CImageTransform Class Reference

#include <imagetransform.h>

Link against: imagetransform.lib

class CImageTransform : public CBase, public CBase

Inherits from

CImageTransform
- CBase
- CBase

Public Member Enumerations
enum	TOptions { EOptionNone, EThumbnail, EIgnoreExifMetadataProcessing, EEnumBoundary }
enum	TTransformations { ETransformationNone, EScale, ECrop, ESqueeze, ..., ETransformEnumBoundary }

Public Member Functions
	~CImageTransform()
IMPORT_C void	CancelTransform()
IMPORT_C void	ClearSourceRect()
IMPORT_C CImageTransformPluginExtension *	Extension()
IMPORT_C CImageTransformPluginExtension *	Extension(TUid, TInt &)
IMPORT_C CImageTransform *	NewL(RFs &)
IMPORT_C void	Reset()
IMPORT_C void	SetDestDataL(HBufC8 *&)
IMPORT_C void	SetDestFilenameL(const TDesC &)
IMPORT_C void	SetDestSizeInPixelsL(const TSize &, TBool)
IMPORT_C void	SetOptionsL(TUint)
IMPORT_C void	SetPluginUidL(TUid)
IMPORT_C void	SetPreserveImageData(TBool)
IMPORT_C void	SetSourceDataL(const TDesC8 &)
IMPORT_C void	SetSourceFilenameL(const TDesC &)
IMPORT_C void	SetSourceImageTypeL(TUid, TUid)
IMPORT_C void	SetSourceMimeTypeL(const TDesC8 &)
IMPORT_C void	SetSourceRect(const TRect &)
IMPORT_C void	SetTransformationsL(TUint)
IMPORT_C void	SetupL()
IMPORT_C void	Transform(TRequestStatus &)

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()

Detailed Description

The public API for clients to call the Image Transform (scaling) library. This class provides functions to scale images held in files or descriptors.

Member Enumeration Documentation

Enum TOptions

Flags to control how the image is transformed. The EThumbnail and EIgnoreExifMetadataProcessing are mutually exclusive, and SHOULD NOT be used together. If they are, then EThumbnail is used.

Enumerator	Value	Description
EOptionNone	0x00	No flag set. This is the default option
EThumbnail	0x01	If set, the destination image will always have a thumbnail. If the source already has a thumbnail, then this is the one that will appear in the destination, otherwise one will be generated.
EIgnoreExifMetadataProcessing	0x02	If set, then the Exif data is not parsed and ExifMetaData() will always return NULL. If the source image is EXIF, then the EXIF information is copied without modification (i.e. without parsing) to the destination. In cases where the source is JFIF, the destination image is also JFIF.
EEnumBoundary	0x04	TOptions should not be set greater than or equal to this value.

Enum TTransformations

Flags to specify the desired transformations. If no flag or "EScale" flag is set then the framework will look for the plugins supporting scaling which includes all the plugins supporting version-1 opaque data and the plugins supporting version-2 opaque data with the scaling flag set. A plug-in supporting Squeeze, Orientation and Overlay in a single transform must perform these transformation in the order: Overlaying, Orientation and then Squeezing

Enumerator	Value	Description
ETransformationNone	0x00	No transformation set
EScale	0x01	If set, the image is scaled based on the parameter passed in SetDestSizeInPixelsL().
ECrop	0x02	If set, the image is clipped based on the parameter passed in SetSourceRect().
ESqueeze	0x04	If set, the image is squeezed
EOrientation	0x08	If set, the image is oriented
EOverlay	0x10	If set, the image is blend with the overlay image
EExif	0x20	If set, the plugin having exif extension is looked for
ETransformEnumBoundary	0x40	TTransformations should not be set greater than or equal to this value

Constructor & Destructor Documentation

~CImageTransform ( )

IMPORT_C

~CImageTransform

(

)

This is the destructor for this class and is responsible for deallocating all resources

Member Function Documentation

CancelTransform ( )

IMPORT_C void

CancelTransform

(

)

Cancels any asynchronous image transform operation currently in progress.

ClearSourceRect ( )

IMPORT_C void

ClearSourceRect

(

)

Clears the clipping region.

Extension ( )

IMPORT_C CImageTransformPluginExtension *

Extension

(

)

const

Gets a pointer to a plugin extension

Return Value: A pointer to a fully constructed CImageTransformPluginExtension NULL, if there is no extension to the plugin

Panic Codes
EIllegalCallSequence	No plugin loaded.

Extension ( TUid, TInt & )

IMPORT_C CImageTransformPluginExtension *	Extension	(	TUid	aExtensionUid,
			TInt &	aError
		)	const

Gets a pointer to a plugin extension

Parameters
aExtensionUid	Uid of the required extension
aError	System wide error

Return Value: A pointer to a fully constructed CImageTransformPluginExtension NULL, if there is no extension to the plugin

Panic Codes
EIllegalCallSequence	No plugin loaded.

NewL ( RFs & )

IMPORT_C CImageTransform *

NewL

(

RFs &

aFs

)

[static]

Constructs a CImageTransform object.

Parameters
aFs	A reference to a file server session for the transform API to use.

Return Value: A pointer to a fully constructed CImageTransform.

