[File:Windows-Phone-8-concept.jpg]]
 +
 +
== Summary ==
 +
So this way, we can create application for Windows Phone 8 that change the lock screen background periodically. We can also set image which located on server as lock screen. This image located over intenret server might have some information written on it as text or image.
 +
 +
So we have seen how to create set a image as lock screen, how to make lock screen image dynamic with images located on app folder or over internet.
 +
 +
== Source code ==
 +
You can find the running source code of this application here [[File:DynamicLockScreen.zip]]

Revision as of 08:25, 28 November 2012

This article explains how to change the Lock screen image of Windows phone 8 using application that can be set in Lock screen setting. Going further, this article also explains how we can change the lock screen periodically with new image which can located on app folder or over internet. We will also see code demo for each method to set lock screen.

Note.pngNote: This is a community entry in the Windows Phone 8 Wiki Competition 2012Q4.

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Article Metadata
Code ExampleTested with
Devices(s): Windows Phone 8 device, Nokia Lumia 920, 820
Compatibility
Platform(s): Windows Phone 8
Windows Phone 8
Device(s): Windows Phone 8 Only
Article
Keywords: LockScreenManager, Background Agent
Created: chintandave_er (06 Nov 2012)
Last edited: hamishwillee (28 Nov 2012)

Contents

Introduction

Windows phone 8 has awesome features like new personalised home screen, Dynamic Lock screen, Integrated VOIP Skype etc. In Windows Phone 8, a user can choose to use an app as its lock screen background image provider. I think best feature is Dynamic Lock Screen as user first see Lock screen on his/her phone.

This article explains how to change the Lock screen image of Windows phone 8 using LockScreenManager. We will also show you how to change the Lockscreen wallpaper in background periodically using Background Agent Scheduler.

To provide the lock screen background image in the phone, we need to declare the app's intent in the app manifest file WMAppManifest.xml, and add code to handle changing the background image and then to change image periodically we need to use Windows phone Scheduler as Background Agent.

Video Demo

Here you can see the app in action changing lock screen image every 30 sec.


We are going to create this app. So let's get started! First we will show you how to set a default image to lock screen by app acting as Background image provide.

Setting up a default lock screen background image

To provide the lock screen background image on Windows phone 8, first we need to update the app manifest file to declare your app as a lock screen background provider so that app can get permission to access the lock screen of the phone.

Updating the app manifest file

To Update the app manifest file so that app can access the lock screen of the phone, we need to update WMAppManifest.xml file as below.

  1. In Solution Explorer, expand Properties, right-click WMAppManifest.xml, click Open With, and then click Source Code (Text Editor) With Encoding.
  2. Add the lock screen background <Extension> element in the <Extensions> element. If the <Extensions> element doesn’t appear in the file, place the entire code example below into the file. The <Extensions> element must be placed below the <Tokens> element.

Here in <Extension> element, we need to define ExtensionName, ConsumerID and TaskID. In your application, you can use same ConsumerID and TaskID as below.

<Extensions>
<Extension ExtensionName="LockScreen_Background" ConsumerID="{111DFF24-AA15-4A96-8006-2BFF8122084F}" TaskID="_default" />
</Extensions>

Now users can see the app in the Lock Screen Settings and choose to let the app change the lock screen.

DefaultLockScreen.jpg

Once, User set our app as default lock screen provide in setting, our default image is set as lock screen as our app service agent is not yet got chance to set image dynamically.So for this reason, we should include a default lock screen background image at the root of your main project's XAP package. Name the image DefaultLockScreen.jpg.

Size of the Lock screen image

Recommended image size for lock screen is 480px X 800px or 960px X 1708px but if provided image is too big than it will be automatically cropped from center and set in lock screen. Also if provided image is too small than it will be re-sized to big automatically but it will be blurred/scratched and look odd.

Adding code to change the Lock screen background

We can change background of Lock screen using Windows.Phone.System.UserProfile.LockScreenManager namespace. To change the background, our app must have selected as Lock screen background provider in Lockscreen setting, to check that Go to Setting -> Lock Screen.

