Class CGifScaler

class CGifScaler : public CBase;

Description

The public API for clients to call the GifScaler scaling and color quantization library.

Derivation

• CBase - Base class for all classes to be instantiated on the heap

• CGifScaler - The public API for clients to call the GifScaler scaling and color quantization library

Members

Defined in CGifScaler:
Cancel(), EHighQualityQuantization, ELowQualityQuantization, EMaximumQualityQuantization, EMediumQualityQuantization, NewL(), NewL(), Scale(), TOptions, ThresholdScale(), ~CGifScaler()

Inherited from CBase:
Delete(), Extension_(), operator new()

static IMPORT_C CGifScaler *NewL(CFbsBitmap &aSource, TOptions aOptions=EHighQualityQuantization);

Description

The function NewL constructs a CGifScaler. This version constructs a scaler for scaling and color quantizing only. No mask data is required in this case)

Parameters

CFbsBitmap &aSource The bitmap to be re-scaled. TOptions aOptions Scaling and color quantization options.

Return value

CGifScaler * A pointer to a fully constructed CGifScaler

Leave codes

KErrArgument if the source bitmap or the options are invalid.

Panic codes

ENoSourceBitmap if the source bitmap has not been created.

static IMPORT_C CGifScaler *NewL(CFbsBitmap &aSource, CFbsBitmap &aSourceMask, TOptions aOptions=EHighQualityQuantization);

Description

The function NewL constructs a CGifScaler. This version constructs a scaler for scaling and color quantizing an image with transparency.

Parameters

CFbsBitmap &aSource The bitmap to be re-scaled. CFbsBitmap &aSourceMask The mask bitmap that provides the transparency data. TOptions aOptions Scaling and color quantization options.

Return value

CGifScaler * A pointer to a fully constructed CGifScaler

Leave codes

KErrArgument if the source bitmap, source mask bitmap, or the options are invalid.

Panic codes

ENoSourceBitmap if the source bitmap has not been created. ENoSourceMaskBitmap if the source mask bitmap has not been created.

IMPORT_C ~CGifScaler();

Description

This is the destructor for the CGifScaler and is responsible for deallocating all resources allocated by the CGifScaler.

IMPORT_C void Scale(TRequestStatus *aStatus, CFbsBitmap &aDestination, CPalette &aPalette, TBool aMaintainAspectRatio=ETrue);

Description

Scale the source bitmap and mask to produce a single 8bpp bitmap and an output palette. If a mask was supplied during construction the last index in the palette will be used for transparency.

The scaling factor is based on the relative sizes of the source and target bitmaps. The operation is asynchronous. When it is complete, successfully or otherwise, the TRequestStatus aStatus is set, passing the state of the operation.

Parameters

TRequestStatus *aStatus Request status to signal when scaling is complete. CFbsBitmap &aDestination The destination bitmap. (EColor256) CPalette &aPalette The output palette. TBool aMaintainAspectRatio ETrue - the aspect ratio is retained; this is the default. The same scaling factor is applied in both the horizontal and vertical directions. This is the smaller of the horizontal scaling factor and the vertical scaling factor. EFalse - the aspect ratio need not be retained.

IMPORT_C void ThresholdScale(TRequestStatus *aStatus, CFbsBitmap &aDestination, CPalette &aPalette, TUint8 aTransparencyThreshold, TBool aMaintainAspectRatio=ETrue);

Description

Scale the source bitmap and mask to produce a single 8bpp bitmap and an output palette, specifying a transparency level to be used when determining whether destination pixels are transparent. If a mask was supplied during construction the last index in the palette will be used for transparency.

The scaling factor is based on the relative sizes of the source and target bitmaps. The operation is asynchronous. When it is complete, successfully or otherwise, the TRequestStatus aStatus is set, passing the state of the operation.

Parameters

TRequestStatus *aStatus Request status to signal when scaling is complete. CFbsBitmap &aDestination The destination bitmap. (EColor256) CPalette &aPalette The output palette. TUint8 aTransparencyThreshold The transparency level used to determine if destination pixels are transparent. TBool aMaintainAspectRatio ETrue - the aspect ratio is retained; this is the default. The same scaling factor is applied in both the horizontal and vertical directions. This is the smaller of the horizontal scaling factor and the vertical scaling factor. EFalse - the aspect ratio need not be retained.

IMPORT_C void Cancel();

Description

Cancel any outstanding activity.

TOptions

Description

TOptions is an enumeration within the namespace CGifScaler The enumeration provides a set of supported quantization levels: (EHighQualityQuantization is the default setting as it provides the best balance between quality and speed)

ELowQualityQuantization Provides the lowest quality, but also the fastest. EMediumQualityQuantization Provides medium quality quantization EHighQualityQuantization Provides high quality quantization EMaximumQualityQuantization Provides the highest quality quantization, but is also the slowest.