Camera key handling in Nokia Belle

Comments

Ashraf fawzy - Very important article

Thank you Lucian Tomuța for this article, Can I ask if you could explain also how to differentiate between starting / launching the application from Homescreen shortcut and from Menu shortcut in Nokia Belle, as you know that UI architecture (Windows group) has slightly changed.

My best regards.

ashraf fawzy 02:12, 9 February 2012 (EET)

Ashraf fawzy - My code to detect if application launched from Homescreen in Symbian Anna

               TApaTaskList taskList( CEikonEnv::Static()->WsSession() );
               TApaTask task = taskList.FindByPos(1);
               TInt WgId = task.WgId();
               CApaWindowGroupName* wgn = CApaWindowGroupName::NewLC(CEikonEnv::Static()->WsSession(), WgId);
               TUid uid = wgn->AppUid();
               CleanupStack::PopAndDestroy();
               if (uid == TUid::Uid(0x102750F0)) // HomeScreen UID
                   {
                           // Launched from Homescreen
                   }

ashraf fawzy 02:49, 9 February 2012 (EET)

Vineet.jain - Ashraf- About the code snippet

Hi Ashraf, Cconsider writing a code-snippet article for the code you wrote in your comment.

Thanks

Vineet

vineet.jain 08:04, 9 February 2012 (EET)

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Nokia Belle's Camera application has changed its handling of the dedicated camera key. This article describes how 3rd party applications can adapt to this change and remain able to handle the camera key event.

Article Metadata

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Tested with

Devices(s): Nokia 701

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Compatibility

Platform(s): Symbian^3 and later

Device(s): All Nokia Belle

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Platform Security

Signing Required: Nokia Publish or Symbian Signed issued developer certificate required.

Capabilities: SwEvent

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Article

Keywords: RWindowGroup::CaptureKey(), RWindowGroup::CaptureKeyUpAndDowns(), RWindowGroup::CancelCaptureKey(), RWindowGroup::CancelCaptureKeyUpAndDowns()

Created: ltomuta (08 Feb 2012)

Last edited: hamishwillee (12 Apr 2012)

Summary

If you are developing a camera application, or any other utility app which intents to use the camera key event for custom user initiated actions, one of the essential tasks is to capture the camera key even and prevent its default handling, which would be starting the built-in Camera application and bringing it to foreground.

The task itself is easy to achieve, all that is required is a call to Symbian's RWindowGroup::CaptureKey() API in order to capture the key pressed event of the camera key, as in line #73 of the code snippet below.

67.     RWsSession &wsSession = CCoeEnv::Static()->WsSession();

68.     TUint wGroupHandle = wsSession.GetWindowGroupHandle(wGroupId);

69.     if (wGroupHandle) {

70.         RWindowGroup wGroup(wsSession);

71.         wGroup.Construct(wGroupHandle);

72.         TBool captureOK = ETrue;

73.         captureOK = captureOK && (wGroup.CaptureKey(EKeyCamera, 0, 0, 100) > 0);

74.         if (!captureOK)

75.             qWarning("Unable to register for camera capture key events, SwEvent capability may be missing");

76.     }

In Nokia Belle, the Camera app is started on the camera key down event so capturing the key pressed event is not enough, your application would have to capture the up and down events as well. This is easily solved with an additional call to RWindowGroup::CaptureKeyUpAndDowns(), as illustrated at line #74 in the code below.

67.     RWsSession &wsSession = CCoeEnv::Static()->WsSession();

68.     TUint wGroupHandle = wsSession.GetWindowGroupHandle(wGroupId);

69.     if (wGroupHandle) {

70.         RWindowGroup wGroup(wsSession);

71.         wGroup.Construct(wGroupHandle);

72.         TBool captureOK = ETrue;

73.         captureOK = captureOK && (wGroup.CaptureKey(EKeyCamera, 0, 0, 100) > 0);

74.         captureOK = captureOK && (wGroup.CaptureKeyUpAndDowns(EStdKeyDevice7, 0, 0, 100) > 0);

75.         if (!captureOK)

76.             qWarning("Unable to register for camera capture key events, SwEvent capability may be missing");

77.     }

Of course the application will have to release the key events to their normal handling as soon as the application no longer requires them. The corresponding calls to RWindowGroup::CancelCaptureKey() and RWindowGroup::CancelCaptureKeyUpAndDowns() will for example have to be made each time your camera application is sent by the user to the background, just as you would also release the camera resource at the same time, in order to allow other applications to make use of them.

Note: The above code snippets are slightly modified extracts from QtMobility's camera example application (camerakeyevent_symbian.cpp), available in the Qt SDK 1.2 under \QtSDK\Examples\QtMobility\camera. The code makes use of Symbian C++ APIs so similar code is to be used on Symbian C++ applications.

Please also note that the CaptureKey* APIs require that your application has the SwEvent capability, for which self-signing is not supported. Before using this API in your application make sure that you have applied for a valid developer certificate and enable its use for signing in your IDE's settings.