Reset ( )

IMPORT_C void

Reset

(

)

Resets all SetXXX() calls so that the state is the same as that immediately after a call to NewL(). Deletes the plugin if one is loaded.

SetDestDataL ( HBufC8 *& )

IMPORT_C void

SetDestDataL

(

HBufC8 *&

aData

)

Defines the destination descriptor. This is a reference to a pointer that is owned by the client app. The pointer should be NULL; the plugin will take responsibility for allocating (and potentially growing) the descriptor.

Parameters
aData	The destination descriptor.

Leave Codes
KErrArgument	The pointer is not NULL

SetDestFilenameL ( const TDesC & )

IMPORT_C void

SetDestFilenameL

(

const TDesC &

aFilename

)

Specifies the name of the destination file where the transformed image is to be written to.

Parameters
aFilename	The destination filename

Leave Codes
KArgument	The length is zero

SetDestSizeInPixelsL ( const TSize &, TBool )

IMPORT_C void	SetDestSizeInPixelsL	(	const TSize &	aDestinationSize,
			TBool	aMaintainAspectRatio = ETrue
		)

Specifies the requested destination image size.

Parameters
aDestinationSize	The requested size of the destination size in pixels.
aMaintainAspectRatio	Requests that the aspect ratio be maintained as far as possible. Defaults to ETrue.

Leave Codes
KErrArgument	The destination size is zero.

SetOptionsL ( TUint )

IMPORT_C void

SetOptionsL

(

TUint

aOptions

)

Defines the options for the image transformation. The specified option must be one of the options supported or a combination of them, see CImageTransform::TOptions.

Parameters
aOptions	The required option or combination of options from CImageTransform::TOptions

Leave Codes
KErrArgument	One or more of the specified option flags is invalid

SetPluginUidL ( TUid )

IMPORT_C void

SetPluginUidL

(

TUid

aPluginUid

)

Specifies the UID of the image transform plugin to load

Parameters
aPluginUid	The plugin's implementation UID

Leave Codes
KErrArgument	The UID is KNullUid

SetPreserveImageData ( TBool )

IMPORT_C void

SetPreserveImageData

(

TBool

aPreserveImageData

)

Specifies that either the original image data is to preserved, as far as possible, or that the image data should be re-encoded to produce a more size-efficient image.

Parameters
aPreserveImageData	Requests that the aspect ratio be preserved Defaults to false

SetSourceDataL ( const TDesC8 & )

IMPORT_C void

SetSourceDataL

(

const TDesC8 &

aData

)

Specifies the source descriptor containing the image to transform. Note that this descriptor must persist while the the image is transformed. i.e. the transformation operation does not make a copy of the data. Special care must be taken when passing a TPtrC8 or TPtr8 to this function: The TPtrC8/TPtr8 itself (as well as the data it points to) must be persistent.

Parameters
aData	The source descriptor

Leave Codes
KErrArgument	The length is zero

SetSourceFilenameL ( const TDesC & )

IMPORT_C void

SetSourceFilenameL

(

const TDesC &

aFilename

)

Specifies the name of the source file containing the image to transform

Parameters
aFilename	The source filename

Leave Codes
KNotFound	The file does not exist

SetSourceImageTypeL ( TUid, TUid )

IMPORT_C void	SetSourceImageTypeL	(	TUid	aImageType,
			TUid	aImageSubType = TUid::Null()
		)

Specifies the source image's type and (optionally) its subtype

Parameters
aImageType	The UID of the source image's type
aImageSubType	The UID of the source image's subtype

Leave Codes
KErrArgument	aImageType is KNullUid

SetSourceMimeTypeL ( const TDesC8 & )

IMPORT_C void

SetSourceMimeTypeL

(

const TDesC8 &

aMIMEType

)

Specifies the MIME type of the source image.

Parameters
aMIMEType	The MIME type of the source image

Leave Codes
KErrArgument	The length is zero

SetSourceRect ( const TRect & )

IMPORT_C void

SetSourceRect

(

const TRect &

aRect

)

Defines a clipping region. Only the specified region will be converted. It is not supported by the Symbian Jpeg ImageTransform Plugin.

Parameters
aRect	The coordinates of the clipping region

SetTransformationsL ( TUint )

IMPORT_C void

SetTransformationsL

(

TUint

aTransformations

)

Defines the transformations to be supported by the desired plug-in. The specified transformation must be one of the transformations specified in CImageTransform::TTransformations or combination of them, see CImageTransform::TTransformations.

Parameters
aTransformations	The required transformation or combination of transformations from CImageTransform::TTransformations.

Leave Codes
KErrArgument	One or more of the specified transformation flags is invalid.

SetupL ( )

IMPORT_C void

SetupL

(

)

Requests that a suitable plugin be selected and instantiated.

Leave Codes
KErrNotFound	No suitable plugin was found
KErrNotReady	A required parameter was not set before this call.
KErrArgument	A parameter incompatible with the transformation options was previously set.

Transform ( TRequestStatus & )

IMPORT_C void

Transform

(

TRequestStatus &

aStatus

)

Initiates an asynchronous image transform operation. The framework will panic if no plugin has been instantiated already.

Parameters
aStatus	Request status to signal when scaling is complete.

Panic Codes
EIllegalCallSequence	No plugin loaded.