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CCamera::CCameraHistogram Class Reference

class CCamera::CCameraHistogram : 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).

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

The client selects histogram parameters calling PrepareHistogramL() . It can then start and stop receiving notifications from the ECam implementation by calling StartHistogramL() and StopHistogramL() . The client application using this API should provide MCameraObserver2 interface to be signalled, with event KUidECamEventCameraHistogram, when histogram data is available to be retrieved from the ECam implementation. The client can then retrieve the histogram data from the ECam implementation calling HistograDataL().

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.

use CCamera::CCameraV2Histogram

Inherits from

CCamera::CCameraHistogram
- CBase

Public Member Functions
	~CCameraHistogram ()
IMPORT_C void	DestroyHistogramL ( TUint )
IMPORT_C void	GetActiveHistogramsL ( RArray < TUint > &)
IMPORT_C void	GetDSAHistogramPropertiesL ( TUint , TPoint &, TSize &, TRgb &)
IMPORT_C MHistogramBuffer &	HistogramDataL ()
IMPORT_C MHistogramBuffer &	HistogramDataL ( TUint )
IMPORT_C CCamera::CCameraHistogram *	NewL ( CCamera &)
IMPORT_C TUint	PrepareDSAHistogramL ( CCamera::CCameraHistogram::THistogramType , const TPoint &, const TSize &, const TRgb &)
IMPORT_C TUint	PrepareHistogramL ( CCamera::CCameraHistogram::THistogramType )
IMPORT_C void	StartHistogramL ( TUint )
IMPORT_C void	StopHistogramL ( TUint )
IMPORT_C TUint32	SupportedHistograms ()
IMPORT_C void	UpdateDSAHistogramPropertiesL ( TUint , const TPoint &, const TSize &, const TRgb &)

Private Member Functions
	CCameraHistogram ( CCamera &)
void	ConstructL ()

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 }

Private Attributes
MCameraHistogram *	iImpl
CCamera &	iOwner

Constructor & Destructor Documentation

CCameraHistogram(CCamera &)

CCameraHistogram

(

CCamera &

aOwner

)

[private]

use CCamera::CCameraV2Histogram::CCameraV2Histogram(CCamera& aOwner)

Constructor for the CCamera::CCameraHistogram class.

Parameters

CCamera & aOwner

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

~CCameraHistogram()

IMPORT_C

~CCameraHistogram

(

)

use CCamera::CCameraV2Histogram::~CCameraV2Histogram()

Destructor for the CCamera::CCameraHistogram class.

Member Functions Documentation

ConstructL()

void

ConstructL

(

)

[private]

use void CCamera::CCameraV2Histogram::ConstructL(const MImplementationFactory& aImplFactory)

CCameraHistogram second phase constructor.

This function used to initialise internal state of the object. It uses reference to the camera to retrieve histogram interface pointer.

leave: KErrNotSupported if this functionality is not supported; also any system wide error.

DestroyHistogramL(TUint)

IMPORT_C void

DestroyHistogramL

(

TUint

aHistHandle

)

only one histogram is available per buffer with the usage of MHistogramV2Buffer and CCameraV2Histogram .

Destroys a histogram on the ECam implementation and releases its handle.

leave: KErrArgument if aHistHandle is out of range; also any system wide error.

Parameters

TUint aHistHandle

The handle identifying the histogram on the ECam implementation.

GetActiveHistogramsL(RArray< TUint > &)

IMPORT_C void

GetActiveHistogramsL

(

RArray < TUint > &

aActiveHistograms

)

use void CCamera::CCameraV2Histogram::GetHistogramStateL(TBool& aIsHistogramActive)

Gets a list of all histograms that are active on the ECam implementation. A histogram is in an active state if StartHistogramL() has been called on it.

leave: KErrNoMemory if the ECam implementation cannot add more histogram handles due to low memory; also any system wide error.

Parameters

RArray < TUint > & aActiveHistograms

Returned list of histogram handles for which StartHistogramL() has been called.

GetDSAHistogramPropertiesL(TUint, TPoint &, TSize &, TRgb &)

IMPORT_C void	GetDSAHistogramPropertiesL	(	TUint	aHistHandle,
			TPoint &	aPosition,
			TSize &	aSize,
			TRgb &	aColor
		)

use void CCamera::CCameraV2Histogram::GetDirectHistogramPropertiesL

Gets the properties of a direct histogram.

leave: KErrArgument if aHistHandle is out of range; also any system wide error.

Note:

If the method leaves, the reference arguments are not guaranteed to be valid.

Parameters

TUint aHistHandle	The handle on the ECam implementation of the direct histogram whose properties are to be retrieved.
TPoint & aPosition	A reference to a TPoint object that will receive the position (in pixels) of the histogram on the screen.
TSize & aSize	A reference to a TSize object that will receive the size of the histogram in pixels.
TRgb & aColor	A reference to a TRgb object that will receive the colour and alpha blending of the histogram.

HistogramDataL()

IMPORT_C MHistogramBuffer &

HistogramDataL

(

)

use MCaptureImageObserver , MCaptureVideoObserver , MDirectViewFinderObserver , and MClientViewFinderObserver which have callback functions which notify the client about availability of histogram data. These are sent when CCameraV2Histogram::StartHistogram() is called after CCameraV2Histogram::PrepareClientHistogramL() . If CCameraV2Histogram::PrepareClientHistogramL() is not called first then the callback returns KErrBadHandle.

