Camera Application Engine API
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Camera Application Engine Interface API supports both image capture and video capture.An important feature available in Camera Application Engine Interface API is that it supports both still capture and burst image capture.
While making use of CCaeEngine class we will have to derive our application Camera Engine class from MCaeStillBurstObserver and MCamAppEngineObserver .These two classes provide a list of callbacks which can be used depending our use case. For example one callback method of MCamAppEngineObserver is
virtual void McaeoSnapImageReady(const CFbsBitmap& a Bitmap,TInt aError)
(pure virtual method)
which will be called asynchronously when we call CCaeEngine::CaptureStill( ) along with snap Image.Then we can make use of Image Encoder (CImageEncoder) to convert the bitmap into Jpeg and then store it in Memory.
Example code
Code for still image capture.
Single shot :
1) Derive your camera application engine class from MCamAppEngineObserver and provide implementation for all the call back methods.
2) In your application ContructL( ) have the following code snippet
void CCamEngine::ConstructL()
{
iCaeEngine=CCaeEngine::NewL();
iCaeEngine->SetCamAppEngineObserver(*this);
iCaeEngine->InitL();
}
3) Calling CCaeEngine::InitL( ) will result in asynchronously calling MCamAppEngine::McaeoInitComplete(..) implementation.
void CCamEngine::McaeoInitComplete (TInt aError)
{
if(!aError)
{
TInt err;
TRAP(err,iCaeEngine->PrepareStillCaptureL(1));
TRAP(err,StartViewFinderL());
}
else
{
//handle error here
}
}
//To Start the Camera Viewfinder
void CCamEngine::StartViewFinderL()
{
iCaeEngine->StartViewFinderBitmapsL(iViewSize);
}
Note:Calling CCaeEngine::StartViewFinderBitmapsL( ) will result in a callback to MCamAppEngineObeserver::McaeoViewFinderFrameReady(…) implementation.
void CCamEngine::McaeoViewFinderFrameReady (CFbsBitmap &aFrame, TInt aError)
{
if(!aError)
{
iContainer.DrawImage(aFrame);
}
else
{
//handle error
}
}
4) Then to capture a still image one should call
iCaeEngine->SetSnapImageCreation(ETrue);
iCaeEngine->CaptureStill();
5) The call to CaptureStill will in turn asynchronously call void MCamAppEngineObserver::McaeoSnapImageReady(const CFbsBitmap& a Bitmap,TInt aError).A typical implementation would like the one given below
void CCamEngine::McaeoSnapImageReady (const CFbsBitmap &aBitmap, TInt aError)
{
SaveImage(aBitmap);
}
void CCamEngine::SaveImage(const CFbsBitmap& aBitmap)
{
if(iEncoder)
{
delete iEncoder;
iEncoder=NULL;
}
//user method to create a new filename every time we save a snap image
GetNextUsableFileName();
iEncoder=CImageEncoder::FileNewL(iFs,iNewFileName,KMimeType);
iCaeEngine->StopViewFinder();
//iSaveBmp is a CFbsBitmap object
iSaveBmp->Duplicate(aBitmap.Handle());
iEncoder->Convert(&iStatus,*iSaveBmp);
SetActive();
}
void CCamEngine::GetNextUsableFileName()
{
TInt index = 0;
do{
//iNewFileName is of type TFileName
iNewFileName.Copy( iImagePath->Des() );
iNewFileName.Append( KImageFileName );
TBuf<KFileNameIndexMaxLength> num;
num.Num( index );
iNewFileName.Append( num );
iNewFileName.Append( KFileExtension );
if(!BaflUtils::FileExists(CEikonEnv::Static()->FsSession(),iNewFileName))
break;
index ++;
} while ( 1 );
}
Burst Capture :
The difference between Still Image capture and Burst Image Capture are the following
1) We will have to call the following methods before our call to CCaeEngine::CaptureStill()
iCaeEngine->SetCaeStillBurstObserver(*this);
iCaeEngine->SetStillCaptureImageCountL(numOfStillImages);
iCaeEngine->SetStillBurstCaptureIntervalL(aInterval);
2) We will have to implement pure virtual methods of MCaeStillBurstObserver. For more information on these classes and the method available one can refer to the documentation that comes as part of SDK Plugin Pack.
Code Snippet for Video Capture
As mentioned implement all the methods of MCamAppEngineObserver.
1) Initialize the VideoRecorder
void CCamEngine::InitializeVideoRecordingL()
{
iCaeEngine->InitVideoRecorderL();
}
2) After initialising the Video Recorder set the filename in which the video recording has to be saved.Then call PrepareVideoRecordingL() API.Call to PrepareVideoRecording() will in result in callback to McaeoVideoPrepareComplete() of MCamAppEngineObserver. There you can call StartRecording().Below is the code snippet of how it has been done.Similarly for stopping the videorecording you will have to call CCaeEngine::StopVideoRecording()
void CCamEngine::HandleVideoRecording()
{
if(!iVidRecOn)//iVidRecOn is a boolean variable
{
iCaeEngine->SetVideoRecordingFileNameL(iNewFileName);
iCaeEngine->PrepareVideoRecordingL(0);
}
else
{
StopRecording();
}
}
void CCamEngine::McaeoVideoPrepareComplete (TInt aError)
{
if(!aError)
{
StartRecording();
}
}
void CCamEngine::StartRecording()
{
iCaeEngine->SetVideoAudioL(ETrue);
iCaeEngine->StartVideoRecording();
}
void CCamEngine::StopRecording()
{
iCaeEngine->StopVideoRecording();
}
30 Sep
2009
Camera Application Engine API are useful in image and video capture. This article demonstrates the use of Camera Application Engine API to capture both type of images, i.e. still image capture and burst image capture, with code example which helps to understand how this API can be used. Note that this API, Camera Application Engine API, is not part of the public SDK. So you have to download it from SDK API Plug-in before using it. Furthermore, the author added a working demo project, which can be used for more detailed study of new opportunities for various kinds of experiments.