Setting DL.png

To check that whether our app is selected as Lock screen image provider or not through code, we can use LockScreenManager.IsProvidedByCurrentApplication method. And if it return false, we use LockScreenManager.RequestAccessAsync() method to ask user to select our app as Provider.

if (!LockScreenManager.IsProvidedByCurrentApplication)
{
// If you're not the provider, this call will prompt the user for permission.
// Calling RequestAccessAsync from a background agent is not allowed.
await LockScreenManager.RequestAccessAsync();
}
 
// Only do further work if the access is granted.
if (LockScreenManager.IsProvidedByCurrentApplication)
{
// change the background here.
}

This code ask user to give permission to our app to access lock screen. Once user click on Yes, our app is granted to change the lock screen and become current Lock screen image provider.

AppAsk DL.png

Then, we need to call the LockScreen.SetImageUri method with the URI of the picture. The URI must be prefixed by ms-appx:/// if the picture is stored in the resources, or ms-appdata:///Local/ if the picture is stored in root folder.

  • ms-appx:/// for resources bundled within the .xap
  • ms-appdata:///local/ for local images within the root folder.


We can not set image located on server using Image URL directly on LockScreen.SetImageUri method. But we do it by downloading image using WebClient and storing it on IsolatedStorage and then can use above ms-appx:/// on LockScreen.SetImageUri method.

The following final code example shows how we can change the lock screen background image. We need to call below function. Here method uses async as 'the user for permission can only be done by using an async call.

private async void LockScreenChange(string filePathOfTheImage, bool isAppResource)
{
if (!LockScreenManager.IsProvidedByCurrentApplication)
{
// If you're not the provider, this call will prompt the user for permission.
// Calling RequestAccessAsync from a background agent is not allowed.
await LockScreenManager.RequestAccessAsync();
}
 
// Only do further work if the access is granted.
if (LockScreenManager.IsProvidedByCurrentApplication)
{
// At this stage, the app is the active lock screen background provider.
// The following code example shows the new URI schema.
// ms-appdata points to the root of the local app data folder.
// ms-appx points to the Local app install folder, to reference resources bundled in the XAP package
var schema = isAppResource ? "ms-appx:///" : "ms-appdata:///Local/";
var uri = new Uri(schema + filePathOfTheImage, UriKind.Absolute);
 
// Set the lock screen background image.
LockScreen.SetImageUri(uri);
 
// Get the URI of the lock screen background image.
var currentImage = LockScreen.GetImageUri();
System.Diagnostics.Debug.WriteLine("The new lock screen background image is set to {0}", currentImage.ToString());
MessageBox.Show("Lock screen changed. Click F12 or go to lock screen.");
}
else
{
MessageBox.Show("Background cant be updated as you clicked no!!");
}
}


Once you say Yes, This app becomes current background image provider of Lock screen and we can see the image set by above method in lock screen by pressing F12 during using in Windows Phone 8 Emulator.

To set lock screen image, call LockScreenChange method as below. Here we need to pass Image file path that we want to set as Lock screen and whether it is in app resources folder or in root.

 LockScreenChange("wallpaper/CustomizedPersonalWalleper_0.jpg", true);


You can see new lock screen image in below image.

Linking to the lock screen settings screen from within your app

We can’t programmatically turn off our app as a lock screen background image provider from within the app. The user will need to visit the phone's settings screen and make the change themselves. Providing a link to the settings screen makes this useful and easy for user. The following code example shows you how you can route a button click to the phone's lock screen settings screen using URI of setting page in Windows Phone 8 .

private async void btnGoToLockSettings_Click(object sender, RoutedEventArgs e)
{
// Launch URI for the lock screen settings screen.
var op = await Windows.System.Launcher.LaunchUriAsync(new Uri("ms-settings-lock:"));
}

Dynamic Lock screen

We saw above how we can change the lock screen image. Now We want to make app that change the lock screen periodically like in built 'Bing' app of Windows Phone 8. To change the lock screen after some period, we need to use Windows Phone Scheduled Task Agent', also known as Background Agent.

Change Lock screen image Dynamically using Background Agent

First we need to add Scheduled Task Agent to our solution from "New Project" as seen below. To do that go to New Project -> Windows Phone Scheduled Task Agent.

In MainPage.xaml.cs class, we need to add PeriodicTask type ScheduleAgentTask as shown below which run after some time (normally after 30 min). But to test this in simulator we cant wait 30 min, so we have made it to run after every 30 sec using LaunchForTest(String, TimeSpan) method which run only on device/simulator when application is in debug mode. You can see we have defined #define DEBUG_AGENT before calling LaunchForTest(String, TimeSpan) method.

