Class MCameraBuffer

class MCameraBuffer;

Description

Class used for passing camera picture data between camera and client in the V2 observer. Used for viewfinder, image capture and video capture.

The class offers APIs for the client to access the data as a descriptor, a bitmap or a handle to a kernel chunk. Depending on the format previously requested by the client, one or more of the API choices may be inappropriate e.g. an image will not be avaiable as a bitmap in the FBS unless the client has specifically requested it.

The buffer may contain multiple frames.

Members

Defined in MCameraBuffer:
BitmapL(), ChunkL(), ChunkOffsetL(), DataL(), FrameSize(), NumFrames(), Release(), iElapsedTime, iIndexOfFirstFrameInBuffer

virtual TInt NumFrames()=0;

Description

Returns the number of frames of image data contained within the buffer. This would be 1 for a image capture, and match the requested count for video capture. For other methods in this class that take a aFrameIndex param, 0 <= aFrameIndex < NumFrames()

Return value

TInt The number of frames of image data in the buffer.

virtual TDesC8 *DataL(TInt aFrameIndex)=0;

Description

Returns a pointer to a descriptor containing a frame of camera data. The format will have been previously specified by a CCamera class method.

Parameters

TInt aFrameIndex The index of the required frame. For a still image this should be 0.

Return value

TDesC8 * A pointer to a descriptor containing a frame of image data.

Leave codes

KErrArgument if aIndex is out of range and KErrNotSupported if the camera data is actually bitmaps in the FBS.

virtual CFbsBitmap &BitmapL(TInt aFrameIndex)=0;

Description

Returns a reference to a FBS bitmap containing a frame of image data.

Parameters

TInt aFrameIndex The index of the required frame. For a still image this should be 0.

Return value

CFbsBitmap & A reference to a FBS bitmap containing a frame of picture data.

Leave codes

KErrArgument if aIndex is out of range and KErrNotSupported if the picture data is not a FBS bitmap.

virtual RChunk &ChunkL()=0;

Description

Returns a handle for the chunk that contains the camera data. The RChunk is exposed so that it can potentially be shared between multiple processes. The ptr returned by DataL(aFrameIndex) is effectively derived from this RChunk (where both are supported simulataneously). The equivalent ptr would be: TPtrC8* ptr; ptr.Set(ChunkL().Base() + ChunkOffset(aFrameIndex), FrameSize(aFrameIndex));

Return value

RChunk & A reference to a handle to the chunk that contains the buffer of picture data.

Leave codes

KErrNotSupported if the chunk is not available.

virtual TInt ChunkOffsetL(TInt aFrameIndex)=0;

Description

Returns the offset into the chunk that contains the frame specified by aFrameIndex. The client would add this offset to the ptr returned by ChunkL().Base() to get the address of the start of the frame data.

Parameters

TInt aFrameIndex

Return value

TInt The offset into the chunk for the start of the frame.

Leave codes

KErrNotSupported if the chunk is not available KErrArgument if aIndex is out of range.

virtual TInt FrameSize(TInt aFrameIndex)=0;

Description

Returns the size of the data in bytes that comprises the frame specified by aIndex.

Parameters

TInt aFrameIndex The index of the required frame. For a still image this should be 0.

Return value

TInt Returns the size of the data in bytes that comprises the frame.

Leave codes

KErrArgument if aIndex is out of range.

virtual void Release()=0;

Description

Releases the buffer. Once the client has processed the picture data it should use this method to signal to CCamera that the buffer can be re-used.

TInt iIndexOfFirstFrameInBuffer;

Description

Sequential frame number of the first frame in the buffer, counting from when CCamera::StartVideoCapture() was called and including frames dropped due to lack of buffers. Always zero for still images.

TTimeIntervalMicroSeconds iElapsedTime;

Description

Time elapsed from when CCamera::StartVideoCapture() was called until the first frame in the buffer was captured. Always zero for still images.