Returns to the client the histogram data for all the histograms generated by the ECam implementation.

Note:

The client application using this API should provide MCameraObserver2 interface to be signalled when histogram data is available to be retrieved from the ECAM implementation.

KUidECamEventCameraHistogram

leave: KErrNoMemory if the ECam implementation has not been able to create the histogram buffer; also any system wide error.

HistogramDataL(TUint)

IMPORT_C MHistogramBuffer &

HistogramDataL

(

TUint

aHistHandle

)

Returns the data for a single histogram from the ECam implementation to the client.

Note:

The client application using this API should provide MCameraObserver2 interface to be signalled when histogram data is available to be retrieved from the ECAM implementation.

KUidECamEventCameraHistogram

leave: KErrNoMemory if the ECam implementation has not been able to create the histogram buffer; also any system wide error.

Parameters

TUint aHistHandle

The handle on the ECam implementation of the histogram whose data is to be retrieved.

NewL(CCamera &)

IMPORT_C CCamera::CCameraHistogram *

NewL

(

CCamera &

aCamera

)

[static]

use static CCamera::CCameraV2Histogram * CreateL(CCamera& aCamera, MImplementationFactory& aImplFactory)

Factory function that creates a new camera histogram object on the heap.

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

Note:

Clients using MCameraObserver are not recommended to use this extension class since they cannot handle events.

Parameters

CCamera & aCamera

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

PrepareDSAHistogramL(CCamera::CCameraHistogram::THistogramType, const TPoint &, const TSize &, const TRgb &)

IMPORT_C TUint	PrepareDSAHistogramL	(	CCamera::CCameraHistogram::THistogramType	aType,
			const TPoint &	aPosition,
			const TSize &	aSize,
			const TRgb &	aColor
		)

use void CCamera::CCameraV2Histogram::PrepareDirectHistogramL

Request to prepare a direct histogram.

Note:

A Direct histogram is directly embedded into the viewfinder.

leave: KErrNotSupported if the histogram type supplied in aType is not supported.

PrepareHistogramL

Parameters

CCamera::CCameraHistogram::THistogramType aType	The type of histogram to be prepared. This must be one of the supported histogram types returned by SupportedHistograms().
const TPoint & aPosition	The position on the screen (in pixels) where the histogram is to be displayed.
const TSize & aSize	The size of histogram in pixels.
const TRgb & aColor	The colour and alpha blending with which the histogram will be displayed.

PrepareHistogramL(CCamera::CCameraHistogram::THistogramType)

IMPORT_C TUint

PrepareHistogramL

(

CCamera::CCameraHistogram::THistogramType

aType

)

use void CCamera::CCameraV2Histogram::PrepareClientHistogramL

Request to prepare a non direct 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: KErrNotSupported if the histogram type supplied in aType is not supported.

PrepareDSAHistogramL

Parameters

CCamera::CCameraHistogram::THistogramType aType

The type of histogram to be prepared. This must be one of the supported histogram types returned by SupportedHistograms().

StartHistogramL(TUint)

IMPORT_C void

StartHistogramL

(

TUint

aHistHandle

)

use void CCamera::CCameraV2Histogram::StartHistogram()

Request to start getting histogram notifications.

leave: KErrArgument if aHistHandle is out of range; also any system wide error.

KUidECamEventCameraHistogram

Parameters

TUint aHistHandle

The handle identifying the histogram on the ECam implementation.

StopHistogramL(TUint)

IMPORT_C void

StopHistogramL

(

TUint

aHistHandle

)

use void CCamera::CCameraV2Histogram::StopHistogram()

Request to stop getting histogram notifications.

leave: KErrArgument if aHistHandle is out of range; also any system wide error.

Parameters

TUint aHistHandle

The handle identifying the histogram on the ECam implementation.

SupportedHistograms()

IMPORT_C TUint32

SupportedHistograms

(

)

use void CCamera::CCameraV2Histogram::GetSupportedHistogramsL(TUint& aSupportedHistogramType)

Gets a list of the types of histograms the ECam implementation supports.

CCamera::CCameraHistogram::THistogramType

UpdateDSAHistogramPropertiesL(TUint, const TPoint &, const TSize &, const TRgb &)

IMPORT_C void	UpdateDSAHistogramPropertiesL	(	TUint	aHistHandle,
			const TPoint &	aPosition,
			const TSize &	aSize,
			const TRgb &	aColor
		)

use void CCamera::CCameraV2Histogram::UpdateDirectHistogramPropertiesL

Updates the properties of a direct histogram.

leave: KErrArgument if aHistHandle is out of range; also any system wide error.

Parameters

TUint aHistHandle	The handle identifying the histogram on the ECam implementation.
const TPoint & aPosition	The new position on the screen (in pixels) where the histogram is to be displayed.
const TSize & aSize	The new size of histogram in pixels.
const TRgb & aColor	The new colour and alpha blending with which the histogram will be displayed.

Member Enumerations Documentation

Enum THistogramType

Supported histogram types.

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.

Member Data Documentation

MCameraHistogram * iImpl

MCameraHistogram *

iImpl

[private]

CCamera & iOwner

CCamera &

iOwner

[private]