Here we also defined ExpirationTime of this PeriodicTask by periodicTask.ExpirationTime to 14 days or less from the current date. The default value is 14 days from the current date. Applications that use ScheduledTask must renew their schedule at least once every two weeks by calling Remove(String) and then Add(ScheduledAction) to add the task when the main application is running in the foreground. This helps to ensure that unused applications are not draining device resources.

Note.pngNote: The LaunchForTest(String, TimeSpan) method is provided so that you can run your agent on a more frequent schedule than it will run on an actual device. This method is only for application development. It will not function except for in applications that are deployed using the development tools. You should remove calls to this method from your production application. In this example, the call is placed in an #if block to enable you to easily switch between debugging and production functionality. To enable the call, put the following line at the top of the ScheduledAgent.cs file. #define DEBUG_AGENT

First we need to define PeriodicTask in MainPage.xaml.cs as below.

PeriodicTask periodicTask;
string periodicTaskName = "PeriodicAgent";

Here is the Method which add our PeriodicTask to ScheduledActionService.

private void StartPeriodicAgent()
{
// is old task running, remove it
periodicTask = ScheduledActionService.Find(periodicTaskName) as PeriodicTask;
if (periodicTask != null)
{
try
{
ScheduledActionService.Remove(periodicTaskName);
}
catch (Exception)
{
}
}
// create a new task
periodicTask = new PeriodicTask(periodicTaskName);
// load description from localized strings
periodicTask.Description = "This is Lockscreen image provider app.";
// set expiration days
periodicTask.ExpirationTime = DateTime.Now.AddDays(14);
try
{
// add this to scheduled action service
ScheduledActionService.Add(periodicTask);
// debug, so run in every 30 secs
#if(DEBUG_AGENT)
ScheduledActionService.LaunchForTest(periodicTaskName, TimeSpan.FromSeconds(30));
System.Diagnostics.Debug.WriteLine("Periodic task is started: " + periodicTaskName);
#endif
 
}
catch (InvalidOperationException exception)
{
if (exception.Message.Contains("BNS Error: The action is disabled"))
{
// load error text from localized strings
MessageBox.Show("Background agents for this application have been disabled by the user.");
}
if (exception.Message.Contains("BNS Error: The maximum number of ScheduledActions of this type have already been added."))
{
// No user action required. The system prompts the user when the hard limit of periodic tasks has been reached.
}
}
catch (SchedulerServiceException)
{
// No user action required.
}
}


In ScheduledTaskAgent1 Project, ScheduledAgent.cs file, in OnInvoke(ScheduledTask) method which call periodically we need to write code that change the lock screen image periodically. We want to set 10 image one by one periodically in this sample application.

We have 10 images in wallpaper folder. Each images name is start with CustomizedPersonalWalleper_ and ends with image number(0 to 9). Here we first check which image is currently set as lock screen by LockScreen.GetImageUri method.

// Get the URI of the lock screen background image.
var currentImage = LockScreen.GetImageUri();


Then we find image number from it by using Substring and String.IndexOf method as below and create the image name that we want to set next and pass it to LockScreenChange method. So logic becomes as shown in code below.

string imgCount = currentImage.ToString().Substring(currentImage.ToString().IndexOf('_') + 1, currentImage.ToString().Length - (currentImage.ToString().IndexOf('_') + 1)).Replace(".jpg", "");
 
if (imgCount != "9")
Imagename = "wallpaper/CustomizedPersonalWalleper_" + Convert.ToString(Convert.ToUInt32(imgCount) + 1) + ".jpg";
else
Imagename = "wallpaper/CustomizedPersonalWalleper_0.jpg";
 
LockScreenChange(Imagename, true);

ScheduledAgent.cs

So Final code of OnInvoke(ScheduledTask) Method is as below.

protected override void OnInvoke(ScheduledTask task)
{
 
// Get the URI of the lock screen background image.
var currentImage = LockScreen.GetImageUri();
string Imagename = string.Empty;
 
string imgCount = currentImage.ToString().Substring(currentImage.ToString().IndexOf('_') + 1, currentImage.ToString().Length - (currentImage.ToString().IndexOf('_') + 1)).Replace(".jpg", "");
 
if (imgCount != "9")
Imagename = "wallpaper/CustomizedPersonalWalleper_" + Convert.ToString(Convert.ToUInt32(imgCount) + 1) + ".jpg";
else
Imagename = "wallpaper/CustomizedPersonalWalleper_0.jpg";
 
