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(TInt)Returns a reference to a FBS bitmap containing a frame of image data.
• ChunkL()Returns a handle for the chunk that contains the camera data. The RChunk is expo...
• ChunkOffsetL(TInt)Returns the offset into the chunk that contains the frame specified by aFrameInd...
• DataL(TInt)Returns a pointer to a descriptor containing a frame of camera data. The format ...
• FrameSize(TInt)Returns the size of the data in bytes that comprises the frame specified by aInd...
• NumFrames()Returns the number of frames of image data contained within the buffer. This wou...
• Release()Releases the buffer. Once the client has processed the picture data it should us...
• iElapsedTime...
• iIndexOfFirstFrameInBufferSequential frame number of the first frame in the buffer, counting from when CCa...

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 < MCameraBuffer::NumFrames()

Return value

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

Return value

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virtual CFbsBitmap& BitmapL(TInt aFrameIndex)=0;

Description

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

Parameters

Return value

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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(MCameraBuffer::ChunkL().Base() + ChunkOffset(aFrameIndex), FrameSize(aFrameIndex));

Return value

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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 MCameraBuffer::ChunkL().Base() to get the address of the start of the frame data.

Parameters

Return value

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virtual TInt FrameSize(TInt aFrameIndex)=0;

Description

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

Parameters

Return value

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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. May also be used by client viewfinders.

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.