Class MExifImageDisplayExtension

class MExifImageDisplayExtension : public MImageDisplayPluginExtension;

Description

This class extends the functionality of the Image Display Library client API defined in the class CImageDisplay. This extension is supported only by the EXIF-specific framework plug-ins. In order to invoke the extended functionality, the user needs to call the CImageDisplay::ExtensionInterface( ) with the KExifImageDisplayExtensionUid interface UID and an interface pointer to the object of this class.

Derivation

• MImageDisplayPluginExtension - This class should be derived by a plugin writer wishing to extend the client API defined in CImageDisplay

• MExifImageDisplayExtension - This class extends the functionality of the Image Display Library client API defined in the class CImageDisplay

Members

Defined in MExifImageDisplayExtension:
GetExifMetadataReader(), SetMaximumReductionFactor(), SetScaleQuality()

Inherited from MImageDisplayPluginExtension:
Release(), Uid()

virtual TInt GetExifMetadataReader(MExifMetadataReader *&aPtr)=0;

Description

Obtains an MExifMetadataReader that can be used to access the EXIF metadata of the image.

Parameters

MExifMetadataReader *&aPtr A reference to a pointer to the MExifMetadataReader that can be used to access the EXIF metadata of the image.

Return value

TInt A system-wide error code.

virtual TInt SetScaleQuality(TInt aQualityLevel)=0;

Description

Sets the level of quality for the scaling algorithm. If quality level is not set by calling this function then the fastest/lowest quality algorithm is used. Note: This function must be called before calling CImageDisplay::Play()

Parameters

TInt aQualityLevel Quality level value for the scaling algorithm. See CBitmapScaler::TQualityAlgorithm for a set of possible values.

Return value

TInt A system-wide error code.

virtual TInt SetMaximumReductionFactor(TInt aMaxReductionFactor)=0;

Description

Sets the maximum quality reduction factor for image decoding. By default, the plug-in calculates an optimal maximum reduction factor and uses it to produce a series of roughly-decoded images, passing each of them to the observer interface with the CImageDisplayPlugin::EStatusPartialFrame flag set. Note: This function must be called before calling CImageDisplay::Play().

Parameters

TInt aMaxReductionFactor The maximum quality reduction factor. Usually the maximum reduction can be specfied in range of 0-3. A value of 0 means no quality reduction is allowed, so a full-quality image will be decoded as the first frame. A value of 1 means (1/2)^1=1/2 of the original image quality. A value of 3 means (1/2)^3=1/8 of the original image quality. If the reduction factor is not set by calling this function then the reduction factor value of 3 is used for jpeg images.

Return value

TInt KErrArgument if the aMaxReductionFactor parameter is not in the supported range, or a system-wide error code.