LockScreenChange(Imagename, true);
 
// If debugging is enabled, launch the agent again in one minute.
// debug, so run in every 30 secs
#if(DEBUG_AGENT)
ScheduledActionService.LaunchForTest(task.Name, TimeSpan.FromSeconds(30));
System.Diagnostics.Debug.WriteLine("Periodic task is started again: " + task.Name);
#endif
 
// Call NotifyComplete to let the system know the agent is done working.
NotifyComplete();
}

Set Lock screen image located over internet (like Bing App)

Setting image as Lock screen directly using LockScreen.SetImageUri() is not possible currently. So how we can set image which located over internet. There is one way to do that by downloading image on IsolatedStorage and then using LockScreen.SetImageUri() we can set image as Lock Screen.

Below we will see how to download image from internet and store it in IsolatedStorage and then how to set that image as Lock screen.

private void DownloadImagefromServer()
{
WebClient client = new WebClient();
client.OpenReadCompleted += new OpenReadCompletedEventHandler(client_OpenReadCompleted);
// give the image url that we need to download and store on IsolatedStorage
client.OpenReadAsync(new Uri("http://ajtroxell.com/wp-content/uploads/2012/02/wp7_vintage.jpg", UriKind.Absolute));
}
void client_OpenReadCompleted(object sender, OpenReadCompletedEventArgs e)
{
BitmapImage bitmap = new BitmapImage();
bitmap.SetSource(e.Result);
//img.Source = bitmap;
 
// Create a filename for JPEG file in isolated storage.
String tempJPEG = "DownloadedWalleper.jpg";
 
// Create virtual store and file stream. Check for duplicate tempJPEG files.
using (IsolatedStorageFile myIsolatedStorage = IsolatedStorageFile.GetUserStoreForApplication())
{
if (myIsolatedStorage.FileExists(tempJPEG))
{
myIsolatedStorage.DeleteFile(tempJPEG);
}
 
IsolatedStorageFileStream fileStream = myIsolatedStorage.CreateFile(tempJPEG);
 
StreamResourceInfo sri = null;
Uri uri = new Uri(tempJPEG, UriKind.Relative);
sri = Application.GetResourceStream(uri);
 
//BitmapImage bitmap = new BitmapImage();
//bitmap.SetSource(sri.Stream);
WriteableBitmap wb = new WriteableBitmap(bitmap);
 
// Encode WriteableBitmap object to a JPEG stream.
Extensions.SaveJpeg(wb, fileStream, wb.PixelWidth, wb.PixelHeight, 0, 85);
 
//wb.SaveJpeg(fileStream, wb.PixelWidth, wb.PixelHeight, 0, 85);
fileStream.Close();
}
 
// call function to set downloaded image as lock screen
LockScreenChange("DownloadedWalleper.jpg", false);
}

You can see below in screenshot that a image located over internet is now set as Lock screen.

ImagefromInternet.png

Dynamic Lock screen image like Bing App

We need to upload different image over internet periodically in other platform so that our app in Windows Phone 8 can download it and set it as Lock screen image. To Upload image periodically over internet in other platform, We can create some Windows Service in .net that will run on Windows and upload images to a specific URL over internet by picking image from provided folder path. OR we can have bunch of image URL to set as lock screen periodically.

Concept becomes Reality

Below concept can now become reality. To make it real, We need to have one image URL path which will have different images periodically with some details written on image and our lock screen app will download image from that Image URL path and set as Lock screen. We just need to upload different images to specific image URL path. To upload image, we can use Windows Service of other platform or we can upload it manually.

We can not write text over image at runtime in Windows Phone 7 and 8 but we can do that in other platform using imaging API for example in .net and upload composed image to specific Image URL and our lock screen app in windows phone 8 will set it as lock screen.

So this way, below concept becomes real app.

Windows-Phone-8-concept.jpg

Summary

So this way, we can create application for Windows Phone 8 that change the lock screen background periodically. We can also set image which located on server as lock screen. This image located over intenret server might have some information written on it as text or image.

So we have seen how to create set a image as lock screen, how to make lock screen image dynamic with images located on app folder or over internet.

Source code

You can find the running source code of this application here File:DynamicLockScreen.zip

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