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CCamera::CCameraV2Histogram Class Reference

class CCamera::CCameraV2Histogram : public CBase

This class allows the client to get histogram data in a specified format for an image (for example, luminance based histogram, average colour value histogram, etc).

Histogram may be created for still images, video, viewfinders and snapshot. Further different types of histogram may be created for any of the imaging modes.

The data generated can be fed to some exposure based algorithm, or directly displayed on the screen. It also allows the client to get and set the properties of a histogram.

The client selects histogram parameters calling PrepareClientHistogramL or PrepareDirectHistogramL. It can then start and stop receiving notifications from the ECam implementation by calling StartHistogram() and StopHistogram() . The client application using this API shall provide the interfaces: MCaptureImageObserver , MCaptureVideoObserver , MDirectViewFinderObserver and MClientViewFinderObserver in order to receive notifications about direct histogram display or client histogram data availablility.

Implementation shall use MHistogramV2Buffer in order to provide client histogram data.

Note:

This class provides a standardised client interface for the camera histogram. Classes cannot be derived from it.

If the class methods leave, the output type parameter value is not guaranteed to be valid.

Inherits from

CCamera::CCameraV2Histogram
- CBase

Nested Classes and Structures

CCamera::CCameraV2Histogram::TDirectHistogramParameters

Public Member Functions
	~CCameraV2Histogram ()
IMPORT_C void	GetDirectHistogramPropertiesL ( TDirectHistogramParameters &)
IMPORT_C void	GetDirectHistogramSupportInfoL ( TBool &)
IMPORT_C void	GetHistogramStateL ( TBool &)
IMPORT_C void	GetSupportedHistogramsL ( TUint &)
IMPORT_C void	PrepareClientHistogramL ( THistogramType )
IMPORT_C void	PrepareDirectHistogramL (const TDirectHistogramParameters &)
IMPORT_C void	StartHistogram ()
IMPORT_C void	StopHistogram ()
IMPORT_C void	UpdateDirectHistogramPropertiesL (const TDirectHistogramParameters &)

Private Member Functions
	CCameraV2Histogram ( CCamera &)
void	ConstructL (const MImplementationFactory &)
IMPORT_C CCamera::CCameraV2Histogram *	CreateL ( CCamera &, MImplementationFactory &)

Inherited Functions
	CBase::CBase()
	CBase::Delete(CBase *)
	CBase::Extension_(TUint,TAny &,TAny )
	CBase::operator new(TUint)
	CBase::operator new(TUint,TAny *)
	CBase::operator new(TUint,TLeave)
	CBase::operator new(TUint,TLeave,TUint)
	CBase::operator new(TUint,TUint)
	CBase::~CBase()

Public Member Enumerations
enum	THistogramType { EHistNone = 0x0000, ELuminance = 0x0001, EAverageRGB = 0x0002, ERedComponent = 0x0004, EBlueComponent = 0x0008, EGreenComponent = 0x0010, EOverExposure = 0x0020, EUnderExposure = 0x0040 }

Private Attributes
MCameraV2Histogram *	iImpl
CCamera &	iOwner

Constructor & Destructor Documentation

CCameraV2Histogram(CCamera &)

CCameraV2Histogram

(

CCamera &

aOwner

)

[private]

Constructor for the CCamera::CCameraV2Histogram class.

Parameters

CCamera & aOwner

A reference to the camera object for which a camera histogram object is to be created.

~CCameraV2Histogram()

IMPORT_C

~CCameraV2Histogram

(

)

Destructor for the CCamera::CCameraV2Histogram class.

Member Functions Documentation

ConstructL(const MImplementationFactory &)

void

ConstructL

(

const MImplementationFactory &

aImplFactory

)

[private]

CCameraV2Histogram second phase constructor

Function used to initialise internal state of the object specifically for a camera mode, for example, still image, video, snapshot and specific viewfinder.

This may be used in other possible cases as well.

leave: KErrNoMemory Out of memory; or any other error code as well.

Note:

This method is supposed to be used by this class only.

Parameters

const MImplementationFactory & aImplFactory

A constant reference to the MImplementationFactory derived object.

CreateL(CCamera &, MImplementationFactory &)

IMPORT_C CCamera::CCameraV2Histogram *	CreateL	(	CCamera &	aCamera,
			MImplementationFactory &	aImplFactory
		)	[private, static]

Factory function that creates a new camera histogram object specifically for a camera mode, for example, still image, video, snapshot and specific viewfinder.

leave: KErrNoMemory if out of memory; also any system wide error.

leave: KErrExtensionNotSupported When NewL/NewDuplicateL used instead of New2L/NewDuplicate2L.

Note:

This method is supposed to be used by internal ECAM components only.

