MCameraBuffer Class Reference

#include <ecam.h>

class MCameraBuffer
Public Attributes
TTimeIntervalMicroSeconds iElapsedTime
TInt iIndexOfFirstFrameInBuffer
Public Member Functions
pure virtual CFbsBitmap &BitmapL(TInt)
pure virtual RChunk &ChunkL()
pure virtual TInt ChunkOffsetL(TInt)
pure virtual TDesC8 *DataL(TInt)
pure virtual TInt FrameSize(TInt)
pure virtual TInt NumFrames()
pure virtual voidRelease()

Detailed 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.

Member Attribute Documentation

iElapsedTime

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

iIndexOfFirstFrameInBuffer

TInt iIndexOfFirstFrameInBuffer

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.

Member Function Documentation

BitmapL ( TInt )

CFbsBitmap &BitmapL(TIntaFrameIndex)[pure virtual]

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

leave
KErrArgument if aIndex is out of range and
leave
KErrNotSupported if the picture data is not a FBS bitmap.
ParameterDescription
aFrameIndexThe index of the required frame. For a still image this should be 0.

Returns: A reference to a FBS bitmap containing a frame of picture data.

ChunkL ( )

RChunk &ChunkL()[pure virtual]

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));

leave
KErrNotSupported if the chunk is not available.

Returns: A reference to a handle to the chunk that contains the buffer of picture data.

ChunkOffsetL ( TInt )

TInt ChunkOffsetL(TIntaFrameIndex)[pure virtual]

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.

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

Returns: The offset into the chunk for the start of the frame.

DataL ( TInt )

TDesC8 *DataL(TIntaFrameIndex)[pure virtual]

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

leave
KErrArgument if aIndex is out of range and
leave
KErrNotSupported if the camera data is actually bitmaps in the FBS.
ParameterDescription
aFrameIndexThe index of the required frame. For a still image this should be 0.

Returns: A pointer to a descriptor containing a frame of image data.

FrameSize ( TInt )

TInt FrameSize(TIntaFrameIndex)[pure virtual]

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

leave
KErrArgument if aIndex is out of range.
ParameterDescription
aFrameIndexThe index of the required frame. For a still image this should be 0.

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

NumFrames ( )

TInt NumFrames()[pure virtual]

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()

Returns: The number of frames of image data in the buffer.

Release ( )

voidRelease()[pure virtual]

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.