Parameters

CCamera & aCamera	A reference to the camera object for which a camera histogram object is to be created.
MImplementationFactory & aImplFactory	A reference to the MImplementationFactory derived object.

GetDirectHistogramPropertiesL(TDirectHistogramParameters &)

IMPORT_C void

GetDirectHistogramPropertiesL

(

TDirectHistogramParameters &

aDirectHistogramParameters

)

const

Retrieves the currently used parameters for the direct histogram.

leave: May leave with any error code.

Parameters

TDirectHistogramParameters & aDirectHistogramParameters

Retrieves the parameters currently being used for the direct histogram.

GetDirectHistogramSupportInfoL(TBool &)

IMPORT_C void

GetDirectHistogramSupportInfoL

(

TBool &

aIsDirectHistogramSupported

)

const

Informs whether or not the direct histogram is supported.

leave: May leave with any error code.

Parameters

TBool & aIsDirectHistogramSupported

ETrue implies that direct histogram is supported. EFalse implies that direct histogram is not supported.

GetHistogramStateL(TBool &)

IMPORT_C void

GetHistogramStateL

(

TBool &

aIsHistogramActive

)

const

Informs whether the histogram is currently active or not. A histogram is in an active state if StartHistogram() has been called on it and has not been yet stopped.

leave: May leave with any error code.

Parameters

TBool & aIsHistogramActive

ETrue indicates that the histogram is active. EFalse indicates that the histogram is inactive.

GetSupportedHistogramsL(TUint &)

IMPORT_C void

GetSupportedHistogramsL

(

TUint &

aSupportedHistogramType

)

const

Retrieves a list of the supported types of histograms.

leave: May leave with any error code.

CCamera::CCameraV2Histogram::THistogramType

Parameters

TUint & aSupportedHistogramType

A reference to bit field representing the supported types of histograms as given by CCamera:: CCameraV2Histogram::THistogramType

PrepareClientHistogramL(THistogramType)

IMPORT_C void

PrepareClientHistogramL

(

THistogramType

aType

)

Request to prepare a client based histogram.

Note:

A direct histogram is directly embedded into the viewfinder. If a non direct histogram is requested the histogram data will be passed to the camera client.

leave: May leave with any error code.

Note:

Each histogram object will either prepare direct histogram or client histogram. Preparing multiple histograms per object is an invalid case.

PrepareDSAHistogramL

Parameters

THistogramType aType

The type of histogram to be prepared. This must be one of the supported histogram types given by GetSupportedHistogramsL.

PrepareDirectHistogramL(const TDirectHistogramParameters &)

IMPORT_C void

PrepareDirectHistogramL

(

const TDirectHistogramParameters &

aDirectHistogramParameters

)

Prepares the direct histogram.

leave: May leave with any error code.

Note:

Each histogram object will either prepare direct histogram or client histogram. Preparing multiple histograms per object is an invalid case.

PrepareClientHistogramL

Parameters

const TDirectHistogramParameters & aDirectHistogramParameters

The parameters required to prepare the direct histogram.

StartHistogram()

IMPORT_C void

StartHistogram

(

)

Request to start getting histogram notifications.

Note:

Histogram should have been prepared before calling this method.

Histogram notifications are sent to the client by using relevant callbacks for image capture, video capture and viewfinders.

MCaptureImageObserver MCaptureVideoObserver MDirectViewFinderObserver MClientViewFinderObserver

StopHistogram()

IMPORT_C void

StopHistogram

(

)

Request to stop generating histogram.

UpdateDirectHistogramPropertiesL(const TDirectHistogramParameters &)

IMPORT_C void

UpdateDirectHistogramPropertiesL

(

const TDirectHistogramParameters &

aDirectHistogramParameters

)

Update the parameters for the direct histogram.

leave: May leave with any error code.

Parameters

const TDirectHistogramParameters & aDirectHistogramParameters

The desired parameters which have to be used to update the direct histogram.

Member Enumerations Documentation

Enum THistogramType

Supported histogram types. The enumeration list may be extended in future.

Enumerators

EHistNone = 0x0000	No histogram has been specified.
ELuminance = 0x0001	Luminance based histogram.
EAverageRGB = 0x0002	The histogram is based on the average value of all three RGB colour components.
ERedComponent = 0x0004	The histogram is based on the value of the red colour component.
EBlueComponent = 0x0008	The histogram is based on the value of the blue colour component.
EGreenComponent = 0x0010	The histogram is based on the value of the green colour component.
EOverExposure = 0x0020	Qualitative Histogram to mark over exposed parts of image.
EUnderExposure = 0x0040	Qualitative Histogram to mark under exposed parts of image.

Member Data Documentation

MCameraV2Histogram * iImpl

MCameraV2Histogram *

iImpl

[private]

CCamera & iOwner

CCamera &

iOwner

[private]